Two colorimetric and ratiometric fluorescence sensors for Zn2+ with 1,10-phenanthroline derivatives

Synthesis of two fluorescent sensors based on 1,10-phenanthroline, 2-(2-fluorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (L1) and 2-(2-iodophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (L2). Their recognition of Fe3+, Co2+, Ni2+, Zn2+, Cd2+, Cu2+, Mn2+, Eu3+, K+, Ca2+, Na+, Mg2+, Cr3+, Ag+, Hg2+, and Fe2+ was investigated using UV–vis absorption and fluorescence emission spectroscopy, and the results showed that L1 and L2 could be detected by significant fluorescence enhancement and naked eye color changes to achieve the identification of Zn2+. The high sensitivity of L1 and L2, with detection limits as low as 0.092 uM and 0.12 uM, respectively, indicates that the sensors have the ability to detect trace amounts of Zn2+. The binding stoichiometry ratio of L1-Zn2+ and L2-Zn2+ was determined by the Job’s plot method to be 3:1. In addition, the test strip test and the actual water sample test showed their potential application in environmental ion identification.