Direct observation of change in the molecular structure of benzyl (Z,Z)-muconate during photoisomerization in the solid statef

摘要

For the solid-state photoisomerization of benzyl (Z,Z)-muconate to the corresponding (E,E)-muconate, the direct observation of a change in the crystal structure has revealed that the isomerization occurs by a topochemical reaction process according to a bicycle-pedal model and is finally accompanied by a phase transition to a stable crystal structure. Organic reactions performed in the solid state have many intrinsic features and merits for synthetic and materials chemistry because of the extremely high selectivity under crystalline-lattice control. A limited number of isomerizations of olefins between E and Z forms in the crystalline state have been reported because of the difficulty in the inevitable change in the size and shape of the space occupied by the substituents of a double bond. The isomerization of polyenes is an important photochemical process in biological systems, and a bicycle-pedal model as the volume-conserving reaction mechanism was first pointed out by Warshel in 1976.