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 Zn2+. 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 Zn2+ in aqueous solution. Importantly, the chemosensor 1 could be used to detect and quantify Zn2+ in water samples. In particular, this chemosensor could clearly distinguish Zn2+ from Cd2+. The binding properties of 1 with Zn2+ ions were investigated by UV-vis, fluorescence, electrospray ionization mass spectroscopy and 1H NMR titration.