A simple triphenylamine based turn-off fluorescent sensor for copper (II) ion detection in semi-aqueous solutions

An efficient donor triphenylamine aldehyde Schiff-base with p-toluene sulfonyl hydrazine fluorescent probe (TPA-PTH) was synthesized and characterized by various spectroscopic techniques. The probe TPA-PTH displayed drastic color changes with Cu2+ ions over metal ions in aqueous environment with a fluorescence-off mechanism.The detection limit of Cu2+ was found to be 1.25 x 10(-8) M by using the equation LOD = K x SD/S. The 2:1 binding stoichiometric mode of TPA-PTH with Cu2+ ion was further tested by HR mass and Job's plot analyses. Furthermore, the proposed probe has been effectively applied to determine the trace amount of Cu2+ ions in different water samples with 96%similar to 98% recoveries. The sensing mechanism of TPA-PTH was further investigated by Density Functional Theory (DFT) calculations using a Gaussian 16 program. DFT calculations were theoretically supported the experimental findings.