Photochemical supramolecular devices

Photochemical supramolecular devices can be conveniently divided into three groups. 

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Outline examples of how photochemical supramolecular devices can be used for energy- and electron-transfer processes, for information processing and as light-driven machines. 

Sabbatini, N. Guardigli, M. Lehn, J.-M. Luminescent lanthanide complexes as photochemical supramolecular devices. Coord. Chem. Rev. 1993,123, 201-228. Sabbatini, N. Guardigli, M. Manet, I. Lanthanide complexes of encapsulating ligands as luminescent devices. Adv. Photochem. 1997, 23, 213—278. 

Sabbatini, N. Guardigli, M. Lehn, J.-M. Luminescent Lanthanide Conq>lexes as Photochemical Supramolecular Devices/ Coord. Chem. Revs. 1993 123, 201. 

Sabbatini N, Guardigli M, Lehn J-M (1993) Luminescent lanthanide complexes as photochemical supramolecular devices. Coord Chem Rev 123 201-228... 

Balzani, V., L. Moggi, and F. Scandola (1987), Towards a Supramolecular Photochemistry Assembly of Molecular Components to Obtain Photochemical Molecular Devices", in V. Balzani, Ed., Supramolecular Photochemistry, NATO ASI Series, Ser. C, Vol. 214, D. Reidel, Dordrecht, Holland. 

When interaction between the metal-based components is weak, polynuclear transition metal complexes belong to the field of supramolecular chemistry. At the roots of supramolecular chemistry is the concept that supramolecular species have the potential to achieve much more elaborated tasks than simple molecular components while a molecular component can be involved in simple acts, supramolecular species can performIn other words, supramolecular species have the potentiality to behave as molecular devices. Particularly interesting molecular devices are those which use light to achieve their functions. Molecular devices which perform light-induced functions are called photochemical molecular devices (PMD). Luminescent and redox-active polynuclear complexes as those described in this chapter can play a role as PMDs operating by photoinduced energy and electron transfer processes. ... 

Balzani, V., Moggi, L., Scandola, F. (1987) Towards a supramolecular photochemistry assembly of molecular components to obtain photochemical molecular devices in Supramolecular Photochemistry, NATO Advanced Science Institutes Series Series C Mathematical and Physical Sciences (ed. V. Balzani), D. Reidel Publishing Company, Dordrecht, vol. 214, pp. 1-28. 

The photochemical and photophysical processes discussed above provide illustrations and incentives for further studies of photoeffects brought about by the formation of supramolecular species. Such investigations may lead to the development of photoactive molecular and supramolecular devices, based on photoinduced energy migration, electron transfer, substrate release, or chemical transformation. Coupling to recognition processes may allow the transduction of molecular infor-... 

Figure 11.1 Photochemical and electrochemical criteria used to classify a complex chemical species as a supramolecular device or a large molecule.

The two most important methods of both probing and stimulating supramolecular devices are photochemical and electrochemical techniques. The most prevalent events to occur in such devices are electron, energy and proton transfer, as well as molecular rearrangement. Any of these events can provide the basis for forms of transducable output on which molecular electronic devices may be based. Therefore, the theories most commonly applied to such electrochemically and photochemically triggered events are outlined in this chapter. In addition, an overview of the mechanisms by which such events occur is provided, identifying the molecular or physical parameters required to make such events feasible in a supramolecular structure. 

Based on their easily tunable photophysical and redox properties, transition metal complexes are versatile components to be used in the construction of photochemical molecular devices. The studies presented in this article show that the combination of the Ru(bpy)22+ photosensitizer and cyanide bridging units allows the synthesis of a variety of polynuclear systems that exhibit interesting photochemical properties. Depending on the nature of the attached metal-containing units, supramolecular systems can be obtained that undergo efficient photoinduced intramolecular energy or electron transfer processes. 

Common components within supramolecular devices as they are studied today are photochemically or redox active molecules, i.e. molecules capable of absorbing and/or emitting light and molecules capable of losing or gaining an electron. The definition of a supramolecular device made up from these components is illustrated in Figure 11.1. If light excitation of a molecule ( o ) results in the formation... 

On the basis of extensive challenging approaches for chromophoric assemblies and supramolecular systems, supramolecular devices such as photoresponsive organic conductors and photochemically acdvated molecular wire have been proposed. 

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