Mechanoresponsive turn-on phosphorescence by a desymmetrization approach

The room-temperature phosphorescence (RTP) of metal-free organic crystals is normally quenched by mechanical stimulation. Herein, we demonstrate the opposite mechanoresponse of turn-on RTP. A desymmetrization of a C 2 -symmetric 1,2-diketone creates space for molecular motion in the crystal, quenching the RTP from the crystal while maintaining that from the amorphous solid. Mechanoresponsive turn-on of room-temperature phosphorescence of a metal-free organic 1,2-diketone is reported. Desymmetrization selectively modifies the emission of the crystal.