Piezofluorochromism and morphology of a new aggregation-induced emission compound derived from tetraphenylethylene and carbazole

A new piezofluorochromic aggregation-induced emission compound was synthesized. The compound had morphology-alterable emission property and its amorphous and crystalline aggregates with various emissions were obtained through evaporation from the solutions in different solvent systems. The spectroscopic properties and morphological structures of the compound were reversed upon pressing and annealing (or fuming). The results show that the piezofluorochromic nature is generated through crystalline–amorphous phase transformation under external pressure. The reason for the phase transformation is ascribed to the twisted conformation of the molecule which leads to poor solid molecular packing and formation of some cavities in the interfaces of lamellar layers, as confirmed by single crystal X-ray diffraction analysis.