Daisuke Hashizume and Yuji Ohashi
The 2-cyanoethyl–isonicotinic acid–cobaloxime complex forms host–guest complexes with secondary amines such as dicyclopentylamine and diphenylamine. The 2-cyanoethyl group in the two host–guest complexes as well as the pure guest complex was isomerized to the 1-cyanoethyl group on exposure to a xenon lamp in the solid state. The analyzed structures of the three crystals indicate that the different reaction rates of the three crystals have a quantitative correlation with the volumes of the reaction cavities for the 2-cyanoethyl groups in the crystals. The reaction rate can be altered by forming the host–guest complexes.