Crystallographic Approach to the [2 + 2] Photocycloaddition Topochemical Reactions of Unsaturated Compounds with Single Crystal Retention

Abstract

Based on the results of authors' studies, an approach to the analysis of [2 + 2] photocycloaddition (PCA) topochemical reactions of unsaturated compounds, occurring in a single crystal with either its retention or decomposition under exposure to visible light, has been developed. The main crystal packings, favorable for photoreaction in crystal, are revealed. Conditions for PCA reaction with single crystal retention are established. The factors increasing the probability of implementing crystal packing motifs that are favorable for this reaction (by chemical modification of structural units) are analyzed. The fact of extraordinary implementation of both direct and back (under UV irradiation) photoreactions in the same single crystal is explained.