Esterifiable/hydrolytic control of photochromism of diarylethenes with 8-hydroxyquinoline derivatives

Three novel diarylethenes 1–3 (refers to Scheme 1) combined with 8-hydroxyquinoline derivatives have been synthesized. They presented some new photochromic phenomenon under UV/Vis light irradiation in chloroform solution. It was found that 1 had well typical photoisomerization upon UV/Vis light irradiation in neutral chloroform solution. 2, which was partly esterifiable from 1, underwent poorly photoisomerization upon UV/Vis light irradiation. 3, which was totally esterifiable from 1, could change from the ring-opening isomer to the ring-closing isomer under ultraviolet light irradiation, but could not change back under visible light irradiation. It was the first time to be found that diarylethene (3) in solution could be stable in the ring-closing isomer after UV/Vis light irradiation. After placed in air for a long time or in hydrochloric acid, 2 and 3 would have definitely hydrolytic action. Esterification/hydrolysis could be used to control the conversion ratio of diarylethene isomers.