Copper(I)/(II) or silver(I) ions towards 2-mercaptopyrimidine: An exploration of a chemical variability with possible biological implication

Abstract

Direct reaction of copper(I) chloride with 2-mercaptopyrimidine (pmtH) in the presence of the triphenylphosphine (tpp) in 1:1:2 M ratio forms the mixed ligand Cu(I) complex with formula [CuCl(tpp) 2(pmtH)] (1). The dimeric {[Cu(tpp)(pmt)] 2 0.5(MeOH)} (2) complex was derived from the reaction of 1 with twofold molar amount of sodium hydroxide. However, the reaction of copper(II) sulfate or nitrate with pmtH and tpp in 1:2:2 M ratio, unexpectedly results in the formation of the [CuSH(tpp) 2(pmtH)] (3) complex. Further studies have shown that the [Cu(tpp) 2(pmt)] (4) complex is formed by reacting copper(II) acetate with pmtH in the presence of tpp in 1:2:2 M ratio, while in the absent of tpp, the Cu(CH 3COO) 2 or CuSO 4 is found to oxidizes pmtH to its corresponding disulfide (pmt) 2. For comparison the mixed ligand silver(I) chloride or nitrate complexes with formula [AgCl(tpp) 2(pmtH)] (5) or [Ag(NO 3)(tpp) 2(pmtH)] (6) are also synthesized by reacting of the AgCl or AgNO 3 with pmtH and tpp in 1:2:2 M ratio. The complexes have been characterized by elemental analyses, m.p., vibrational spectroscopy (mid-, far-FT-IR and Raman), 1H NMR, UV-Vis, ESI-MS, TG-DTA spectroscopic techniques and single crystal X-ray crystallography at ambient conditions. Photolysis of 1-6, was also studied and the results showed formation of triphenylphosphine oxide. The complexes 1-6, were used to study their influence upon the catalytic peroxidation of the linoleic acid by the enzyme lipoxygenase (LOX) experimentally and theoretically. The binding of 1-4 with LOX was also investigated by saturation transfer difference 1H NMR experiments (STD). © 2011 Elsevier B.V. All rights reserved.