2025 Volume 62 Issue 12 Pages 709-715
Mechanical stimuli such as grinding and pressing can change the emission color of crystalline organic powders. Such mechanochromic luminescence (MCL) is promising for mechanosensors and security inks, although rational tuning remains challenging. This article reviews recent advances in controlling MCL in crystalline organic powders. Indole-substituted benzothiadiazoles exhibit self-recovering MCL, which is tunable through electronic effects of the substituent and molecular mobility in the amorphous state. Phenanthroimidazole derivatives show that steric effects of the substituent determine whether amorphization causes a red or a blue shift of the emission wavelength. Preparation of segregated crystals provides a rational way to increase the magnitude of the mechanically induced emission wavelength change. Chiral pyrenylamide derivatives exhibit mechanically switchable circularly polarized luminescence. These findings provide practical design principles for controlling MCL and contribute to the development of advanced mechanoresponsive materials.
