Pressure Effect on Reaction Cavity of Photochromism inSpiropyran Crystals

摘要

Spiropyrans usually show photochromism insolution.However,the spiropyran salt([Me-SP]I) shows crystalline-statephotochromism.In this salt,the pyridinium ringis tilted toward anion during photochromism.Thus,it is important for photoisomerization toconsider the cavities in the crystal structure.Wehave determined the crystal structures of the saltswith various anions and found that the reactioncavity volume larger than 8.9 A~3 is necessary for isomerization.In this study,the volumesof reaction cavity of [R-SP]X were controlled by physical pressure using diamond anvil cell(DAC) and chemical pressure effect from functional group substitution.