Synthesis and photochromic reactivity of macromolecules incorporating four dithienylethene units

Two macrocycles bearing four dithienylethene units were synthesized. Upon irradiation of the macrocycles 5 and 6 with ultraviolet light, only one or two photo-induced cyclization reaction occurs. Each isomers were isolated and analyzed by H-1 NMR spectrum. The quantum yield of 5 and 6 are 0.58 and 0.64, respectively. The high value is due to the presence of enforced antiparallel conformation in the macrocycles 5 and 6. (c) 2005 Elsevier Ltd. All rights reserved.