Schiff base derivatives containing thiodiazole: Twisted molecular conformation avoiding π … π stacking promotion aggregation-induced emission enhancement

Abstract

Three novel 2-(4-methoxyphenyl)-1, 3, 4-thiadiazole based Schiff base derivatives (T1-T3) had been synthesized and characterized by 1H NMR, 13C NMR, MS and IR. The spectroscopic properties of T1-T3 were investigated by UV–vis absorption and fluorescence emission spectroscopy, which were coincident with theoretical calculations that three compounds possessed obvious intramolecular charge transfer (ICT) process. Their fluorescence emission performance in solution and aggregation state showed that three compounds all owned obvious aggregation-induced emission enhancement (AIEE) properties. To further understand AIEE nature, dynamic light scattering (DLS) and scanning electron microscopy (SEM) were comparatively investigated, which demonstrated that the small and uniform particles contributed to improve fluorescence emissions. Crystal structures of T1 and T3 showed that the twisted molecular conformation played an important role in AIEE. What's more, T2 and T3 had good biocompatibility, which were successfully applied in live-cell imaging.