Detection of Cu 2+ Ions Through Colorimetric Methods Utilising a Schiff-Base Probe, Along with its Application in Actual Water Samples and Theoretical Insights

A new schiff base sensor, L1 ((4-((E)-1-(((E)-2-hydroxybenzylidene)hydrazono)ethyl)benzene-1,3-diol), was synthesized by the condensation of (E)-4-(1-hydrazonoethyl)benzene-1,3-diol and 2-hydroxybenzaldehyde. The interaction between the synthesized sensor L1 and various metal ions was investigated employing ultraviolet-visible (UV-Vis) spectroscopy. Experimental results revealed that UV-Vis and colorimetry alterations in L1 were markedly pronounced in the presence of Cu²⁺ ions. The sensor displayed a 1:1 stoichiometric ratio with the Cu²⁺ ion, and the binding constant for the L1 -Cu²⁺ complex was obtained as 0.4 × 10⁵ M⁻¹. Additionally, UV-Vis spectral variations in L1 across a range of pH conditions demonstrated its efficacy over an extensive pH spectrum. The sensor facilitated the detection of Cu²⁺ ions in sub-second timeframes, with a limit of detection established at 32.2 nM. Moreover, the recyclability of the sensor was assessed through the introduction of 1–10 equivalents of ethylenediaminetetraacetic acid (EDTA) to a solution containing the L1 -Cu²⁺ complex. Density functional theory (DFT) simulations corroborated the 1:1 binding stoichiometry of the L1 -Cu²⁺ complex, reinforcing its stability and suitability for cupric ion detection. Molecular docking studies elucidated substantial binding affinities of the synthesized Schiff base sensor L1 with myoglobin, hemoglobin, bovine serum albumin (BSA), and human deoxyribonucleic acid (DNA), suggesting its potential applicability in biological systems. The practical effectiveness of the synthesized sensor for Cu²⁺ detection in authentic water samples was also substantiated.