A colorimetric chemosensor for selective detection of copper ions

A water-applicable hexamethylbenzene (HMB) chemosensor, (E)-2-((2-hydroxy-3-methoxybenzylidene)amino)benzamide, displayed a selective colour change from colourless to yellow in the existence of copper ions. The detection limit was computed as 1.57 mu mol/L, which is substantially lower than the World Health Organisation guideline (31.5 mu mol/L) for copper ions. Probe HMB could also sense and quantify copper ions in real water samples. The coordination mode of HMB to copper ions was demonstrated through Job plot, electrospray ionisation mass spectroscopy and proton nuclear magnetic resonance titration, and was also supported by theoretical studies.