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8/8/2019 Supra Super Molecular Architecture DC
1/17
Synthesis ofSynthesis of SuprasupermoleculesSuprasupermolecules
andand
Molecular ArchitectureMolecular Architecture
by
8/8/2019 Supra Super Molecular Architecture DC
2/17
Supramolecular chemistry is one of the most active fields in coordination
chemistry for applications in new nanomaterials and biological systems.
Noncovalent intermolecular interactions, such as hydrogen bonds or -
stacking, exhibit environmentally sensitive spectroscopic properties (polarsolvents, temperature, pH). They govern molecular association, catalysis, and a
multitude of biochemical processes
Supramolecular entities possess a primary structure, corresponding to the
molecular skeletons of their building blocks ,
The ultimate aim of supramolecular chemistry is to become the science of
informed matter which create functioning , process information, and machine-
like systems that mimic nature.
Supramolecular entities which coordinatively bonds between suitable metal
ions and organic heterocyclic ligands have proven extremely useful for thegeneration of regularly shaped molecules (molecular architecture).
The combination of appropriate angular and linear building
blocks(metals/ligands) can process information. The 90 angles of square-
planar or octahedral metal entities are ideal for the formation of square planar,
rectangular or box-like structures.
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The advantages of employing transition metals to build self-assembly
supramolecular complexes include,
(1) The involvement of d orbitals which offer more bonding modes and
geometrical symmetries than organic molecules.
(2) A range of electronic and steric properties that can be finely-tuned.
(3) The ability to easily modify the size of the desired supramolecules by
utilizing different lengths of bridging ligands.
Distinct properties such as spectral, magnetic, redox, photophysical and
photochemical properties can be incorporated.
Figure 1. a) Square using pyrazene as linear ligand and calix[4]arene protected Pt as a corner metal, b) Square usingpyrazene as linear ligand and diethyleneamine protected Pd as a corner metal.
a) b)
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Figure 2). Molecular library for the preparation of regular shaped molecules
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Long-range energy- and electron- transfer processes are amongst the most
interesting and challenging reactions both from a theoretical and an application
perspective.
Different approaches related to the feasibility to construct long rigid systemswhere an electron- or energy- donor moiety is separated by a long connector to
an acceptor system.
Research in molecular-electronics widely use supramolecules to mimic the
active and passive components (switches, memory circuits, rectifiers, logic
gates, sensors, diodes, resistors and LEDs) of electronic or integrated circuits.
Dendrimers dedicate themselves in the field of molecular-electronics.
These compounds can be grown either by convergent or by divergent synthetic
methodology.Specific properties can be incorporated in the dendrimers by altering the
building blocks and it is tailored to absorb visible light, to give luminescence,
and to undergo reversible multielectron redox processes.
8/8/2019 Supra Super Molecular Architecture DC
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Metallodendrimers or suprasupermolecular species possess novel physical,
optical, electrochemical, photochemical, biological, and catalytic properties.
Such species could find applications as components in molecular electronics as
photochemical molecular devices for solar energy conversion and information
storage.
In this suprasupermolecular architecture 2,2:6,2 -terpyridine (tpy) is
widely used.Design and synthesis of such smart materials may function as a molecular
switch.
These materials can exhibit both on and off states, which modulate both
their chemical and physical properties. The M-tpy complexes were selected
because of their appealing photophysical and electrochemical properties.
Figure 3. a) Representation of a dendrimer, b) Divergent approach, and c) Convergent approach
a) b) c)
8/8/2019 Supra Super Molecular Architecture DC
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These complexes have been employed as building blocks for the design of
supramolecular assemblies and metallodendrimers which can be used in
1 Fabrication of dye-sensitized solar cells.
2 In artificial photosynthesis.
3 In light-to-chemical energy conversion.
4 In light harvesting antennas.
5 In nonlinear optics.6 DNA probes.
Ruthenium(II) polypyridyl complexes have been widely used in a variety of
systems as photoactive components because of long excited-state lifetimes and
high luminescent efficiencies.Ru(II) and Os(II) complexes of 2,2-bipyridine (bpy) and related bidentate
ligands exhibit strong MLCT absorption in visible region and long-lived
emitting 3MLCT excited states.
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Therefore synthesis of Ru(II) and Os(II) complexes of 6-tolyl-2,2:4,2-
terpyridine (tpbpy), 4-tolyl-2,2:6,2-terpyridine (ttpy) is used to design
metallodendrimer and 4-tolyl-2,2:6,2-terpyridine (ttpy) is used in
developing molecular architectures.
The relevant properties of Ru(II) and Os(II) polypyridine complexes are
(i) Good stability of the ground as well as the excited states.
(ii) Absorption in the visible region, due to intense spin allowed (and in the case
of osmium compounds, also spin forbidden) metal-to-ligand charge transfer(MLCT) bands.
(iii)Relatively long-lived (typically in the microsecond time range) and
luminescent excited states. Emission is usually due to radiative deactivation
of the lowest-lying 3MLCT level(s).
(iv)Reversible metal-centered oxidation and ligand-centered reduction
processes at accessible potentials.
(v) Tunability of all the properties by a judicious choice and combination of the
ligands.
8/8/2019 Supra Super Molecular Architecture DC
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Synthesis of 6-tolyl-2,2:4,2-terpyridine (tpbpy) and 4-tolyl-2,2:6,2
terpyridine (ttpy)
CH3
CHO
+N COCH3
2
N
NN
+N
N
N
CH3CONH2
CH3COONH4
NaOH
1,4- Michael addition 1,2- Michael addition
FAS, KPF6KOH,H2O2
N
NN
N
N
N
Toulene wash
NBS,CCl4
6 h Reflux
NBS,CCl4
6 h RefluxN
N
N
Br
N
NN
Br
mp 174C
White needles
mp 176C
Yellow sponge
135 C dec
Yellow sponge
mp 115 C
Yellow
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Synthesis of the precursor
N
N
N
Br
+ HN
OH
OH
2CO3,TH
24 r
fl
stirri g
N
N
N
HON
OH
500 MHz 1H NMR in CDCl3 125 MHz13C NMR in CDCl3
DART-MS
[M+1]bromo 6-tolyl-2,2:4,2-
terpyridine (br-tpbpy)Yellow oil
8/8/2019 Supra Super Molecular Architecture DC
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Synthesis of the 2-(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)benzyloxy)-N-(2-(4-
(2,6-di(pyridin-2-yl)pyridin-4-yl)benzyloxy)ethyl)-N-(4-(4,6-di(pyridin-2-
yl)pyridin-2-yl)benzyl)ethanamine
N
N
N
M
N
N
N
N
N
N
M
N
N
N
NN
N
N N
N
N
N
N
N
N
N
N
N
NN
N
N
N
N
N
N
O O
N
N
N
N
N
NN
N
N
NO
O
N
N
N
N
M
O
O
MM
M
M
M = Ru orOs
14 PF6
YellowNN
N
HON
OH
N
NN
Br
+ 2NaH,THF
0 oC
N
N
N
N
N
N
N
N
N
NO
O
8/8/2019 Supra Super Molecular Architecture DC
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N
N
N
M
N
N
N
N
N
N
N
N
N
N
N
N
NN
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
O
N
N
N
N
N
N
N
N
N
N
N
N
N
N
NM
N
N
N
N
N
N
M
N
N
N
NN
N
N N
N
N
N
N
N
N
N
N
N
NN
N
N
N
N
N
N
O O
N
N
N
N
N
N
N
N
N
NO
O
N
N
N
N
M
O
O
MM
M
M
N
N
O
O
O
O
NO
N
N
O
O
N
O
O
O
O
N
N
NN
N
N
N
N
N
N
N
N
M
NN
NM
M
M
M
M
M
M
N
N
N
M
N
N
N
M
N
N
N
M
M
rOs
38
8/8/2019 Supra Super Molecular Architecture DC
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Synthesis of (E)-N-((E)-4-((E)-4-((4-((E)-(pyridin-2-
ylimino)methyl)phenoxy)methyl)benzyloxy)benzylidene)pyridin-2-amine
CH3
CH3
NBS
CCl4
Br
Br
mp 77 C
White powder
OH
CHO
N NH2+
EtOH
N N C OH
(E)-4-((pyridin-2-
ylimino)methyl)phenol
Yellow oil
mp 180 C dec
White powder
NH2
NH2
NH2
NH2
H2N
H2NPt
Pt
N NC O O
NNC
N
N
C
O
O
N
N
C
Pt
Pt
NNCOO
N NC
N
N
C
O
O
N
N
C
NH2
NH2
8+
rt
+Br Br
N NC O O
NNC
r fl and stirring
2CO3,THF
N NC OH
50 C
8/8/2019 Supra Super Molecular Architecture DC
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Synthesis of (E)-4-((4-methylpyridin-2-ylimino)methyl)phenol
OH
CHO
N NH2
+EtOH
N NC OH
Yellow oil
NH2
NH2
NH2
NH2
H2N
H2NPt
Pt
N NC O O
NNC
N
N
C
O
O
N
N
C
Pt
Pt
NNCOO
N NC
N
N
C
O
O
N
N
C
NH2
NH2
8+
8/8/2019 Supra Super Molecular Architecture DC
15/17
N
N
N
O
N
N
N
N
N
O
N
N
Ru
Pt
N
NN
O
N
N
N
NN
O
N
N
Ru
PtPt
N
N
N
O
N
N
N
N
N
O
N
N
Ru
N
N N
O
N
N
N
N N
O
N
N
Ru
Pt
H2N
H2N
H2N
H2N
NH2
NH2
NH2
NH2
1 +
N
NC OH+ N
NH2OH
CHO
EtOH
Synthesis of (E)-N-(4-(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)benzyloxy)-
benzylidene)pyridin-4-amine
Yellow oil
Brown solid
rt
+
N
NN
Br
2CO3,THF
r fluxand stirringN
N
N
O
N
N
N
N C OH24
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8/8/2019 Supra Super Molecular Architecture DC
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The photochemical and photophysical properties of transition metal complexes of polypyridine
ligands is incorporating light-sensitizing chromophores capable of transferring their excited-state
energy to the bound metal ion wherein the metal-centered luminescence is amplified by indirect
excitation (sensitization or antenna effect).