A rapid selective colorimetric and ‘On–Off’ fluorimetric sensor for detecting Cu2+ ions in aqueous media based on a simple bis-schiff-base derivative

Abstract

A simple colorimetric and fluorimetric ‘On–Off’ sensor L (3,3′-dimethyl -[1,1′-biphenyl]-4,4′-diyl)bis(azanylylidene)bis(methanylylidene)bis(naphthalen-2-ol) for Cu2+ ions bearing o-tolidine substituents has been designed and synthesised, and exhibits significant fluorimetric and colorimetric response for Cu2+ in DMSO/H2O (8:2, v/v) HEPES buffer (pH 7.2) solution. The detection limit of the sensor towards Cu2+ is 7.25 × 10− 8 M and the association constant Ka of 9.86 × 104 M− 1 was determined. Furthermore, other anions, including Fe3+, Hg2+, Ag+, Ca2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+ and Mg2+ have almost no influence on the probe's behaviour. Test strips based on the sensor L were fabricated, which could act as convenient and efficient Cu2+ test kits.