Colorimetric Detection of Co 2+ , Cu 2+ , and Zn 2+ by a Multifunctional Chemosensor in Aqueous Solution

A novel multifunctional colorimetric sensor HMBC ((E)‐3‐((2‐hydroxy‐3‐methoxybenzylidene)amino)benzofuran‐2‐carboxamide), based on 3‐aminobenzofuran‐2‐carboxamide and 2‐hydroxyl‐3‐methoxylbenzaldehyde, was designed and synthesized. The chemosensor HMBC could sense Co 2+ , Cu 2+ , and Zn 2+ by color changes from colorless to yellow. Limits of detection (0.38, 0.41, and 1.02 μM) of HMBC for Co 2+ , Cu 2+ , and Zn 2+ were much lower than the New Jersey Department of Environmental Protection (NJDEP) standard (1.70 μM) for Co 2+ and the WHO guidelines (31.5 μM and 76 μM) for Cu 2+ and Zn 2+ . Significantly, HMBC could be applied for the quantification of Co 2+ , Cu 2+ , and Zn 2+ in real samples. The sensing process of HMBC for Co 2+ , Cu 2+ , and Zn 2+ was well demonstrated by 1 H NMR and UV–Visible titrations, Job plots, theoretical calculations, and ESI‐mass spectroscopy.