Highly sensitive and selective “naked eye” sensing of Cu(II) by a novel acridine-based sensor both in aqueous solution and on the test kit

Abstract A highly selective and sensitive acridine-based colorimetric sensor 2-((7-chloro-2-methoxybenzo[b][1,5]naphthyridin-10-yl)amino)phenol ( NAP ) was developed for detection of Cu 2+ ions both in aqueous solution and on test papers. Sensor NAP responses to Cu 2+ ions by changing its color from yellow to pink, which could be easily observed by the naked eyes. Furthermore, the mechanism of the binding model of NAP -Cu 2+ complex was investigated by 1 H NMR, HRMS analysis, and DFT calculations.