A cyanostilbene derivative containing –CF₃: Synthesis and applications in sensors, information rewritable, encryption and LED

An organic small molecule fluorescent material α-cyanostilbene derivative (2) containing trifluoromethyl (electron acceptor) and dimethylamino (electron donor) has been designed and synthesized by a simple two-step reaction and mild conditions. The structure of target product 2 was characterized using elemental analysis, FT-IR and NMR (¹H, ¹³C, ¹⁹F) methods. Compound 2 has strong luminescence in solution and solid states (i.e., dual-state emission, DSE) and aggregation-induced enhanced emission, (AIEE) effect. 2 can be used to recognition the polarity of solvents by “naked eye” under a UV lamp or by fluorescence spectrometer because of its obvious solvatochromic behaviour. 2 can be applied in information rewritable storage, encryption and acid/base sensor, owing to its colour and emission wavelength/intensity can be switched under grinding and acid/base stimulation. The acid/base titration ¹H NMR spectra of 2 prove that acidichromism results from the conversion of protonation (2-H⁺)/deprotonation (2). The results of powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) confirm that the mechanochromic is caused by the morphological transition of 2. Moreover, 2 can be used in light emitting diode (LED) due to its desirable solid-state luminescence performance.