A Ratiomeric Fluorescent Sensor for Zn2+ Based on N,N'-Di(quinolin-8-yl)oxalamide.

A new ratiometric fluorescent sensor (DQO) based on N,N'-Di(quinolin-8-yl) oxalamide has been designed and synthesized for selective detection of Zn2+. The fluorescence ratio (I 536 nm/I 450 nm) of DQO was enhanced 10-fold when Zn2+ was present in a buffer aqueous solution at pH 8.66. The sensor showed linear response toward Zn2+ in the concentration range 0-15 μM, and the detection limit was calculated to be 2.4 μM. A Job's plot implied the formation of a DQO/Zn2+ complex with 1:1 stoichiometry, and the apparent association constant of DQO/Zn2+ complex was computed to be 1.5 × 104 M-1.