THE SPECTROSCOPY AND PHOTOCHEMISTRY OF NATURALLY OCCURRING AND SYNTHETIC CHROMENES

Abstract

Abstract— –All naturally occurring and synthetic chromenes studied exhibit photochromism at — 196°C and in some cases at room temperature. Chromenes containing a coumarin moiety have the least photochemistry and also exhibit the strongest emissions. Chromenes containing a hydroxyl group ortho to an acetyl group exhibit solely a phosphorescence. Lapachenole (a 7,8‐benzochromene) shows the most rapid and highest percentage conversion to the colored form and no emission. Photocolored form of evodione can be produced by a triplet energy transfer from benzophenone.