AdewaleO.AdeloyeandPeterA.Ajibadedownloads.hindawi.com/journals/tswj/2014/570864.pdfAdewaleO.AdeloyeandPeterA.Ajibade Department of Chemistry, Faculty of Science and Agriculture, University

Research ArticleSynthesis and Photophysical and Electrochemical Properties ofFunctionalized Mono- Bis- and Trisanthracenyl Bridged Ru(II)Bis(22101584061015840210158401015840-terpyridine) Charge Transfer Complexes

Adewale O Adeloye and Peter A Ajibade

Department of Chemistry Faculty of Science and Agriculture University of Fort Hare Private Bag X1314 Alice 5700 South Africa

Correspondence should be addressed to Peter A Ajibade pajibadeufhacza

Received 6 November 2013 Accepted 31 December 2013 Published 30 April 2014

Academic Editors R Fallahpour H Ishida B I Kharisov and A I Matesanz

Copyright copy 2014 A O Adeloye and P A Ajibade This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

With the aim of developing new molecular devices having long-range electron transfer in artificial systems and as photo-sensitizers a series of homoleptic ruthenium(II) bisterpyridine complexes bearing one to three anthracenyl units sandwichedbetween terpyridine and 2-methyl-2-butenoic acid group are synthesized and characterized The complexes formulated asbis-41015840-(9-monoanthracenyl-10-(2-methyl-2-butenoic acid) terpyridyl) ruthenium(II) bis(hexafluorophosphate) (RBT1) bis-41015840-(9-dianthracenyl-10-(2-methyl-2-butenoic acid) terpyridyl) ruthenium(II) bis(hexafluorophosphate) (RBT2) and bis-41015840-(9-trianthracenyl-10-(2-methyl-2-butenoic acid) terpyridyl) ruthenium(II) bis(hexafluorophosphate) (RBT3) were characterized byelemental analysis FT-IR UV-Vis photoluminescence 1H and 13C NMR spectroscopy and electrochemical techniques byelemental analysis FT-IR UV-Vis photoluminescence 1H and 13CNMR spectroscopy and electrochemical techniquesThe cyclicvoltammograms (CVs) of (RBT1) (RBT2) and (RBT3) display reversible one-electron oxidation processes at 119864

12= 113 V 071 V

and 099V respectively (versus AgAgCl) Based on a general linear correlation between increase in the length of 120587-conjugationbond and the molar extinction coefficients the Ru(II) bisterpyridyl complexes show characteristic broad and intense metal-to-ligand charge transfer (MLCT) band absorption transitions between 480ndash600 nm 120576 = 945 times 103Mminus1 cmminus1 and appreciablephotoluminescence spanning the visible region

1 Introduction

Ruthenium(II) polypyridyl complexes have attracted wideattention in the past 30 years because of their use as photosen-sitizers in the storage of solar energy and in the decomposi-tion of waterThis has led to a detailed understanding of theirphotophysics photochemistry and redox chemistry Thesecomplexes have high emission quantum yields long emissionlifetimes and good redox characteristics Through a carefulchoice of ligands and substituents such complexes havebeen used in the fabrication of molecular devices molecularprobes electronics and sensors [1ndash10]

In the development of dyes for example both absorp-tion in wide range of solar spectrum and high molecularextinction coefficient are required The black dye exhibits

better near-IR photoresponse than the N3 dye becauseof its expanded 120587 conjugated field Moreover the higherefficiencies were obtained with the black dye [11] On theother hand a structural modification of the black dye [12ndash17] is sparse though that of the N3 dye has been widelyinvestigated to increase the stability and the performance Adifficult synthesis ofmodified terpyridine ligands is one of themajor factors From this point of view the syntheses of newforms of black dye take an important role in increasing thepotential of dyes

Different authors have prepared several homoleptic andheteroleptic ruthenium complexes using various approachesand in particular the extension of the excited-state life-times of ruthenium(II) bisterpyridine complexes The mainfocus has been on modifications that affect the emitting

Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 570864 10 pageshttpdxdoiorg1011552014570864

2 The Scientific World Journal

triplet metal-to-ligand charge transfer (3MLCT) states thusminimizing their interaction with higher-lying 3MC statesThis has been achieved by the use of substituents [18]cyclometalating ligands [19] and ligands with extended 120587systems [20ndash22] Most of these attempts have resulted ina lowering of the 3MLCT energy A few recent studieshave more specifically aimed at increasing the ligand fieldstrength by the use of strong 120590-donor ligands [23 24] astrategy however that results in a concomitant decrease ofthe 3MLCT state energy and thus limits the reactivity [25]The dye solar cells devices based on such complexes forexample display good photovoltaic performance and alsostrongmetal-to-ligand charge transition (MLCT) band in thevisible region of absorption Nevertheless further extensionof the conjugation length of the ancillary ligand faces thesituation that the 120587-orbital energy of the ancillary ligandsincreases tomatch that of themetal centre with the result thatthe 120587-orbital of the ancillary ligand participates significantlyin the HOMO of the complex The result is the reduction ofthe absorption coefficient of the MLCT band and thereforedecreased efficiency [26]

This paper reports the recent attempts based on the intro-duction of anthracene functionality in a stepwise increaseinto terpyridine ligands and the successful complexationof these ligands to a transition metal ion [ruthenium(II)]Our research goal is specifically focused on improving themolar extinction coefficient increasing the wavelength ofcomplexes towards the near-infrared region and improvingdye stability

2 Experimental Section

21 Materials and General Physical Measurements All com-mercial reagents used were analytically pure without furtherpurification The ligand precursors 41015840-(9-bromanthracenyl)-terpyridine (L1) 41015840-(9-bromodianthracenyl)-terpyridine(L2) and 41015840-(9-bromotrianthracenyl)-terpyridine (L3) wereprepared as described in the literature [27] The thin layerchromatography (tlc) analyses were done with aluminiumsheet precoated with normal phase silica gel 60 F

254(Merck

020mm thickness) except otherwise stated The tlc plateswere developed using any of the following solvent systemsSolvent system A Dichloromethane-Methanol (9 1) Solventsystem B Dichloromethane-Methanol (7 3) Solvent systemC Dichloromethane-Benzene (3 7) Solvent system DChloroform-Methanol (1 1) Gel filtration was performedusing Sephadex LH-20 previously swollen in specifiedsolvent (s) prior to loading of extract onto the column(35 cm times 85 cm)

Melting points were determined using Gallenkamp elec-trothermal melting point apparatus Microanalyses (C HN) were carried out with a Fisons elemental analyser andinfrared spectra were obtained with KBr discs or nujol on aPerkin Elmer System 2000 FT-IR Spectrophotometer UV-Visand fluorescence spectra were recorded in 1 cm path lengthquartz cell on a Perkin Elmer Lambda 35 spectrophotometerand Perkin Elmer Lambda 45 spectrofluorometer respec-tively 1H and 13C Nuclear Magnetic Resonance spectra were

run on a Bruker EMX 400MHz spectrometer for 1H and100MHz for 13C The chemical shift values were reportedin parts per million (ppm) relative to (TMS) as internalstandard Chemical shifts were also reported with respect toDMSO d

6at 120575c 4098 and DMSO d

6at 120575H 250 ppm All

electrochemical experiments were performed using Autolabpotentiostat PGSTAT 302 (EcoChemie Utrecht The Nether-lands) driven by the general purpose Electrochemical Systemdata processing software (GPES software version 49) Squarewave voltammetric analysis was carried out at a frequencyof 10Hz amplitude of 50mV and step potential of 5mV Aconventional three-electrode system was used The workingelectrode was a bare glassy carbon electrode (GCE) Ag|AgClwire and platinum wire were used as the pseudoreferenceand auxiliary electrodes respectively The potential responseof the Ag|AgCl pseudoreference electrode was less than theAg|AgCl (3MKCl) by 0015 plusmn 0003V Prior to use the elec-trode surface was polished with alumina on a Buehler felt padand rinsed with excess millipore water All electrochemicalexperiments were performed in freshly distilled dry DMFcontaining TBABF

4as supporting electrolyte

211 Synthesis of Ruthenium(II)-bis(9-monoanthracenyl-10-(2-methyl-2-butenoic acid)-terpyridyl)-bis(hexafluorophos-phate) Complex RBT1 The ruthenium complex precursorRuCl2(DMSO)

4and the corresponding ruthenium bister-

pyridine complexes were prepared with a slight modifica-tion to literature method [28ndash30] 41015840-(9-bromoanthracenyl)-terpyridine (L1) (0195 g 040mmol) was reacted withRuCl2(DMSO)

4(0097 g 020mmol) in DMF (40mL) The

resulting mixture was refluxed for 8 h in the dark andcool to room temperature Without isolation of the darkred complex 2-methyl-2-butenoic acid (004 g 040mmol)triethylamine (1mL) and KOH (005 g 080mmol) wereadded and the reaction mixture further allowed to refluxfor another 4 hours The crude product was allowed tocool to room temperature and filtered to remove unreactedsolid products Distilled water was added and extracted intochloroformThe organic layer was collected and concentratedto dryness in vacuo on rotary evaporator A 10mL solutionof NaOH (005M) was added and the mixture turned toa deep orange red colour After filtration pH was adjustedto 3 with HNO

305M and resulting solution was left

to stand in the fridge for 12 h The acidic solution afterfiltration of the insoluble precipitate was concentrated toafford a semisolid product which was purified by columnchromatography on Sephadex LH20 in ethanol-toluene 50vv) Column fractions with similar tlc characteristics werebulked together and concentrated under reduced pressureand excess ammonium hexafluorophosphate in water wasused to precipitate the complex to afford (RBT1) as a darkbrown solid (018 g Percentage Yield = 321 mp = 196-197∘C) IR data (KBr cmminus1) 3418 3121 2926 2852 23661917 1678 1621 1592 1451 1384 1304 1284 1256 1170 10971054 1028 926 839 772 747 694 558 468 423 120582maxnm(120576103Mminus1 cmminus1) (CH

3ClMeOH 1 1 vv) 1012 (0937) 916

(1074) 486 (5337) 405 (17368) 383 (19391) 364 (15062)120582em = 681 nm (Int 932)1H NMR (400MHz DMSO-d

6)

The Scientific World Journal 3

120575 908 (d 119869 = 81Hz 2H H-31015840 51015840) 881 (d 119869 = 80Hz2H H-3 310158401015840) 854 (dd 119869 = 32 68Hz 3H H-a) 821 (dd119869 = 33 58Hz 2H H-b) 808 (t 119869 = 79 81 Hz 4H H-4410158401015840) 794 (dd 119869 = 32 57Hz 1H H-c) 780 (dd 119869 = 3268Hz 1H H-d) 742 (d 119869 = 53Hz 2H H-6 610158401015840) 726 (t119869 = 66 68Hz 2H H-5 510158401015840) 273 (s CH

3) 256 (s CH

3) 13C

NMR (400MHz DMSO-d6) 120575 18249 15769 15473 15201

13806 13587 13454 13299 13032 13008 12845 1277312673 12449 12395 12275 3575 3436 Elemental analysisFound C 5837H 365 N 554 Calculated C 5808H 358N 598 (Molecular formulae RuC

68H50N6O4P2F12)

212 Synthesis of Ruthenium(II)-bis(9-dianthracenyl-10-(2-methyl-2-butenoic acid)-terpyridyl)-bis(hexafluorophosphate)Complex RBT2 The complex was prepared using the sameprocedure as reported forRBT1 (L2) (025 g 038mmol) andRuCl2(DMSO)

4(009 g 019mmol) 2-methyl-2-butenoic

acid (004 038mmol) triethylamine (10mL) and KOH(005 g 076mmol) (RBT2) was obtained as a deep orangesolid Weight = 024 g Percentage Yield = 459 mp = 195ndash197∘C) IR data (KBr cmminus1) 3429 3076 2926 2864 22721953 1678 1616 1516 1431 1384 1332 1304 1285 1256 11701053 1028 839 776 747 693 558 120582maxnm (120576103Mminus1 cmminus1)(CH3ClMeOH 1 1 vv) 1012 (1171) 916 (1343) 554 (2543)

484 (9453) 404 (27783) 383 (28685) 364 (20644) 120582em =743 nm (Int 754) 1H NMR (400MHz DMSO-d

6) 120575 908

(d 119869 = 82Hz 2H H-31015840 51015840) 882 (d 119869 = 87Hz 2H H-3 310158401015840) 875 (dd 119869 = 47 87Hz H-a1015840) 863 (d 119869 = 81HzH-b1015840) 860 (dd 119869 = 38 88Hz H-c1015840) 853 (dd 119869 = 3468Hz 3H H-a10158401015840) 821 (dd 119869 = 34 58Hz 2H H-b10158401015840) 806(t 119869 = 68 80Hz 4H H-4 410158401015840) 794 (dd 119869 = 33 58Hz1H H-c10158401015840) 790 (dd 119869 = 50 55Hz H-c1015840) 787 (dd 119869 = 6180Hz H-d1015840) 779 (dd 119869 = 31 68 Hz 1H H-d10158401015840) 743 (d119869 = 53Hz 2H H-6 610158401015840) 726 (t 119869 = 69 71 Hz 2H H-5 510158401015840)273 (s CH

3) 256 (s CH

3) 13CNMR (400MHzDMSO-d

6)

120575 18248 15769 15709 15690 15486 15474 15203 1381513453 13299 13030 13007 12902 12844 12772 1276812761 12672 12450 12417 12276 12249 12175 12119 35743435 3074 Elemental analysis Found C 6529 H 362N 446 Calculated C 6557 H 378 N 478 (Molecularformulae RuC

96H66N6O4P2F12)

213 Synthesis of Ruthenium(II)-bis(9-trianthracenyl-10-(2-methyl-2-butenoic acid)-terpyridyl)-bis(hexafluorophosphate)Complex RBT3 The complex was prepared as reported forRBT1 (L3) (025 g 029mmol) and RuCl

2(DMSO)

4(007 g

015mmol) 2-methyl-2-butenoic acid (003 029mmol) tri-ethylamine (10mL) and KOH (003 g 060mmol) (RBT3)was obtained (Bright orange solid 022 g Percentage Yield= 361 mp = 205ndash207∘C) IR data (KBr cmminus1) 3429 30753028 2925 2852 1940 1678 1621 1593 1437 1385 1332 13041285 1256 1170 1027 926 839 746 694 578 558 120582maxnm(120576103Mminus1 cmminus1) (CH

3ClMeOH 1 1 vv) 1012 (2217) 916

(1778) 554 (4004) 481 (9130) 402 (45975) 380 (49346)360 (39677) 120582em = 734 nm (Int = 754) 1H NMR(400MHz DMSO-d

6) 120575 908 (d 119869 = 82Hz 2H H-31015840

51015840) 882 (d 119869 = 87Hz 2H H-3 310158401015840) 875 (dd 119869 = 4787Hz H-a1015840) 863 (d 119869 = 81Hz H-b1015840) 860 (dd 119869 = 38

88Hz H-c1015840) 853 (dd 119869 = 34 68Hz 3H H-a10158401015840) 821 (dd119869 = 34 58Hz 2H H-b10158401015840) 806 (t 119869 = 68 80Hz 4HH-4 410158401015840) 794 (dd 119869 = 33 58Hz 1H H-c10158401015840) 790 (dd119869 = 50 55Hz H-c1015840) 787 (dd 119869 = 61 80Hz H-d1015840)779 (dd 119869 = 31 68Hz 1H H-d10158401015840) 743 (d 119869 = 53Hz2H H-6 610158401015840) 726 (t 119869 = 69 71 Hz 2H H-5 510158401015840) 273(s CH

3) 256 (s CH

3) 13C NMR (400MHz DMSO-d

6)

120575 18248 15769 15710 15691 15682 15486 15204 1382013453 13301 13031 12845 12773 12762 12672 1245012417 12396 12276 12249 Elemental analysis Found C7033 H 339 N 378 Calculated C 7055 H 392 N 398(Molecular formulae RuC

124H82N6O4P2F12)

3 Results and Discussion

31 Syntheses The synthetic route to the formation ofthe ligands precursors 41015840-(9-bromoanthracenyl)-terpyridine(L1) 41015840-(9-bromodianthracenyl)-terpyridine (L2) and 41015840-(9-bromotrianthracenyl)-terpyridine (L3) has been reportedelsewhere [27] The homoleptic complexes (RBT1) (RBT2)and (RBT3) were prepared following a slight modification ofstandard procedures [20 28ndash30] when two equivalents of theligand (L1) (L2) or (L3) were reacted with RuCl

2(DMSO)

4

in dimethylformamide to form the initial homoleptic bro-moanthracenyl terpyridyl ruthenium(II) complexes whichwere not isolated and a further subsequent addition of 2-methyl-2-butenoic acid (2 equivalents) in a one-pot synthesisunder basic reactionmedium (Scheme 1) All complexes werecharacterized by elemental analyses FT-IR1H and 13CNMRand these were in accordance with the assigned structures

32 Infrared Spectra The infrared spectra of the complexes(RBT1) (RBT2) and (RBT3) share common features oneof which is the strong broad bands in the region of2737 and 3430 cmminus1 due to hydroxyl groups of the car-boxylic acid moieties on the complexes The spectral of thecomplexes display broad asymmetric carboxylate stretchingbands ]asym(COOminus) in the regions 1950 and 1678 cmminus1 Bothbands are indicative of a protonated carboxylate group on theanthracene Other common features at the functional groupregion are the presence of the carboxylate symmetric bandat 1384 cmminus1 ](COOs

minus) together with broad ](C=N) of thepolypyridyl group at 1593 1516 and 1451 cmminus1 [31]The bandsin the regions 1600ndash1400 cmminus1 are ascribed to the stretchingmode of terpyridine and the alkenyl groups The presence ofbroad peaks in the regions 770 and 690 cmminus1 demonstratesthe existence of four adjacent hydrogen atoms which existin all spectra These results indicate that the coupling ofanthracene rings at the 9 10-positions led to the formationof polyanthracene chains The weak absorption frequenciesin the region 470 and 420 cmminus1 respectively gave indicationof the coordination of nitrogen atoms of the ancillary ligandsto ruthenium central metal atom [32]

33 Electronic Absorption and Emission Spectra

331 Electronic Absorption Spectroscopy The electronicabsorption maxima molar extinction coefficients and


N

N

N

Br

Ru N

N

N

BrN

N

N

Br

Ru N

N

N

N

N

N

H

n n

n

nn

CH3

CH3

CH3

(PF6)2

(Where n = 1 2 3)

Where n = 1 2 3

RuCl2(DMSO)4 +

DMF reflux 110ndash120∘C 8h

2+

(ii) HNO3 NaOH

(iv) Excess aq NH4PF6

(i) Tiglic acid triethylamine KOH4h

(iii) Column chromatography (EtOHTol 1 1 vv)

HOOC

H3C

COO

Scheme 1 General reaction scheme for preparation of novel Ru(II) bis(terpyridyl-oligo-anthracene) bis(hexafluorophosphate) complexes

emission properties of (RBT1) (RBT2) and (RBT3)are listed in Table 1 The absorption excitation andemission spectra of the complexes at room temperaturein CH

3ClMeOH (1 1 vv) are plotted in Figures 1 and

2 respectively The three complexes exhibit the typicalsinglet metal-to-ligand charge transfer (1MLCT) absorptionbands of ruthenium polypyridyl complexes with maximaat 486 484 and 481 nm (120576 = 530ndash950 times 103Mminus1 cmminus1)respectively All the complexes showed small but significantshoulder peaks at sim554 nm (120576 = 190ndash400 times 103Mminus1 cmminus1)as their extinction coefficients descend steadily towardslonger wavelengths Moreover there exists weak shoulderbands in the long wavelength tail region of the absorptionspectra at 916 nm (120576 = 100ndash180 times 103Mminus1 cmminus1) and1012 nm (120576 = 090ndash220 times 103Mminus1 cmminus1) these have beenassigned to the triplet metal-to-ligand charge transfer(3MLCT) transitions with complex (RBT3) having a molar

extinction coefficient better than (RBT1) and (RBT2)[1 23 24] These bands are similar to that reported forother bipyridyl phenanthrolyl and terpyridyl complexesGroups which extend the delocalization of the 120587 systemsof polycyclic arenes cause further bathochromic shiftsbut the extents of these shifts vary with the positions ofsubstitution [20 33] Ligand centered 120587 rarr 120587lowast transitionsof the terpyridine occur at higher energy in the ultravioletregion between 250 and 300 nm (not shown) while thenear-visible region of absorption was characterized by threedistinct intense vibronic peaks at 364 383 and 405 nmfor (RBT1) and (RBT2) and slight blue-shift wavelengthsobserved for (RBT3) at 360 380 and 402 nm which may bedue to increase in the energy of the LUMO of the ligand Theabsorption bands in this regionwere attributed to wavelengthcharacteristics of anthracene derivatives however the molarextinction coefficients of these peaks increase with increasein the number of anthracenes due to extended 120587-bond


0

05

15

25

1

2

0

05

15

25

1

2

630530430330

630 730 830 930 1030530430330

Wavelength (nm)

Wavelength (nm)

0

05

15

25

1

2

6530430330

Wavelength (nm)

Abso

rban

ce (a

u)

Abso

rban

ce (a

u)

(a)

08

06

04

02

0

Abso

rban

ce (a

u)

410 460 510 560 610

Wavelength (nm)RBT 1

RBT 2

RBT 3

(b)

800 850 950 1000 1050 1100900

Wavelength (nm)

005

01

0

Abso

rban

ce (a

u)

RBT 1

RBT 2

RBT 3

(c)

Figure 1 UV-Vis absorption spectra of the (RBT1 RBT2 and RBT3) complexes at a concentration of 0001 gdmminus3 in (CH3ClMeOH 1 1

vv)

conjugation in the molecules The enhanced absorptioncross sections between 350 and 405 nm from the anthracenylchromophores provide an antenna system for the efficientharvesting of UV light (Figure 1) In all the three ruthenium

complexes there are indications that the molecules arestrongly coupled and behave more like supermoleculesrather than as two individual units Since the lowest energyanthracene bands are well removed from the [Ru(terpy)

2]2+


Table 1 Photophysical properties and electrochemical data of RBT1 RBT2 and RBT3 complexes

Complex 120582absnm (120576 times 103Mminus1 cmminus1)a 120582em(nm)b 119864paVc

11986412Vc

RBT1 364 (151) 383 (194) 405 (174) 486 (53)554 (19)916 (11)1012 (09)

681 (932)i 030 057085 113

minus025minus054

RBT2 364 (206) 383 (287) 404 (278) 484 (95)554 (25)916 (13)1012 (12)

743 (754)i 028 071minus021minus046minus069

RBT3 360 (397) 380 (494) 402 (459) 481 (91)554 (40)916 (18)1012 (22)

743 (754)i 073 099 minus090

ab(CH3ClMeOH 1 1 vv) cfreshly distilled DMF containing 01M TBABF4 supporting electrolyteiemission intensity

600

400

200

0

800

750 800700600 650

Wavelength (nm)

RBT 1

RBT 2

RBT 3

1000

Emiss

ion

inte

nsity

(au

)

Figure 2 Emission spectra of the RBT1 (red) RBT2 (green) andRBT3 (purple) complexes at a concentration of 0001 gdmminus3 in(CH3ClMeOH 1 1 vv)

transitions good photoselectivity in this wavelength regioncan be achieved [18]

332 Emission Study Upon excitation into the 1LC and1MLCT bands (120582exc = 500 nm) the complexes (RBT1)(RBT2) and (RBT3) display appreciable luminescence atroom temperature However it was observed that (RBT1)showed better emission intensity at lower wavelength (120582em =681 nm) than (RBT2) and (RBT3) at 120582em = 743 nm(Figure 2)The intensity of this MLCT transition is unusuallyhigh but strong MLCT bands appear to be a characteristicof ldquoRu(terpy)rdquo based chromophores bearing a conjugatedsubstituents at the 41015840-position [34 35] The photophysicalproperties of ldquoRu(terpy)rdquo based chromophores are particu-larly sensitive to the energy gap between emittingMLCT stateand a higher energy metal centred state [36] it is not clear atthe moment to adduce the difference in wavelengths betweenRBT1 RBT2 and RBT3 simply to an influenced loweringof the triplet energy It has been reported that the emissionproperties of the complexes relate to the substituents on

the coordinating nitrogen and their complexity [37] Withthe choice of ligands however it is well thought that theenergy positions of MC MLCT and LC excited states ofthe complexes depend on the ligand field strength [1]The B3LYP6-31G theoretical calculations showed that theelectronic structures of anthracene derivatives are perturbedby the side substitutes on the anthracene block and the slightvariation of the electronic structures results in the enhancedelectron accepting ability and the decrease of the HOMO-LUMO energy gap which is the origin of the shifting ofemission wavelength to the blue-green region [38]

34 NMR Spectra The 1H NMR spectra of the homolepticcomplexes RBT1 RBT2 and RBT3 display similarities inthe chemical shifts of protons for the terpyridine ligand andthe anthracene rings in the aromatic region The terpyridineprotons were conspicuously found as three doublet and twotriplet peaks at 120575 908 887 742 and 801 726 ppm dueto H31015840 H51015840 H3 H310158401015840 H4 H410158401015840 and H6 H610158401015840 H5 H510158401015840respectively The 1H NMR spectra of the complexes alsodisplay a characteristic downfield shifts 120575 854 821 794and 780 ppm and AA1015840BB1015840 coupling patterns (doublet ofdoublet) characteristic of peri protons (resulting from 3119869and 4119869) for the anthracene molecules Unlike in complexRBT1 higher integral values are recorded for these protonsin both complexesRBT2 andRBT3 which accounted for theadditional anthracene molecules attached to the terpyridinering In addition three prominent singlet peaks at 120575 721 708and 696 ppm were unambiguously assigned to OH peaksin the complexes In the aliphatic region of the spectra thesinglet peaks at 120575 289 273 and 122 ppmwere assigned to themethyl protons The 13C-NMR spectra of complexes RBT1RBT2 and RBT3 showed the chemical shifts characteristicsof terpyridine and anthracene derivatives In the aromaticregion (120575 182ndash120 ppm) six to eight quaternary carbonresonance signals were observed at 18249 15768 and 1569013820 13031 12396 12249 ppm accounting for the carbonyland the nonhydrogenated carbon atoms in the moleculeThe methine carbon resonance peaks of the terpyridyl andanthracenyl molecules are found at 15486 15204 1330012845 12772 12450 and 13453 12672 respectively Theintensity ratio for the methyl carbons at the aliphatic regionis too low as compared to the number of anthracenes in thecomplexes


minus1 minus05 05 1510

60120583A

III

III

CV of RBT1

Potential (V) versus Ag|AgCl

(a)


Sqw of RBT1

40120583A

III

I

II

IV

V

(b)

Figure 3 Cyclic and square wave voltammetry profiles of 1 times 10minus3Mof RBT1 in freshly distilled DMF containing 01M TBABF4supporting

electrolyte Step potential 5mV amplitude 50mV versus Ag|AgCl frequency 10Hz Scan rate 100mVsminus1 versus Ag|AgCl

minus15 minus1 minus05 05 1510

I

IIIII

CV of RBT2

50120583A


(a)


I

II

III

IV

V

10

Sqw of RBT2

60120583A


(b)

Figure 4 Cyclic and square wave voltammetry profiles of 1 times 10minus3M of RBT2 complex in freshly distilled DMF containing 01M TBABF4

supporting electrolyte Step potential 5mV amplitude 50mV versus Ag|AgCl and frequency 10 Hz Scan rate 100mVsminus1 versus Ag|AgCl

35 Electrochemical Study The cyclic and square wavevoltammograms of the (RBT1 RBT2 and RBT3) complexeswere examined in the potential range +15 to minus15 V and ata scan rate 50mV sminus1 using Ag|AgCl electrode in DMF sol-vent with 01M tetrabutylammonium hexafluorophosphateas supporting electrolyte Figures 3 4 and 5 display thecyclic and square wave voltammogram of RBT1 RBT2and RBT3 respectively The voltammograms display theRu(III)Ru(II) couple at positive potentials and the ligand-based reduction couples at negative potentialsThe potentialsare summarized in Table 1 The complexes showed well-defined one-electron oxidation reversible waves at 113 071

and 099V for RBT1 RBT2 and RBT3 respectively Thesepotentials were assigned to the Ru(III)Ru(II) couple [39]Other ligand based oxidation potentials forRBT1were foundat 030 057 and 085VAt the negative potentialRBT1 showsreduction potentials at 119864

12= minus025 and minus054V For RBT2

and RBT3 complexes two irreversible oxidation processesIV and II at 028 and 073V respectively were observedand assigned unequivocally to the ring oxidation of theanthracenyl andor the terpyridine ligands At the reductionpotential RBT2 showed three quasi-reversible reductionpeaks processes I II and III at 119864

12= minus021 minus046 and

minus069VThese peaks though were not well defined in the CV


I

III

II


CV of RBT3

50120583A


(a)

I

III

II


Sqw of RBT3

40120583A


(b)


supporting electrolyte Step potential 5mV amplitude 50mV versus Ag|AgCl frequency 10Hz Scan rate 100mVsminus1 versus Ag|AgCl

but conspicuously shown in the square-wave voltammetryA reversible reduction peak process I at 119864

12= minus090V was

observed in RBT3 Based on the strong negative potentialin RBT2 and RBT3 compared to RBT1 the influence ofconjugation is shown thus giving the support to the increasein number of anthracene molecular units in the complexesand a corresponding increase in the electron donating ability

4 Conclusions

Terpyridines are versatile and important ligands for a widevariety of transitionmetal ions Bis(terpyridyl) ruthenium(II)complexes in particular have been used in a diverse rangeof applications We have rationally designed and synthesizedcoordinating Ru(II) bis(terpyridyl) complexes by a stepwiseincrease in the number of attached anthracene anchoredto an 120572 120573-unsaturated carboxylic acid derivative on ter-pyridine which have resulted in a better molar extinctioncoefficient and red shifting of the luminescence towards thenear-infrared region The highly conjugated ruthenium(II)terpyridyl complexes (RBT1 RBT2 and RBT3) combine theorganic semiconductor property of anthracene and extended120587-conjugation of the acid functionality thus leading to anenhanced molar extinction coefficients The results obtainedin this study gave indication that the luminescence propertysuch as the lifetime of complexes is possible through syntheticcontrol of the number of anthracenyl group units sinceprolongation of MLCT lifetimes is valuable for the advance-ment of analytical luminescence-based technologies such aslifetime-based sensing [40ndash44] However an optimum num-ber of anthracenesmay be required for a better electron trans-fer processes as well as reduction in molecular aggregationThe complexes investigated showed better photophysical andelectrochemical characteristics which may endeared them

to be used as suitable candidates for larger supramolecularsystems based on Ru(II) polypyridine compounds capable ofperforming long-range photoinduced electron andor energytransfer functions photosensitizers electronic devices andcomponents in molecular assemblies for generating charge-separated states To support the potential capability of thesecomplexes as sensitizers for dye-sensitized solar cells thephotovoltaic and electrochemical impedance spectroscopyexperiments are in progress

Conflict of Interests

The authors declare no conflict of interests

Acknowledgments

Theauthors are grateful to theGovanMbeki ResearchCentrethe University of Fort Hare Alice and College of ScienceEngineering and Technology (CSET) University of SouthAfrica Pretoria South Africa for financial support Theyare most grateful to Dr Akinbulu Isaac and Dr OlomolaTemitope for kindly providing access to electrochemical andNMR equipment

References

[1] K S Schanze and R H Schmehl ldquoApplications of inorganicphotochemistry in the chemical and biological sciencesmdashcontemporary developmentsrdquo Journal of Chemical Educationvol 74 no 6 pp 633ndash640 1997

[2] W W Miller M Yafuso C F Yan H K Hui and S ArickldquoPerformance of an in-vivo continuous blood-gasmonitor withdisposable proberdquo Clinical Chemistry vol 33 no 9 pp 1538ndash1542 1987


[3] J N Demas and B A DeGraff ldquoApplications of luminescenttransitionmetal complexes to sensor technology andmolecularprobesrdquo Journal of Chemical Education vol 74 no 6 pp 690ndash695 1997

[4] G E Collins and S L Rose-Pehrsson ldquoChemiluminescentchemical sensors for inorganic and organic vaporsrdquo Sensors andActuators B Chemical vol 34 no 1ndash3 pp 317ndash322 1996

[5] M J Cook A P Lewis G S G McAuliffe et al ldquoLumines-cent metal complexes Part 1 Tris-chelates of substituted 221015840-bipyridyls with ruthenium(II) as dyes for luminescent solarcollectorsrdquo Journal of the Chemical Society Perkin Transactions2 no 8 pp 1293ndash1301 1984

[6] L Li and D R Walt ldquoDual-analyte fiber-optic sensor for thesimultaneous and continuous measurement of glucose andoxygenrdquo Analytical Chemistry vol 67 no 20 pp 3746ndash37521995

[7] K-Y Wong M-Q Zhang X-M Li and W Lo ldquoAluminescence-based scanning respirometer for heavy metaltoxicity monitoringrdquo Biosensors and Bioelectronics vol 12 no2 pp 125ndash133 1997

[8] MD Marazuelaa B Cuestaa MC Moreno-Bondi and AQuejidob ldquoFree cholesterol fiber-optic biosensorfor serumsamples with simplex optimizationrdquo Biosensors Bioelectronicsvol 12 no 3 pp 233ndash240 1997

[9] A J Guthrie R Narayanaswamy and N A Welti ldquoSolid-stateinstrumentation for use with optical-fibre chemical-sensorsrdquoTalanta vol 35 no 2 pp 157ndash159 1988

[10] M Gratzel ldquoHighly efficient nanocrystalline photovoltaicdevices Charge transfer sensitizers based on ruthenium andosmium achieve outstanding performancerdquo Platinum MetalsReview vol 38 no 4 pp 151ndash159 1994

[11] Y Chiba A Islam Y Watanabe R Komiya N Koide and LHan ldquoDye-sensitized solar cells with conversion efficiency of111rdquo Japanese Journal of Applied Physics vol 45 no 24ndash28pp L638ndashL640 2006

[12] Z S Wang and F Liu ldquoStructure-property relationships oforganic dye with D-120587-a structure in dye-sensitized solar cellsrdquoFrontiers of Chemistry in China vol 5 no 2 pp 150ndash161 2010

[13] Z-S Wang C-H Huang Y-Y Huang et al ldquoPhotoelectricbehavior of nanocrystalline TiO

2electrode with a novel ter-

pyridyl ruthenium complexrdquo Solar Energy Materials and SolarCells vol 71 no 2 pp 261ndash271 2002

[14] M Hissler A El-ghayoury A Harriman and R ZiesselldquoFine-Tuning the Electronic Properties of BinuclearBis(terpyridyl)ruthenium(II) complexesrdquo Angewandte ChemieInternational Edition vol 37 no 12 pp 1717ndash1720 1998

[15] T Yamagushi M Yanagida R Kator H Sugihara and HArakawa ldquoSynthesis and application of ruthenium(II) tricar-boxyterpyridyl complex with a nitrogen chelate ligand for solarcells based on nanocrystalline TiO

2filmsrdquo Chemistry Letters

vol 33 pp 986ndash987 2004[16] A Islam F A Chowdhury Y Chiba et al ldquoRuthenium(II)

tricarboxyterpyridyl complex with a fluorine-substituted 120573-diketonato ligand for highly efficient dye-sensitized solar cellsrdquoChemistry Letters vol 34 no 3 pp 344ndash345 2005

[17] H Sugihara L P Singh K Sayama H Arakawa MK Nazeeruddin and M Gratzel ldquoEfficient photosensitiza-tion of nanocrystalline TiO

2films by a new class of sen-

sitizer cis-dithiocyanato bis(47-dicarboxy-110-phenanthro-line)ruthenium(II)rdquo Chemistry Letters no 10 pp 1005ndash10061998

[18] D S Tyson and F N Castellano ldquoIntramolecular singlet andtriplet energy transfer in a ruthenium(II) diimine complexcontaining multiple pyrenyl chromophoresrdquo Journal of PhysicalChemistry A vol 103 no 50 pp 10955ndash10960 1999

[19] K K-W Lo K Y Zhang and S P-Y Li ldquoDesign of cyclomet-alated iridium(iii) polypyridine complexes as luminescent bio-logical labels and probesrdquo Pure and Applied Chemistry vol 83no 4 pp 823ndash840 2011

[20] AO Adeloye and P A Ajibade ldquoSynthesis and characterizationof a heteroleptic Ru(II) complex of phenanthroline containingOligo-anthracenyl carboxylic acidmoietiesrdquo International Jour-nal of Molecular Sciences vol 11 no 9 pp 3158ndash3176 2010

[21] F Schramm V Meded H Fliegl et al ldquoExpanding the coordi-nation cage a ruthenium(11)mdashpolypyridine complex exhibitinghigh quantum yields under ambient conditionsrdquo InorganicChemistry vol 48 no 13 pp 5677ndash5684 2009

[22] T Renouard R-A Fallahpour M K Nazeeruddin et alldquoNovel ruthenium sensitizers containing functionalized hybridtetradentate ligands synthesis characterization and INDOSanalysisrdquo Inorganic Chemistry vol 41 no 2 pp 367ndash378 2002

[23] A Chouai S E Wicke C Turro et al ldquoRuhenium(II) com-plexes of 1 12-Diazaperylene and their interaction with DNArdquoInorganic Chemistry vol 44 pp 5966ndash6003 2005

[24] A O Adeloye T O Olomola A I Adebayo and P A AjibadeldquoA high molar extinction coefficient bisterpyridyl homolepticRu(II) complex with trans-2- ethyl-2-butenoic acid function-ality potential dye for dye-sensitized solar cellsrdquo InternationalJournal of Molecular Sciences vol 13 no 3 pp 3511ndash3526 2012

[25] R PThummel ldquoRecent advances in the synthesis and chemistryof 110-phenanthroline derivativesrdquo in Advances in NitrogenHeterocycles C J Moody Ed vol 4 p 107 JAI Press StamfordNY USA 2000

[26] P Wang S M Zakeeruddin J E Moser et al ldquoStable newsensitizer with improved light harvesting for nanocrystallinedye-sensitized solar cellsrdquo Advanced Materials vol 16 no 20pp 1806ndash1811 2004

[27] A O Adeloye and P A Ajibade ldquoSynthesis characterizationand preliminary investigation of the electro redox propertiesof anthracenyl-functionalized terpyridyl ligandsrdquo TetrahedronLetters vol 52 no 2 pp 274ndash277 2011

[28] M Jeong H Nam O J Sohn et al ldquoSynthesis of phenathro-line derivatives by Sonogashira reaction and the use of theirruthenium complexes as optical sensorsrdquo Inorganic ChemistryCommunications vol 11 pp 97ndash100 2008

[29] I P Evans A Spencer and G Wilkinson ldquoDichlorote-trakis(dimethyl sulphoxide) ruthenium(II) and its Use as aSource Material for Some New Ruthenium(II) ComplexesrdquoJournal of the Chemical Society Dalton pp 204ndash208 1973

[30] C A Mitsopoulou I Veroni A I Philippopoulos and PFalaras ldquoSynthesis characterization and sensitization proper-ties of two novel mono and bis carboxyl-dipyrido-phenazineruthenium(II) charge transfer complexesrdquo Journal of Photo-chemistry and PhotobiologyA Chemistry vol 191 no 1 pp 6ndash122007

[31] M Yanagida T Yamaguchi M Kurashige et al ldquoNanocrys-talline solar cells sensitized with monocarboxyl or dicarboxylpyridylquinoline ruthenium(II) complexesrdquo Inorganica Chim-ica Acta vol 351 no 1 pp 283ndash290 2003

[32] M K Nazeeruddin S M Zakeeruddin J-J Lagref et alldquoStepwise assembly of amphiphilic ruthenium sensitizers andtheir applications in dye-sensitized solar cellrdquo CoordinationChemistry Reviews vol 248 no 13-14 pp 1317ndash1328 2004


[33] P Zhang B Xia Y Sun et al ldquoElectronic structures and opticalproperties of two anthracene derivativesrdquo Chinese Science Bul-letin vol 51 no 20 pp 2444ndash2450 2006

[34] MHissler AHarriman A Khatyr and R Ziessel ldquoIntramolec-ular triplet energy transfer in pyrenemdashmetal polypyridinedyads a strategy for extending the triplet lifetime of the metalcomplexrdquo ChemistrymdashA European Journal vol 5 no 11 pp3366ndash3381 1999

[35] A C Benniston V Grosshenny A Harriman and R ZiesselldquoPhotophysical properties of closely-coupled binuclear ruthe-nium(II) bis(2210158406101584021015840-terpyridine) complexesrdquo Dalton Trans-actions no 8 pp 1227ndash1232 2004

[36] J R Winkler T L Netzel C Creutz and N Sutin ldquoDirectobservation of metal-to-ligand charge-transfer (MLCT) excitedstates of pentaammineruthenium(II) complexesrdquo Journal of theAmerican Chemical Society vol 109 no 8 pp 2381ndash2392 1987

[37] N Aydin and C-W Schlaepfer ldquoNew luminescent Ru(II) com-plexes containing a dangling amine group Ru(bpy)

2(dien)2+

and Ru(bpy)2(entn)2+rdquo Polyhedron vol 20 no 1-2 pp 37ndash45

2001[38] C J Sumby and P J Steel ldquoMono- and dinuclear ruthe-

nium complexes of bridging ligands incorporating two di-2-pyridylamine motifs synthesis spectroscopy and electrochem-istryrdquo Polyhedron vol 26 no 18 pp 5370ndash5381 2007

[39] Md K Nazeeruddin A Kay I Rodicio et al ldquoConversionof light to electricity by cis-X

2(dcbpy)

2Ru(II) CT sensitizers

on nanocrystalline TiO2electrodesrdquo Journal of the American

Chemical Society vol 115 no 14 pp 6382ndash6390 1993[40] J R Lakowicz Principles of Fluorescence Spectroscopy Kluwer

AcademicPlenum New York NY USA 2nd edition 1999[41] J R Lakowicz Topics in Fluorescence Spectroscopy vol 4 of

Probe Design and Chemical Sensing Plenum Press New YorkNY USA Edited by J R Lakowicz1994

[42] H Szmacinski and J R Lakowicz ldquoFluorescence lifetime-basedsensing and imagingrdquo Sensors and Actuators B Chemical vol29 no 1ndash3 pp 16ndash24 1995

[43] F N Castellano and J R Lakowicz ldquoA water-soluble lumines-cence oxygen sensorrdquo Photochemistry and Photobiology vol 67pp 179ndash183 1998

[44] J R Lakowicz F N Castellano J D Dattelbaum L TolosaG Rao and I Gryczynski ldquoLow-frequency modulation sensorsusing nanosecond fluorophoresrdquo Analytical Chemistry vol 70pp 5115ndash5121 1998

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


triplet metal-to-ligand charge transfer (3MLCT) states thusminimizing their interaction with higher-lying 3MC statesThis has been achieved by the use of substituents [18]cyclometalating ligands [19] and ligands with extended 120587systems [20ndash22] Most of these attempts have resulted ina lowering of the 3MLCT energy A few recent studieshave more specifically aimed at increasing the ligand fieldstrength by the use of strong 120590-donor ligands [23 24] astrategy however that results in a concomitant decrease ofthe 3MLCT state energy and thus limits the reactivity [25]The dye solar cells devices based on such complexes forexample display good photovoltaic performance and alsostrongmetal-to-ligand charge transition (MLCT) band in thevisible region of absorption Nevertheless further extensionof the conjugation length of the ancillary ligand faces thesituation that the 120587-orbital energy of the ancillary ligandsincreases tomatch that of themetal centre with the result thatthe 120587-orbital of the ancillary ligand participates significantlyin the HOMO of the complex The result is the reduction ofthe absorption coefficient of the MLCT band and thereforedecreased efficiency [26]

This paper reports the recent attempts based on the intro-duction of anthracene functionality in a stepwise increaseinto terpyridine ligands and the successful complexationof these ligands to a transition metal ion [ruthenium(II)]Our research goal is specifically focused on improving themolar extinction coefficient increasing the wavelength ofcomplexes towards the near-infrared region and improvingdye stability

2 Experimental Section

21 Materials and General Physical Measurements All com-mercial reagents used were analytically pure without furtherpurification The ligand precursors 41015840-(9-bromanthracenyl)-terpyridine (L1) 41015840-(9-bromodianthracenyl)-terpyridine(L2) and 41015840-(9-bromotrianthracenyl)-terpyridine (L3) wereprepared as described in the literature [27] The thin layerchromatography (tlc) analyses were done with aluminiumsheet precoated with normal phase silica gel 60 F

254(Merck

020mm thickness) except otherwise stated The tlc plateswere developed using any of the following solvent systemsSolvent system A Dichloromethane-Methanol (9 1) Solventsystem B Dichloromethane-Methanol (7 3) Solvent systemC Dichloromethane-Benzene (3 7) Solvent system DChloroform-Methanol (1 1) Gel filtration was performedusing Sephadex LH-20 previously swollen in specifiedsolvent (s) prior to loading of extract onto the column(35 cm times 85 cm)

Melting points were determined using Gallenkamp elec-trothermal melting point apparatus Microanalyses (C HN) were carried out with a Fisons elemental analyser andinfrared spectra were obtained with KBr discs or nujol on aPerkin Elmer System 2000 FT-IR Spectrophotometer UV-Visand fluorescence spectra were recorded in 1 cm path lengthquartz cell on a Perkin Elmer Lambda 35 spectrophotometerand Perkin Elmer Lambda 45 spectrofluorometer respec-tively 1H and 13C Nuclear Magnetic Resonance spectra were

run on a Bruker EMX 400MHz spectrometer for 1H and100MHz for 13C The chemical shift values were reportedin parts per million (ppm) relative to (TMS) as internalstandard Chemical shifts were also reported with respect toDMSO d

6at 120575c 4098 and DMSO d

6at 120575H 250 ppm All

electrochemical experiments were performed using Autolabpotentiostat PGSTAT 302 (EcoChemie Utrecht The Nether-lands) driven by the general purpose Electrochemical Systemdata processing software (GPES software version 49) Squarewave voltammetric analysis was carried out at a frequencyof 10Hz amplitude of 50mV and step potential of 5mV Aconventional three-electrode system was used The workingelectrode was a bare glassy carbon electrode (GCE) Ag|AgClwire and platinum wire were used as the pseudoreferenceand auxiliary electrodes respectively The potential responseof the Ag|AgCl pseudoreference electrode was less than theAg|AgCl (3MKCl) by 0015 plusmn 0003V Prior to use the elec-trode surface was polished with alumina on a Buehler felt padand rinsed with excess millipore water All electrochemicalexperiments were performed in freshly distilled dry DMFcontaining TBABF

4as supporting electrolyte

211 Synthesis of Ruthenium(II)-bis(9-monoanthracenyl-10-(2-methyl-2-butenoic acid)-terpyridyl)-bis(hexafluorophos-phate) Complex RBT1 The ruthenium complex precursorRuCl2(DMSO)

4and the corresponding ruthenium bister-

pyridine complexes were prepared with a slight modifica-tion to literature method [28ndash30] 41015840-(9-bromoanthracenyl)-terpyridine (L1) (0195 g 040mmol) was reacted withRuCl2(DMSO)

4(0097 g 020mmol) in DMF (40mL) The

resulting mixture was refluxed for 8 h in the dark andcool to room temperature Without isolation of the darkred complex 2-methyl-2-butenoic acid (004 g 040mmol)triethylamine (1mL) and KOH (005 g 080mmol) wereadded and the reaction mixture further allowed to refluxfor another 4 hours The crude product was allowed tocool to room temperature and filtered to remove unreactedsolid products Distilled water was added and extracted intochloroformThe organic layer was collected and concentratedto dryness in vacuo on rotary evaporator A 10mL solutionof NaOH (005M) was added and the mixture turned toa deep orange red colour After filtration pH was adjustedto 3 with HNO

305M and resulting solution was left

to stand in the fridge for 12 h The acidic solution afterfiltration of the insoluble precipitate was concentrated toafford a semisolid product which was purified by columnchromatography on Sephadex LH20 in ethanol-toluene 50vv) Column fractions with similar tlc characteristics werebulked together and concentrated under reduced pressureand excess ammonium hexafluorophosphate in water wasused to precipitate the complex to afford (RBT1) as a darkbrown solid (018 g Percentage Yield = 321 mp = 196-197∘C) IR data (KBr cmminus1) 3418 3121 2926 2852 23661917 1678 1621 1592 1451 1384 1304 1284 1256 1170 10971054 1028 926 839 772 747 694 558 468 423 120582maxnm(120576103Mminus1 cmminus1) (CH

3ClMeOH 1 1 vv) 1012 (0937) 916

(1074) 486 (5337) 405 (17368) 383 (19391) 364 (15062)120582em = 681 nm (Int 932)1H NMR (400MHz DMSO-d

6)



3) 256 (s CH

3) 13C

NMR (400MHz DMSO-d6) 120575 18249 15769 15473 15201


68H50N6O4P2F12)





6) 120575 908


3) 256 (s CH


6)


96H66N6O4P2F12)


2(DMSO)

4(007 g


3ClMeOH 1 1 vv) 1012 (2217) 916


6) 120575 908 (d 119869 = 82Hz 2H H-31015840



3) 256 (s CH


6)


124H82N6O4P2F12)



2(DMSO)

4







N

N

N

Br

Ru N

N

N

BrN

N

N

Br

Ru N

N

N

N

N

N

H

n n

n

nn

CH3

CH3

CH3

(PF6)2

(Where n = 1 2 3)

Where n = 1 2 3

RuCl2(DMSO)4 +


2+

(ii) HNO3 NaOH




HOOC

H3C

COO







0

05

15

25

1

2

0

05

15

25

1

2

630530430330

630 730 830 930 1030530430330

Wavelength (nm)

Wavelength (nm)

0

05

15

25

1

2

6530430330

Wavelength (nm)

Abso

rban

ce (a

u)

Abso

rban

ce (a

u)

(a)

08

06

04

02

0

Abso

rban

ce (a

u)

410 460 510 560 610


RBT 2

RBT 3

(b)

800 850 950 1000 1050 1100900

Wavelength (nm)

005

01

0

Abso

rban

ce (a

u)

RBT 1

RBT 2

RBT 3

(c)


vv)



2]2+




11986412Vc

RBT1 364 (151) 383 (194) 405 (174) 486 (53)554 (19)916 (11)1012 (09)

681 (932)i 030 057085 113

minus025minus054

RBT2 364 (206) 383 (287) 404 (278) 484 (95)554 (25)916 (13)1012 (12)


RBT3 360 (397) 380 (494) 402 (459) 481 (91)554 (40)916 (18)1012 (22)

743 (754)i 073 099 minus090


600

400

200

0

800

750 800700600 650

Wavelength (nm)

RBT 1

RBT 2

RBT 3

1000

Emiss

ion

inte

nsity

(au

)








60120583A

III

III

CV of RBT1


(a)


Sqw of RBT1

40120583A

III

I

II

IV

V

(b)




I

IIIII

CV of RBT2

50120583A


(a)


I

II

III

IV

V

10

Sqw of RBT2

60120583A


(b)










I

III

II


CV of RBT3

50120583A


(a)

I

III

II


Sqw of RBT3

40120583A


(b)




12= minus090V was


4 Conclusions





Acknowledgments


References














































2(dien)2+





2(dcbpy)


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



3) 256 (s CH

3) 13C

NMR (400MHz DMSO-d6) 120575 18249 15769 15473 15201


68H50N6O4P2F12)





6) 120575 908


3) 256 (s CH


6)


96H66N6O4P2F12)


2(DMSO)

4(007 g


3ClMeOH 1 1 vv) 1012 (2217) 916


6) 120575 908 (d 119869 = 82Hz 2H H-31015840



3) 256 (s CH


6)


124H82N6O4P2F12)



2(DMSO)

4







N

N

N

Br

Ru N

N

N

BrN

N

N

Br

Ru N

N

N

N

N

N

H

n n

n

nn

CH3

CH3

CH3

(PF6)2

(Where n = 1 2 3)

Where n = 1 2 3

RuCl2(DMSO)4 +


2+

(ii) HNO3 NaOH




HOOC

H3C

COO







0

05

15

25

1

2

0

05

15

25

1

2

630530430330

630 730 830 930 1030530430330

Wavelength (nm)

Wavelength (nm)

0

05

15

25

1

2

6530430330

Wavelength (nm)

Abso

rban

ce (a

u)

Abso

rban

ce (a

u)

(a)

08

06

04

02

0

Abso

rban

ce (a

u)

410 460 510 560 610


RBT 2

RBT 3

(b)

800 850 950 1000 1050 1100900

Wavelength (nm)

005

01

0

Abso

rban

ce (a

u)

RBT 1

RBT 2

RBT 3

(c)


vv)



2]2+




11986412Vc

RBT1 364 (151) 383 (194) 405 (174) 486 (53)554 (19)916 (11)1012 (09)

681 (932)i 030 057085 113

minus025minus054

RBT2 364 (206) 383 (287) 404 (278) 484 (95)554 (25)916 (13)1012 (12)


RBT3 360 (397) 380 (494) 402 (459) 481 (91)554 (40)916 (18)1012 (22)

743 (754)i 073 099 minus090


600

400

200

0

800

750 800700600 650

Wavelength (nm)

RBT 1

RBT 2

RBT 3

1000

Emiss

ion

inte

nsity

(au

)








60120583A

III

III

CV of RBT1


(a)


Sqw of RBT1

40120583A

III

I

II

IV

V

(b)




I

IIIII

CV of RBT2

50120583A


(a)


I

II

III

IV

V

10

Sqw of RBT2

60120583A


(b)










I

III

II


CV of RBT3

50120583A


(a)

I

III

II


Sqw of RBT3

40120583A


(b)




12= minus090V was


4 Conclusions





Acknowledgments


References














































2(dien)2+





2(dcbpy)


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


N

N

N

Br

Ru N

N

N

BrN

N

N

Br

Ru N

N

N

N

N

N

H

n n

n

nn

CH3

CH3

CH3

(PF6)2

(Where n = 1 2 3)

Where n = 1 2 3

RuCl2(DMSO)4 +


2+

(ii) HNO3 NaOH




HOOC

H3C

COO







0

05

15

25

1

2

0

05

15

25

1

2

630530430330

630 730 830 930 1030530430330

Wavelength (nm)

Wavelength (nm)

0

05

15

25

1

2

6530430330

Wavelength (nm)

Abso

rban

ce (a

u)

Abso

rban

ce (a

u)

(a)

08

06

04

02

0

Abso

rban

ce (a

u)

410 460 510 560 610


RBT 2

RBT 3

(b)

800 850 950 1000 1050 1100900

Wavelength (nm)

005

01

0

Abso

rban

ce (a

u)

RBT 1

RBT 2

RBT 3

(c)


vv)



2]2+




11986412Vc

RBT1 364 (151) 383 (194) 405 (174) 486 (53)554 (19)916 (11)1012 (09)

681 (932)i 030 057085 113

minus025minus054

RBT2 364 (206) 383 (287) 404 (278) 484 (95)554 (25)916 (13)1012 (12)


RBT3 360 (397) 380 (494) 402 (459) 481 (91)554 (40)916 (18)1012 (22)

743 (754)i 073 099 minus090


600

400

200

0

800

750 800700600 650

Wavelength (nm)

RBT 1

RBT 2

RBT 3

1000

Emiss

ion

inte

nsity

(au

)








60120583A

III

III

CV of RBT1


(a)


Sqw of RBT1

40120583A

III

I

II

IV

V

(b)




I

IIIII

CV of RBT2

50120583A


(a)


I

II

III

IV

V

10

Sqw of RBT2

60120583A


(b)










I

III

II


CV of RBT3

50120583A


(a)

I

III

II


Sqw of RBT3

40120583A


(b)




12= minus090V was


4 Conclusions





Acknowledgments


References














































2(dien)2+





2(dcbpy)


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0

05

15

25

1

2

0

05

15

25

1

2

630530430330

630 730 830 930 1030530430330

Wavelength (nm)

Wavelength (nm)

0

05

15

25

1

2

6530430330

Wavelength (nm)

Abso

rban

ce (a

u)

Abso

rban

ce (a

u)

(a)

08

06

04

02

0

Abso

rban

ce (a

u)

410 460 510 560 610


RBT 2

RBT 3

(b)

800 850 950 1000 1050 1100900

Wavelength (nm)

005

01

0

Abso

rban

ce (a

u)

RBT 1

RBT 2

RBT 3

(c)


vv)



2]2+




11986412Vc

RBT1 364 (151) 383 (194) 405 (174) 486 (53)554 (19)916 (11)1012 (09)

681 (932)i 030 057085 113

minus025minus054

RBT2 364 (206) 383 (287) 404 (278) 484 (95)554 (25)916 (13)1012 (12)


RBT3 360 (397) 380 (494) 402 (459) 481 (91)554 (40)916 (18)1012 (22)

743 (754)i 073 099 minus090


600

400

200

0

800

750 800700600 650

Wavelength (nm)

RBT 1

RBT 2

RBT 3

1000

Emiss

ion

inte

nsity

(au

)








60120583A

III

III

CV of RBT1


(a)


Sqw of RBT1

40120583A

III

I

II

IV

V

(b)




I

IIIII

CV of RBT2

50120583A


(a)


I

II

III

IV

V

10

Sqw of RBT2

60120583A


(b)










I

III

II


CV of RBT3

50120583A


(a)

I

III

II


Sqw of RBT3

40120583A


(b)




12= minus090V was


4 Conclusions





Acknowledgments


References














































2(dien)2+





2(dcbpy)


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




11986412Vc

RBT1 364 (151) 383 (194) 405 (174) 486 (53)554 (19)916 (11)1012 (09)

681 (932)i 030 057085 113

minus025minus054

RBT2 364 (206) 383 (287) 404 (278) 484 (95)554 (25)916 (13)1012 (12)


RBT3 360 (397) 380 (494) 402 (459) 481 (91)554 (40)916 (18)1012 (22)

743 (754)i 073 099 minus090


600

400

200

0

800

750 800700600 650

Wavelength (nm)

RBT 1

RBT 2

RBT 3

1000

Emiss

ion

inte

nsity

(au

)








60120583A

III

III

CV of RBT1


(a)


Sqw of RBT1

40120583A

III

I

II

IV

V

(b)




I

IIIII

CV of RBT2

50120583A


(a)


I

II

III

IV

V

10

Sqw of RBT2

60120583A


(b)










I

III

II


CV of RBT3

50120583A


(a)

I

III

II


Sqw of RBT3

40120583A


(b)




12= minus090V was


4 Conclusions





Acknowledgments


References














































2(dien)2+





2(dcbpy)


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



60120583A

III

III

CV of RBT1


(a)


Sqw of RBT1

40120583A

III

I

II

IV

V

(b)




I

IIIII

CV of RBT2

50120583A


(a)


I

II

III

IV

V

10

Sqw of RBT2

60120583A


(b)










I

III

II


CV of RBT3

50120583A


(a)

I

III

II


Sqw of RBT3

40120583A


(b)




12= minus090V was


4 Conclusions





Acknowledgments


References














































2(dien)2+





2(dcbpy)


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


I

III

II


CV of RBT3

50120583A


(a)

I

III

II


Sqw of RBT3

40120583A


(b)




12= minus090V was


4 Conclusions





Acknowledgments


References














































2(dien)2+





2(dcbpy)


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of












































2(dien)2+





2(dcbpy)


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of







2(dien)2+





2(dcbpy)


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Documents

AdewaleO.AdeloyeandPeterA.Ajibadedownloads.hindawi.com/journals/tswj/2014/570864.pdfAdewaleO.AdeloyeandPeterA.Ajibade Department of Chemistry, Faculty of Science and Agriculture, University