Tautomeric forms study of 1H-(2′-pyridyl)-3-methyl-5-hydroxypyrazole and 1H-(2′-pyridyl)-3-phenyl-5-hydroxypyrazole. Synthesis, structure, and cytotoxic activity of their complexes with palladium(II) ions

Abstract

In this article the synthesis of new 1H-(2′-pyridyl)-3-methyl-5-hydroxypyrazole and 1H-(2′-pyridyl)-3-phenyl-5-hydroxypyrazole complexes with palladium(II) ions is reported. The structures of obtained compounds have been characterized by X-ray crystallography and DFT (density functional theory) calculations. The cytotoxicity of complexes and ligands has been examined for two human leukemia cell lines (HL-60 and NALM-6) and one human melanoma cell line (WM-115). The palladium(II) complex with 1H-(2′-pyridyl)-3-phenyl-5-hydroxypyrazole has been shown to possess greater activity than carboplatin against the WM-115 melanoma cell line. Additionally, the ligands’ tautomeric forms existence in different solvents (chloroform, methanol, DMSO) has been characterized by ¹H nuclear magnetic resonance (NMR) analysis and DFT calculations. The obtained results have been compared with those from other studies of similar compounds.

Keywords::

• Palladium(II) complexes
• antitumor agents
• density functional calculations
• tautomerism

Acknowledgements

Financial support from the Ministry of Science and Higher Education (Research Grant No. N N405 428434 to EB), the award of a DAAD fellowship (No. A/07/73915 to MC), and access to supercomputing facilities at AGH Cyfronet Krakow (Grant No. MNiSW/SGI3700/UMLodz/004/2008 to MC) are gratefully acknowledged.

Declaration of interest: The authors report no conflicts of interest.