A Turn-on Fluorescent Chemosensor for Zn(2+) Based on Quinoline in Aqueous Media

A simple "off-on fluorescence type" chemosensor 1 3-((2-(dimethylamino)ethyl)amino)-N-(quinolin-8-yl)propanamide has been synthesized for Zn(2+). The receptor 1 comprises the quinoline moiety as fluorophore and the N,N(')-dimethylethane-1,2-diamine as a binding site. 1 showed a remarkable fluorescence enhancement in the presence of Zn(2+) in aqueous solution. Importantly, the chemosensor 1 could be used to detect and quantify Zn(2+) in water samples. In particular, this chemosensor could clearly distinguish Zn(2+) from Cd(2+). The binding properties of 1 with Zn(2+) ions were investigated by UV-vis, fluorescence, electrospray ionization mass spectroscopy and (1)H NMR titration.