Highly efficient probe of dinuclear zinc complex for selective detection of oxalic acid

Oxalic acid (OA) existing widely in animal, plants, and factory processes may affect human health and result in environmental pollution. It is highly desired to develop a rapid fluorescent sensing for accurate determination of OA content in food and wastewater. We are the first to design an easy-to-prepare rhodamine-6G based zinc complex as a fluorescent probe for the selective detection of OA and explore the sensing mechanism between zinc complex and OA. The zinc complex presents the coordination with two Zn2+ and both of rapid color and linear fluorescent response toward OA in the range of 0-10 μM. The detection limit of the probe for OA can reach to 1.20 μM, which is superior to those reported in the literature. Compared with other dicarboxylic acids, the binuclear zinc complex probe displays rapid detection and high selectivity for OA over a wide pH range due to the steric hindrance and ring strains. The recycling of the probe can be achieved by the treatment with sodium sulfide to form zinc sulfide and regenerate the intermediate.