Polymorphism and memory mechanochromic emission of a novel molecular fluorophore, 1-cyano-1-(2-naphthyl)-2-[4-(diphenylamino)phenyl]ethylene

Abstract A titled molecular fluorophore (DPACNA) has been designed and synthesized. In addition to glass formation, DPACNA was found to exhibit polymorphism taking two distinct crystal structures. Both crystalline forms and the amorphous film exhibited fluorescence, all with different emission spectra. The spectra of both crystals changed to the same spectra as for the amorphous film upon grinding the crystals. Interestingly, the resulting ground samples remembered their original crystalline states and could be restored by fuming or annealing.