Photoinduced Reactions in Supramolecular Species

Receptor-substrate binding may affect the photochemical reactivity of either or of both species. The recognition process could thus modify the course of a reaction, 

The complexation of coordination compounds may make it possible to control their photochemical behaviour via the structure of the supramolecular species formed. For instance, the binding of cobalt(m) hexacyanide by macrocyclic polyammonium receptors markedly affects their photoaquation quantum yield in a structure-dependent manner [8.73-8.77]. It thus appears possible to orient the photosubstitution reactions of transition-metal complexes by using appropriate receptor molecules. Such effects may be general, applying to complex cations as well as to complex anions [2.114]. 

The course of a number of other photoreactions could be altered or oriented by selective binding. In particular, substances effecting single- or double-strand nucleic acid recognition and fitted with a photoreactive group may perform sequence specific photocleavage [4.56, 5.29, 5.30]. 

The incorporation of photoactive compounds into organized supramolecular assemblies allows the induction of specific reactions and structural changes such as, for instance, in the photocrosslinking of photopolymerizable components in lipid vesicles, a powerful approach to the control of polymolecular architectures [7.10, 8.78]. 

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