Photochemical reactivity in organized assemblies. 15. Photoreactions of metalloporphyrins in supported monolayer assemblies and at assembly-solution interfaces. Reductive addition of palladium complexes with surfactant and water-soluble dialkylanilines

Abstract

The photoreactivity of surfactant metalloporphyrins anchored in organized multilayer assemblies formed from sequential deposition of monolayer films has been investigated. Although metal complexes studied include the zinc and tin porphyrins, the most extensive results have been obtained with palladium(II) complexes. Two palladium(il) porphyrins have been used; one resides in a hydrophilic site in films and multilayer assemblies while the other occupies a hydrophobic site. The anchored porphyrins undergo reduction and reductive photoaddition reactions with a number of reagents penetrating the assemblies in interfacial processes from a contacting aqueous solution. The palladium porphyrins yield reductive photoadducts with MA-dimethylaniline (DMA) analogous to their reaction with the same reagent in homogeneous solution; the results indicate that DMA readily penetrates and reacts in both hydrophilic and hydrophobic regions of the supported multilayer. Studies with the surfactant analogue of DMA, A/TV-dioctadecylaniline (DOA), also indicate reductive photoaddition for the palladium porphyrins and DOA when both are incorporated into supported multilayers. Results obtained with assemblies formed by a number of different deposition sequences indicate that considerable migration of supposedly "anchored" reagents such as DOA can occur in the assemblies.