supra super molecular architecture dc

8/8/2019 Supra Super Molecular Architecture DC

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Synthesis ofSynthesis of SuprasupermoleculesSuprasupermolecules

andand

Molecular ArchitectureMolecular Architecture

by


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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.


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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)


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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.


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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


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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


12/17

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


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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


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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+


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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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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).

supra super molecular architecture dc

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