Heating and mechanical force-induced turn on fluorescence of cyanostilbene derivative with H-type stacking

A cyanostilbene-based derivative with aggregation induced-emission was obtained, which exhibited multi-luminescent intensity under external stimuli. The as-prepared crystals of the desired dye showed a rather faint luminescence. Upon heating, its fluorescence could be turned on with the quantum yields of 13.3%. The quantum yields of the melted and solidified powders were further increased to 28.6%. Powder X-ray diffractometry, fluorescence spectroscopy, fluorescence lifetime experiments and single crystal XRD analyses were applied to investigate the changes of molecular packing modes. Such a transformation of fluorescence dark-bright, easily distinguished by naked eye, was related to the phase transition. The planar cyanostilbene with H-type packing and multiple mutable interactions may be the essential factor for the multi-luminescent intensity properties.