A photoresponsive molecular switch.: Reaction of CO2 and epoxide regulated by aluminum porphyrin-stilbazole system

A novel example of a 'photoresponsive molecular switch', the light-driven on-off switching system for chemical reaction, composed of aluminum porphyrin and stilbazole is found to regulate the reaction of carbon dioxide and propylene oxide to give propylene carbonate. The reaction is catalyzed by aluminum porphyrin through the photoisomerization of stilbazole. In the dark, the reaction of carbon dioxide and propylene oxide to give propylene carbonate proceeds very slowly for the methoxyaluminum porphyrin - trans-stilbazole system. However, the reaction was accelerated by UV light (lambda = 290 - 360 nm), but less so by visible light (lambda > 380 nm).