In-situ crystal structure analysis and control of photochromism with dual-mode photoreactive soft crystals

Photochromic compounds are of great interest currently owing to their potential applications. Their three-dimensional structure must be clarified to understand the photochromism mechanism. In-situ X-ray crystal structure analysis is a powerful tool for determining the structure directly after the photochromic reaction. In this review, I discuss about solid-state photochromic compounds, their direct X-ray observation in the crystal form, and in-situ control of photochromism in “dual photoreactive soft crystals”, which is a novel approach.