A novel dihydro phenylquinazolinone-based two-in-one colourimetric chemosensor for nickel(ii), copper(ii) and its copper complex for the fluorescent colourimetric nanomolar detection of the cyanide anion

Currently, considerable efforts have been devoted to the detection and quantification of hazardous multi-analytes using a single probe. Herein, we have developed a simple, environment-friendly colourimetric sensor for the sensitive, selective and rapid detection of Ni(2+) and Cu(2+) ions using a simple organic Schiff base ligand L in methanol–Tris–HCl buffer (1 : 1 v/v, 10 mM, pH = 7.2). The probe L exhibited a binding-induced colour change from colourless to yellow and fluorescence quenching in the presence of both Ni(2+) and Cu(2+) ions. The interactions between L and the respective metal ions were studied by Job's plot, electrospray ionisation-mass spectrometry (ESI-MS), Fourier-transform infrared spectroscopy (FT-IR), density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations. The limit of detection (LOD) of L towards Ni(2+) and Cu(2+) was calculated to be 7.4 × 10(−7) M and 4.9 × 10(−7) M, respectively. Furthermore, the L–Cu(2+) complex could be used as a new cascade fluorescent-colourimetric sensor to detect CN(−) ions with a very low level of detection (40 nM). Additionally, L could operate in a wide pH range, and thus was successfully applied for the detection and quantification of Ni(2+) and Cu(2+) in environmental samples, and for building OR- and IMPLICATION-type logic gates.