PHOTOCYCLODIMERIZATION OF CINNAMIC ACID ON A REACTION MATRIX - STRUCTURAL EFFECT OF MOLECULAR ASSEMBLIES CONSTRUCTED BY AMPHIPHILIC COMPOUNDS

Light scattering measurement, video-enhanced differential interference microscopic and electron microscopic observations, H-1-NMR measuremen t, and photocyclodimerization were carried out for aqueous solutions o f alkyldimethylamine oxides (C(12)DAO and C(16)DAO) and dioctadecyldim ethylammonium chloride (2C(18)DAC) with addition of cinnamic acid. Mol ecular assemblies in C(n)DAO:cinnamic acid solutions were converted fr om micelles to vesicles with increasing mixing ratios of cinnamic acid , while 2C(18)DAC in water always formed vesicles with addition of cin namic acid. Structural changes of molecular assemblies constructed by amphiphilic compounds were reflected in the reactivity and stereochemi cal selectivity of photocyclodimerization. It was concluded that the p hotodimerization proceeded effectively in vesicles rather than in mice lles. The dimerization yields increased with mixing ratio and were in the order of syn-HT < syn-HH < anti-HH (where HT and HH represent head -to-rail and head-to-head, respectively). The product selectivity was discussed in relation to the arrangement of cinnamic acid on molecular assemblies.