A highly selective chemosensor for naked-eye sensing of nanomolar Cu(II) in an aqueous medium

A novel highly selective and sensitive colorimetric chemosensor L for the detection of Cu2+ ion with a fast response time was designed and synthesized. Receptor L detected Cu2+ ion by changing its color from colorless to magenta in a semi-aqueous solution. The limit of detection for Cu2+ was calculated to be as low as 28 nM. The possible binding mode of compound L with Cu2+ ion was studied using the Job's method, HRMS, FTIR spectroscopy and H-1 NMR spectroscopy titration. Importantly, test strips containing L were fabricated as a naked-eye indicator for Cu2+ ion in pure water samples.