Photocontraction of Liquid Spiropyran-Merocyanine Films

Amorphous films of a photochromic spiropyran containing a mesogenic group melt, when exposed to heat together with irradiation, to yield a red fluid. This fluid contains aggregates of merocyanine molecules and exhibits marked contraction under light illumination. The mechanism of the photocontraction is dependent upon a specialized microstructure, which may be termed a "quasi-liquid."