Reversible control of properties of materials by thermally irreversible photochromism

Photochromism of thermally irreversible fulgides and diarylethenes can control not only the absorption spectra but also other chemical/physical properties by photoirradiation, such as supramolecular interaction to guest molecules, cholesteric liquid crystalline properties, and the chiroptical properties. The association constants originated from the triplex hydrogen bonds between the colored form of an indolylfulgimide and an acylated 2,6-bisaminopyridine increased when it was irradiated by visible light. The cholesteric pitch length was increased when a cholesteric liquid crystal composed of a mixture of the colored form of a binaphthol-condensed indolylfulgide and a nematic liquid crystal was irradiated by visible light. An allylic 1,3-strain-controlled diastereoselective photochromic ring-closing reaction of a bisthienylethene showed as high as 88% diastereomer excess (de) with 85% conversion to the colored form in various solvents at room temperature.