Mechanochromic Luminescence Characteristics of Pyridine-Terminated Chromophores in the Solid State and in a Poly(vinyl alcohol) Matrix

Mechanoresponsive luminophores containing different substituted pyridine rings at the molecular terminus are synthesized and their photoluminescence properties are investigated. The solid chromophore with a 4-substituted pyridine ring exhibits a reversible photoluminescent color change, while the 2-substituted chromophore shows only a small change in luminescence, and the 3-substituted chromophore displays an irreversible photoluminescent color change with mechanical grinding. A change of the sample color in response to mechanical grinding is also achieved for a dye-dispersed poly(vinyl alcohol) film. Furthermore, a simultaneous acid and mechanoresponsive photoemission color change is achieved in the dye-dispersed film.