Synthesis, Antimicrobial Potential and Copper (II) Sensing Application of New Thiosemicarbazone and Semicarbazone Derivatives.

Abstract

Thiosemicarbazone (TSC) and semicarbazone (SC) derivatives have been evaluated as ligands for the detection Cu²⁺ by using UV-visible spectroscopy and fluorescence quenching techniques. TSC outperformed SC across all the parameters demonstrating a lower limit of detection (LOD) of 0.99 µM as compared to 1.82 µM for SC and a higher binding constant (8.33 × 10² M^-1 for TSC and 7.62 × 10² M^-1 for SC) as determined by the Benesi-Hildebrand plot. Job's plot analysis confirmed the formation of stable 1:1 copper-ligand complexes. DFT studies further supported superior binding efficiency and electronic properties in favour of TSC. Antimicrobial activity results displayed that TSC derivative exhibited highly effective response against Klebsiella pneumoniae, Bacillus subtilis, Staphylococcus aureus, Fusarium oxysporum & Aspergillus janus (MIC- 8 µg/ml). The sensors successfully detected Cu²⁺ ions in tap, river and mineral water demonstrating their environmental applicability. These investigations collectively established the TSC derivative as a more promising ligand, owing to its dual functionality exhibiting both effective antimicrobial activity and Cu²⁺ sensing attributed to its high sensitivity, strong binding affinity, and stable complex formation.