Gomathy Chakkaradhari

DissertationsDepartment of ChemistryUniversity of Eastern Finland

No. 151 (2019)

121/2014 KEKÄLÄINEN Timo: Characterization of petroleum and bio-oil samples by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry122/2014 BAZHENOV Andrey: Towards deeper atomic-level understanding of the structure of magnesium dichloride and its performance as a support in the Ziegler-Natta catalytic system123/2014 PIRINEN Sami: Studies on MgCl2/ether supports in Ziegler–Natta catalysts for ethylene polymerization124/2014 KORPELA Tarmo: Friction and wear of micro-structured polymer surfaces125/2014 HUOVINEN Eero: Fabrication of hierarchically structured polymer surfaces126/2014 EROLA Markus: Synthesis of colloidal gold and polymer particles and use of the particles in preparation of hierarchical structures with self-assembly127/2015 KOSKINEN Laura: Structural and computational studies on the coordinative nature of halogen bonding128/2015 TUIKKA Matti: Crystal engineering studies of barium bisphosphonates, iodine bridged ruthenium complexes, and copper chlorides129/2015JIANGYu:Modificationandapplicationsofmicro-structuredpolymersurfaces130/2015 TABERMAN Helena: Structure and function of carbohydrate-modifying enzymes 131/2015KUKLINMikhailS.:Towardsoptimizationofmetaloceneolefinpolymerizationcatalystsvia structuralmodifications:acomputationalapproach132/2015SALSTELAJanne:Influenceofsurfacestructuringonphysicalandmechanicalpropertiesof polymer-cellulosefibercompositesandmetal-polymercompositejoints133/2015 CHAUDRI Adil Maqsood: Tribological behavior of the polymers used in drug delivery devices134/2015 HILLI Yulia: The structure-activity relationship of Pd-Ni three-way catalysts for H2S suppression135/2016 SUN Linlin: The effects of structural and environmental factors on the swelling behavior of Montmorillonite-Beidellite smectics: a molecular dynamics approach136/2016 OFORI Albert: Inter- and intramolecular interactions in the stabilization and coordination of palladium and silver complexes: DFT and QTAIM studies137/2016 LAVIKAINEN Lasse: The structure and surfaces of 2:1 phyllosilicate clay minerals138/2016 MYLLER Antti T.: The effect of a coupling agent on the formation of area-selective monolayers of iron a-octabutoxy phthalocyanine on a nano-patterned titanium dioxide carrier139/2016KIRVESLAHTIAnna:Polymerwettabilityproperties:theirmodificationandinfluencesupon water movement140/2016 LAITAOJA Mikko: Structure-function studies of zinc proteins141/2017 NISSINEN Ville: The roles of multidentate ether and amine electron donors in the crystal structure formation of magnesium chloride supports 142/2017 SAFDAR Muhammad: Manganese oxide based catalyzed micromotors: synthesis, characterization and applications143/2017 DAU Thuy Minh: Luminescent coinage metal complexes based on multidentate phosphine ligands144/2017AMMOSOVALena:Selectivemodificationandcontrolleddepositiononpolymersurfaces145/2017 PHILIP Anish: PEI-mediated synthesis of gold nanoparticles and their deposition on silicon oxide supports for SERS and catalysis applications146/2017 RAHMAN Muhammad Rubinur: Structure and function of iron-sulfur cluster containing pentonate dehydratases147/2018 ANKUDZE Bright: Syntheses of gold and silver nanoparticles on support materials for trace analyses using surface-enhanced Raman spectroscopy148/2018 PENTTINEN Leena: Structure determination of enzymes with potential in processing of cell wall compounds149/2018 SIVCHIK Vasily: Tuning the photoluminescence of cyclometalated platinum(II) compounds via axial and non-axial interactions150/2019 MIELONEN Kati: Hierarchically structured polymer surfaces: Curved surfaces and sliding behavior on ice

Tuning the emission properties of oligophosphine copper and silver complexes with ancillary ligands

Gom

athy Chakkaradhari: Tuning the em

ission properties of oligophosphine copper and silver complexes w

ith ancillary ligands

151

Tuning the emission properties of oligophosphine

copper and silver complexes with ancillary ligands

Gomathy Chakkaradhari

Department of Chemistry

University of Eastern Finland

Finland

Joensuu 2019

2

Gomathy Chakkaradhari

Department of Chemistry, University of Eastern Finland

Supervisor

Prof. Igor O Koshevoy, University of Eastern Finland

Referees

Prof. Axel Klein, University of Cologne, Germany

Dr. Christophe Lescop, Institute of Chemical Sciences of Rennes, France

Opponent

Doc. Raija Oilunkaniemi, University of Oulu, Finland

To be presented with the permission of the Faculty of Science and Forestry of the

University of Eastern Finland for public criticism in Auditorium M101, Yliopistokatu 7,

Joensuu, on May 3rd 2019 at 12 o’ clock noon.

Copyright © 2019 Gomathy Chakkaradhari

ISBN: 978-952-61-3055-2 (Print)

ISBN: 978-952-61-3056-9 (PDF)

ISSN: 2242-1033

Grano Oy Jyväskylä

Jyväskylä 2019

ABSTRACT

Coinage metal complexes, which form light emitting materials, have attracted a great

deal of research attention due to their versatile chemistry, natural abundance, and many

potential applications. These compounds are used as emitters in solid state lighting, a

variety of sensors, cell imaging, and photocatalysis. In the early days, significant

progress in the field of photofunctional metal-containing molecular materials was

associated with the derivatives of noble metals, which are often expensive and toxic. The

past two decades clearly demonstrate that further scientific developments in metal-based

chromophores have significantly shifted to environmentally friendly compounds of

copper and silver. As one might expect, the physical properties of these species are

primarily defined by the constituting organic fragments, which form the coordination

environment around the metal centers. Thus, it is not surprising that noticeable evolution

of inorganic and organometallic luminescent complexes occurs upon introducing new

ligands or ligand combinations, and upon adjusting their electronic and stereochemical

characteristics.

In examining the nearly 50-year history of copper luminophores, it is easy to track how

extensive experimental and theoretical investigations gradually improved our

understanding of structure-property relationships and of the processes occurring in the

excited state, on the molecular level. Consequently, this knowledge has allowed for a

remarkable advance from the first weakly luminescent diimine and phosphine-halide

copper complexes to highly efficient emitters with vastly improved quantum yields and

widely variable colors. Nevertheless, we are currently far from utilizing the entire

potential of coordination complexes of copper, and particularly of silver, d10 ions; the

utilization of the latter has been largely underestimated until recently due to frequently

encountered photodegradation. Moreover, our ability to predict and rationally

manipulate the photophysical characteristics of the transition metal luminophores in the

solid state, and therefore to develop next generation photofunctional materials, remains

at an early stage.

In this thesis, a series of copper(I) and silver(I) luminescent compounds was synthesized

with the aid of sterically demanding tri- and tetradentate organophosphorus ligands as

primary building blocks, which have rarely been utilized in the coordination chemistry

of d10 complexes prior to this work. The chosen molecular design complies with a

general strategy established for copper emitters, according to which bulkier ligands

suppress the radiationless relaxation of the excited state. Following this concept, very

efficient luminescence was attained; in particular, one of the highest quantum yield for

silver complex, that had been reported at the time, was realized. Although the metal-

phosphine framework plays a pivotal role in the observed emission, the ancillary ligands

proved to have an important influence on the electronic transitions, which occur during

the excitation and emission processes. In addition to the molecular features, which can

be tuned synthetically, it was demonstrated that the solid-state luminescence crucially

depends on the intermolecular arrangement in the bulk solid. As a result, a delicate

interplay of molecular and crystal engineering can produce novel materials with

interesting optical functionalities.

4

LIST OF ORGINAL PUBLICATIONS

This dissertation is a summary of original publications I-V.

I Chakkaradhari, G.; Belyaev, A. A.; Karttunen, A. J.; Sivchik, V.; Tunik, S. P.;

Koshevoy, I. O., Alkynyl triphosphine copper complexes: synthesis and

photophysical studies, Dalton Trans., 2015, 44, 13294-13304.

II Chakkaradhari, G.; Chen, Y-T.; Karttunen, A. J.; Dau, M. T.; Janis, J.; Tunik,

S. P.; Chou, P-T.; Ho, M-L.; Koshevoy, I. O., Luminescent Triphosphine

Cyanide d10 Metal Complexes. Inorg. Chem., 2016, 55 (5), 2174-2184.

III Dau, M. T.; Asamoah, B. D.; Belyaev, A. A.; Chakkaradhari, G.; Hirva, P.;

Janis, J.; Grachova, E. V.; Tunik, S. P.; Koshevoy, I. O., Adjustable

coordination of a hybrid phosphine-phosphine oxide ligand in luminescent Cu,

Ag and Au complexes. Dalton Trans., 2016, 45, 14160-14173.

IV Chakkaradhari, G.; Eskelinen, T.; Degbe, C.; Belyaev, A. A.; Melnikov, A. S.;

Grachova, E. V.; Tunik, S. P.; Hirva, P.; Koshevoy, I. O., Oligophhosphine-

thiocyante copper(I) and silver(I) complexes and their borane derivatives

showing delayed fluorescence. Inorg. Chem., 2019, 58, 3646-3660.

V Pan, Z-B.; Wang, Y-C.; Chakkaradhari, G.; Zhu, J. F.; He, R-Y.; Koshevoy, I.

O., Chou, P-T.; Pand, S-W.; Ho, M-L., Silver Metal Complex as a Luminescent

Probe for Enzymatic Sensing of Blood Glucose and Urine, Dalton Trans., 2018,

47, 8346-8355.

AUTHOR’S CONTRIBUTION

The results presented in the publications I, II, IV are based on the ideas proposed by the

authors and the supervisor. The author designed and prepared all complexes in these

works (except terminal di- and trialkynes in I, compounds 11 and 12 in IV). The joint

publications III and V include the materials provided by the author (compounds 11–16

in III and Ag3 in V). The author carried out the X-ray diffraction analysis, IR and NMR

spectroscopic measurements (except 19F and low temperature NMR experiments).

Theoretical analysis and photophysical investigations were performed by the

collaborating groups, the author took part in the interpretation of these data. The author

has co-written the publications in collaboration with the supervisor and co-authors.

5

CONTENTS

Abstract ......................................................................................................................... 3

List of original publications ......................................................................................... 4

Contents ......................................................................................................................... 5

Abbreviations ................................................................................................................ 6

1. Introduction .............................................................................................................. 7

1.1. Selection of phosphine and ancillary ligands ...................................................... 9

1.2. Evolution of Cu(I) luminescent compounds ...................................................... 10

1.3. Silver(I) complexes: an alternative class of luminophore ................................. 16

1.4. Applications ....................................................................................................... 19

1.4.1. Oxygen gas sensing ................................................................................ 19

1.4.2. Cu(I) complexes in photocatalysis ......................................................... 22

1.5. Aims of the study ............................................................................................... 24

2. Experimental ........................................................................................................... 25

2.1. Phosphine ligands .............................................................................................. 25

2.2. Synthesis of metal complexes ............................................................................ 25

2.3. Purification and characterization ....................................................................... 27

3. Results and discussion ............................................................................................ 28

3.1. Mononuclear tri- and tetraphosphine d10 complexes ......................................... 28

3.1.1. Triphosphine cyanide complexes ............................................................. 29

3.1.2. Tri- and tetraphosphine thiocyanate complexes ....................................... 31

3.1.3. Triphosphine halide complexes ................................................................ 32

3.1.4. Tri and tetraphosphine isothiocyantoborate complexes............................ 33

3.1.5. Triphosphine alkyne complexes ............................................................... 35

3.2. Photophysical properties of mononuclear complexes ........................................ 36

3.2.1. [Cu(P3)X] halides and pseudohalides ....................................................... 36

3.2.2. [Ag(P3)X] halides, pseudohalides, and [Au(P3)CN] ................................ 39

3.2.3. [M(P4)X] thiocyanate and isothiocyanatoborate complexes .................... 41

3.3. Dinuclear bi- and triphosphine d10 complexes .................................................... 43

3.3.1. Thiocyanate bridged dinuclear complexes .............................................. 43

3.3.2. Cyanide bridged di- and trinuclear complexes ........................................ 45

3.3.3. Alkynyl bridged di-and trinuclear complexes ......................................... 47

3.4. Photophysical properties of di- and trinuclear complexes ................................... 49

4. Conclusions ............................................................................................................. 53

Acknowledgements ..................................................................................................... 55

5. References ............................................................................................................... 56

6

ABBREVIATIONS

FTIR Fourier Transformation Infra-red

NMR Nuclear Magnetic Resonance

MS Mass spectra

EA Elemental analysis

P3 bis(2-diphenylphosphinophenyl) phenylphosphine

P4 Tris(2-diphenylphosphino) phenylphosphine

SCN Thiocyanate anion

CN Cyanide anion

NCS Isothiocyanate ligand

NC Isocyanide ligand

OLEDs Organic light emitting diodes

LEECs Light emitting electrochemical cells

EQE External quantum yield

TADF Thermally activated delayed fluorescence

ISC Intersystem crossing

RISC Reverse intersystem crossing

HOMO Highest occupied molecular orbital

MLCT Metal to ligand charge transfer

LLCT Ligand to ligand charge transfer

LMCT Ligand to metal charge transfer

LC Ligand center

DFT Density functional theory

PMMA Polymethylmethacrylate

THF Tetrahydrofuran

KBr Potassium bromide

tfpb tetrakis(bis-3,5-trifluoromethyl phenyl) borate

pftpb tetrakis(pentafluorophenyl) borate

PF6 Hexafluoro phosphate

BF4 Tetrafluoro borate

PPh3 Triphenyl phosphine

tBu Tertiary butyl

2-MeTHF 2-Methyl tetrahydrofuran

TEA Triethyl amine

NHC N-heterocyclic carbene

PS Photosensitizer

Ksv Stern-Volmer constant

Im Imidazole

7

1. INTRODUCTION

To what extent are we conscious of the importance of the copper, silver, and gold metals,

which constitute the group 11 d-block elements in the periodic table? Olympic medals

for first, second, and third place have been awarded in the order of gold (yellow), silver

(white) and bronze (red-brown) since 1904 (Figure 1).1 The sequence of the winners runs

from gold to bronze (which is an alloy principally containing copper) according to the

natural abundance of these metals. They have a relatively stable nd10(n+1)s1 electronic

configuration with a completely filled d-shell and are called coinage metals, since they

were used to make coins due to their noticeable inertness (particularly silver and gold).

Figure 1. Olympic medals for first, second, and third place.1

Organometallic compounds of late transition metals often demonstrate advantageous

optoelectronic properties and therefore play an important role in the development of new

chromophores. In this respect, the coinage metal series has attracted a great deal of

attention in diverse fields such as organic light emitting diodes (OLEDs),2-8 light-

emitting electrochemical cells (LEECs),9-10 sensing applications,11-14 and

photocatalysis.15-19 In this respect, silver and, to a greater extent, copper compounds have

been extensively investigated due to their high natural abundance and low toxicity.

In general, the applications of compounds of silver and copper are extremely diverse.

Thus, copper (II) salts efficiently control the algae in water reservoirs (including lakes,

ponds, etc.).20 Copper (I) oxide is used as an antifouling paint, as a catalyst for numerous

organic reactions, and as a powerful absorbent for carbon monoxide.20 Copper plays an

important role in human growth; the average requirement for this micronutrient in the

human body is 1.5–3 mg per day.21 It is used in medicines and food products.21 The

appearance of the tetraamine copper (II) complex [Cu(NH3)4]2+ was the first

scientifically documented observation of a coordination compound (1597), although it

could not be properly formulated at that time.22 The application of silver halides in

photography has been known since the beginning of the nineteenth century, when the

first images were produced by J. Herschel, J. N. Nicepce, and L. Daguerre,23 using an

AgBr suspension in gelatin to produce a black and white photographic film. The

antibacterial nature of silver is extensively exploited in different kinds of healthcare

products (creams and ointments). The Ag-NHC (NHC = N-heterocyclic carbene)

compounds are widely used in medicinal applications, as the strong Ag-C bonds produce

stable compounds.24 The various fields of practical applications of Cu(I) and Ag(I) metal

complexes are summarized in Figure 2.

8

Figure 2. The use of Cu(I) and Ag(I) compounds in different fields.

The peculiar behavior of Cu(I) and Ag(I) compounds largely results from a variable

coordination number, and, therefore, a variety of accessible structural arrangements,

which dramatically influence the optoelectronic behavior of these species. The

photophysical and photochemical properties of Cu(I) complexes have been actively

investigated since the early 1970s.25 The first luminescent coinage metal complexes, of

the general formula LmCunXn (L = P/AsPh3), X = Br or Cl), were reported by Dori and

co-workers in 1970.26 McMillin et al. documented the first observation of room

temperature phosphorescence in solution for the [Cu(dmp)2]+ (dmp = 2,9-dimethyl-1,10-

phenanthroline) complex.27

In early 1960, Allison et al. studied the effect of metal atoms on the luminescence spectra

of porphyrins28 and noted that the silver derivatives did not show any emission. Later, in

1970, the influence of temperature on the luminescence of the silver halides AgCl and

AgBr was described by Marinchik.29 Despite the photo-instability of many Ag(I)

derivatives, the last two decades have seen a steady growth in the number of articles

dealing with silver luminescent materials (30–50 articles per year, according to the

Scopus search results for “silver luminescent compound”).

Although many early Cu(I) compounds were unstable to vacuum sublimation and

solution processing, the impressive progress in molecular design and understanding of

structure-property relationships has led to a number of highly stable, luminescent

complexes of Cu(I) and Ag(I) being reported since 2000. Furthermore, optoelectronic

devices, developed on their basis, have comparable performances to those utilizing the

noble metals (see the discussion in sections 1.2 and 1.3). This makes the copper(I) and

silver(I) luminophores attractive and affordable candidates for photophysical study.

9

1.1 SELECTION OF PHOSPHINE AND ANCILLARY LIGANDS

The use of different ligands containing the heteroatoms P or S (soft donors) and N or O

(hard donors) combined with transition metals allows tuning of the optical properties of

the resultant complexes. The phosphine ligands show high affinities for the late transition

group 11 metals, Cu, Ag, and Au, in the +1 oxidation state. The stereochemistry, bonding

nature, and steric and electronic properties of polyphosphine chelating ligands result in

different coordination modes, providing diverse opportunities for formation of stable

coordination complexes, the emission properties of which are typically tuned by

changing the ligands.

Special interest has been focused on the sterically demanding tri- and tetradentate

phosphine ligands, as they produce a robust structural arrangement around the metal

centers that improves the rigidity of the resulting complexes, required for efficient

luminescence.

Representative examples of reported tri- and tetradentate chelating phosphine ligands

are depicted in Figure 3 (A30-33, B30, 34-37, C38-40, D41, E42-43, F44, G45, H45, I46), many of

which (A, C, E, and similar ) have been used for the preparation of d10 metal complexes.

Figure 3. Reported tri- and tetradentate ligands.

In addition to the phosphine ligand, the selection of ancillary ligands is highly important

for adjusting the spectroscopic characteristics of the metal complexes. The coordination

number of the Cu(I) and Ag(I) ions depends on the joint effect of the donor properties

of the ligand environment. Different stoichiometries of metals and ligands can produce

10

mono-, di-, and multinuclear complexes.47 Several types of ancillary ligand are typically

combined with polyphosphines in coinage metal complexes:

(i) halides,

(ii) pseudohalides (CN, SCN, NCS, NC),

(iii) alkynyls,

(iv) thiolates,

(v) carbenes

An interesting characteristic of the halides, pseudohalides, and alkynes is that they can

act as bridges between two or more metal atoms. The first luminescent Cu(I) compounds

with bridging halides, [CuI(Py-X)]4 (X = I or Br), were reported by Hardt and co-

workers.48-49 Subsequently, many research groups have studied phosphine coinage metal

complexes with alkyne,50-51 halide51 and pseudohalide25 ancillary ligands.

1.2 EVOLUTION OF Cu(I) LUMINESCENT COMPOUNDS

The development of energy efficient light emitting devices based on metal complexes is

primarily associated with Ir(III), Pt(II), and Os(II) noble metal compounds. Generally,

phosphorescent emitters undergo radiative relaxation of the triplet excited states, which

is characterized by a longer lifetime, whereas in fluorescent materials the emission

occurs only from the singlet excited state. An inexpensive alternative to materials

containing high-cost heavy metals is offered by the compounds of more abundant and

cheaper metals such as Cu(I) and Ag(I) derivatives.52-54 In contrast to the noble metal-

based phosphors, copper and silver species often demonstrate the thermally activated

delayed fluorescence (TADF) phenomenon. In the TADF process, the conversion

between the first excited singlet state (S1) and the triplet excited state (T1), termed as an

intersystem crossing (ISC), is reversible under ambient conditions and is followed by

the reverse intersystem crossing (RISC) from T1 to S1, due to the small energy difference

between the lowest excited singlet and triplet states (which is ideally less than 1000 cm-

1 and therefore the thermal energy at 298 K is sufficient to overcome this barrier). As a

result of this process, the system radiatively returns to the ground state (S0) from the first

singlet excited state (S1), although with a delay in the order of microseconds.

Numerous Cu(I) complexes have been found to behave as TADF materials due to a low

activation energy ΔE(S1-T1), which facilitates fast RISC.55 During the last 20 years, the

number of publications devoted to Cu(I) compounds showing delayed fluorescence has

dramatically increased,55 thanks to facile tuning of their physical properties by changing

the ancillary ligands and to their successful application in the fabrication of efficient

electroluminescent devices.56-59

The dawn of investigations into Cu(I) chromophores is associated with the pioneering

research of McMillin, who studied the electronic properties of [Cu(NN)2]+ mononuclear

homoleptic complexes (Figure 4). These compounds show rich absorption and emission

behavior, which principally depends on the nature of the phenanthroline system and the

substituents within it.60-64 It has been shown that the tetrahedral geometry of the ground

11

state is distorted to a flattened, planar-like arrangement in the excited state, significantly

affecting the electronic structure. In general, these complexes are weakly emissive

(quantum yields are typically less than 1%) in solution due to the structural

reorganization in the excited state, which may lead to the formation of Cu(II) complexes.

Furthermore, the formation of an exciplex in the excited state (from the association of

pentacoordinate transition complexes with the solvent molecules or counter ions) can

induce ultra-fast non-radiative transitions and emission quenching in [Cu(NN)2]+

compounds.64

Reducing the possibility of exciplex formation can increase the lifetime and the quantum

yield of the emission. According to a general trend observed for a series of

phenanthroline [Cu(NN)2]+ complexes, the substituents in the 2 and 9 positions of the

NN ligand dramatically influence the lifetime, which varies from 90 to 920 ns for

aliphatic groups of variable bulkiness (Figure 4). The major factors causing the lifetime

increase are related to the growing number of substituents in the phenanthroline system

and particularly to the sizes of the substituents in the 2 and 9 positions.65

Figure 4. Reported [Cu(NN)2]+ complexes and their excited state lifetimes.65

In order to achieve better emission properties, heteroleptic [Cu(PP)(NN)]+ complexes

were introduced by McMillin in the late 1970s.66-67 This type of N, P- mixed ligand

compound started to receive considerable attention in the 21st century. McMillin and

coworkers were the first to report the highly emissive [Cu(POP)(dmp)]+ complex (τ =

14.3 µs and Φ = 0.15, in oxygen-free dichloromethane solution).68 Tailoring the

chelating ligands (PP) and (NN) to tune the electronic and steric features strongly

influences the emissive properties of the resulting copper(I) coordination compounds.

The quantum yields depend on the structural rigidity of the complexes; bulkier

substituents induce a higher intensity of luminescence. Nevertheless, manipulating the

excited state lifetimes of these complexes, in a rational manner, on the molecular level

12

still presents a substantial puzzle. Many [Cu(PP)(NN)]+ species69-72 have since been

synthesized and subsequently applied in electroluminescent devices (OLEDs5, 7, 73 and

LEECs).74

The following examples, 9–11 (Figure 5), illustrate the significant changes in

photophysical properties achieved by varying the ligand environment in [Cu(PP)(NN)]

type complexes.75 These compounds have a small energy gap ΔE(S1-T1), and, as

powders, exhibit fast TADF (blue-green emission) with quantum yields from 70% to

90% at 300 K (Figure 5).

Figure 5. Schematic structures of 9–11 (left); luminescence decay time versus temperature for

powder samples of 9–11 (right).

The importance of steric bulkiness in [Cu(PP)(NN)] complexes was clearly shown by

inserting additional methyl groups into the bipyridyl moiety.76 The weak solid state

emission of 13 (Φ = 9%) increased dramatically, up to 74% for 12, with increasing

molecular rigidity, due to the higher repulsion between bipyridine and the diphosphine

ligands (Figure 6). This interaction inhibited the non-radiative transitions and thus

enhanced the quantum yield.

Figure 6. Schematic structures of copper complexes 12 and13.

Aside from the diphosphine-diimine [Cu(PP)(NN)]+ family of copper(I) luminophores,

other types of ligand sphere have been introduced in order to alter the optical

characteristics. For instance, combining phosphines, halides, and N-heterocyclic ligands

(L) resulted in a series of compounds of the general formula [Cu2(µ-X)2(PPh3)(L)],

13

which possess halide-bridged bimetallic units77 and which exhibit emission colors

ranging from blue to red.77 Simple mononuclear Cu(I) compounds [CuX(PPh3)2(4-

methylpyridine)] (X = Cl (14), Br (15), I (16), Figure 7), synthesized from commercially

available starting materials, demonstrated intense blue emission at room temperature, in

the solid-state, and reached 100% quantum efficiency.78

Figure 7. Schematic structure of copper complexes 14–16.

Tsuboyama and coworkers described halide-bridged dinuclear complexes, supported by

the bidentate P-donor ligand 1,2-bis(diphenylphosphino)benzene (17–19), which

showed solid-state room temperature luminescence with quantum yields of 80%, 60%,

and 60% respectively (Figure 8). Specifically, compound 17 was used to prepare an

electroluminescent device with an external quantum efficiency (EQE) of 4.8%.79

Furthermore, strongly emissive dicopper complexes Cu2I2(PyrPhos)(PR3)2 (20a–c)

(Figure 8), stabilized by the bridging pyridyl-phosphine and comprised of monodentate

phosphines and phosphites have been developed.80

Figure 8. Schematic structures of compounds 17–24.

14

These materials demonstrated delayed fluorescence due to a small energy separation

ΔE(S1-T1), with high emission quantum yields reaching 99% in powdered samples (85%

in thin films), under ambient conditions, which makes them suitable for OLED

fabrication. In the case of heterodentate N, P donor ligands, quantum yields of nearly

100%, in the solid state at 77 K, and of up to 65% at 298 K, were attained for compounds

21–24 (Figure 8). These complexes show thermally activated delayed fluorescence,

which is highly attractive for electroluminescent applications.81

Active progress in organometallic carbene chemistry, particularly of Ag(I)- and Au(I)-

NHC (NHC = N-heterocyclic carbenes) complexes, stimulated the synthesis of Cu(I)-

NHCs, which were unknown until 2009.82 Using heterodentate imine-carbene ligands as

NC chelating analogues of common diimines, four-coordinate tetrahedral Cu(I)

complexes of the general formula [Cu(PP)(NC)]+ can be readily generated (Figure 9).

Photophysical study of NHC derivatives 25 and 26 revealed their TADF behavior (λem

= 520 and 570 nm, respectively) with moderate solid-state quantum yields (56% and

35% respectively).83 In the recently reported congeners 27a–c, the decoration of the

pyridine-moiety of the py-NHC ligand with electron donating and withdrawing groups

resulted in the shift of the emission energy to shorter and longer wavelengths,

respectively (489, 518, 539 nm). In contrast, the strength of these substituents does not

correlate in the same way with the emission wavelength, probably due to the contribution

of the py-NHCs ligands to both the HOMOs and LUMOs.84

Figure 9. Schematic structures of complexes 25–27.

Compared with complexes with conventional four coordinate geometry, two- and three-

coordinate Cu(I) complexes are expected to undergo less structural distortion in the

excited state. A new series of 2-coordinate copper complexes with cyclic alkyl(amino)

carbene ligands (28–31) (Figure 10) was introduced by Stefen and coworkers. The

phosphoresence emission of these compounds varied from violet, at 398 nm (31), to

green, at 512 nm (28–30), in the solid state, with quantum yields of up to 65%.85 Recently

the same group reported a family of linear Cu(I) complexes of the general formula

[Cu2{tBuIm(CH2)3tBuIm}X2] (X = PF6, n = 3), (X = BF4, n = 3), (X = BF4, n = 1)

[Cu(tBu2Im)2]PF6 (Im = imidazole), which showed mechanochromic phosphoresecence.

Their solid state quantum efficiencies varied between 4% and 51%.86

15

Figure 10. Schematic structures of complexes 28–31.

Peters et al. reported three-coordinate amidophosphine complexes, 32–34, which

demonstrate a significant alteration of the emission color from blue to yellow (Figure

11).87

Figure 11. Schematic structures of complexes 32–34.

For the purpose of stabilizing low coordination number compounds, bulky NHC ligands

are particularly attractive due to their strong bonding to transition metal ions and high

steric demand, which lead to robust complexes. Thompson and coworkers prepared the

trigonal planar three-coordinate Cu(I) NHC complexes, 35 and 36 (Figure 12), which

are phosphorescent in solution (maximum Ф = 1.4%) and in the solid state (maximum

Ф = 58%).88 In a continuation of this work, modification of the chelating pyridyl-azolate

(NN) ligands of the NHC complexes 37a–d (Figure 12) was carried out. A systematic

investigation of the physical properties of the resulting complexes revealed a significant

change in the quantum yields of compound 37a (in soution, Ф = 17%) and 37c (as a neat

crystalline material, Ф = 62%).89

16

Figure 12. Schematic structures of the three-coordinate complexes 35–37.

Taking into account the wide range of ligands suitable for binding to the Cu(I) ion, it is

evidently possible to generate an extensive library of compounds with readily tunable

optoelectronic properties, the photophysical performance of which would be comparable

to that of d6 metal chromophores. As a result of impressive synthetic effort and

comprehensive analysis of structure-property relationships, Cu(I) complexes have

developed from weakly emissive [Cu(NN)2+] species to excellent emitters with nearly

100% quantum efficiencies by means of rational design of the ligand environment. In

general, the optical properties of these luminophores can be influenced by modulating

the steric and electronic factors of the constituent ligands. In addition to the dramatically

improved quantum yields, a color variation from red to green-blue has been achieved by

tuning the nature of the emissive excited state, which can be comprised of different

contributions from MLCT (metal-to-ligand charge transfer), LLCT, and ligand centered

origins.

1.3 SILVER(I) COMPLEXES: AN ALTERNATIVE CLASS OF LUMINOPHORE

Luminescent organometallic silver complexes often occur as polynuclear assemblies and

their emission properties strongly depend on the metal-metal interactions and the

geometry of the metal core. This type of interaction induces the combination of metal

centered and ligand-to-metal charge transfer (LMCT) electronic transitions.90-91 In

contrast, in the absence of metal-metal bonding, the luminescence of silver(I) complexes

typically originates from ligand-centered (LC) or LLCT excited states, as the low energy

17

metal-to-ligand charge transfer is less favorable for the Ag(I) ion due to its higher

oxidation potential compared to that of Cu(I).90, 92-95

This is exemplified by complex 38 (Figure 13), the emission of which is associated with

ligand-to-ligand charge transfer (LLCT) transitions.96 Osawa et al. studied the

luminescence and photochemistry of a homoleptic mononuclear Ag(I) compound

containing diphosphine ligands (39, Figure 13). Interestingly, at 298 K, orange

luminescence was observed with a maximum at 670 nm, while at 77 K the luminescence

was hypsochromically shifted to 456 nm, in degassed 2-MeTHF. The large red shift (220

nm) of the emission and low quantum yield at 298 K indicate that the excited state was

MLCT in origin, with charge transfer occuring from the Ag(I) ion to the diphosphine.

This indicates that the structural modification from a tetrahedral to a planar arrangement

in the relaxed excited state results in orange luminescence at 298 K.97 For 39 and the

related mononuclear diphosphine complex 40 (Figure 13) it was suggested that, in the

excited state, they are attacked by the nucleophilic solvent molecules to a lesser extent

than are Cu(I) congeners, which decreases the possibility of non-radiative deactivation.

These results indicate that better quantum efficiently might be realized for Ag(I)

complexes in comparison to those of Cu(I).98

It is worth noting that investigations of thermally activated delayed fluorescence in Ag(I)

complexes are less frequently reported with respect to those of Cu(I) metal complexes.58,

99

Figure 13. Schematic structures of complexes 38–41.

As mentioned above, Cu(I) complexes tend to undergo MLCT electronic transitions due

to the low oxidation potential of the Cu(I) metal ion.23, 100 On the contrary, stabilization

of 4d silver orbitals frequently leads to ligand-centered emission. Thus, it is challenging

to optimize the TADF properties of Ag(I) compounds. To develop silver complexes with

delayed fluorescence, electron-donating phosphine ligands have been introduced to

destabilize the low-lying 4d metal orbitals.52 For instance, the dichloro bridged Ag(I)

18

dimer with a dppd ligand (41, Figure 13) shows blue emission at room temperature,

ascribed to TADF, with an impressive quantum yield of 93%; and an energy gap ΔE(S1-

T1) between the lowest singlet and triplet excited states of 980 cm-1.100

Yersin and coworkers have recently reported highly efficient TADF emitters of the

general Ag(NN)(PP) type (42–44, Figure 14).101 The nido-carborane-bis-

(diphenylphosphine)(P2-nCB), with a negatively charged backbone, serves as strong

electron donor. These compounds reach 100% quantum yields with short decay times of

1.4 µs, which is even shorter than the reported lifetime of 1.5 µs for the strongly

phosphorescent Ir(ppy)3 complex.102 It is important to note that, so far, this is the shortest

radiative lifetime determined for Ag(I) and Cu(I) luminophores. Introducing the methyl

and n-butyl groups into the 2 and 9 positions of the 1,10-phenanthroline ligand

influenced the optical properties of these Ag(I) complexes. An increase in the structural

robustness of these species reduces the non-radiative decay and leads to the maximum

quantum efficiency.

Figure 14. Schematic structures of silver complexes 42–44.

The combination of the tetradentate phosphine ligand, tpbz, with a terminal halide and

ancillary phosphine produces dinuclear silver complexes with the general formula

[(Ag(PPh3)(X)]2(tpbz) (X = Cl 45, Br 46, I 47) (Figure 15). Solid-state light-blue to green

emissions (TADF), with maxima between 471 nm and 495 nm, and quantum yields of

up to 98%, were observed for these compounds. The tetraphosphine ligand serves as a

bis-bidentate bridge between the two silver atoms. Its phenylene spacer is a major

contributor to the LUMO; the HOMO is primarily distributed among Ag, P, and the

halides, as predicted by the DFT calculations.54 The same tetradentate ligand, utilized

together with the strongly electron-donating carborane-diphosphine (P2-nCB), produced

the dinuclear Ag(I) complex 48 (Figure 15), which showed highly efficient TADF with

a 1.9 µs decay time and a low energy gap ΔE(S1-T1) = 480 cm-1, as a result of

(M+L)L´CT transitions, which lead to the excited states.103

19

Figure 15. Schematic structures of silver complexes 45–47 (left) and complex 48 (right).

1.4 APPLICATIONS

In addition to the abovementioned application of copper(I) emitters for the fabrication

of light-emitting devices (OLEDs and LEECs), it is worth highlighting two notable areas

where these molecular materials could be successfully utilized.

1.4.1 OXYGEN GAS SENSING

Solid state oxygen sensors can be made with the help of supporting materials16, 104-105 or

with pure porous phosphorescent compounds.105-107 A limitation of the supporting

materials is possible degradation of the polymer matrix, which stimulated the

development of pure compounds as oxygen sensors. Early progress in this direction

involved the expensive d-block noble metals Ru108, Pt109, and Ir110-111, due to their long-

lived triplet excited states, induced by high spin-orbit coupling. To reduce the production

cost, the focus moved to the search for oxygen sensing materials based on

environmentally friendly elements. In this respect, complexes of highly abundant Cu

metal, capable of forming metal-to-ligand charge transfer (MLCT) emissive states with

long lifetimes, have drawn considerable attention as potential oxygen sensors.104

The photoluminescent sensing of oxygen is based on collisional non-radiative quenching

of the triplet excited state of the probe (i.e. complex) via collisional interaction with an

oxygen molecule in its triplet ground state. In inert (non-aerated) conditions, these

phosphorescent compounds are emissive, but in contact with air, weak to negligible

emission is observed. The oxygen concentration can be measured by estimating the

degree of the decrease in emission intensity. For the favorable cases, when the material

is uniform and the emission occurs from only one site, linear fitting of the intensity

change (I0/I) vs O2 concentration (Stern–Volmer plot) can be performed for analytical

purposes. Otherwise, a non-linear dependence suggests that the emission is generated by

the two different sites, which have different susceptibilities to quenching.104

The supported sensing materials containing copper luminophores are exemplified by

compounds of the [Cu(PP)(NN)]+ type (49–51) and by the neutral [Cu(PP)(NN)]

molecule, 52 (Figure 16), embedded into polymeric matrices such as polystyrene,104, 112

PMMA13, and MCM-41.113

The crystal engineering approach to obtain efficient, non-supported sensing materials

aims to increase the void space in the crystal structure using ionic compounds. The most

common anions are BF4- (tetrafluoroborate) and tfpb (sodium tetrakis [3,5-

20

bis(trifluoromethyl)phenyl] borate. The void space plays a crucial role in oxygen

diffusion into the crystal lattice and in regulating the collisional interactions with the

emitter molecules. Additionally, it is necessary to consider not only the void space (i.e.

porosity) of the compounds, but the emission lifetime, brightness, and stability of the

compounds, and the reproducibility, which are important factors, essential for efficient

sensing.11

Figure 16. Schematic structures of copper complexes, 49–52, used with supporting materials

for oxygen gas sensing.

Selected properties (void space, KSV, and quantum yield in both aerated (O2) and non-

aerated conditions) of the prominent crystalline copper(I) sensors 53–58 (Figure 17),

prepared by Mann and coworkers, are listed in Table 1.12, 107 These compounds show

better quantum yields and sensitivities (approximately 10 times greater) than reported

homoleptic [Cu(NN)2]+ derivatives (NN = 1,10-phenanthroline (phen), 2,9-dimethyl-

1,10-phenanthroline (dmp), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (bdmp),

2,9-diisopropyl-1,10-phenanthroline (dipp), and 2,9-di-tert-butyl-1,10-phenanthroline

(dbp)).11 In particular, compound 54 has an excellent quantum yield of 0.66(5)% (under

N2) and Stern–Volmer constant (KSV = 5.65 atm-1), compared to the previously published

pure crystalline system [Ru(4,7-Me2Phen)3](tfpb)2] (Φ = 0.11(2)% (under N2), KSV =

4.76 atm-1).106 Furthermore, compounds 57 and 58 are almost non-emissive in aerated

conditions and brightly emissive in un-aerated conditions (Figure 18).

21

Figure 17. Schematic structures of copper complexes 53–58, reported as crystalline oxygen gas

sensors.

Table 1. Void spaces and quantum yields (aerated and non-aerated) for compounds 53–58.12, 107

a The estimated detection limit is 5 x 10-3atm-1.

Compound

Number

Void

space %

Quantum

yield (N2)

Quantum

yield (O2)

KSV atm-1

53 4.6 0.88 (9) 0.19 (2) 3.60(2)a

54 3.3 0.66 (5) 0.084 (3) 5.65(8)a

55 2.0 0.95 (5) 0.22 (1) 3.41(9)a

56 2.0 0.47 (4) 0.31 (3) 0.153(2)a

57 2.3 0.228 (5) 0.0029 (2) 96(1)

58 3.7 0.226 (9) 0.0021 (5) 91.9(3)

22

Figure 18. Emission spectra (uncorrected) of 57 and 58 at different O2 concentrations. Pure

nitrogen (blue) and oxygen (red) and oxygen to nitrogen mole fractions of 0.095, 0.241, and

0.467 (black), from top to bottom.107

A rare example of oxygen gas sensing by a silver compound is demonstrated by a metal

organic framework constructed from the silver-chalcogenolate cluster 59,

(Ag12(StBu)8(CF3COO)4(bpy)4]n.14 The quantum yields of this silver cluster under

vacuum and air are 61% and 12.1%, respectively; the homogeneous crystalline material

has a reproducible KSV of 0.639 kPa-1.

1.4.2 Cu(I) COMPLEXES IN PHOTOCATALYSIS

A photocatalyst is a compound or material that accelerates a photochemical reaction

without itself undergoing a permanent chemical change. The photocatalytic process

requires the use of a specific photosensitizer (PS) which absorbs light energy.

[Ru(bipy)3]2+ was the first complex used as a photosensitizer, in the 1970s.114 A number

of photocatalytic systems involving complexes of noble metals (platinum,115-117

rhenium,118-119 and ruthenium120) have been reported. The development of low-cost metal

PSs has been limited compared to that of noble metals and in this respect Cu(I)-based

photosensitizers offer an attractive alternative.

Generation of H2 gas from water is considered a prospective way to source renewable

energy. A series of Cu(I) complexes, 59–63 (Figure 19), with diphosphine and different

NN ligands, was used as photosensitizers with [Fe3(CO)12] as a water reduction catalyst,

in presence of TEA as a sacrificial reductant. Among the series, photosensitizer 63

showed the best results (TON (turn over number) (Cu) = 804, in the shorter time of 6 h),

which might be due to the bulkier and more robust PP ligand (with a larger bite angle),

which reduces the nonradiative quenching and thus provides a longer lifetime.121

Complex 64 [Cu(dpp)(binc)]BF4 (Figure 19) was successfully used as a photo-redox

catalyst under mild visible-light conditions in atom transfer radical addition and

allylation reactions.122

23

Figure 19. Schematic structures of copper catalyst complexes, 59–64, reported in the literature.

The water reduction process has been significantly enhanced by employing electron

transfer from the [Cu(NN)(PP)] sensitizer, upon visible light excitation, to the water

reduction catalyst [Rh(NN)2Cl2]+, in the presence of an electron donor. The absence of

the Cu(I) photosensitizer completely suppressed hydrogen production and shows the

importance of this component. The comparison of photosensitizers 65 and 65a (Figure

20), which differ in substituents on the biquinoline ligand, shows how careful

modification of the ligand can affect the electronic properties of the complex and

subsequently impact the sensitizing activity.123

Figure 20. Schematic representation of the hydrogen generation reaction.123

24

1.5 AIMS OF THE STUDY

Copper (I) and Ag(I) heteroleptic phosphine complexes have been extensively utilized

as photofunctional molecular materials. Their success has largely been defined by the

tunability of the optical behavior via facile modulation of the ligand environment, which

is often comprised of diphosphine, PP, and diimine, NN, or halide ligands. However,

chelating tri- and tetradentate phosphines have rarely been employed in the preparation

of luminescent coinage metal complexes.124-126 In particular, the joint effect of

polydentate phosphine and pseudo-halide ligands on the emission properties of copper

and silver luminophores has been virtually overlooked prior to this work.

In view of the literature data, the overall goal of my research project was to prepare a

series of photoluminescent copper and silver compounds supported by oligophosphine

ligands. The utilization of different coordinating pseudohalides (cyanide and

thiocyanide) and terminal alkynyl groups was aimed at the study of the effect of the

ancillary ligand on the optical behavior of the resulting compounds. Consequently, the

potentially ambidentate character of the anionic fragments was intended to be utilized

for the construction of di- and trinuclear assemblies.

25

2. EXPERIMENTAL

2.1 PHOSPHINE LIGANDS

The preparation of commercially unavailable tri- and tetradentate phosphine ligands was

carried out by adopting the method published by Hartley et al.42 These reactions are air-

and temperature- sensitive, therefore all solvents were distilled under an inert atmosphere

prior to use. All other reagents, including the diphosphines (Figure 21) were used as

received. All reactions were performed under a nitrogen atmosphere.

Scheme 1. Preparation of the phosphine ligands.

The phosphines were prepared in a two-step process; the first step is common to both tri-

and tetradentate ligands. In accordance with the literature procedure,42 1,2-

dibromobenzene was used as a starting material to obtain intermediate 1-bromo-2-

diphenylphosphinobenzene, which was subsequently lithiated and reacted with Cl2PPh

and PCl3 to afford tri- (P3) and tetradentate (P4) phosphine ligands, respectively (Scheme

1). In addition, commercially available diphosphine ligands (Figure 21) were used to

prepare heteroleptic dinuclear coinage metal complexes.

Figure 21. Diphosphine ligands used in this work.

2.2 SYNTHESIS OF THE METAL COMPLEXES

The copper subgroup metal precursors MX (X = (pseudo)halide type ligand) were treated

with a phosphine ligand to produce mono-, di-, and trinuclear complexes, 1–38 (Table

26

2). The starting terminal di- and tri-alkynes were prepared according to the reported

procedures127-129 using a standard protocol for Sonogashira cross-coupling reactions.

Table 2. The list of compounds 1-38 synthesized in the course of this work.

The listed metal complexes correspond to the following publications

Publication I - 1-3, 30-33

Publication II - 19-23, 34-38

Publication III - 8-13

Publication IV – 4-7, 14-18, 24-29

Publication V - 31a

Mononuclear

1 (P3)Cu(CN)

2 (P3)Ag(CN)

3 (P3)Au(CN)

4 (P3)Cu(SCN)

5 (P3)Ag(SCN)

6 (P4)Cu(SCN)

7 (P4)Ag(SCN)

8 (P3)Cu(Cl)

9 (P3)Ag(Cl)

10 (P3)Cu(Br)

11 (P3)Ag(Br)

12 (P3)Cu(I)

13 (P3)Ag(I)

14 [(P3)Cu{NCS:B(C6F5)3}]

15 [(P3)Ag{NCS:B(C6F5)3}]

16 [(P3S)Cu{NCS:B(C6F5)3}]

17 [(P4)Cu{NCS:B(C6F5)3}]

18 [(P4)Ag{NCS:B(C6F5)3}]

19 (P3)Cu(C2Ph)

20 (P3)Cu(C2-4-OCH3C6H4)

21 (P3)Cu(C2-4- NO2C6H4)

22 (P3)Cu(C2-4- CF3C6H4)

23 (P3)Cu(C2-2-C6H5N)

Dinuclear

24 [Cu(SCN)dppb]2

25 [Cu(SCN)DPEphos]2

26 [Cu(SCN)Xantphos]2

27 [Ag(SCN)dppb]2

28 [Ag(SCN)DPEphos]2

29 [Ag(SCN)Xantphos]2

30 [(P3)Cu(CN)Cu(P3)](CF3SO3)

30a [(P3)Cu(CN)Cu(P3)](BF4)

31 [(P3)Ag(CN)Ag(P3)](BF4)

31a [(P3)Ag(CN)Ag(P3)](tfpb)

32 [(P3)Au(CN)Ag(P3)](CF3SO3)

34 Cu2(P3)2(1,4-C2C6H4C2)

35 Cu2(P3)2(4,4´-C2(C6H4)2C2)

36 Cu2(P3)2(4,4´´-C2(C6H4)3C2)

Trinuclear

33 [{Cu(P3)NC}2Au](CF3SO3)

37 Cu3(P3)3(1,3,5-(C2C6H4)3C6H3)

38 Cu3(P3)3(1,3,5-(C2C6H4C2C6H4)3C6H3)

27

2.3. PURIFICATION AND CHARACTERIZATION

The polyphosphine ligands and their intermediates were purified by column

chromatography and/or recrystallization. The metal complexes were generally

recrystallized via slow evaporation or gas-phase diffusion techniques. The FTIR

measurements were performed on a KBr disc using a Bruker Vertex 70 FTIR instrument.

Structural studies were carried out by single-crystal diffraction analysis; the

corresponding data were collected with a Bruker SMART Apex II, Kappa Apex II, or

Kappa Apex II Duo diffractometer using Mo Kα radiation (λ = 0.71073 Å). The

multinuclear (1H, 31P, 19F) NMR spectroscopic investigations in solution were carried out

on a Bruker Avance 400, 500, or AMX 400 instrument. The electrospray ionization mass

spectra were measured on a Bruker APEX-QeQh-FT-ICR mass spectrometer in positive

ion mode.

Collaborators at the National Taiwan University (Taiwan), Soochow University

(Taiwan), St.-Petersburg State University (Russia), and Aalto University (Finland)

carried out computational and photophysical investigations of the compounds and

materials prepared by the author.

28

3. RESULTS AND DISCUSSION

3.1. MONONUCLEAR TRI- AND TETRAPHOSPHINE d10 COMPLEXES

The development of coinage metal complexes exhibiting efficient luminescence requires

rational molecular design in order to decrease structural flexibility and consequently

suppress geometrical distortions in the excited state that, in turn, block the non-radiative

relaxation pathways. Following the chosen general strategy, a series of copper subgroup

metal complexes was obtained utilizing stereochemically rigid tri- and tetradentate

phosphine ligands, which have previously been sparsely employed in the preparation of

photofunctional d10 compounds.124-125, 130-131

The families of structurally related species [(P3)M(CN)] (M = Cu, Ag, Au; 1–3),

[(P3)M(SCN)] (M = Cu, Ag; 4 and 5), [(P4)M(SCN)] (M = Cu, Ag; 6 and 7),

[(P3)M(Hal)] (Hal = Cl, Br, I; M = Cu, 8, 10, 12; M = Ag 9, 11, 13) were obtained and

investigated (Scheme 2). Furthermore, the boronated thiocyanate derivates

[(P3)M{SCN:B(C6F5)3}] (M = Cu, Ag; 14 and 15), [(P3S)Cu{SCN:B(C6F5)3}] (16),

[(P4M{SCN:B(C6F5)3}] (M = Cu, Ag; 17 and 18) and the alkynyl compounds

[(P3)Cu(C2R)] (19–23) [R=Ph 19, 4-OCH3-C6H4 20, 4-NO2-C6H4 21, 4-CF3-C6H4 22, 2-

NC6H5 23) were synthesized. By means of variation of the metal centers (Cu, Ag, Au)

and of the auxiliary halide/pseudo-halide ligands, it was possible to study their influence

on the formation and structural and photophysical characteristics of the target complexes.

Scheme 2. Preparation of the mononuclear, neutral complexes 1–23.

29

3.1.1 TRIPHOSPHINE CYANIDE COMPLEXES

Neutral tetracoordinate complexes of the general formula [(P3)M(CN)] (M = Cu 1, Ag 2,

Au 3) were conventionally synthesized by reacting the P3 ligand with an equimolar

quantity of the metal cyanide MCN (M = Cu, Ag, or Au) at ambient temperature (Scheme

2). The products were isolated as crystalline materials in good yields. Complexes 1–3

crystallized in the P21/n space group and afforded isomorphous crystals with nearly

identical unit cell dimensions. Selected structural parameters are listed in Table 3 and

indicate that the main deviations of the bond distances and angles are associated with the

different sizes and coordination preferences of the metal centers.

Table 3. Selected bond lengths and angles for complexes 1–3.

1 (M = Cu) 2 (M = Ag) 3 (M = Au)

Bond lengths, Å

P(1)-M(1) 2.294(4) 2.527(3) 2.401(4)

P(2)-M(1) 2.272(5) 2.516(4) 2.409(5)

P(3)-M(1) 2.289(5) 2.484(4) 2.413(5)

C(1)-M(1) 1.937(2) 2.123(1) 2.064(2)

Bond angles, deg

N(1)-C(1)-M(1) 178.0(2) 173.4(1) 175.6(2)

C(1)-M(1)-P(1) 120.04(5) 118.37(3) 118.80(5)

C(1)-M(1)-P(2) 123.05(5) 128.16(4) 128.84(5)

C(1)-M(1)-P(3) 117.42(5) 126.41(3) 119.30(5)

P(1)-M(1)-P(3) 114.04(2) 108.89(1) 112.91(2)

P(2)-M(1)-P(3) 87.35(2) 81.81(1) 84.20(2)

P(2)-M(1)-P(1) 87.14(2) 80.32(1) 84.44(2)

Figure 22. Crystal structures of complexes 1–3.

Unsurprisingly, the larger van der Waals radius for Ag compared to those of Cu and Au

metals results in systematically longer M–CN and M–P bond distances for the silver

complex, 2. The central metal ions in compounds 1–3 adopt pseudo-tetrahedral geometry

in the ligand sphere (Figure 22), which is composed of the phosphine coordinated in a

30

tridentate mode, and of the carbon-bound cyanide group. The P–M separations in 1

somewhat exceed those reported for other tetracoordinated Cu complexes.132 Structural

parameters of compounds 2 and 3 are very close to the values found for their chloride

congeners M(P3)Cl.124 Furthermore, the M–CN contacts in these species are comparable

to those of previously characterized coinage metal complexes.132-133

The C≡N stretching frequencies in the IR spectra of compounds 1–3 revealed

characteristic strong bands at 2108, 2116 and 2112 cm-1, respectively; these values are

similar to those of previously reported cyanide compounds.132 The solution behavior of

1–3 was studied by NMR spectroscopy; the corresponding data are in good agreement

with the solid-state structures. The 1H and 1H-1H COSY spectra of these compounds

demonstrate well-resolved patterns generated by the aromatic protons of the phosphine

ligands (Figure 23).

Figure 23. (Top) the 31P{1H} NMR spectra of 1–3, CD2Cl2, 298 K. (Bottom) the 400 MHz 1H-1H COSY NMR spectrum of 1, CD2Cl2, 298 K (assignment of the rings A and B is arbitrary).

The 31P{1H} NMR spectra of complexes 1 and 3 illustrate splitting patterns typical for

the A2B spin system. In contrast, the silver congener, 2, shows two resonances, the

31

multiplicity of which is compatible with the first-order A2X system of 31P atoms,

additionally split by coupling with Ag nuclei (the isotopomers with 107,109Ag atoms

remain unresolved, Figure 23).

3.1.2 TRI- AND TETRAPHOSPHINE THIOCYANATE COMPLEXES

Mononuclear compounds 4–7 [(P3/P4)M(SCN)] [P3 (M = Cu 4, Ag 5), P4 (M = Cu 6, Ag

7)] were prepared by complexation of metal thiocyanates, MSCN, with phosphine

ligands P3/P4, using dichloromethane as a solvent, at ambient temperature (Scheme 2).

The IR spectra of these compounds exhibit characteristic C≡N vibrations in the range of

2080 to 2097 cm-1; these values are in line with those of similar, previously reported

species.134-135 The silver complexes (5 and 7) have higher C≡N stretching frequencies

than the copper (4 and 6) analogues, which could be attributed to the different bonding

modes of the ambidentate SCN ligand in these compounds.

Figure 24. Crystal structures showing molecular views of 5, 6, 7a, and 7n.

In the Ag complexes, the thiocyanate group is predominantly attached to the metal center

through the S atom, which leads to a bent Ag–SCN motif, similar to the reported

complexes,14, 16-17 as confirmed by X-ray crystallographic analysis. In contrast, a linear

Cu–NCS arrangement is observed for 4 and 6 (Figure 24). The central metal atoms in

these compounds are supported by three phosphorous atoms from the P3/P4 ligands and

the fourth coordination site is occupied by the terminal SCN ion, resulting in a distorted

tetrahedral shape. In complexes 6 and 7, containing the P4 ligand, one of the terminal

PPh2 groups is not bound to the metal (Cu/Ag) ions.

The tetraphosphine complexes adopt multiple forms depending on the solvents used for

crystallization. Thus, in addition to the yellow-green diethyl ether solvate 6, this

compound was obtained as a yellow solvate 6a (containing highly disordered solvent),

32

and a solvent-free yellow-orange minor form derivative, 6b. The silver analog, 7,

crystallizes in two solvent free forms (minor, poorly reproducible, pale green 7 and

yellow 7a; pseudo-polymorphs) and as two solvates (THF and methanol containing 7b

and 7c, respectively). Furthermore, a linkage isomer with N-bonded thiocyanate (7n) has

been isolated (Figure 24). It is noteworthy that coinage metal complexes with the P4

ligand remain scarce.136-137

The bond distances between the metal and phosphorous atoms are similar to those of

[M(P3)CN] congeners 1–3 and their close relatives in the [M(P3)Cl] series.124 The

separations between the free PPh2 groups and the metal centers are 4.101 Å (M = Cu, 6)

and 3.848 Å (Ag, 7), which are similar to those in their alkynyl congeners.136 The Ag–S

bond length (2.49–2.50 Å) is comparable to the values reported for other mono134 and

dinuclear138-139 complexes.

In the 31P NMR spectra recorded in solution, broad peaks were observed for the Cu(I)

complexes, 4 and 6, at 193 K. In contrast, Ag(I) complexes, 5 and 7, demonstrate well-

resolved patterns corresponding to the AX2 and AX3 spin systems and further splitting

due to the P–Ag magnetic interactions (1JP-107Ag = 179 and 112 Hz, 1JP-109Ag = 203 and 129

Hz, Figure 25). The high symmetry of the tetraphosphine coordination in 7, observed in

solution even at low temperature, suggests the dissociation of the SCN anion to produce

a [Ag(P4)]+ cation. This hypothesis is also in line with the crystallization of two linkage

isomers of this complex. The proton NMR spectra for 4–7 are consistent with the 31P data

and support the symmetric arrangement of the phosphine ligands around the metal ion.

Figure 25. Experimental (top, 193 K, CD2Cl2) and simulated (bottom) 400 MHz 31P{1H} NMR

spectra of 7.

3.1.3 TRIPHOSPHINE HALIDE COMPLEXES

In order to compare the photophysical properties of [M(P3)X] compounds with different

X type ligands, the corresponding copper and silver halide derivatives were synthesized.

The coordination of triphosphine ligand P3 to the CuX halide salts readily leads to

mononuclear complexes [Cu(P3)X] (X = Cl 8, Br 10, I 12) in high yields. The [Ag(P3)X]

complexes (X = Cl 9, Br 11, I 13) can be conveniently prepared by treating AgPF6 with

NBu4X, followed by P3 ligand (Scheme 2). The compounds (8, 9, 11, and 13) had

33

previously been reported for electroluminescence applications.125-126 Among them, the

crystal structure of 9 had previously been described.124

Figure 26. Crystal structures of complexes 8 and 11.

The single crystal structures of compounds 8, 10, 11, and 13 have molecular skeletons

and M–P bond distances which are close to those for the reported structure of 9 as well

as to those of the cyanide (1 and 2) and thiocyanate (4 and 5) congeners (Figure 26).

Similar to the pseudohalide derivatives, the central metal ions in complexes 8, 10, 11,

and 13 adopt a tetrahedral arrangement with the chelating tridentate phosphine P3 and the

halide ligands. As expected, the M–X bond distance increases with the size of the

ancillary halogens (Cu–Cl 2.2748 Å, Cu–Br 2.3986 Å; Ag–Br 2.57221 Å, Ag–I 2.7050

Å).

The solution 1H, 1H-1H COSY and 31P NMR spectra for the halide complexes are

consistent with the solid-state structures. In particular, the 31P NMR data confirm that all

the phosphorus atoms are coordinated to the metal ions; the resonances of compounds 8–

13 are moderately shifted to higher field compared to those of the cyanides [M(P3)CN]

(1 and 2), which may reflect the effect of the ancillary X ligand on the electronic features

of the metal center.

3.1.4 TRI- AND TETRAPHOSPHINE ISOTHIOCYANATOBORATE

COMPLEXES

The ambidentate nature of the terminal SCN groups was utilized to initiate an additional

donor-acceptor interaction with the Lewis acid B(C6F5)3 in order to produce

isothiocyanatoborate complexes [(P3/P4)M{NCS:B(C6F5)3}] [P3 (M = Cu 14, Ag 15), P4

(M = Cu 17, Ag 18)] (Scheme 2), which were isolated as crystalline materials in high

yields. These compounds are formed upon the reaction of neutral compounds 4–7 with

B(C6F5)3, in an equimolar ratio, in dry THF, under a nitrogen atmosphere. In all these

species the SCN:B(C6F5)3 ligand is S-bound to the metal centers, thus forming bent M–

SCN fragments even though a linear Cu–NCS skeleton is found in the parent complexes

4 and 6. This rearrangement can be explained in terms of hard-soft acid-base theory. The

hard B(C6F5)3 acid shows a clear preference for binding to a hard donor, which is the N

atom in the ambidentate SCN ligand; thus, the copper and silver metal ions invariably

bind to the sulfur functions, leading to bent M–SCN products.

34

Remarkably, the crystallization of compound 14 from an acetone/diethyl ether mixture

results in the formation of derivative 16, [(P3S)Cu{NCS:B(C6F5)3}], in which the P3

ligand has one sulfidated PPh2 group, evidently due to decomposition of thiocyanate

(Figure 27). It is important to note that this is the first example of a hetero-tridentate

diphosphine-phosphine sulfide ligand (PPP=S).

Figure 27. Crystal structures of complexes 16 and 17.

The X-ray structural analysis of isothiocyantoborate complexes, 16–18, confirmed the S-

coordination of the thiocyanate to the metal atoms and N-bonding to the boron. The

distorted tetrahedral environment of copper and silver ions is completed by P3/P4 ligands.

The linear arrangement of SCN:B motifs and the corresponding structural parameters for

14–18 are comparable to those of the published compound [K(18-crown-

6)][SCN:BR3].140 Due to the B-NCS interaction, the C≡N bond distances in 16–18

(1.136–1.152 Å) are shorter than in the parent compounds 4–7 (1.152–1.160 Å); this

structural observation is consistent with the changes in C≡N stretching frequencies,

which are significantly increased in 16–18 (2189–2181 cm-1) with respect to 4–7 (2080–

2097 cm-1) and which are similar to the values reported for cyano-boronated

complexes.141-142

In 16, the pseudo-tetrahedral geometry is achieved by coordinating two of the P-donor

atoms of the heterodentate P3S ligand and the two sulfur atoms from P3S and the

SCN:BR3 ion (Figure 28). Despite the anionic nature of the latter, the S–Cu distance

involving the PPh2=S group (2.304 Å), is slightly shorter than that with the SCN:

B(C6F5)3 function (2.346 Å); both values agree with the reported data for copper

thiocyanate47, 143-144 and phosphine sulfide145-147 compounds.

The attachment of the B(C6F5)3 group causes a shift in the 31P NMR signals for the

isothiocyanatoborate complexes compared to the those of the parent complexes, which

confirms the formation of products 14–18. The silver compounds 15 and 18 produce 31P

spectroscopic profiles corresponding to the A2B and A3X spin systems, respectively,

which are similar to those of the parent complexes 5 and 7 (Figure 28).

35

Figure 28. The 31P NMR spectrum of 16 at 298 K (top); the 31P NMR spectrum of 18 at 210 K,

400 MHz (black) and its simulation (red), assuming the AX3 spin system (bottom).

The copper isocyanotoborate complex, 14, showed two broad signals (2:1 ratio) in the 31P NMR spectrum at 298 K, whereas 17 displayed one resonance, at room temperature,

and proved to be less rigid than its precursor, 6. The 31P NMR spectrum of compound 16

is consistent with its solid-state structure and displayed three doublets with a 1:1:1 ratio

of their relative intensities; the low field signal evidently originates from the Ph2P=S

group (Figure 28). Additionally, a characteristic set of resonances with a 2:2:1 ratio,

corresponding to the ortho-, meta-, and para-F atoms, was observed in the 19F NMR

spectra of isothiocyanatoborate complexes.

3.1.5 TRIPHOSPHINE ALKYNE COMPLEXES

Neutral alkyne coinage metal complexes of the general formula [CuP3(C2R)] (19–23) [R

= Ph 19, 4-OCH3-C6H4 20, 4-NO2-C6H4 21, 4-CF3-C6H4 22, 2-NC6H5 23) were

synthesized by the reaction of a stoichiometric amount of [Cu(P3)]+ cationic precursor

prepared in situ and an alkyne, in the presence of a base (Scheme 2). The products were

obtained as yellow solids, which are somewhat unstable in chlorinated solvents.

A nearly identical set of multiplets appeared in the 31P NMR spectra of compounds 19–

23, which is assigned to an A2B spin system. The downfield shift of the resonances

relative to those of the free ligand confirms that all three phosphorus atoms of the P3

ligand are coordinated to the metal ion. The similarity of the 31P NMR chemical shifts

within this series indicates that the electronic properties of the alkynyl groups have a

small influence on the copper, and consequently the P atoms. The complete assignment

36

of the 1H NMR spectra for 19–23 is in line with the composition [CuP3(C2R)] and the

symmetrical structural arrangement of these complexes in solution.

Figure 29. Crystal structures of complexes 19, 21, and 23.

The structural characterization of compounds 19, 21, and 23 (Figure 29) proved the

tridentate character of the triphosphine coordination to the copper center, accompanied

by the terminal alkynyl group, thus providing pseudo tetrahedral ligand arrangement,

with observed M–P and M–C≡C distances which were quite similar to those of the

reported congener complexes.131, 148-149 It is important to note that these compounds were

the first monomeric alkynyl complexes of Cu(I), which typically aggregate via a σ–π

bridging mode of the –C≡CR groups.130, 149-152

3.2 PHOTOPHYSICAL PROPERTIES OF MONONUCLEAR COMPLEXES

The photophysical investigations of complexes 1–23 focused on their solid-state

behavior, due to the weak or even negligible luminescence of these species in solution;

where measurements were performed for selected compounds only (1–3, 7, 14–15, 17–

18).

3.2.1 [Cu(P3)X] HALIDES AND PSEUDOHALIDES

Table 4 summarizes the photophysical data for mononuclear triphosphine copper

compounds in the solid state at 298 K and 77 K. Compounds 1 and 4 show strong green

emission with high quantum yields of 70% and 57%, respectively. From quantum

chemical calculations, the lowest excited state for compound 1 corresponds to MLCT

(metal-to-ligand charge transfer, L = triphosphine ligand) along with ligand-to-ligand

CN → P3 charge transfer (Figure 30), whereas for compound 4, mainly L´LCT transitions

(L´ = SCN), with some MLCT character, were predicted. Among the mononuclear Cu(I)

complexes, 1 shows the highest quantum yield and the longest observed lifetime (τ = 15

μs at 298 K) compared to those of other reported Cu(I) complexes.58, 76, 153 In contrast, 4

has the shortest lifetime, at 5 μs, at room temperature, in comparison with those of

[Cu(P3)X] (X = Cl 8, Br 10, I 12, and CN 1, Table 4). Furthermore, there was a drastic

change in the lifetime of 4 (694 μs) when frozen at 77 K. The dependence of lifetime on

temperature for 4 (Figure 30) confirms the presence of TADF, which implies that

37

different excited states are responsible for the emission at low (T1) and ambient (S1)

temperatures.

The addition of the B(C6F5)3 group to 4, which converts it into 14, results in a slight blue

shift of the emission wavelength from 520 nm to 505 nm (Δν = 571 cm-1) with respect to

that of the parent compound, 4. The S1 and T1 excited states of 14 are assigned as

(L+M)LCT type (L = phosphine) with a less than 2% contribution from the SCN:

B(C6F5)3 ligand, which is different from the transitions found for 4. The gradual increase

in the lifetime upon cooling (174 fold) suggests TADF properties (Figure 30). It is

noteworthy that the longest lifetime (3067 μs) among the reported compounds is

observed for 14 at 77 K.

Figure 30. Electron density difference plots for the lowest energy triplet emission (T1 → S0) of

the Cu(I) complex, 1 (left). During the electronic transition, the electron density increases in the

blue areas and decreases in the red areas. Temperature dependencies of the average decay times

of 4 and 14 (right).

Strong blue-green emissions with maxima between 504 and 517 nm were observed for

halide derivatives 8, 10, and 12; these bands are slightly blue-shifted relative to those of

the pseudohalide congeners, 1 and 4. Among the halide series (8, 10, and 12), the

emission energy increases from [Cu(P3)Cl] (517 nm) to [Cu(P3)I] (504 nm). In the same

order, the room temperature quantum yields (21–37%) show substantial growth (Table

4). The drastic increase (up to 66 fold) in the decay time at low temperature, together

with the bathochromic shift, indicate that these compounds demonstrate delayed

fluorescence behavior.99, 154 The emission of these compounds originated mainly from a

MXLCT type excited state.

The series of compounds, 19–23, bearing terminal alkynyl ligands, revealed a significant

red-shift of the emission maxima, up to 722 nm (21) (Table 4 and Figure 31). However,

quantum yields for those complexes were substantially lower compared to those of the

halides (8, 10, and 12) and pseudohalides (1 and 4). The triplet excited state of

compounds 19–23 was largely determined by the alkynyl ligands, with a small

contribution from the metal ions, i.e. they can be classified as having intra-ligand origin

mixed with some MLCT character (Figure 31). The T1 state in this case is different from

those for of the pseudohalide derivatives, 1 and 4, in which MLCT and a mixture of

38

MLCT+L´LCT transitions make major contributions, according to quantum mechanical

calculations.

Table 4 The photophysical properties of neutral mononuclear copper complexes 1, 4, 8, 10, 12,

14, and 19–23, at 298 and 77 K, in the solid state.

298K 77K

No Ancillary

ligands

λex,

nm

λem,

nm

Ф,

%

τav,a

μs

λex,

nm

λem,

nm

τobs,a

μs

1 CN 415 530 70 15

4 SCN 295,367 520 57 5 370 520 694

8 Cl 370 517 21 9 363, 397 520 566

10 Br 370 507 36 12 363, 397 523 794

12 I 370 504 37 11 311 512 137

14 NCS:

B(C6F5)3 316, 365 505 39 18 323, 364 515 3067

19 415 602 6 2 415 612 246a

20 415 602 8 2 415 612 73a

21 580 722 0.1 - 415 717 -

22 340, 415 573 11 3 370 579 59a

23 415 573 19 4 415 579 149a a The average emission lifetime for the two exponential decay was calculated using τav = (A1τ12 +

A2τ22)/(A1τ1 + A2τ2); Ai = weight of the i exponent.

Similar to halide compounds 8, 10, and 12, complexes 19–23 are likely to exhibit TADF

properties, which is indicated by the lifetime values measured at 298 K and 77 K. Upon

cooling, the lifetime increased up to 130-fold compared to its magnitude at room

temperature (Table 4).

Figure 31. a) Electron density difference plots for the lowest energy triplet emission (T1 → S0)

of the Cu(I) complex, 19, (isovalue 0.002 a.u.). During the electronic transition, the electron

density increases in the blue areas and decreases in the red areas. b) Normalized solid-state

excitation (left) and emission (right) spectra of 19 and 23 at 298 K (dashed line) and 77 K (solid

line).

39

3.2.2 [Ag(P3)X] HALIDES, PSEUDOHALIDES AND [Au(P3)CN]

Intense green emission maximized at 525 nm with 87% quantum yield is observed for

silver compound 2, which has the longest observed lifetime (29 µs) and highest quantum

yield at room temperature among the mononuclear series (Tables 4 and 5). Gold

compound 3 shows red-shifted luminescence (λem = 640 nm) and a lower quantum yield

of 8%, which is different from the performance of 1 and 2 (Figure 32). Notably, the

ancillary ligand in 3 has a significant influence on the emission intensity, as [Au(P3)I]155

emits at the same wavelength as 3 but with 4-times greater intensity (λem = 640 nm and

Ф = 35%). A similar trend in emission colors was reported for M(PP)(PS) (M = Cu, Ag

and Au) [PP = (1,2-bis(diphenylphosphino)benzene; PS = 2-diphenylphosphine

benzenethiolate] complexes.153

Table 5 The photophysical properties of neutral mononuclear silver complexes 2, 3, 5, 9, 11, 13,

and 15, at 298 K and 77 K, in the solid state.

298K 77K

No Ancillary

ligands

λex,

nm

λem,

nm

Ф,

%

τav, a

μs

λex,

nm

λem,

nm

τobs, a

μs

2 CN 400 525 87 29

3 CN 459 640 8 1

5 SCN 320, 365 538 32 15 314, 365 548 1121

9 Cl 347, 441 521 40 27 329, 375 535 596

11 Br 393 521 41 26 329, 375 535 538

13 I 312, 483 513 39 14 329, 375 525 180

15 NCS:

B(C6F5)3 356 482 12 23 350 478 1480

a The average emission lifetime for the two exponential decay was calculated using τav = (A1τ12 +

A2τ22)/(A1τ1 + A2τ2); Ai = weight of the i exponent.

Figure 32. Normalized solid-state excitation (solid line) and emission (solid line with symbol)

spectra of 1–3 at 298 K. λex = 406 nm for emission(left). Temperature dependencies of the

average decay times of 5 and 15 (right).

It is noteworthy that the emission spectra of complexes 1–3 were measured in solution

(degassed dichloromethane, 298 K). Compounds 1 and 2 show red-shifted emission at

665 nm and 675 nm, with low quantum yields of 7×10-4 and 8×10-4%, respectively, while

3 is virtually nonemissive. This is typically attributed to the geometrical distortion

40

(planarization) of the excited state geometry, which can then undergo non-radiative

relaxation.97, 156-157

A slight red shift in the emission wavelength is observed for silver thiocyanate, 5, (538

nm) compared with that of its cyanide relative, 2 (525 nm, Δν = 460 cm-1, Table 4), which

is opposite to the behavior observed for the copper analogues (for which a blue shift is

detected). Introducing the borane group, B(C6F5)3, into 5 shifts the emission of resulting

compound 15 by approximately 56 nm (Δν = 2160 cm-1) towards the blue region, to 482

nm. Similar to the Cu (I) thiocyanate pair, 4 and 14, in the case of Ag(I) congeners, 5 and

15, a lower quantum yield (5 = 32%, 15 = 12%, Table 5) and an increase in the lifetimes

(at 298 K and 77 K) were observed for the boronated compound. Computational analysis

indicates that the lowest excited states correspond to a mixture of L’LCT (SCN → P3),

with some MLCT character, in 5; however, (L+M)LCT transitions are predicted to

control the excitation of 15. Temperature-dependent analysis of the decay time clearly

demonstrated the TADF phenomenon in 5 and 15 (ΔE = 838 and 1608 cm-1, respectively,

Figure 32). The boronated complex, 15, showed a longer phosphorescent decay time

τ(T1) = 1466 µs compared to parent compound 5 (1117 µs) tentatively assigned to the

differences in the electronic structures (Figure 33).

Figure 33. The appearance of the highest occupied molecular orbitals in the singlet ground

states (S0) and the first excited states (T1) of 5 and 15.

The emission wavelengths for silver halide derivatives 9, 11, and 13 are observed

between 513 and 521 nm, which are slightly red-shifted relative to the Cu(I) compounds

8, 10, and 12. Quantum yields of the silver halide compounds (9, 11, and 13) fall in the

range of 38–40%, which are higher than those of the copper analogues, however, they

are lower than that of the cyanide complex, 2. The emission of these compounds was

ascribed to MXLCT type. The room temperature lifetimes (14–27 µs) of silver halide

41

derivatives 9, 11, and 13 are significantly increased upon cooling (77 K), which suggests

TADF behavior (Tables 4 and 5).

3.2.3 [M(P4)X] THIOCYANATE AND ISOTHIOCYANATOBORATE

COMPLEXES

The pertinent photophysical data for mononuclear tri and tetraphosphine Cu(I) (6 and 17)

and Ag(I) (7 and 18) compounds at 298 K and 77 K are listed in Table 6. Complex 16

did not show appreciable emission and was therefore not investigated.

Table 6 The photophysical properties of homometallic complexes 6, 6a, 7, 7a, 7c, 7n, 17, 17a,

and 18, at 298 K and 77 K, in the solid state.

a The average emission lifetime for the two exponential decay was calculated using τav = (A1τ12 +

A2τ22)/(A1τ1 + A2τ2); Ai = weight of the i exponent.

Figure 34. a) Normalized solid-state excitation and emission spectra at 298 K (dotted) and 77 K

(solid) of 7a–c, 7n (inset picture shows appearance of 7a–c, 7n under UV light at 298 K). b)

Normalized solid-state emission spectra at 298 K of 17 and 17a (inset picture shows appearance

of 17 and 17a under UV light at 298 K).

298K 77K

No λex,

nm λem,

nm Ф,

% τav, a

μs λex,

nm λem,

nm

τobs, a

μs

6 360 543 27 5 360 552 1387

6a 400 575 23 4 396 575 1045

7a 367 552 27 10 367 507 747

7c 368 630 19 7 365 645 890

7n 366 525 44 10 365 518 598

17 395 505 17 2 380 500 1984

17a 370 625 11 4 370 666 1276

18 310, 365 575 9 8 375 630 1018

42

As mentioned in Section 3.1.2, compounds 6 and 7 [Cu/AgNCS(P4)] crystallized in

different pseudopolymorphs; the optical properties were studied for two solvates, 6 and

6a, and for three forms of 7 (solvates 7 and 7c, solvent free 7a, and the linkage isomer

7n). For the THF solvate, 7b, only the emission spectra were recorded due to the presence

of at least two crystalline forms. Compared to that of triphosphine complex 4 (λem = 520

nm, Ф = 56%), significant red shifts in the emissions were observed for the solvated

forms 6 and 6a (λ = 543 and 573 nm, Δν = 814 and 1779 cm-1, respectively) and quantum

yields for the tetraphosphine species were lower, at 27% and 23%. The emissions of the

different crystalline forms of compound 7 cover a wide range of the visible spectrum

(Figure 34a). The emission maxima of solvent-free forms 7n and 7a were observed in

the green to yellow region (λem = 525 and 552 nm, respectively). In contrast, a

bathochromic shift was observed for the THF solvate 7b (605 nm) and the emission

maximum reached 630 nm for methanol solvate 7c (Table 6).

Substantially blue-shifted emissions were observed for borane-containing complexes 17

and 18 in comparison to those of parent compounds 6 and 7 (solvated form). Two

crystalline forms of 17 emit at the dramatically different wavelengths of 505 nm and 625

nm (Figure 34b), similar to materials 6 and 6a. Complex 18, obtained in one form,

exhibits an emission band at 575 nm. The presence of the B(C6F5)3 group in 17 and 18

affects the quantum yields (9–17%), which are smaller than those of 6, 6a, 7, and 7a

(Table 6). Furthermore, grinding compound 7 produces a uniform material with yellow-

orange luminescence, which is converted into a solid with strong green luminescence

upon addition of acetonitrile (Figure 35a).

Figure 35. Changes in the emission spectra of 7 upon grinding (dotted orange line) and upon the

addition of acetonitrile (solid green line) (left). Temperature dependencies of the average decay

times for compounds 7, 7a, 15, and 18 (right).

Similar to the case in triphosphine complexes, a mixture of MLCT (d → P4) and L´LCT

(SCN → P4) transitions contribute to the excited state for compound 6–7. For compound

6, the temperature dependence of the decay time increased continuously at 77 K and

therefore could not be treated using the two-state model. However, it is consistent with

the TADF character of the emission, pointing to a low energy difference (less than 500

cm-1) between the S1 and T1 levels. In the case of 7, the profile of the dependence of

43

lifetime on temperature clearly shows the TADF behavior of this luminophore (Figure

35b).

The composition of the excited states for complexes 17 and 18 is principally of

(L+M)LCT (d,p(M,P)→πP4) character with a small involvement of the SCN:B(C6F5)3

ligand, which is in contrast with those of the respective precursor compounds, 6 and 7.

One specific trend is perceived for boronated compounds 17 and 18, which exhibit

systematically longer lifetimes at 77 K. The TADF behavior of 17 and 18 was confirmed

by variable temperature studies of their lifetimes (Figure 35b).

The luminescence of compounds 7, 17, and 18 was also measured in degassed THF

solution. Remarkably, the emission bands are observed in the red region, ranging from

620 to 690 nm with 0.9–2.4% quantum yields. The lowered quantum yields are

presumably due to structural distortions occurring in the excited state, which lead to non-

radiative deactivation.101 Among the investigated compounds, compound 7 exhibits the

longest emission wavelength, 690 nm at 298 K, with a quantum efficiency of 2.1%.

3.3 DINUCLEAR BI- AND TRIPHOSPHINE d10 COMPLEXES

The ambidentate nature of thiocyanate and cyanide pseudohalides allowed the

preparation of a series of bimetallic complexes, which is comprised of neutral compounds

[M(SCN)P2]2 (dppb, DPEphos, Xantphos, M = Cu 24–26; M = Ag 27–29) and ionic

species [(MP3)CN(P3M)]+ (M = Cu 30; Ag 31; Au, Ag 32). Hetero-trinuclear complex

[(P3)Cu-NC-Au-CN-Cu(P3)]+ 33 was also synthesized to extend this approach, where the

pseudo-halides act as bridges between the two metal centers. Alternatively, neutral

copper compounds were obtained using di- and tri alkynyl spacers along with P3 ligand;

the number of terminal alkyne groups determines the complex nuclearity affording linear

[{(P3)CuC2}2R)] (R = -(C6H4)-n; n = 1 34, n = 2 35, n = 3 36) and star shaped

[{(P3)CuC2}3R)] (R= 1,3,5-(C6H4)3-C6H3 37, 1,3,5-(C6H4-4-C2C6H4)3-C6H3 38)

complexes.

3.3.1 THIOCYANATE-BRIDGED DINUCLEAR COMPLEXES

The bidentate P2 ligands (Figure 21) were reacted with copper and silver thiocyanates

according to the reported protocol139, 158 to generate neutral homo-bimetallic complexes

with the molecular formula [M(SCN)P2]2 (M = Cu, P2 = dppb 24, DPEphos 25, Xantphos

26; M = Ag, P2 = dppb 27, DPEphos 28, Xantphos 29) in moderate to high yields of 50–

88% (Scheme 3). The Cu complexes 24–26 were obtained as yellow crystals, with lower

yields compared to the Ag analogues 27–29, due to the formation of insoluble

unidentified side products.

The C≡N stretching vibrations of 24–29 were observed at frequencies between 2088 and

2108 cm-1 as sharp peaks (Figure 36) and these values were consistent with those of the

previously synthesized thiocyanate Ag(I) and Cu(I) compounds.139, 158 Generally,

according to Nakamoto theory,159 the wavenumber of C≡N stretches for SCN bridges

falls above 2100 cm-1. However, many complexes have been reported which do not obey

44

this theory.47, 160 Except for those of 24, the IR data for complexes 25–29 were not in the

Nakamoto range but were similar to those of other reported thiocyanate bridged

complexes.161-162 The 31P NMR spectra of copper compounds 24–26 show broad singlet

peaks, evidently due to structural flexibility of the complexes in solution. In the case of

Ag(I) compounds 27 and 28, sharp doublets were observed due to the silver-phosphorous

magnetic interactions, with coupling constants, JP-107Ag/109Ag, of 366 and 374 Hz. These

values are comparable with those of published compounds.160, 163

Figure 36. Solid state infrared spectra of compounds 24–29.

Scheme 3. Preparation of the di- and trimetallic complexes.

To evaluate the structural arrangements, the X-ray single crystallographic analysis was

carried out for compounds 24–29 (Figure 37). The dinuclear complexes 24–27, and 29

formed 8-membered rings composed of thiocyanate anions coordinated in µ2,κ2-mode

and metal ions. The metal centers adopted distorted tetrahedral geometries and the

phosphines were found in trans-positions in the centrosymmetric molecules (except 26);

a similar framework was observed in previously reported Cu(I) and Ag(I) dinuclear

45

complexes.139, 160-161, 164-165 In 26, probably as a result of the steric properties of Xantphos

and repulsion between the phenyl rings, there was a decrease in the molecular symmetry,

resulting in a cis-disposition of the phosphines. Disparately, compound 28 consists of a

4-membered ring formed by two metals and two SCN anions, bound in μ2,k1-mode

through the S atoms; Nicola et al. reported an analogous framework for AgSCN:dpph

(1:1)2 (dpph = Ph2P(CH2)5PPh2) and AgSCN:dppf (1:1)2 (dppf =

bis(diphenylphosphino)ferrocene) complexes.135, 166

Among these compounds, the M–S bond distances are longer in the Ag(I) than in the

Cu(I) species; the longest one is 2.6817(9) Å, which was observed in 27, and the shortest

is 2.3630(9) Å in 24. The CN bond distances (1.153(4)–1.164(2) Å) were comparable to

those in cyanide complexes 1–3, which confirms that the C-N motif is of multiple order

(Figure 37).

Figure 37. Crystal structures of complexes 26–28.

3.3.2 CYANIDE-BRIDGED DI AND TRINUCLEAR COMPLEXES

The cyanide ligand was used to form bridged metal compounds with higher nuclearities.

Monometallic compounds with free terminal cyanide functions were used to build

dinuclear homo-bimetallic coinage metal compounds [(MP3)CN(P3M)]+X- (M = Cu; X

= -CF3SO3 30, BF4 30a) (M = Ag; X- = BF4 31, B[C6H3(CF3)2]4 31a). These compounds

were constructed by reacting equimolar amounts of mononuclear compounds 1–3 with

corresponding metal salts at ambient temperature, using dichloromethane as a solvent.

In general, attempts to produce heteronuclear compounds were unsuccessful, only for

the combination of Au(I) and Ag(I) was the complex [(AuP3)CN(P3Ag)]+ (32)

synthesized. Furthermore, the hetero-trimetallic compound [(P3)Cu-NC-Au-CN-

Cu(P3)]+ 33 was obtained in good yield by treating the [Cu(P3)]+ ion, generated in situ

from P3 and [Cu(NCMe)4]+, with K[Au(CN)2] (Scheme 3).

Intense IR vibrational bands observed between 2126 and 2172 cm-1 in the spectra of

compounds 30–33 confirm the presence of cyanide C≡N groups. The stretching

46

frequencies of the bridging cyanides C≡N display higher wavenumbers than the terminal

ones in 1–3 (2108–2116 cm-1). The C≡N stretch of 33 at 2172 cm-1, clearly indicates the

coordination of the Au[CN]2 motif to the Cu metal ions. These IR frequencies were in

good agreement with those of reported cyanide compounds.166-168

X-ray crystallographic analysis was performed to characterize compounds 30 and 31.

Unfortunately, 32 and 33 did not produce crystals suitable for X-ray measurements. In

compounds 30 and 31, two MP3 moieties were connected through the CN linker resulting

in a linear arrangement. The coordination geometries of the metal centers in 30 and 31

were generally similar to their precursor compounds, 1 and 2, respectively. No

significant differences were observed between the MP3 fragments in 1 and in bimetallic

complex 30. In the case of dinuclear Ag(I) compound 31, the central Ag–P bond is

significantly longer than the terminal ones and the corresponding bond in the

mononuclear complex, 2. In structures 30 and 31, the counterions behave as bridges

connecting the neighboring cationic units through a system of hydrogen bonds (Figure

38).

Figure 38. Molecular view of complex 31 with BF4– counter ions.

In the 31P NMR spectrum of the dinuclear Cu(I) compound in solution, two different sets

of signals were observed. This is possibly due to the unequal electronic properties of the

C and N atoms of the cyanide ligand, which affect the shielding of the phosphorus nuclei

and differentiate the Cu(P3)-C and Cu(P3)–N moieties (Figure 39). In contrast, the 31P

NMR spectrum of the dinuclear Ag(I) complex is an example of a single A2B spin system

with a well resolved splitting pattern due to the presence of the two silver isotopes, 107Ag

and 109Ag, with characteristic coupling constant values J(PB–107Ag) 245 Hz, J(PB–109Ag)

282 Hz; J(PA–107Ag) 138 Hz, J(PA–109Ag) 160 Hz). This spectral pattern indicates a small

difference in the shielding of P atoms within the Ag(P3) units by the C and N functions.

Two broad signals were detected for the trimetallic complex 33, their JPP values are

similar to those of dinuclear copper compound 30.

47

Figure 39. 31P{1H} NMR spectrum of 30, CD2Cl2, 298 K.

The 31P NMR spectrum of 32 shows that several species exist in a dynamic equilibrium

in solution. The phase purity of crystalline compound 32 was confirmed by

photophysical data, which were completely different from those of compounds 2 and 31.

Additionally, the complete assignment of the 1H NMR data for compounds 30, 31, and

33 is consistent with the solid-state structures.

Figure 40. ESI-MS of the complexes 30–33.

In the ESI-MS spectra, signals at m/z 1412.23, 1500.18, 1635.20, and 1590.24 correspond

to singly charged cations of compounds 30–33, respectively, and provide clear evidence

of the existence of these species in solution (Figure 40).

3.3.3 ALKYNYL-BRIDGED DI AND TRINUCLEAR COMPLEXES

In this study, di and tridentate alkynyl ligands were used to assemble the homo bi- and

trimetallic compounds [{(P3)CuC2}2R)] (R = -(C6H4)-n; n = 1 34, n = 2 35, n = 3 36),

[{(P3)CuC2}3R)] (R = 1,3,5-(C6H4)3-C6H3 37, 1,3,5-(C6H4-4-C2C6H4)3-C6H3 38)

(Scheme 3), which were prepared in a similar manner to the mononuclear alkynyl series.

The stereochemistry of the alkynyl spacers resulted in the formation of linear and star-

shaped neutral complexes.

48

The 31P NMR spectra of compounds 34–38 display one set of resonances, which

indicates a symmetrical arrangement of the complexes in solution, and therefore the

equivalence of the CuP3 fragments. The A2B spin system pattern and the values of

chemical shifts were similar to those of the mononuclear complexes 19–23. The 1H NMR

signals of the alkynyl spacers and tridentate phosphine ligand are clearly separated and

were assigned in agreement with the suggested stereochemistry. For example, the proton

spectrum for compound 38 (Figure 41) is consistent with the C3v symmetry point group

of the idealized geometric arrangement. Overall, the NMR data analyses for the alkynyl

series, 34–38, were in good agreement with the proposed structures.

Figure 41 31P{1H} (top) and 400 MHz 1H-1H COSY (bottom) NMR spectra of

complex 38 (CD2Cl2, 298 K).

49

3.4 PHOTOPHYSICAL PROPERTIES OF DI- AND TRINUCLEAR COMPLEXES

This section first describes the photophysical properties of bimetallic thiocyanate

complexes 24, 25, and 27, secondly, those of bi- and trimetallic cyanide complexes 30–

33, and finally, those of bi- and trimetallic alkynyl complexes 34–38, in the solid state.

The others were not measured due to their weak emission, both in the solid state and in

solution. Furthermore, the optical properties of compounds 30–33 were studied in

degassed solution, at 298 K.

The bimetallic compounds 24, 25, and 27 exhibit broad emission bands from blue (448

nm) to yellow-orange (571 nm) in color, which thus cover a wide range of the energies

of the visible spectrum (Figure 42a). The excited states for 24 and 25 were assigned as

(M+L´)LCT in character using computational analysis; the charge transfer involved a

mixture of d(Cu) → phosphine and SCN → phosphine transitions. The L´LCT

contribution is higher in comparison to that of the MLCT in silver complex 27. The

dependencies of lifetime on temperature confirm the TADF properties of these

compounds (Figure 42b). In particular, compound 27 has the longest lifetime (12 µs), at

298 K, among the bimetallic compounds (Table 7).

Figure 42. a) Normalized solid-state excitation and emission spectra of 24, 25, and 27 at 298 K

(solid line) 77 K (dashed line) (appearance of these compounds under UV light depicted in the

inset picture). b) Temperature dependence of decay times for 24, 25, and 27.

A small hypsochromic shift in the emissions of 30 and 31 and a significant bathochromic

shift in the emission of 33 were observed compared with those of mononuclear

compounds 1 and 2. The emission maximum of heterobimetallic compound 32 (λem =

590 nm) was positioned between those of Ag (λem = 525 nm) and Au (λem = 640 nm)

monomeric compounds 2 and 3 (Table 7). The different emission maximum and decay

time of 32 compared with those of 2 and 31 suggested that the crystalline sample of 32

contains only the Au–Ag heterometallic compound without appreciable quantities of

admixtures 2 and 31. A significant decrease in the quantum yields and lifetimes for 30–

33 was observed, compared to those of monomeric compounds 1–3. As was the case for

the mononuclear complexes, MLCT character was assigned to the excited states of 30–

33.

50

Table 7 The photophysical properties of homometallic complexes 24, 25, 27, and 30–38, at 298

K and 77 K, in the solid state.

298K 77K

No λex,

nm

λem,

nm

Ф,

%

τav, a

μs

λex,

nm

λem,

nm

τobs, a

μs

24 370 571 14 2 340, 400 571 118

25 310, 365 448 15 3 341 452 628

27 332 505 35 12 323 472 1701

30 405 520 0 1 ns

31 405 510 15 6

32 450 590 28 3

33 415 545 21 6

34 424 603 3 2 401 540sh, 581, 635 50

35 341, 441 616 1 2 426 556, 642 13

36 347, 441 629 0.6 2 426 574, 622, 683 -

37 393 638 2 1 426 530, 575sh, 640 166

38 313, 483 560 ~0.1 0.3 442 524, 570, 607,

647sh -

a The average emission lifetime for the two exponential decay was calculated using τav = (A1τ12 +

A2τ22)/(A1τ1 + A2τ2); Ai = weight of the i exponent.

Remarkably, crystalline 30 showed an appreciable sensitivity to O2, which caused strong

emission quenching; when exposed to O2 (1 atm), the emission intensity decreased by

99.05% (Figure 43). This behavior can be explained by the presence of void space in the

crystalline material, which allows O2 to penetrate into the bulk solid and collisionally

quench the luminescence.11, 105 As this sensing ability depends on the morphology of the

solid, sample 30a, with BF4– as the counterion, was synthesized analogously to 30, which

contains the CF3SO3– anion.

Both crystalline compounds are strong emitters under an inert atmosphere or under

vacuum (λ = 520 nm, τobs = 6 µs for 30 and 9 µs for 30a). In contrast, they are very

weakly luminescent in air, with lower lifetimes of 45 ns and 1 ns for 30 and 2 µs and 58

ns for 30a. The emission behavior was monitored under repeated variation of the

concentration of O2 in N2 to determine the reversibility of the oxygen sensing response

and the stability of the materials (Figure 43).

51

Figure 43. Emission spectra of complexes 30 (a) and 30a (b) under different concentrations of

O2. (c and d) Corresponding SV plots of 30 and 30a. (e and f) Intensity-response during

variation between 1 atm of N2 and 1 atm of O2.

The emission intensity of 30 is quenched by up to 99.05% at an O2 pressure of 1 atm,

which is higher compared to the value reported for [Cu(CN-xylyl)2(dmp)]tfpb, (dmp =

2,9-dimethyl-1,10-phenanthroline; CN-xylyl = 2,6-dimethylphenylisocyanide) copper

compound107 but lower than that of the copper azolate system.13 The Stern–Volmer plot

of the intensity versus the molar concentration of oxygen is not linear, presumably due

to the heterogeneity of the sample, and can be fitted using a two-site model. The

sensitivity of compound 30 to O2 (Ksv = 319 atm-1) is three times better than those

previously reported for mononuclear copper complexes (Ksv = 96 atm-1).107 The

sensitivity of 30a (Ksv = 639 cm-1) is twice that of compound 30 (Figure 43).

Similar to 30 and 30a, emission quenching by O2 was observed for disilver compound

31a, with the [B(C6H3(CF3)2]4 counter ion (Figure 44). The bulkier counter ion was

selected to prepare non-crystalline material with improved uniformity, significant

porosity, and low density. The quenching constant of 31a, Ksv1 = 47.6 atm-1, is higher

compared to those of silver nanoparticles containing Pd-porphyrin169 and Ru170

complexes, but lower than that reported for a silver cluster based metal-organic

framework.14 The large quenching constant and significant stability of 31a allowed this

complex to be employed in the fabrication of a low-cost, paper-based glucose sensor,

which permits its the detection of Glucose at physiologically important concentrations

in human blood and urine samples, with a fast response time (10 s) and good selectivity.

52

Figure 44. The effect of different O2(g) mole fractions in nitrogen on the responses of 31a on

paper (solid line). λex = 405 nm (left). Stern–Volmer plot for the oxygen quenching of 31a

(right).

In degassed solution, compounds 30–33 have higher quantum yields, between 1.0 and

2.3 x 10-3 %, with a hypsochromic shift compared to those of homometallic series 1–3.

By extending the alkynyl ligands in the di- and trinuclear series of compounds, 34–38,

the emission bands were shifted towards the red region of 560–638 nm and the intensity

was varied between approximately 0.1 and 2.6% (Table 7). The lowered quantum

efficiencies, compared to those of the mononuclear analogues, are tentatively explained

by the increasing size of the alkynyl backbone, which reduced the rate of radiative decay.

The lowest lying triplet excited states for compounds 34–38 were assigned as ILCT type

with mixed MLCT/LLCT character; the largest contributions from the copper metal

atom and the phosphine ligand were predicted for dinuclear compound 34 (Figure 45).

Figure 45. a) Electron density difference plots for the lowest energy triplet emission (T1 → S0)

of the Cu(I) complexes 34 and 37 (isovalue 0.002 a.u.). During the electronic transition, the

electron density increases in the blue areas and decreases in the red areas.

53

4. CONCLUSIONS

The research presented in this thesis focused on the synthesis and photophysical studies

of novel series of copper and silver coordination complexes 1–38, based on

oligophosphine ligands.

With the aim of developing new luminophores, sterically demanding organophosphorus

ligands were employed for molecular construction. This approach, in general, allowed

the preparation of stereochemically rigid compounds, which were capable of efficient

room temperature solid state emission. Chelating tri- and tetradentate ligands P3/P4,

rarely previously encountered in the coordination chemistry of coinage metals, were

successfully used as key building blocks to generate a family of mononuclear complexes

[(P3/P4)M(X)] (X = halides, CN, SCN, alkynyls), which were synthesized using

straightforward one step process utilizing commercially available metal salts, MX, or

terminal alkynes. Notably, the latter species included the first examples of monometallic

alkynyl Cu(I) species.

The variation of the anionic ligands, X, proved to have an substantial effect on the

photophysical behavior of these luminophores. Thus, in the case of the copper alkynyl

compounds, the different localizations of the lowest excited singlet and triplet states, as

predicted by computational analysis, might be responsible for the low quantum yields

(Ф = 0.1–19%, 19–23) and a considerable red-shift of the emission (λem = 573–722 nm).

In contrast, changing the alkynyl group for cyanide dramatically improved the

efficiency of the luminescence, to 70% for copper and 87% for silver complexes; the

latter value was one of the highest among the silver emitters at the time of reporting. In

contrast, the comparison of the thiocyanate compounds and their isocyanoborate

SCN:B(C6F5)3 derivatives illustrated how the nature of the excited states and decay

times can be manipulated by altering the electronic properties of the ancillary groups.

Furthermore, the tetraphosphine derivatives, [(P4)M(SCN)], showed a pronounced

tendency to provide a diversity of solid forms, with a remarkable variation in emission

wavelengths achieved in 7 (λem = 525–630 nm) and 17 (λem = 505–625 nm).

Taking the advantage of the ambidentate nature of cyanide and thiocyanate groups, and

increasing the number of alkynyl groups in the organic ligands allowed the engineering

of bi- and trimetallic systems, which include [M(SCN)P2]2 dimers with [MSCN]2

metallacycles, linearly arranged cyanide [(MP3)2CN]+ and [{(MP3)2CN}2Au]+ species,

alkynyl-bridged linear [{(P3)CuC2}2R], and star-shaped [{(P3)CuC2}2R] complexes.

Importantly, the emission characteristics of cationic cyanide-bridged [(MP3)2CN]+

compounds exhibited significant sensitivity to molecular oxygen, which depended on

the morphology of the solid sample and reached a maximum in porous crystalline solids.

In addition, satisfactory sensitivity was realized in amorphous materials containing

bulky counter ions; this behavior was successfully employed in the fabrication of a

simple-to-prepare and cost-effective sensor to determine the glucose level in blood and

urine samples.

54

Overall, the described affordable luminescent metal complexes, which were easily

prepared from multidentate phosphines and readily available copper and silver

precursors, contribute to a promising approach to molecular materials, the optical

functionality of which can be effectively modulated on both the molecular and

macroscopic levels.

55

ACKNOWLEDGEMENTS

This research work was carried out at the Department of Chemistry, University of

Eastern Finland between 2014-2019. The financial support provided by the University

of Eastern Finland and the Academy of Finland is gratefully acknowledged. The author

also acknowledged the ERKO funding for the personal financial support.

First and foremost, I would like to express my sincere gratitude to my supervisor, Prof.

Igor Koshevoy for giving me the opportunity to work with his guidance and for his

invaluable advice, patience throughout my research life at UEF.

This thesis would not have been completed without additional support from the

collaborative research groups: Prof. Sergey Tunik (St. Petersburg State University),

Prof. Pi-Tai Chou (National Taiwan University), Prof. Antti Karttunen (Aalto

University). I would like to express my special thanks to Docent. Pipsa Hirva, Prof.

Janne Jänis making their contribution to the publications. I owe to my deepest gratitude

to Emeritus prof. Tapani Pakkanen for his advice to select my research area at UEF.

I would like to offer my sincere thanks to Prof. Axel Klein and Dr. Christope Lescop

for their reviews and permission to defend the thesis. I am grateful to Doc. Raija

Oilunkaniemi for accepting her role as an opponent.

I would particularly like to thank inorganic group members Andrey, Vasily, Minni, Toni

and Cecilia (master student, UEF) for their contribution to the publications. Also, I

would like to thank Ilya and others for their support and being for helpful during the

years. I am grateful to several persons at the department of chemistry, who helped me

during my studies. Especially, I thank Taina for assisting in the lab and microanalysis,

together with Päivi Inkinen, Tarja Virrantalo for supporting in chemical supply. I

appreciate Sirpa Jääskeläinen for the opportunity to meet the visitors from school. I am

also thankful to Mari Heiskanen, Sari Suvanto, Eija Faari-Kapanen, Katri Mustonen and

Leila Tiihonen for their administrative support. A special mention goes to Anish, Lin,

Mubin, Chiara, Paulina, Kristina and Muthu for their lively chatting and discussions.

I would like to convey my special thanks to all my friends for their invaluable bond

during my stay in Joensuu.

I would like to express my heartfelt thanks to my parents Chakkaradhari, Thayammal,

and family members: Madhavapriya, Janani, Bhavishya, Sathish, Raghavendran,

Chandra for their unfaltering source of love, encouragement and constant support every

step in my life. Finally, I must express my deepest gratitude to my beloved husband

Senthil, our prince Nikhilan and the little one who is yet to be born for their immense

support, no matter what. You have given me the courage and strength that have led my

accomplishments.

Gomathy Chakkaradhari

Joensuu 2019

56

5. REFERENCES

1. www.olympic.org.

2. Liu, Z.; Qiu, J.; Wei, F.; Wang, J.; Liu, X.; Helander, M. G.; Rodney, S.; Wang, Z.; Bian,

Z.; Lu, Z.; Thompson, M. E.; Huang, C., Simple and High Efficiency Phosphorescence

Organic Light-Emitting Diodes with Codeposited Copper(I) Emitter. Chem. Mater. 2014,

26 (7), 2368-2373.

3. Minaev, B.; Baryshnikov, G.; Agren, H., Principles of phosphorescent organic light emitting

devices. Phys. Chem. Chem. Phys. 2014, 16 (5), 1719-1758.

4. Dumur, F., Recent advances in organic light-emitting devices comprising copper

complexes: A realistic approach for low-cost and highly emissive devices? Org. Electron.

2015, 21, 27-39.

5. Zhang, Q.; Zhou, Q.; Cheng, Y.; Wang, L.; Ma, D.; Jing, X.; Wang, F., Highly Efficient

Green Phosphorescent Organic Light-Emitting Diodes Based on CuI Complexes. Adv.

Mater. 2004, 16 (5), 432-436.

6. Moudam, O.; Kaeser, A.; Delavaux-Nicot, B.; Duhayon, C.; Holler, M.; Accorsi, G.;

Armaroli, N.; Seguy, I.; Navarro, J.; Destruel, P.; Nierengarten, J. F., Electrophosphorescent

homo- and heteroleptic copper(I) complexes prepared from various bis-phosphine ligands.

Chem. Commun. 2007, (29), 3077-3079.

7. Jia, W. L.; McCormick, T.; Tao, Y.; Lu, J.-P.; Wang, S., New Phosphorescent Polynuclear

Cu(I) Compounds Based on Linear and Star-Shaped 2-(2‘-Pyridyl)benzimidazolyl

Derivatives:  Syntheses, Structures, Luminescence, and Electroluminescence. Inorg. Chem.

2005, 44 (16), 5706-5712.

8. Hsu, C. W.; Lin, C. C.; Chung, M. W.; Chi, Y.; Lee, G. H.; Chou, P. T.; Chang, C. H.; Chen,

P. Y., Systematic investigation of the metal-structure-photophysics relationship of emissive

d10-complexes of group 11 elements: the prospect of application in organic light emitting

devices. J. Am. Chem. Soc. 2011, 133 (31), 12085-12099.

9. Armaroli, N.; Accorsi, G.; Holler, M.; Moudam, O.; Nierengarten, J.-F.; Zhou, Z.; Wegh,

R. T.; Welter, R., Highly Luminescent CuI Complexes for Light-Emitting Electrochemical

Cells. Adv. Mater. 2006, 18 (10), 1313-1316.

10. Yang, C.-H.; Beltran, J.; Lemaur, V.; Cornil, J.; Hartmann, D.; Sarfert, W.; Fröhlich, R.;

Bizzarri, C.; De Cola, L., Iridium Metal Complexes Containing N-Heterocyclic Carbene

Ligands for Blue-Light-Emitting Electrochemical Cells. Inorg. Chem. 2010, 49 (21), 9891-

9901.

11. Smith, C. S.; Mann, K. R., Void Space Containing Crystalline Cu(I) Phenanthroline

Complexes As Molecular Oxygen Sensors. Chem. Mater. 2009, 21 (21), 5042-5049.

12. Smith, C. S.; Branham, C. W.; Marquardt, B. J.; Mann, K. R., Oxygen Gas Sensing by

Luminescence Quenching in Crystals of Cu(xantphos)(phen)+ Complexes. J. Am. Chem.

Soc. 2010, 132 (20), 14079-14085.

13. Liu, X.; Sun, W.; Zou, L.; Xie, Z.; Li, X.; Lu, C.; Wang, L.; Cheng, Y., Neutral cuprous

complexes as ratiometric oxygen gas sensors. Dalton Trans. 2012, 41 (4), 1312-1319.

57

14. Huang, R.-W.; Wei, Y.-S.; Dong, X.-Y.; Wu, X.-H.; Du, C.-X.; Zang, S.-Q.; Mak, T. C. W.,

Hypersensitive dual-function luminescence switching of a silver-chalcogenolate cluster-

based metal–organic framework. Nat. Chem. 2017, 9, 689-697.

15. Baralle, A.; Fensterbank, L.; Goddard, J.-P.; Ollivier, C., Aryl Radical Formation by

Copper(I) Photocatalyzed Reduction of Diaryliodonium Salts: NMR Evidence for a

CuII/CuI Mechanism. Chem. Eur. J. 2013, 19 (33), 10809-10813.

16. Medina-Rodríguez, S.; Orriach-Fernández, F. J.; Poole, C.; Kumar, P.; de la Torre-Vega,

Á.; Fernández-Sánchez, J. F.; Baranoff, E.; Fernández-Gutiérrez, A., Copper(I) complexes

as alternatives to iridium(III) complexes for highly efficient oxygen sensing. Chem.

Commun. 2015, 51 (57), 11401-11404.

17. Tang, X.-J.; Dolbier, W. R., Efficient Cu-catalyzed Atom Transfer Radical Addition

Reactions of Fluoroalkylsulfonyl Chlorides with Electron-deficient Alkenes Induced by

Visible Light. Angew. Chem. Int. Ed. 2015, 54 (14), 4246-4249.

18. Yang, Q.; Dumur, F.; Morlet-Savary, F.; Poly, J.; Lalevée, J., Photocatalyzed Cu-Based

ATRP Involving an Oxidative Quenching Mechanism under Visible Light. Macromolecules

2015, 48 (7), 1972-1980.

19. Garra, P.; Dumur, F.; Mokbel, H.; Monnier, V.; Morlet-Savary, F.; Dietlin, C.; Gigmes, D.;

Fouassier, J.-P.; Lalevée, J., New Synthetic Route to an Highly Efficient Photoredox

Catalyst by Mechanosynthesis. ACS Omega 2018, 3 (9), 10938-10944.

20. Industrial inorganic chemicals and productions. Wiley-VCH: 1998; Vol. 2.

21. Sahoo Subash, C.; Kataria, R.; Mehta, S. K., 10. Copper and its complexes: A

pharmaceutical perspective. In Chemical Drug Design, 2016; pp 215-242.

22. Ribas, G. J., Coordination chemistry. Wiley-VCH: 2008; p 1-600.

23. Barbieri, A.; Accorsi, G.; Armaroli, N., Luminescent complexes beyond the platinum group:

the d10 avenue. Chem. Commun. 2008, (19), 2185-2193.

24. Johnson, N. A.; Southerland, M. R.; Youngs, W. J., Recent Developments in the Medicinal

Applications of Silver-NHC Complexes and Imidazolium Salts. Molecules 2017, 22 (8),

1263-1283.

25. Cariati, E.; Lucenti, E.; Botta, C.; Giovanella, U.; Marinotto, D.; Righetto, S., Cu(I) hybrid

inorganic–organic materials with intriguing stimuli responsive and optoelectronic

properties. Coord. Chem. Rev. 2016, 306, 566-614.

26. Ziolo, R. F.; Lipton, S.; Dori, Z., The photoluminescence of phosphine complexes of d10

metals. J. Chem. Soc. D 1970, (17), 1124-1125.

27. Blaskie, M. W.; McMillin, D. R., Photostudies of copper(I) systems. 6. Room-temperature

emission and quenching studies of [Cu(dmp)2]+. Inorg. Chem. 1980, 19 (11), 3519-3522.

28. Allison, J. B.; Becker, R. S., Effect of metal atom perturbations on the luminescent spectra

of porphyrins. J. Chem. Phys. 1960, 32 (5), 1410-1417.

29. Marinchik, V. K.; Belous, V. M.; Bugrienko, V. I., Influence of temperature on the

luminescence and photoelectret state of silver halides. Sov. Phys. Crystallogr. 1970, 14 (6),

880-883.

58

30. Shang, R.; Ilies, L.; Nakamura, E., Iron-Catalyzed Ortho C–H Methylation of Aromatics

Bearing a Simple Carbonyl Group with Methylaluminum and Tridentate Phosphine Ligand.

J. Am. Chem. Soc. 2016, 138 (32), 10132-10135.

31. Zank, J.; Schier, A.; Schmidbaur, H., Aurophilicity-impaired internal molecular motion of

trinuclear gold(I) complexes J. Chem. Soc., Dalton Trans. 1998, (3), 323-324.

32. Schreiter, W. J.; Monteil, A. R.; Peterson, M. A.; McCandless, G. T.; Fronczek, F. R.;

Stanley, G. G., Improved synthesis of a trisphosphine ligand and crystallographic

characterization of the ligand and nickel thiocyanate complex. Polyhedron 2013, 58, 171-

178.

33. Craig, D.; Roberts, N.; Tanswell, J., The ortho Metalation of N,N,N',N'-Tetramethyl-P-

phenyl-phosphonothioic Diamide. Aust. J. Chem. 1990, 43 (9), 1487-1496.

34. Miyata, K.; Hasegawa, Y.; Kuramochi, Y.; Nakagawa, T.; Yokoo, T.; Kawai, T.,

Characteristic Structures and Photophysical Properties of Nine-Coordinate Europium(III)

Complexes with Tandem-Connected Tridentate Phosphane Oxide Ligands. Eur. J. Inorg.

Chem. 2009, 2009 (32), 4777-4785.

35. Derrah, E. J.; Ladeira, S.; Bouhadir, G.; Miqueu, K.; Bourissou, D., Original phenyl-P(O)

bond cleavage at palladium(0): a combined experimental and computational study. Chem.

Commun. 2011, 47 (30), 8611-8613.

36. Derrah, E. J.; Martin, C.; Ladeira, S.; Miqueu, K.; Bouhadir, G.; Bourissou, D.,

Coordination of a diphosphine–phosphine oxide to Au, Ag and Rh: when polyfunctionality

rhymes with versatility. Dalton Trans. 2012, 41 (47), 14274-14280.

37. Martin, C.; Mallet-Ladeira, S.; Miqueu, K.; Bouhadir, G.; Bourissou, D., Combined

Experimental/Computational Study of Iridium and Palladium Hydride PP(O)P Pincer

Complexes. Organometallics 2014, 33 (2), 571-577.

38. Fox, M. A.; Chandler, D. A., A semiconductive nickel--phosphine coordination polymer.

Adv. Mater. 1991, 3 (7‐8), 381-385.

39. McFarlane, H. C. E.; McFarlane, W., Polyphosphorus ligands—V. The synthesis,

phosphorus-31 NMR spectra and conformations of the polykis(diphenylphosphino) benzens

(Ph2P)nC6H6−n (n = 1–4). Polyhedron 1988, 7 (19), 1875-1879.

40. Kongprakaiwoot, N.; Luck, R. L.; Urnezius, E., New synthetic route to polyphosphine

ligands bearing 1,2,4,5-tetrakis(phosphino)benzene framework: structural characterizations

of 1,4-(PPh2)2-2,5-(PR2)2-C6F2 (R=Ph, iPr, Et). J. Organomet. Chem. 2004, 689 (21), 3350-

3356.

41. Eller, P. G.; Meek, D. W., Syntheses of new tetrafluoroaryl derivatives of phosphorus and

sulfur. J. Organomet. Chem. 1970, 22 (3), 631-636.

42. Hartley, J. G.; Venanzi, L. M.; Goodall, D. C., The Preparation and Complex-forming

Properties of One Tritertiary and One Tetratertiary Phosphine. J. Chem. Soc. 1963, 3930-

3936.

43. Dawson, J. W.; Venanzi, L. M., Phosphorus-31 Nuclear Magnetic Resonance Studies of

Coordination Compounds. I. The Stereochemistry of Some Complexes with Multidentate

Ligands. J. Am. Chem. Soc. 1968, 7229-7233.

59

44. Bauer, R. C.; Gloaguen, Y.; Lutz, M.; Reek, J. N. H.; de Bruin, B.; van der Vlugt, J. I.,

Pincer ligands with an all-phosphorus donor set: subtle differences between rhodium and

palladium. Dalton Trans. 2011, 40 (35), 8822-8829.

45. Wassenaar, J.; Siegler, M. A.; Spek, A. L.; de Bruin, B.; Reek, J. N.; van der Vlugt, J. I.,

Versatile new C3-symmetric tripodal tetraphosphine ligands; structural flexibility to

stabilize CuI and RhI species and tune their reactivity. Inorg. Chem. 2010, 49 (14), 6495-

6508.

46. Ray, M. J.; Randall, R. A.; Arachchige, K. S.; Slawin, A. M.; Buhl, M.; Lebl, T.; Kilian, P.,

Synthetic, structural, NMR, and computational study of a geminally bis(peri-substituted)

tridentate phosphine and its chalcogenides and transition-metal complexes. Inorg. Chem.

2013, 52 (8), 4346-4359.

47. Bowmaker, G. A.; Hanna, J. V.; King, S. P.; Marchetti, F.; Pettinari, C.; Pizzabiocca, A.;

Skelton, B. W.; Sobolev, A. N.; Tăbăcaru, A.; White, A. H., Complexes of Copper(I)

Thiocyanate with Monodentate Phosphine and Pyridine Ligands and theP(,N)-Donor

Diphenyl(2-pyridyl)phosphine. Eur. J. Inorg. Chem. 2014, 2014 (35), 6104-6116.

48. Hardt, H. D.; Pierre, A., Fluorescence thermochromism and symmetry of copper(I)

complexes. Inorg. Chim. Acta 1977, 25, L59-L60.

49. De Ahna, H. D.; Hardt, H. D., Fluoreszenz und Fluoreszenz-Thermochromie bei Alkyl-

pyridinokupfer(I)-Halogeniden. Z. Anorg. Allg. Chem. 1972, 387 (1), 61-71.

50. Gupta, A. K.; Orthaber, A., Alkynyl Coinage Metal Clusters and Complexes-Syntheses,

Structures, and Strategies. Chem. Eur. J. 2018, 24 (30), 7536-7559.

51. Ford, C. P.; Cariati, E.; Bourassa, J., Photoluminescence Properties of Multinuclear

Copper(I) Compounds. Chem. Rev. 1999, 99, 3625-3647.

52. Yersin, H.; Czerwieniec, R.; Shafikov, M. Z.; Suleymanova, A. F., TADF Material Design:

Photophysical Background and Case Studies Focusing on CuI and AgI Complexes. Chem.

Phys. Chem. 2017, 18 (24), 3508-3535.

53. Shafikov, M. Z.; Suleymanova, A. F.; Czerwieniec, R.; Yersin, H., Design Strategy for

Ag(I)-Based Thermally Activated Delayed Fluorescence Reaching an Efficiency

Breakthrough. Chem. Commun. 2017, 29 (4), 1708-1715.

54. Chen, J.; Teng, T.; Kang, L.; Chen, X. L.; Wu, X. Y.; Yu, R.; Lu, C. Z., Highly Efficient

Thermally Activated Delayed Fluorescence in Dinuclear Ag(I) Complexes with a Bis-

Bidentate Tetraphosphane Bridging Ligand. Inorg. Chem. 2016, 55 (19), 9528-9536.

55. Czerwieniec, R.; Leitl, M. J.; Homeier, H. H. H.; Yersin, H., Cu(I) complexes – Thermally

activated delayed fluorescence. Photophysical approach and material design. Coord. Chem.

Rev. 2016, 325, 2-28.

56. Deaton, J. C.; Switalski, S. C.; Kondakov, D. Y.; Young, R. H.; Pawlik, T. D.; Giesen, D.

J.; Harkins, S. B.; Miller, A. J. M.; Mickenberg, S. F.; Peters, J. C., E-Type Delayed

Fluorescence of a Phosphine-Supported Cu2(μ-NAr2)2 Diamond Core: Harvesting Singlet

and Triplet Excitons in OLEDs. J. Am. Chem. Soc. 2010, 132 (27), 9499-9508.

57. Hashimoto, M.; Igawa, S.; Yashima, M.; Kawata, I.; Hoshino, M.; Osawa, M., Highly

efficient green organic light-emitting diodes containing luminescent three-coordinate

copper(I) complexes. J. Am. Chem. Soc. 2011, 133 (27), 10348-51031.

60

58. Czerwieniec, R.; Yu, J.; Yersin, H., Blue-light emission of Cu(I) complexes and singlet

harvesting. Inorg. Chem. 2011, 50 (17), 8293-8301.

59. Chen, X.-L.; Yu, R.; Zhang, Q.-K.; Zhou, L.-J.; Wu, X.-Y.; Zhang, Q.; Lu, C.-Z., Rational

Design of Strongly Blue-Emitting Cuprous Complexes with Thermally Activated Delayed

Fluorescence and Application in Solution-Processed OLEDs. Chem. Mater. 2013, 25 (19),

3910-3920.

60. Miller, M. T.; Karpishin, T. B., Phenylethynyl Substituent Effects on the Photophysics and

Electrochemistry of [Cu(dpp)2]+ (dpp = 2,9-Diphenyl-1,10-phenanthroline). Inorg. Chem.

1999, 38 (23), 5246-5249.

61. Phifer, C. C.; McMillin, D. R., The basis of aryl substituent effects on charge-transfer

absorption intensities. Inorg. Chem. 1986, 25 (9), 1329-1333.

62. Ichinaga, A. K.; Kirchhoff, J. R.; McMillin, D. R.; Dietrich-Buchecker, C. O.; Marnot, P.

A.; Sauvage, J. P., Charge-transfer absorption and emission of Cu(NN)2+ systems. Inorg.

Chem. 1987, 26 (25), 4290-4292.

63. Cunningham, C. T.; Cunningham, K. L. H.; Michalec, J. F.; McMillin, D. R., Cooperative

Substituent Effects on the Excited States of Copper Phenanthrolines. Inorg. Chem. 1999, 38

(20), 4388-4392.

64. Everly, R. M.; McMillin, D. R., Concentration-dependent lifetimes of cu(NN)+2 systems:

exciplex quenching from the ion pair state. Photochem. Photobiol. 1989, 50 (6), 711-716.

65. Armaroli, N., Photoactive mono- and polynuclear Cu(I)–phenanthrolines. A viable

alternative to Ru(I)–polypyridines? Chem. Soc. Rev. 2001, 30 (2), 113-124.

66. Buckner, M. T.; McMillin, D. R., Photoluminescence from copper(I) complexes with low-

lying metal-to-ligand charge transfer excited states. J. Chem. Soc., Chem. Commun. 1978,

(17), 759-761.

67. Rader, R. A.; McMillin, D. R.; Buckner, M. T.; Matthews, T. G.; Casadonte, D. J.; Lengel,

R. K.; Whittaker, S. B.; Darmon, L. M.; Lytle, F. E., Photostudies of [Cu(bpy)(PPh3)2]+,

[Cu(Phen)(PPh3)2]+, and [Cu(dmp)(PPh3)2]+, in solution and in rigid, low-temperature

glasses. Simultaneous multiple emissions from intraligand and charge-transfer states. J. Am.

Chem. Soc. 1981, 103 (19), 5906-5912.

68. Cuttell, D. G.; Kuang, S.-M.; Fanwick, P. E.; McMillin, D. R.; Walton, R. A., Simple Cu(I)

Complexes with Unprecedented Excited-State Lifetimes. J. Am. Chem. Soc. 2002, 124 (1),

6-7.

69. Saito, K.; Arai, T.; Takahashi, N.; Tsukuda, T.; Tsubomura, T., A series of luminescent

Cu(i) mixed-ligand complexes containing 2,9-dimethyl-1,10-phenanthroline and simple

diphosphine ligands. Dalton Trans. 2006, (37), 4444-4448.

70. Kuang, S.-M.; Cuttell, D. G.; McMillin, D. R.; Fanwick, P. E.; Walton, R. A., Synthesis and

Structural Characterization of Cu(I) and Ni(II) Complexes that Contain the Bis[2-

(diphenylphosphino)phenyl]ether Ligand. Novel Emission Properties for the Cu(I) Species.

Inorg. Chem. 2002, 41 (12), 3313-3322.

71. Howell, S. L.; Gordon, K. C., Spectroscopic and Density Functional Theory Studies of 1,10-

Phenanthroline, Its Radical Anion, and [Cu(Phen)(PPh3)2]+. J. Phys. Chem. A 2004, 108

(13), 2536-2544.

61

72. McCormick, T.; Jia, W.-L.; Wang, S., Phosphorescent Cu(I) Complexes of 2-(2‘-

pyridylbenzimidazolyl)benzene:  Impact of Phosphine Ancillary Ligands on Electronic and

Photophysical Properties of the Cu(I) Complexes. Inorg. Chem. 2006, 45 (1), 147-155.

73. Che, G.; Su, Z.; Li, W.; Chu, B.; Li, M.; Hu, Z.; Zhang, Z., Highly efficient and color-tuning

electrophosphorescent devices based on CuI complex. Appl. Phys. Lett. 2006, 89 (10),

103511-103513.

74. Slinker, J. D.; Rivnay, J.; Moskowitz, J. S.; Parker, J. B.; Bernhard, S.; Abruña, H. D.;

Malliaras, G. G., Electroluminescent devices from ionic transition metal complexes. J.

Mater. Chem. 2007, 17 (29), 2976-2988.

75. Czerwieniec, R.; Yersin, H., Diversity of Copper(I) Complexes Showing Thermally

Activated Delayed Fluorescence: Basic Photophysical Analysis. Inorg. Chem. 2015, 54 (9),

4322-4327.

76. Linfoot, C. L.; Leitl, M. J.; Richardson, P.; Rausch, A. F.; Chepelin, O.; White, F. J.; Yersin,

H.; Robertson, N., Thermally Activated Delayed Fluorescence (TADF) and Enhancing

Photoluminescence Quantum Yields of [CuI(diimine)(diphosphine)]+ Complexes—

Photophysical, Structural, and Computational Studies. Inorg. Chem. 2014, 53 (20), 10854-

10861.

77. Araki, H.; Tsuge, K.; Sasaki, Y.; Ishizaka, S.; Kitamura, N., Luminescence Ranging from

Red to Blue:  A Series of Copper(I)−Halide Complexes Having Rhombic {Cu2(μ-X)2} (X =

Br and I) Units with N-Heteroaromatic Ligands. Inorg. Chem. 2005, 44 (26), 9667-9675.

78. Ohara, H.; Kobayashi, A.; Kato, M., Simple and extremely efficient blue emitters based on

mononuclear Cu(I)-halide complexes with delayed fluorescence. Dalton Trans. 2014, 43

(46), 17317-17323.

79. Tsuboyama, A.; Kuge, K.; Furugori, M.; Okada, S.; Hoshino, M.; Ueno, K., Photophysical

Properties of Highly Luminescent Copper(I) Halide Complexes Chelated with 1,2-

Bis(diphenylphosphino)benzene. Inorg. Chem. 2007, 46 (6), 1992-2001.

80. Volz, D.; Zink, D. M.; Bocksrocker, T.; Friedrichs, J.; Nieger, M.; Baumann, T.; Lemmer,

U.; Bräse, S., Molecular Construction Kit for Tuning Solubility, Stability and Luminescence

Properties: Heteroleptic MePyrPHOS-Copper Iodide-Complexes and their Application in

Organic Light-Emitting Diodes. Chem. Mater. 2013, 25 (17), 3414-3426.

81. Leitl, M. J.; Kuchle, F. R.; Mayer, H. A.; Wesemann, L.; Yersin, H., Brightly blue and green

emitting Cu(I) dimers for singlet harvesting in OLEDs. J. Phys. Chem. A 2013, 117 (46),

11823-11836.

82. Lin, J. C. Y.; Huang, R. T. W.; Lee, C. S.; Bhattacharyya, A.; Hwang, W. S.; Lin, I. J. B.,

Coinage Metal−N-Heterocyclic Carbene Complexes. Chem. Rev. 2009, 109 (8), 3561-3598.

83. Wang, Z.; Zheng, C.; Wang, W.; Xu, C.; Ji, B.; Zhang, X., Synthesis, Structure, and

Photophysical Properties of Two Four-Coordinate Cu(I)-NHC Complexes with Efficient

Delayed Fluorescence. Inorg. Chem. 2016, 55 (5), 2157-2164.

84. Wang, Z.; Sun, X.; Fu, W.; Xu, C.; Ji, B., Four-coordinate Cu(I) complexes supported by

N-heterocyclic carbene ligands bearing electron-donating/withdrawing groups: Synthesis,

structures and photophysical properties. J. Lumin. 2018, 204, 618-625.

62

85. Gernert, M.; Müller, U.; Haehnel, M.; Pflaum, J.; Steffen, A., A Cyclic

Alkyl(amino)carbene as Two-Atom π-Chromophore Leading to the First Phosphorescent

Linear CuI Complexes. Chem. Eur. J. 2017, 23 (9), 2206-2216.

86. Hupp, B.; Nitsch, J.; Schmitt, T.; Bertermann, R.; Edkins, K.; Hirsch, F.; Fischer, I.; Auth,

M.; Sperlich, A.; Steffen, A., Stimulus-Triggered Formation of an Anion–Cation Exciplex

in Copper(I) Complexes as a Mechanism for Mechanochromic Phosphorescence. Angew.

Chem. Int. Ed. 2018, 57 (41), 13671-13675.

87. Lotito, K. J.; Peters, J. C., Efficient luminescence from easily prepared three-coordinate

copper(I) arylamidophosphines. Chem. Commun. 2010, 46 (21), 3690-3692.

88. Krylova, V. A.; Djurovich, P. I.; Whited, M. T.; Thompson, M. E., Synthesis and

characterization of phosphorescent three-coordinate Cu(I)–NHC complexes. Chem.

Commun. 2010, 46 (36), 6696-6698.

89. Krylova, V. A.; Djurovich, P. I.; Aronson, J. W.; Haiges, R.; Whited, M. T.; Thompson, M.

E., Structural and Photophysical Studies of Phosphorescent Three-Coordinate Copper(I)

Complexes Supported by an N-Heterocyclic Carbene Ligand. Organometallics 2012, 31

(22), 7983-7993.

90. Wing-Wah Yam, V.; Kam-Wing Lo, K.; Kit-Mai Fung, W.; Wang, C.-R., Design of

luminescent polynuclear copper(I) and silver(I) complexes with chalcogenides and

acetylides as the bridging ligands. Coord. Chem. Rev. 1998, 171, 17-41.

91. Montali, M.; Credi, A.; Prodi, L.; Gandolfi, M. T., Handbook of photochemistry. 2006.

92. Dong, Y.-B.; Sun, T.; Ma, J.-P.; Zhao, X.-X.; Huang, R.-Q., Ag(I) and Cu(II) Discrete and

Polymeric Complexes Based on Single- and Double-Armed Oxadiazole-Bridging Organic

Clips. Inorg. Chem. 2006, 45 (26), 10613-10628.

93. Wang, Y.; Ding, B.; Cheng, P.; Liao, D.-Z.; Yan, S.-P., Tuned Triazolatesilver(I)

Luminescent Complexes from Zero- to Three-Dimensionality Based on Bi- to Tetratopic

Bridged Ligands. Inorg. Chem. 2007, 46 (6), 2002-2010.

94. Li, Q.; Liu, X.; Fu, M.-L.; Guo, G.-C.; Huang, J.-S., Two luminescent alkali-silver

heterometallic sulfonates. Inorg. Chem. Commun. 2006, 359 (7), 2147-2153.

95. Kunkely, H.; Vogler, A., Can silver exert a heavy-atom effect in organic ligands? Intraligand

phosphorescence of Ag(binap)NO3 with binap=2,2′-bis (diphenylphosphino)-1,1′-

binaphthyl under ambient conditions. Inorg. Chem. Commun. 2006, 9 (8), 866-868.

96. Kunkely, H.; Vogler, A., Optical properties of Ag(tripod)X with tripod=1,1,1-tris(diphenyl-

phosphinomethyl)ethane and X−=Cl− and I−: Intraligand and ligand-to-ligand charge

transfer. Inorg. Chem. Commun. 2006, 359 (1), 388-390.

97. Osawa, M.; Hoshino, M., Photochemistry and photophysics of the tetrahedral silver(I)

complex with diphosphine ligands: [Ag(dppb)2]PF6 (dppb = 1, 2-

bis[diphenylphosphino]benzene). Chem. Commun. 2008, (47), 6384-6386.

98. Matsumoto, K.; Shindo, T.; Mukasa, N.; Tsukuda, T.; Tsubomura, T., Luminescent

mononuclear Ag(I)-bis(diphosphine) complexes: correlation between the photophysics and

the structures of mononuclear Ag(I)-bis(diphosphine) complexes. Inorg. Chem. 2010, 49

(3), 805-814.

63

99. Yersin, H.; Rausch, A. F.; Czerwieniec, R.; Hofbeck, T.; Fischer, T., The triplet state of

organo-transition metal compounds. Triplet harvesting and singlet harvesting for efficient

OLEDs. Coord. Chem. Rev. 2011, 255 (21-22), 2622-2652.

100. Yersin, H.; Leitl, M. J.; Czerwieniec, R., TADF for singlet harvesting: next generation

OLED materials based on brightly green and blue emitting Cu(I) and Ag(I) compounds.

SPIE Organic Photonics + Electronics 2014, 9183, 1-11.

101. Shafikov, M. Z.; Suleymanova, A. F.; Czerwieniec, R.; Yersin, H., Thermally Activated

Delayed Fluorescence from Ag(I) Complexes: A Route to 100% Quantum Yield at

Unprecedentedly Short Decay Time. Inorg. Chem. 2017, 56 (21), 13274-13285.

102. Hofbeck, T.; Yersin, H., The Triplet State of fac-Ir(ppy)3. Inorg. Chem. 2010, 49 (20), 9290-

9299.

103. Shafikov, M. Z.; Suleymanova, A. F.; Schinabeck, A.; Yersin, H., Dinuclear Ag(I) Complex

Designed for Highly Efficient Thermally Activated Delayed Fluorescence. J. Phys. Chem.

Lett. 2018, 9 (4), 702-709.

104. Wang, Y.; Li, B.; Liu, Y.; Zhang, L.; Zuo, Q.; Shi, L.; Su, Z., Highly sensitive oxygen

sensors based on Cu(I) complex–polystyrene composite nanofibrous membranes prepared

by electrospinning. Chem. Commun. 2009, (39), 5868-5870.

105. Wang, X.-d.; Wolfbeis, O. S., Optical methods for sensing and imaging oxygen: materials,

spectroscopies and applications. Chem. Soc. Rev. 2014, 43 (10), 3666-3761.

106. McGee, K. A.; Veltkamp, D. J.; Marquardt, B. J.; Mann, K. R., Porous Crystalline

Ruthenium Complexes Are Oxygen Sensors. J. Am. Chem. Soc. 2007, 129 (49), 15092-

15093.

107. Smith, C. S.; Mann, K. R., Exceptionally long-lived luminescence from

[Cu(I)(isocyanide)2(phen)]+ complexes in nanoporous crystals enables remarkable oxygen

gas sensing. J. Am. Chem. Soc. 2012, 134 (21), 8786-8789.

108. McGee, K. A.; Mann, K. R., Inefficient Crystal Packing in Chiral [Ru(phen)3](PF6)2 Enables

Oxygen Molecule Quenching of the Solid-State MLCT Emission. J. Am. Chem. Soc. 2009,

131 (5), 1896-1902.

109. Huo, C.; Zhang, H.; Zhang, H.; Zhang, H.; Yang, B.; Zhang, P.; Wang, Y., Synthesis and

Assembly with Mesoporous Silica MCM-48 of Platinum(II) Porphyrin Complexes Bearing

Carbazyl Groups:  Spectroscopic and Oxygen Sensing Properties. Inorg. Chem. 2006, 45

(12), 4735-4742.

110. Huynh, L.; Wang, Z.; Yang, J.; Stoeva, V.; Lough, A.; Manners, I.; Winnik, M. A.,

Evaluation of Phosphorescent Rhenium and Iridium Complexes in Polythionylphosphazene

Films for Oxygen Sensor Applications. Chem. Mater. 2005, 17 (19), 4765-4773.

111. DeRosa, M. C.; Mosher, P. J.; Yap, G. P. A.; Focsaneanu, K. S.; Crutchley, R. J.; Evans, C.

E. B., Synthesis, Characterization, and Evaluation of [Ir(ppy)2(vpy)Cl] as a Polymer-Bound

Oxygen Sensor. Inorg. Chem. 2003, 42 (16), 4864-4872.

112. Xu, J., A phosphorescent copper(I) complex: Synthesis, characterization, photophysical

property, and sensing performance towards molecular oxygen. Synth. Met. 2011, 161 (9-

10), 919-924.

64

113. Shi, L.; Li, B.; Yue, S.; Fan, D., Synthesis, photophysical and oxygen-sensing properties of

a novel bluish-green emission Cu(I) complex. Sens. Actuator B-Chem. 2009, 137 (1), 386-

392.

114. Kalyanasundaram, K.; Kiwi, J.; Grätzel, M., Hydrogen Evolution from Water by Visible

Light, a Homogeneous Three Component Test System for Redox Catalysis. Helv. Chim.

Acta 1978, 61 (7), 2720-2730.

115. Du, P.; Knowles, K.; Eisenberg, R., A Homogeneous System for the Photogeneration of

Hydrogen from Water Based on a Platinum(II) Terpyridyl Acetylide Chromophore and a

Molecular Cobalt Catalyst. J. Am. Chem. Soc. 2008, 130 (38), 12576-12577.

116. Okazaki, R.; Masaoka, S.; Sakai, K., Photo-hydrogen-evolving activity of

chloro(terpyridine)platinum(II): a single-component molecular photocatalyst. Dalton

Trans. 2009, (31), 6127-6133.

117. Hijazi, A.; Walther, M. E.; Besnard, C.; Wenger, O. S., Spectroscopy and photoredox

properties of soluble platinum(II) alkynyl complexes. Polyhedron 2010, 29 (2), 857-863.

118. Mak, C. S. K.; Wong, H. L.; Leung, Q. Y.; Tam, W. Y.; Chan, W. K.; Djurišić, A. B., The

use of sublimable chlorotricarbonyl bis(phenylimino)acenaphthene rhenium(I) complexes

as photosensitizers in bulk-heterojunction photovoltaic devices. J. Organomet. Chem. 2009,

694 (17), 2770-2776.

119. Jiang, W.; Liu, J.; Li, C., Photochemical hydrogen evolution catalyzed by trimetallic [Re–

Fe] complexes. Inorg. Chem. Commun. 2012, 16, 81-85.

120. Heussner, K.; Peuntinger, K.; Rockstroh, N.; Nye, L. C.; Ivanovic-Burmazovic, I.; Rau, S.;

Streb, C., Solution and solid-state interactions in a supramolecular ruthenium

photosensitizer–polyoxometalate aggregate. Chem. Commun. 2011, 47 (24), 6852-6854.

121. Luo, S.-P.; Mejía, E.; Friedrich, A.; Pazidis, A.; Junge, H.; Surkus, A.-E.; Jackstell, R.;

Denurra, S.; Gladiali, S.; Lochbrunner, S.; Beller, M., Photocatalytic Water Reduction with

Copper-Based Photosensitizers: A Noble-Metal-Free System. Angew. Chem. Int. Ed. 2013,

52 (1), 419-423.

122. Knorn, M.; Rawner, T.; Czerwieniec, R.; Reiser, O.,

[Copper(phenanthroline)(bisisonitrile)]+-Complexes for the Visible-Light-Mediated Atom

Transfer Radical Addition and Allylation Reactions. ACS Catal. 2015, 5 (9), 5186-5193.

123. McCullough, B. J.; Neyhouse, B. J.; Schrage, B. R.; Reed, D. T.; Osinski, A. J.; Ziegler, C.

J.; White, T. A., Visible-Light-Driven Photosystems Using Heteroleptic Cu(I)

Photosensitizers and Rh(III) Catalysts To Produce H2. Inorg. Chem. 2018, 57 (5), 2865-

2875.

124. Zank, J.; Schier, A.; Schmidbaur, H., Gold and silver cations in the “Procrustean Bed” of

the bis[2-(diphenylphosphino)phenyl]phenylphosphine ligand. Obervations and

conclusions. J. Chem Soc., Dalton Trans. 1999, 415-420.

125. Kobayashi, N.; Higashimura, H.; Takashi, K., Preparation of triphenylphosphine-silver

complexes and luminescent membrane containing silver complexes. Japan pat., 2011,

WO2011152358A1.

65

126. Kobayashi, N.; Higashimura, H.; Kaikoh, T., Preparation of bis(o-

diphenylphosphinophenyl)phenylphosphine-copper complexes for organic

electroluminescent devices Japan pat., 2012, WO2012144530A1.

127. Koshevoy, I. O.; Lin, C. L.; Karttunen, A. J.; Janis, J.; Haukka, M.; Tunik, S. P.; Chou, P.

T.; Pakkanen, T. A., Stepwise 1D growth of luminescent Au(I)-Ag(I) phosphine-alkynyl

clusters: synthesis, photophysical, and theoretical studies. Inorg. Chem. 2011, 50 (6), 2395-

2403.

128. Simpson, C. D.; Mattersteig, G.; Martin, K.; Gherghel, L.; Bauer, R. E.; Räder, H. J.;

Müllen, K., Nanosized Molecular Propellers by Cyclodehydrogenation of Polyphenylene

Dendrimers. J. Am. Chem. Soc. 2004, 126 (10), 3139-3147.

129. Jiang, J.-X.; Su, F.; Trewin, A.; Wood, C. D.; Niu, H.; Jones, J. T. A.; Khimyak, Y. Z.;

Cooper, A. I., Synthetic Control of the Pore Dimension and Surface Area in Conjugated

Microporous Polymer and Copolymer Networks. J. Am. Chem. Soc. 2008, 130 (24), 7710-

7720.

130. Pawlowski, V.; Knör, G.; Lennartz, C.; Vogler, A., Luminescence and Theoretical Studies

of Cu(tripod)X [tripod = 1,1,1-Tris(diphenylphosphanylmethyl)ethane; X– = Halide,

Thiophenolate, Phenylacetylide]. Eur. J. Inorg. Chem. 2005, 2005 (15), 3167-3171.

131. Paraskevas, A.; J., C. P.; Konstantinos, K.; C., T. A., Structural and Spectroscopic Properties

of New Copper(I) Complexes with 1,1,1‐Tris(diphenylphosphanylmethyl)ethane and

Heterocyclic Thiolates. Eur. J. Inorg. Chem. 2008, 2008 (32), 5029-5037.

132. Lin, Y.-Y.; Lai, S.-W.; Che, C.-M.; Fu, W.-F.; Zhou, Z.-Y.; Zhu, N., Structural Variations

and Spectroscopic Properties of Luminescent Mono- and Multinuclear Silver(I) and

Copper(I) Complexes Bearing Phosphine and Cyanide Ligands. Inorg. Chem. 2005, 44,

1511-1524.

133. Celik, M. A.; Dash, C.; Adiraju, V. A. K.; Das, A.; Yousufuddin, M.; Frenking, G.; Dias,

H. V. R., End-On and Side-On π-Acid Ligand Adducts of Gold(I): Carbonyl, Cyanide,

Isocyanide, and Cyclooctyne Gold(I) Complexes Supported by N-Heterocyclic Carbenes

and Phosphines. Inorg. Chem. 2013, 52 (2), 729-742.

134. Omondi, B.; Venter, G. J.; Roodt, A.; Meijboom, R., Isomorphism in monomeric 1:3

complexes of silver(I) salts with tri-p-tolylphosphine. Acta Crystallogr. B 2009, 65 (Pt 6),

699-706.

135. Di Nicola, C.; Effendy; Pettinari, C.; Skelton, B. W.; Somers, N.; White, A. H., The

structural definition of adducts of stoichiometry AgX:dppf (1:1)(n), X=simple anion,

dppf=bis(diphenylphosphino)ferrocene. Inorg. Chim. Acta 2005, 358 (3), 695-706.

136. Belyaev, A.; Dau, T. M.; Jänis, J.; Grachova, E. V.; Tunik, S. P.; Koshevoy, I. O., Low-

Nuclearity Alkynyl d10 Clusters Supported by Chelating Multidentate Phosphines.

Organometallics 2016, 35 (21), 3763-3774.

137. Belyaev, A.; Eskelinen, T.; Dau, T. M.; Ershova, Y. Y.; Tunik, S. P.; Melnikov, A. S.; Hirva,

P.; Koshevoy, I. O., Cyanide-Assembled d10 Coordination Polymers and Cycles: Excited

State Metallophilic Modulation of Solid-State Luminescence. Chem. Eur. J. 2017, 24 (6),

1404-1415.

138. Wu, b.; Wu, X. T.; Tian, X.; Sun, W.-H., Synthesis and circular dichroism spectra of

silver(I) complexes with R,R-DIOP (4R,5R-trans-4,5-bis[(diphenylphosphino)methyl]-

66

2,2-dimethyl-1,3- dioxalane): crystal structures of [AgCl(R,R-DIOP)]2·2CHCl3,

{[AgBr(R,R-DIOP)]2}2·CH2Cl2·2H2O, [AgI(R,R-DIOP)]2 and [AgSCN(R,R-DIOP)]2. J.

Organomet. Chem. 2001, 640, 57-64.

139. Yang, L.; Zhu, c.; Li, d., Di-µ-thiocyanato-bis{[1,2-bis(diisopropylphosphanyl)-1,2-

dicarba-closododecaborane]silver(I)}. Acta Crystallogr. E 2011, E67, m2.

140. Munro, O. Q.; Pearson, N., The isothiocyanate complex of triphenylborane forms an unusual

coordination polymer with [K(18-crown-6)]+, both in the solid state and in solution. Acta

Crystallogr. C 2003, C59, m407-m412.

141. Chan, K. C.; Chu, W. K.; Yiu, S. M.; Ko, C. C., Synthesis, characterization, photophysics

and electrochemical study of luminescent iridium(III) complexes with isocyanoborate

ligands. Dalton Trans. 2015, 44 (34), 15135-44.

142. Chu, W. K.; Wei, X. G.; Yiu, S. M.; Ko, C. C.; Lau, K. C., Strongly phosphorescent neutral

rhenium(I) isocyanoborato complexes: synthesis, characterization, and photophysical,

electrochemical, and computational studies. Inorg. Chem. 2015, 21 (6), 2603-2612.

143. Bowmaker, G. A.; Hanna, J. V.; Hart, R. D.; Healy, P. C.; King, S. P.; Marchetti, F.;

Pettinari, C.; Skelton, B. W.; Tabacaru, A.; White, A. H., Mechanochemical and solution

synthesis, X-ray structure and IR and 31P solid state NMR spectroscopic studies of

copper(I) thiocyanate adducts with bulky monodentate tertiary phosphine ligands. Dalton

Trans. 2012, 41 (25), 7513-7525.

144. Artem'ev, A. V.; Ryzhikov, M. R.; Taidakov, I. V.; Rakhmanova, M. I.; Varaksina, E. A.;

Bagryanskaya, I. Y.; Malysheva, S. F.; Belogorlova, N. A., Bright green-to-yellow emitting

Cu(I) complexes based on bis(2-pyridyl)phosphine oxides: synthesis, structure and effective

thermally activated-delayed fluorescence. Dalton Trans. 2018, 47 (8), 2701-2710.

145. Doux, M.; Ricard, L.; Le Floch, P.; Mézailles, N., Group 11 metal complexes of SPS-based

pincer ligands: Syntheses, X-ray structures and reactivity. Dalton Trans. 2004, (16), 2593-

2600.

146. Jarvis, A. G.; Whitwood, A. C.; Fairlamb, I. J. S., CuI complexes containing a multidentate

and conformationally flexible dibenzylidene acetone ligand (dbathiophos): Application in

catalytic alkene cyclopropanation. Dalton Trans. 2011, 40 (14), 3695-3702.

147. Tsukuda, T.; Miyoshi, R.; Esumi, A.; Yamagiwa, A.; Dairiki, A.; Matsumoto, K.;

Tsubomura, T., Sulfur transfer reaction from phosphine sulfides to phosphines assisted by

metal ions. Inorg. Chim. Acta 2012, 384, 149-153.

148. Cain, M. F.; Hughes, R. P.; Glueck, D. S.; Golen, J. A.; Moore, C. E.; Rheingold, A. L.,

Synthesis and Structure of Intermediates in Copper-Catalyzed Alkylation of

Diphenylphosphine. Inorg. Chem. 2010, 49 (17), 7650-7662.

149. Bruce, M. I.; Zaitseva, N. N.; Skelton, B. W.; Somers, N.; White, A. H., Crystal and

molecular structures of {Cu(μ-CCPh)(triphos)}2 [triphos=(PPh2CH2)3CMe]. Inorg. Chim.

Acta 2007, 360 (2), 681-685.

150. Yam, V. W.; Fung, W. K.-M.; Cheung, K.-K., Luminescence Behavior of Polynuclear

Alkynylcopper(I) Phosphines. J.Clust. Sci. 1999, 10, 37-64.

67

151. Chan, W.-H.; Zhang, Z.-Z.; Mak, T. C. W.; Che, C.-M., A highly luminescent tetranuclear

copper(I) cluster: structure and photophysical properties. J. Organomet. Chem. 1998, 556

(1), 169-172.

152. Lo, W.-Y.; Lam, C.-H.; Yam, V. W.-W.; Zhu, N.; Cheung, K.-K.; Fathallah, S.; Messaoudi,

S.; Le Guennic, B.; Kahlal, S.; Halet, J.-F., Synthesis, Photophysics, Electrochemistry,

Theoretical, and Transient Absorption Studies of Luminescent Copper(I) and Silver(I)

Diynyl Complexes. X-ray Crystal Structures of [Cu3(μ-dppm)3(μ3-η1-C⋮CC⋮CPh)2]PF6 and

[Cu3(μ-dppm)3(μ3-η1-C⋮CC⋮CH)2]PF6. J. Am. Chem. Soc. 2004, 126 (23), 7300-7310.

153. Osawa, M.; Kawata, I.; Ishii, R.; Igawa, S.; Hashimoto, M.; Hoshino, M., Application of

neutral d10 coinage metal complexes with an anionic bidentate ligand in delayed

fluorescence-type organic light-emitting diodes. J. Mater. Chem. C 2013, 1 (28), 4375-4383.

154. Hofbeck, T.; Monkowius, U.; Yersin, H., Highly Efficient Luminescence of Cu(I)

Compounds: Thermally Activated Delayed Fluorescence Combined with Short-Lived

Phosphorescence. J. Am. Chem. Soc. 2015, 137 (1), 399-404.

155. Glebko, N.; dau, M. T.; Melnikov, A. S.; Grachova, E. V.; Solovyev, I. V.; Belyaev, A.;

karttunen, A. J.; Koshevoy, I. O., Luminescence Thermochromism of Gold(I) Phosphane–

Iodide Complexes: A Rule or an Exception? Chem. Eur. J. 2018, 24, 3021-3029.

156. Czerwieniec, R.; Hofbeck, T.; Crespo, O.; Laguna, A.; Concepcion Gimeno, M.; Yersin, H.,

The lowest excited state of brightly emitting gold(I) triphosphine complexes. Inorg. Chem.

2010, 49 (8), 3764-3767.

157. Igawa, S.; Hashimoto, M.; Kawata, I.; Hoshino, M.; Osawa, M., Photoluminescence

properties, molecular structures, and theoretical study of heteroleptic silver(I) complexes

containing diphosphine ligands. Inorg. Chem. 2012, 51 (10), 5805-13.

158. Trivedi, M.; Ujjain, S. K.; Singh, G.; Kumar, A.; Dubey, S. K.; Rath, N. P., Syntheses,

characterization, and electrochemistry of compounds containing 1-diphenylphosphino-1′-

(di-tert-butylphosphino)ferrocene (dppdtbpf). J. Organomet. Chem. 2014, 772-773, 202-

209.

159. Nakamoto, K., Infrared and Raman Spectra of Inorganic and Coordination Compounds

Part B. John Wiley & sons, Inc.: Hoboken, New Jersey, 2009.

160. Bowmaker, G. A.; Di Nicola, C.; Effendy; Hanna, J. V.; Healy, P. C.; King, S. P.; Marchetti,

F.; Pettinari, C.; Robinson, W. T.; Skelton, B. W.; Sobolev, A. N.; Tabacaru, A.; White, A.

H., Oligo-nuclear silver thiocyanate complexes with monodentate tertiary phosphine

ligands, including novel 'cubane' and 'step' tetramer forms of AgSCN : PR3 (1:1)4. Dalton

Trans. 2013, 42 (1), 277-291.

161. Cingolani, A.; Di Nicola, C.; Effendy; Pettinari, C.; Skelton, B. W.; Somers, N.; White, A.

H., New oligo-/poly-meric forms for MX:dpex (1:1) complexes (M=CuI, AgI; X=(pseudo-

)halide; dpex=Ph2E(CH2)xEPh2, E=(P), As; x=1, 2). Inorg. Chim. Acta 2005, 358 (3), 748-

762.

162. Bowmaker, G. A.; Pakawatchai, C.; Saithong, S.; Skelton, B. W.; White, A. H., 1 : 1

complexes of silver(I) thiocyanate with (substituted) thiourea ligands. Dalton Trans. 2009,

(14), 2588-98.

68

163. Bowmaker, G. A.; Effendy; Harvey, P. J.; Healy, P. C.; Skelton, B. W.; White, A. H.,

Spectroscopic and structural studies on 1 : 2 adducts of silver(I) salts with

tricyclohexylphosphine. J. Chem. Soc., Dalton Trans., 1996, 2449-2457.

164. Bowmaker, G. A.; Hanna, J. V.; Hart, R. D.; Healy, P. C.; King, S. P.; Marchetti, F.;

Pettinari, C.; Skelton, B. W.; Tabacaru, A.; White, A. H., Mechanochemical and solution

synthesis, X-ray structure and IR and 31P solid state NMR spectroscopic studies of copper(I)

thiocyanate adducts with bulky monodentate tertiary phosphine ligands. Dalton Trans.

2012, 41 (25), 7513-25.

165. Chawla, S. K.; Arora, M.; Nättinen, K.; Rissanen, K., Unique copper ion catalyzed

hydrolytic cleavage of C–N(2) bond of thiosemicarbazide. Polyhedron 2006, 25 (3), 627-

634.

166. Effendy; Di Nicola, C.; Fianchini, M.; Pettinari, C.; Skelton, B. W.; Somers, N.; White, A.

H., The structural definition of adducts of stoichiometry MX:dppx (1:1) M=CuI, AgI,

X=simple anion, dppx=Ph2P(CH2)xPPh2, x=3–6. Inorg. Chim. Acta 2005, 358 (3), 763-795.

167. Jaafar, M.; Pevec, A.; Akerboom, S.; Alsalme, A.; Al-Farhan, K.; Ghazzali, M.; Reedijk, J.,

Synthesis, structure and spectroscopic properties of two new cyanido-bridged trinuclear 9-

atom molecular AgNCCuNCAuCN assembly of formula [AgCuAu(CN)3(PPh3)5](H2O)2

and a dinuclear gold–copper one-dimensional coordination polymer of formula

[AuCu(CN)2(PPh3)2](H2O)2. Inorg. Chim. Acta 2014, 423, 233-237.

168. Liu, Y.-l.; Han, L.-j.; Qiao, G.-R.; Yang, M.; Zhang, Q.; Wang, J.-g.; Zhan, S.-z., Synthesis,

Structures, and Properties of Binuclear and Trinuclear Silver(I) Complexes Supported by P

Ligands (dppm, PPh3). Synth. React. Inorg. M 2012, 42 (2), 183-189.

169. Önal, E.; Ay, Z.; Yel, Z.; Ertekin, K.; Gürek, A. G.; Topal, S. Z.; Hirel, C., Design of oxygen

sensing nanomaterial: synthesis, encapsulation of phenylacetylide substituted Pd(II) and

Pt(II) meso-tetraphenylporphyrins into poly(1-trimethylsilyl-1-propyne) nanofibers and

influence of silver nanoparticles. RSC Adv. 2016, 6 (12), 9967-9977.

170. Ozturk, O.; Oter, O.; Yildirim, S.; Subasi, E.; Ertekin, K.; Celik, E.; Temel, H., Tuning

oxygen sensitivity of ruthenium complex exploiting silver nanoparticles. J. Lumin. 2014,

155, 191-197.

Gomathy Chakkaradhari

DissertationsDepartment of ChemistryUniversity of Eastern Finland

No. 151 (2019)

121/2014 KEKÄLÄINEN Timo: Characterization of petroleum and bio-oil samples by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry122/2014 BAZHENOV Andrey: Towards deeper atomic-level understanding of the structure of magnesium dichloride and its performance as a support in the Ziegler-Natta catalytic system123/2014 PIRINEN Sami: Studies on MgCl2/ether supports in Ziegler–Natta catalysts for ethylene polymerization124/2014 KORPELA Tarmo: Friction and wear of micro-structured polymer surfaces125/2014 HUOVINEN Eero: Fabrication of hierarchically structured polymer surfaces126/2014 EROLA Markus: Synthesis of colloidal gold and polymer particles and use of the particles in preparation of hierarchical structures with self-assembly127/2015 KOSKINEN Laura: Structural and computational studies on the coordinative nature of halogen bonding128/2015 TUIKKA Matti: Crystal engineering studies of barium bisphosphonates, iodine bridged ruthenium complexes, and copper chlorides129/2015JIANGYu:Modificationandapplicationsofmicro-structuredpolymersurfaces130/2015 TABERMAN Helena: Structure and function of carbohydrate-modifying enzymes 131/2015KUKLINMikhailS.:Towardsoptimizationofmetaloceneolefinpolymerizationcatalystsvia structuralmodifications:acomputationalapproach132/2015SALSTELAJanne:Influenceofsurfacestructuringonphysicalandmechanicalpropertiesof polymer-cellulosefibercompositesandmetal-polymercompositejoints133/2015 CHAUDRI Adil Maqsood: Tribological behavior of the polymers used in drug delivery devices134/2015 HILLI Yulia: The structure-activity relationship of Pd-Ni three-way catalysts for H2S suppression135/2016 SUN Linlin: The effects of structural and environmental factors on the swelling behavior of Montmorillonite-Beidellite smectics: a molecular dynamics approach136/2016 OFORI Albert: Inter- and intramolecular interactions in the stabilization and coordination of palladium and silver complexes: DFT and QTAIM studies137/2016 LAVIKAINEN Lasse: The structure and surfaces of 2:1 phyllosilicate clay minerals138/2016 MYLLER Antti T.: The effect of a coupling agent on the formation of area-selective monolayers of iron a-octabutoxy phthalocyanine on a nano-patterned titanium dioxide carrier139/2016KIRVESLAHTIAnna:Polymerwettabilityproperties:theirmodificationandinfluencesupon water movement140/2016 LAITAOJA Mikko: Structure-function studies of zinc proteins141/2017 NISSINEN Ville: The roles of multidentate ether and amine electron donors in the crystal structure formation of magnesium chloride supports 142/2017 SAFDAR Muhammad: Manganese oxide based catalyzed micromotors: synthesis, characterization and applications143/2017 DAU Thuy Minh: Luminescent coinage metal complexes based on multidentate phosphine ligands144/2017AMMOSOVALena:Selectivemodificationandcontrolleddepositiononpolymersurfaces145/2017 PHILIP Anish: PEI-mediated synthesis of gold nanoparticles and their deposition on silicon oxide supports for SERS and catalysis applications146/2017 RAHMAN Muhammad Rubinur: Structure and function of iron-sulfur cluster containing pentonate dehydratases147/2018 ANKUDZE Bright: Syntheses of gold and silver nanoparticles on support materials for trace analyses using surface-enhanced Raman spectroscopy148/2018 PENTTINEN Leena: Structure determination of enzymes with potential in processing of cell wall compounds149/2018 SIVCHIK Vasily: Tuning the photoluminescence of cyclometalated platinum(II) compounds via axial and non-axial interactions150/2019 MIELONEN Kati: Hierarchically structured polymer surfaces: Curved surfaces and sliding behavior on ice

Tuning the emission properties of oligophosphine copper and silver complexes with ancillary ligands

Gom

athy Chakkaradhari: Tuning the em

ission properties of oligophosphine copper and silver complexes w

ith ancillary ligands

151