Mechano-induced photoluminescence colour change in an alkyltolane-terminated cyanostilbene

Abstract

Luminescent materials with liquid-crystalline properties can form metastable structures and thus exhibit mechanochromic luminescence. Herein, we prepared a novel rod-like alkyltolane-terminated cyanostilbene luminophore, determined its solid structure, and investigated its mechanoresponsive photoluminescence. Although no mechanoresponsive behaviour was observed in the crystal state, the photoluminescence colour depended on the precipitation method, and a red or blue shift in the photoluminescence spectrum was observed upon mechanical grinding. This switch in mechanochromic luminescence behaviour was attributed to a change in the molecular packing of the metastable aggregated structure formed upon precipitation under different conditions. Given that materials exhibiting mechanochromic luminescence are expected to be broadly applicable as stimuli-responsive sensors, the obtained results facilitate the development of such sensors for a wide range of fields.