AIE-active and reversible mechanochromic tetraphenylethene-tetradiphenylacrylonitrile hybrid luminogens with re-writable optical data storage application

Abstract

Two new tetraphenylethene-based diphenylacrylonitrile derivatives (TPEDPAN1 and TPEDPAN2) were synthesized in high yields and their reversible mechanochromic luminescence and aggregation-induced emission characteristics are reported. These luminogen crystals exhibiting green fluorescence could be transformed into powders emitting an orange-yellow color upon grinding, and the green emission could be restored when the ground powders were fumed with dichloromethane. To reveal the mechanochromic mechanism, a series of tests including powder XRD, single-crystal X-ray, DSC, and solid state UV–visible absorbance were carried out. These studies suggested that the reversible mechanochromism originated from the transformation of a crystalline state into an amorphous state and vice versa. The single crystal structure of TPEDPAN1 revealed that the poor intermolecular interactions of C-N (3.087 Å) with in the dimer, would give loose packing of the molecular conformation, thus yielding mechanochromic behavior in the crystals upon grinding.