2H‐Naphthopyran‐Based Three‐State Systems: From Solution Studies to Photoresponsive Organic/Inorganic Hybrid Materials

Abstract

Densely packed self‐assembled monolayers with photoresponsive naphthopyrans attached to COOH headgroups on Si(111) were studied at the solid/inert‐gas interface. We demonstrate that 2H‐naphtho[1,2‐b]pyrans are suitable three‐state photochromic systems for solution and surface studies. Switching between three states on the surface was realized using UV light, thermal relaxation and visible light as trigger and release elements as analyzed by ATR‐FTIR. Compared to solution studies, surface polarity and environmental effects, especially steric hindrance, contribute to state formation by stabilization of photoisomers, acceleration and deceleration of photochemical processes, and slowed down of thermal fading.