Mechanofluorochromism of D-A typed phenothiazine derivative

A D-A typed phenothiazine derivative MPTPM has been designed and synthesized via a Friedel-Crafts reaction, which contains two benzoyl groups. It was found that MPTPM gave strong emission in solution and in solid state, and the solid fluorescence quantum yield was as high as 0.60. Moreover, an excellent reversible mechano-fluorochromic behavior was realized upon the treatment of grinding/fuming with CH2Cl2 or heating in spite of a very simple molecular structure. The emission color of MPTPM changed from green to orange-yellow after grinding and could be restored via fuming with CH2Cl2 or heating with a spectra shift of similar to 63 nm. Photophysical, XRD, DSC studies indicated the mechanofluorochromic properties of MPTPM originating from the transformation between crystalline phase and amorphous phase.