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

摘要

New photochromic surfactants, 1-aIkyl-4-(4′-alkylstyryl)lpyridinium halides (C_nStzRX; n = 0, 4, 6, 8; R = Me, Et, CH_2CH_2OH, n-Bu, n-C_9H_(19); X = Br, I), were synthesized and the photochemical behavior of their miceliar aggregates in water was characterized in relation to non-micellizing 1-methyl-4-stilbazolium ions. Reversible trans-cis isomerization through a photothermal cycle was observed for the micellized C_nStzRX. Furthermore, photoreactions upon prolonged irradiation of C_nStzRX micelles resulted in a 3-31% formation of thermodynamically least stable syn-head-to-head and ca. 3% of anti- head-to-head dimers. These findings indicate that the self aggregation process of C_nStzRX may provide some topologically organized microenvironment affecting the steric and like-charge repulsions of the aggregate components.