End-group effects of piezofluorochromic aggregation-induced enhanced emission compounds containing distyrylanthracene

Distyrylanthracene derivatives, AnP3 and AnP3P with triphenylethylene end-groups, and AnP4 and AnP4P with tetraphenylethylene end-groups, were synthesized and characterized using nuclear magnetic resonance, mass spectrometry, elemental analysis, photoluminescence, ultraviolet-visible absorption, wide-angle X-ray diffraction, differential scanning calorimetry and other techniques. The results show that the piezofluorochromic properties of these four aggregation-induced enhanced emission (AIEE) compounds were influenced significantly by the structures of the end-groups in the molecules. The AnP4 and AnP4P derivatives with tetraphenylethylene end-groups exhibited distinct piezofluorochromic properties, which might be switched reversibly upon pressing or annealing because of crystalline-amorphous phase transformation. Thus, we propose that those AIEE compounds that contain steric hindrance groups may exhibit evident piezofluorochromic activities.