(Pyrazolylmethyl)pyridine platinum(II) and gold(III) complexes: Synthesis, structures and evaluation as anticancer agents

Tebogo V. Segapelo, Ilia A. Guzei, Lara C. Spencer, Werner E. Van Zyl, James Darkwa

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)

Abstract

Reactions of 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L1), 2-(3,5-diphenylpyrazol-1-ylmethyl)pyridine (L2), 2-(3,5-di-tert-butylpyrazol-1-ylmethyl)pyridine (L3) and 2-(3-p-tolylpyrazol-1-ylmethyl)pyridine (L4) with K2[PtCl4] in a mixture of ethanol and water formed the dichloro platinum complexes [PtCl2(L1)] (1), [PtCl2(L2)] (2), [PtCl2(L3)] (3) and [PtCl2(L4)] (4). Complex 1, [PtCl2(L1)], could also be prepared in a mixture of acetone and water. Performing the reactions of L2 and L3 in a mixture of acetone and water, however, led to C-H activation of acetone under mild conditions to form the neutral acetonyl complexes [Pt(CH2COCH3)Cl(L2)] (2a) and [Pt(CH2COCH3)Cl(L3)] (3a). The same ligands reacted with HAuCl4 · 4H2O in a mixture of ethanol and water to form the gold salts [AuCl2(L1)][AuCl4] (5) [AuCl2(L2)][Cl] (6) [AuCl2(L3)][Cl] (7) and [AuCl2(L4)][AuCl4] (8); however, with the pyrazolyl unit in the para position of the pyridinyl ring in 4-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L5), 4-(3,5-diphenylpyrazol-1-ylmethyl)pyridine (L6) neutral gold complexes [AuCl3(L5)] (9) and [AuCl2(L6)] (10) were formed; signifying the role the position of the pyrazolyl group plays in product formation in the gold reactions. X-ray crystallographic structural determination of L6, 2, 3 3a, 8 and 10 were very important in confirming the structures of these compounds; particularly for 3a and 8 where the presence of the acetonyl group confirmed C-H activation and for 8 where the counter ion is AuCl4 -. Cytotoxicity studies of L2, L4 and complexes 1-10 against HeLa cells showed the Au complexes were much less active than the Pt complexes.

Original languageEnglish
Pages (from-to)3314-3324
Number of pages11
JournalInorganica Chimica Acta
Volume362
Issue number9
DOIs
Publication statusPublished - 1 Jul 2009

Keywords

  • (Pyrazol-1-ylmethyl)pyridine ligands
  • Antitumor activity
  • C-H activation
  • Gold complexes
  • Platinum complexes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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