A highly sensitive and colorimetric fluorescent sensor for visualizing Zn in aqueous solution.

A new colorimetric fluorescent sensor QPEBT was developed by merging the N,N-di(2-picolyl)ethane-1,2-diamine and 2,2'-bithiophene moieties into the quinolimide backbone. QPEBT could sensitively detect Zn through the remarkable fluorescence enhancement with distinct color changes from light orange to pink in visible light and from ginger to orange-yellow in 365 nm UV irradiation. The 1:1 stoichiometry between QPEBT and Zn was verified by the spectra titrations, Job's and HRMS analyses, and theoretical calculations. Moreover, QPEBT quickly and reversibly detected Zn with the LOD of 47.4 nM, and analyzed Zn in the pH range of 6.4-9.6. Practically, QPEBT could visualize Zn in aqueous solution and test strips by the naked eyes, and determine Zn through the RGB analysis. As a reliable sensor, QPEBT showed many applications for monitoring Zn in actual water samples along with fluorescence imaging in mungbean sprouts and yeast cells.