New 2-pyridinealdehyde N⁴-hydroxyethyl thiosemicarbazone and their Cd(II) and Cu(II) complexes: synthesis, spectral, in vitro antibacterial activity and molecular and supramolecular structure study

Abstract

N ⁴-hydroxyethyl-pyridinealdehyde thiosemicarbazone (HL, 1) as a tridentate Schiff base has been synthesized by 1:1 reaction of S-methyl-3-((pyridyl)methyl) dithiocarbazate and 2-aminoethanol. Complexes [Cd(HL)₂](NO₃)₂ (2), [Cd(HL)I₂] (3), [Cd(HL)Cl₂] (4), [Cu(HL)₂](NO₃)₂ (5) and [Cu(HL)Cl₂] (6) have been obtained and characterized by elemental analyses, molar conductivities, and spectroscopic studies. The ligand molecule binds the metal ion using pyridyl nitrogen, azomethine nitrogen and the sulfur atoms. The crystal structure analysis of 3 has been determined and showed to be a distorted square pyramidal geometry complex. The inter- and intramolecular interactions give rise to a supramolecular network. Compounds 2, 3, 5 and 6 were assayed for their bioactivities against selected pathogens. Copper(II) complexes 5 and 6 showed antimicrobial activities against Gram-positive (Bacillus anthracis) and Gram-negative (Pseudomonas aeruginosa and Yersinia pseudotuberculosis) bacteria, complexes 2–4 showed antimicrobial activities against Bacillus atrophaeus, while the ligand itself showed antimicrobial activities against Escherichia coli and Y. pseudotuberculosis.

Keywords:

• thiosemicarbazone
• transition metal complex
• antibacterial activity
• crystal structure
• supramolecular

Acknowledgements

We are grateful to Payame Noor University (PNU) for financial support and thank Mohammad Reza Hassani for his help.