A purine based fluorescent chemosensor for the selective and sole detection of Al3+ and its practical applications in test strips and bio-imaging.

Abstract

A novel purine Schiff base fluorescent probe (WYW), (E)-4-methyl-2-((2-(9-(naphthalen-1-yl)-8-(thiophen-2-yl)-9H-purin-6-yl)hydrazono)methyl)phenol, was designed and prepared as an excellent reversible fluorescent chemosensor for monitoring Al3+. The fluorogenic "turn-on" sensor WYW exhibited high selectivity towards Al3+ over other coexistent metal ions, accompanying with an obvious visual color change in DMSO/H2O (9/1, v/v, pH=7.4) media. The enhancement fluorescence of WYW could be attributed to the inhibition of PET and ESIPT process induced by Al3+. Notably, the WYW-Al3+ complex exhibited a fluorescence "turn-off" response towards F- with exceptional selectivity via the displacement approach. The detection limit of WYW for Al3+ was calculated to be as low as 82nM. The formation of complex WYW-Al3+ (1:1 stoichiometry) was confirmed by Job's methods and further verified by density functional theory (DFT) calculations. Furthermore, the probe WYW with low cytotoxicity and excellent membrane-permeable property has also been successfully applied for detecting low concertation Al3+ in living HeLa cells.