Photoisomerization‐induced solubility change of a photochromic diarylethene (DAE) derivative is investigated by a combination of theoretical calculations and experimental measurements. A significant solubility change is experimentally observed between two DAE photoisomers (open and closed forms) in n ‐octane solution. To elucidate the reason for the observed solubility change, we adopt a thermodynamic model and consider both ideal and nonideal contributions. The analysis revealed that both the crystalline stability of the isomers and their solute–solvent interactions play critical roles in determining the solubility difference. We believe that the current elucidation of thermodynamic properties will be useful to develop new functions of the DAE derivatives and future applications.
Nakamura et al. (2026) studied this question.