2-hydroxy-1- Naphthaldehyde Based Colorimetric Probe for the Simultaneous Detection of Bivalent Copper and Nickel with High Sensitivity and Selectivity.

A neoteric colorimetric probe based on 2-hydroxy-1-naphthaldehyde (PMB3) was designed and synthesized for the real-time as well as on-site naked-eye detection of Cu/Ni ions. Various physicochemical methods were employed to characterize the probe, and its colorimetric response to different metal ions was meticulously investigated. The probe, PMB3, exhibited a sensitive colorimetric response to Cu/Ni ions among other competing metal ions, culminating in a prominent colour change from colourless to yellow. The stoichiometry of the ligand metal complexes was ascertained to be in a 1:1 ratio using Job's plot analysis, which was further corroborated by ESI-MS data. With detection limits of 4.56 µM for Cu and 2.68 µM for Ni, the method was effectively extended to real sample analysis, ensuring propitious results that closely aligned with the actual values.