Diamantane: a thread stitching up photochromism and liquid crystals

Diamantane, one of the diamondoid family molecules, was introduced to thermally reversible photochromic heliofulgides. They exhibited good thermally reversible photochromism. A chiral photochromic indolylfulgide derivative was used to control the pitch length of cholesteric liquid crystalline state by photoirradiation. However, as the indolylfulgide derivative has absorption in the visible light region, it is not a suitable agent to control the selective reflection wavelength. Chiral benzofurylfulgide derivative, possessing shorter absorption maximum wavelength, was employed for this purpose. Diamantane has a long barrel-like C 3 -symmetric structure with the corresponding symmetric axis. Several derivatives, with long alkyl or related substituents on the carbon atoms at both ends of the molecule, showed liquid crystalline properties. Thus, diamantane worked as a thread stitching up photochromism and liquid crystals.