Structural understanding of solid-state photodimerization reactions of cinnamic amide derivatives in terms of reaction cavities – color developer for thermosensitive paper

The crystal structures of novel cinnamic amide derivatives, which are candidates for new color developers for thermosensitive paper, were investigated to reveal reactivity differences in solid-state photodimerization, in which one derivative was reactive, whereas the other was not. Unexpectedly, the traditional Schmidt's rule was not sufficient to explain the photoreactivity differences, and it was found that the partial reaction cavities around a specific region, and overlap of olefinic double bonds, were important factors in understanding the photoreactivity differences.