Fluorescence detection of Al3+ ion in aqueous medium and live cell imaging by ESIPT probe (E)-N'-(5-bromo-2-hydroxybenzylidene)-4-hydroxybenzohydrazide.

The molecule (E)-N'-(5-bromo-2-hydroxybenzylidene)-4-hydroxybenzohydrazide (BHHB) has been synthesized and its photophysical properties have been investigated by using steady state absorption, emission and time resolved emission spectroscopy. The molecule shows excited state intramolecular proton transfer (ESIPT) process with characteristics large Stoke shifted emission. Fluorescence enhancement of BHHB only in presence of Al3+ ion is used as selective aluminium ion sensor in the sub-nano molar scale in aqueous solution. BHHB-Al3+ ion complex can penetrate through live Hepatocellular Carcinoma (HepG2) cell membranes and is capable for imaging of nucleus of live cells by fluorescence confocal microscopy.