PHOTOCHEMICAL BEHAVIOR OF MICELLIZED 4-(4'-ALKYLSTYRYL)PYRIDINIUM SALTS

New photochromic surfactants, 1-alkyl-4-(4'-alkylstyryl)lpyridinium ha lides (C(n)StzRX; n = 0, 4, 6, 8; R = Me, Et, CH2CH2OH, n-Bu, n-C9H19; X = Br, I), were synthesized and the photochemical behavior of their micellar aggregates in water was characterized in relation to non-mice llizing 1-methyl-4-stilbazolium ions. Reversible trans-cis isomerizati on through a photothermal cycle was observed for the micellized C(n)St zRX, Furthermore, photoreactions upon prolonged irradiation of C(n)Stz RX micelles resulted in a 3-31% formation of thermodynamically least s table syn-head-to-head and ca. 3% of anti- head-to-head dimers, These findings indicate that the self aggregation process of C(n)StzRX may p rovide some topologically organized microenvironment affecting the ste ric and like-charge repulsions of the aggregate components.