Exploring novel ethyl carbazate salts of 2-thiobarbituric acid: DFT-based reactivity, antimicrobial docking, toxicological evaluation and nitrophenol reduction catalysis

This study reports the synthesis and characterization of three novel ethyl carbazate salts of 2-thiobarbituric acid in an aqueous medium, with the molecular formulae: [(C₃H₉N₂O₂)⁺(C₄H₃N₂O₂S)⁻] (1), [(C₃H₉N₂O₂)⁺(C₄H₃N₂O₂S)⁻(C₃H₈N₂O₂)] (2), and [(C₃H₉N₂O₂)⁺(C₄H₃N₂O₂S)⁻(C₄H₄N₂O₂S)] (3). Structural characterization via elemental analysis, UV–Vis spectroscopy, FT-IR, ¹H NMR, ¹³C NMR, mass spectroscopy, and TG-DTA confirmed the proposed structures and demonstrated thermal stability of these compounds up to 600 °C. FT-IR spectra verified the presence of a hydrazine functional group, while ¹H NMR analysis identified NH proton signals at approximately δ 6.96 ppm. DFT calculations revealed the lowest HOMO–LUMO gap (3.445 eV) for compound 3, indicating enhanced reactivity. Molecular docking studies showed superior binding affinities of compound 3 toward Staphylococcus aureus (−7.19 kcal/mol) and Escherichia coli (−6.36 kcal/mol). ADMET analysis further supported favorable drug-like properties of all compounds. Antioxidant assays indicated strong 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity for compound 3, suggesting therapeutic relevance. Cytotoxicity evaluations revealed significant cell viability reduction by compound 3, highlighting potential anticancer activities. Additionally, compound 3 exhibited superior catalytic efficiency in the reduction of 4-nitrophenol and 2-nitrophenol, with observed rate constants of −0.0342 and −0.0827 min⁻¹, respectively. Overall, these findings establish compound 3 as a promising candidate for pharmaceutical and environmental applications.