Synthesis, characterization, X-ray crystal structure and antibacterial activity of nickel, palladium and platinum complexes with Schiff base derived from N-cyclohexylhydrazinecarbothioamide and 5-(tert-butyl)-2-hydroxybenzaldehyde

Abstract

A new 2-(5-(tert-butyl)-2-hydroxybenzylidene)-N-cyclohexylhydrazine-1-carbothio amide (H₂TBNCA) Schiff base ligand has been synthesized contain N, S and O coordinating sites and has been chelated to Ni(II), Pd(II) and Pt(II) metal ions. In all three coordination compounds, the metal ion is in square planar geometry Na[Ni(TBNCA)·OAc], [Pd(TBNCA)·dmso] and [Pt(TBNCA)·dmso] are mononuclear complexes. The structure of H₂TBNCA was elucidated by X-ray diffraction analysis. In the broth dilution method, Na[Ni(TBNCA)·OAc] exhibited significant antibacterial activity against Escherichia coli and Staphylococcus aureus with minimum inhibition concentration (MIC) of 12.5 and 6.25 µg mL⁻¹, respectively. [Pt(TBNCA)·dmso] also showed antibacterial activities against E. coli and S. aureus with MIC value of 25 µg mL⁻¹, while [Pd(TBNCA)·dmso] showed lesser activity with MIC values in the range of 50–100 µg mL⁻¹. In the disk diffusion method, the complexes showed significant antibacterial properties against both E. coli and S. aureus, whereas the ligand did not show any significant activity.

GRAPHICAL ABSTRACT

Keywords:

• Thiosemicarbazone Schiff base
• antibacterial activity
• Group-10 metal complexes
• NMR spectroscopy
• X-ray crystal structure

Acknowledgments

The authors wish to thank Universiti Sains Malaysia and The World Academy of Science for (USM-TWAS) fellowship to Md. Azharul Arafath.

Disclosure statement

There are no conflicts of interest to declare.