Multi-functional materials based on α-cyanostilbene: Response to mechanical stimuli and selective detection of PNA

Two α-cyanostilbene derivatives NCS1 and NCS2 were designed and synthesized. Both two compounds exhibited AIE properties. Solid compounds showed excellent mechanochromism with 29/26 nm redshift and distinct acid-base vapor chromotropism, which could be applied for relevant sensors. XRSD and PXRD spectra revealed the intrinsic relationship between mechanochromism and molecular packing mode. The twisted molecular conformation became more planar with an increase in conjugation after grinding, resulting in the redshift in fluorescence spectra. Moreover, the emission spectra of NCSs showed obvious fluorescence quenching for p-nitroaniline (PNA) with excellent selectivity. The fluorescence intensity showed better linear relationship at low concentration of PNA. The limit of detections were as low as 0.42 μmol L−1 and 0.60 μmol L−1, respectively. DFT theory proved that this sensing mechanism was attributed to the process of photoinduced electron transfer (PET). Importantly, NCSs were successfully used for PNA detection in real environments. We provide the working basis for developing high-performance multi-functional materials. [Display omitted] •A novel type of multi-functional α-cyanostilbene derivatives (NCSs) were synthesized.•The two crystals showed distinct mechanochromism and acid-base vapor chromotropism.•NCSs exhibited a hypersensitive response to PNA with excellent selectivity and were successfully used for PNA detection in real environments.•DFT theory proved that this sensing mechanism was attributed to the PET process.