Fluorescence emission modification of triphenylamine derivatives by aggregate formation in solution or by mechanical stress in solid state

Abstract

Two derivatives of triphenylamine, 4-(diphenylamino)benzaldehyde and 2-(4- (diphenylamino)benzylidene)malononitrile, with acceptor mesomeric groups, an aldehyde moiety and a dicyanovinyl group respectively, were synthesized and found to have aggregation-induced emission (AIE) or aggregation-induced enhanced emission (AIEE) properties in several DMF/H2O mixtures. The size of the formed aggregates was studied with Dynamic Light Scattering (DLS) and a significant change of approximately 200 nm was observed according to the water fraction in DMF. Mechanoluminochromism characteristics in the solid state were also observed. A shift in the emission bands was noticed when comparing the solid before and after grinding, as well as when comparing the crystalline and amorphous form.