Micelle light induced electron transfer

The primary effect of micelles on light-induced electron transfer involves the intervention of an interfacial region which can significantly influence the radical ion association and dissociation equilibria by a combination of electrostatic and hydro-phobic interactions. Diffusive encounters of reaction partners are controlled within a micelle by the diffusion of one reactant to the highly polar surface, by collision of two reactants confined within the hydrophobic region in the interior of the micelle, and by the reaction of two reactants whose motions are confined to diffusion along the micellar surface. 

We have prepared and studied a number of surfactant, hydrophobic and water soluble luminescent metal complexes. These can serve as excited substrates in light-induced electron transfer reactions. Both the quenching processes and subsequent reactions can be strongly affected by incorporation of the substrate and/or quencher in an organized assembly. This paper focuses mainly on studies in micelles. 

Electron-transfer Reactions - Light-induced electron transfer from a donor to a suitable acceptor has been described for numerous bimolecular systems. The reagents have been dispersed in a polar solvent,at microscopic or macroscopic interfaces, in latex dispersions, in nematic liquid crystals, in reverse micelles, in vesicles, and in lipid bilayer membranes. Additional studies have been concerned with electron transfer... 

Molecular assemblies in anionic environments influence the efficiency of fluorescence quenching by electron transfer . Viseu and Costa use a combination of steady state and time resolved fluorescence quenching data to evaluate partition coefficients of fluorescent molecules into micelles. The breakdown of rod-like micelles and light induced viscosity changes in micelles are effects that can both be induced by isomerization of azo-compounds in a variety of surfactants. ... 

SDS micelles have also been used as a basis for light-induced charge separation processes. A hydrophobic, photooxidizable dye (e.g., a zinc porphyrinate) was, for example, dissolved in an anionic SDS micelle with copper(II) counterions. Upon excitation with visible light an electron was transferred first and very fast to the copper(II) coating, which then was reoxidized by anionic ferricyanide in the bulk water phase. The reduced ferrocyanide ion formed did not react with the oxidized porphyrin, because the anionic micelles and reductant repelled each other and the ferrocyanide was highly diluted by ferricyanide (Fig. 2.5.5). The energy of sunlight has thus initiated a simple vectorial reaction in a primitive membranous system. 

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