Synthesis and characterization of a vitamin B6-tetrazole hydrazone as a fluorescence probe for selective detection of Cd2+ and Ga3+ ions

A simple selective fluorescence probe for cadmium(II) and gallium(III) ions was designed and prepared by a reaction of hydrazone formation between pyridoxal-5′-phosphate and 5-hydrazinyl-1H-tetrazole. The probe shows an enhanced blue fluorescence in the presence of Cd2+ ions and a yellow-green fluorescence in the presence of Ga3+ ions in aqueous DMSO. The conditional stability constants and stoichiometry of the Cd2+ and Ga3+ complexes were determined using the maximum likelihood method. Gallium(III) ions form two complexes of different structures with probe in solution. The DFT quantum chemical calculations were performed for obtaining molecular structures of probe 1 and its complexes with Ga3+ and Cd2+. Simulation of electronic absorption spectra and NMR spectra by TDDFT and GIAO methods allowed to determine the structures, which was obtained. The probe demonstrated a low detection limit of 0.19 μM for Cd2+ and 0.97 μM for Ga3+, making it suitable for water analysis. This research offers important insights into the design and enhancement of fluorescence probes for the selective detection of metal ions. •Probe 1 are synthesized for selective recognition of Cd2+ and Ga3+.•Structure of 1 are confirmed by 1H, 13C NMR, FT-IR, and mass spectrometry.•Cd2+ ions turn-on the blue fluorescence of probe 1.•Ga3+ ions turn-on the yellow-green fluorescence of probe 1.•Structure of 1, 1+Cd2+ and 1+Ga3+ is studied by quantum chemistry.