The analytical, antimicrobial and mechanistic behavior of a newly synthesized hydrazinecarbothiohydrazide Schiff base derivative and its heavy metal ions’ complexes”

In the present study, a novel N/S-containing Schiff base hydrazinecarbothiohydrazide derivative is synthesized by refluxing hydrazinecarbothiohydrazide and Z-3-(hydroxyimino) butane-2-one to yield N-((2E,3Z)-3(hydroxylamine)butan-2-ylidene) hydrazinecarbothiohydrazide (A1). Characterization of the A1 ligand and its metal complexes with Fe(III), Co(II), Cu(II), and Ni(II) was conducted using elemental analysis, UV-Vis spectroscopy, FTIR, and 1H NMR. Additionally, biological activity assessments were performed. Spectroscopic investigations indicated an octahedral configuration for all complexes. Additionally, the spectroscopic data showed that the sulfure and NH2 group acts as a bidentate ligand within the complex structures. The A1 ligand was utilized for quantitative flotation and spectrophotometric determination of Fe(III), Cu(II), Ni(II), and Co(II) in media of diverse origin, employing oleic acid (HOL) surfactant and FAAS. The study examined various parameters affecting the flotation process, including pH, ligand, metal and surfactant concentrations, temperature, sample volume, and interfering ions. At pH 6, the complexing agent formed 1:2 (M: L) complexes with the metal ions, producing distinctive colors in aqueous solution: yellow for Fe(III) and Cu(II), green for Ni(II), and brown for Co(II). These complexes were isolated via flotation using HOL as the anionic surfactant. Beer's law was applicable within a concentration range of 1.0-5.0 (µgmL-1). Analytical detection limits were established as 0.66, 0.49, 0.58, and 0.12 (µgL-1) for Ni(II), Co(II), Cu(II), and Fe(III), respectively. Analysis of synthetic mixtures and water samples yielded recoveries surpassing 98% for all four metal ions and a preconcentration factor of 200. The developed flotation- FAAS method was successfully applied to quantify trace amounts of Fe(III), Cu(II), Ni(II), and Co(II) in , natural water and pharmaceutical preparations samples. Additionally, the research explored the antimicrobial activity of the synthesized N/S ligand (A1) and its metal ion complexes against Gram-negative and Gram-positive bacterial strains. The newly synthesized Cu(II), Co(II), Ni(II), and Fe(III) complexes demonstrated enhanced antibacterial properties in comparison to the ligand alone and exhibited excellent efficacy against E. coli and S. aureus when compared to standard antibiotics. Based on the experimental results, a flotation mechanism is proposed.