Structural features of mono- and tri-nuclear Zn(II) complexes with a non-steroidal anti-inflammatory drug as ligand.

The interaction of Zn(II) with the non-steroidal anti-inflammatory drug tolfenamic acid leads to the formation of the structurally characterized trinuclear [Zn(3)(tolfenamato)(6)(CH(3)OH)(2)] complex. In the presence of the N,N'-donor heterocyclic ligands 1,10-phenanthroline and 2,2'-bipyridine at a range of ratios, the mononuclear Zn complexes of the general formulae [Zn(tolfenamato)(N,N'-donor)Cl] and [Zn(tolfenamato)(2)(N,N'-donor)] have been isolated and structurally characterized by X-ray crystallography. The deprotonated tolfenamato ligands are coordinated to the Zn(II) ion through carboxylato oxygen atoms. Tolfenamic acid and its complexes exhibit good binding propensity to human or bovine serum albumin protein having relatively high binding constant values.