Fluorescent sensing of Al3+ by benzophenone based Schiff base chemosensor and live cell imaging applications: Impact of keto-enol tautomerism.

Developing simple probes to sense Al 3+ in vivo and in vitro in real time is highly desirable as Al 3+ imbalance has been linked to a variety of diseases in human being. Here, we introduce a new, highly selective and sensitive Schiff base chemosensor, H 2 bpet , based on benzophenone that can detect Al 3+ in a 0.01% ethanol in 50 mM HEPES buffer medium by fluorimetric sensing. The structure of the probe, H 2 bpet involves existence of keto−–enol tautomerism. Single crystal X-ray diffraction study reveals prevalence of keto form of H 2 bpet in the solid state. The binding properties of H 2 bpet with Al 3+ was thoroughly investigated by fluorescence spectroscopy and ESI–MS analyses. The binding of Al 3+ to the probe H 2 bpet , induces distinct 1 H and 13 C NMR shifts in favour of H 2 bpet (keto form):Al 3+ aggregate. The sensing mechanism of H 2 bpet toward Al 3+ and composition of H 2 bpet:Al 3+ aggregate was proposed and established by DFT/TDDFT calculations. Its application in fluorescent imaging in HepG2 cells was also tested. This report demonstrates an advancement in detection of Al 3+ with the introduction of a new benzophenone containing Schiff base chemosensor. [ABSTRACT FROM AUTHOR]