Both Visual and Fluorescent Sensor for Zn²⁺ Based on Quinoline Platform

A fluorescent Zn2+ sensor 2-(hydroxymethyl)-4-methyl-6-((quinolinyl-8-imino)methyl)phenol (HMQP) based on the 8-aminoquinoline platform has been synthesized. This sensor displays high selectivity, sensitive fluorescence enhancement, strong binding ability, and ratiometric response to Zn2+ in Tris−HCl (50 mM, pH 7.54), THF−H2O (9:1, v/v). And an obvious color change between HMQP and Zn2+−MQP− can be visually observed by the naked eye. The composition of the complex Zn2+−MQP− has been found to be 1:2 based on the fluorescence/absorption titration and further confirmed by X-ray crystallography.