Pyrophosphate prompted aggregation-induced emission: chemosensor studies, cell imaging, cytotoxicity, and hydrolysis of the phosphoester bond with alkaline phosphatase

Abstract

Two benzimidazole-based zinc complexes [(Zn)2(L2)2Cl2(DMSO)2] (R1) and [Zn(L2)2(NO3)2(H2O)2] (R2) were synthesized and characterized with various spectroscopic data. The single X-ray structure determination reveals that complex R1 is dinuclear and tetrahedral in geometry, while complex R2 is mononuclear and octahedral in geometry. Further, both zinc complexes were investigated for pyrophosphate sensing in an aqueous medium. Complex R1 is found to be selective towards pyrophosphate; it leads to 5.5-fold enhancement in the sion intensity due to aggregation-induced emission. However, complex R2 has shown binding with all, ATP, AMP, ADP, and pyrophosphate, which is attributed to the chelate effect. Consequently, complex R1 was utilized for the intracellular detection of pyrophosphate in HeLa cells. Furthermore, the PPi based zinc complex R1 is also used as a bio-analytical tool to construct a real-time fluorescence assay for the enzymatic activity of alkaline phosphatases (ALP).