Organo Sn(IV) and Pd(II) complexes with various oxygen and sulphur donor ligands: Synthesis, spectroscopy and biological activity

Abstract

Two Pd(II) complexes, (HL¹CSS)₂Pd (1) and (KL²CSS)₂Pd (2), were synthesized by stirring 2-(1-piperazinyl)ethanol (HL¹H)/l-lysine (HL2H) monohydrate in methanol with KOH, CS₂ and PdCl_2(aq). Homobimetallic (Sn, Sn) products, Ph₃SnL³Sn(Cl)Bu₂ (3) and Ph₃SnL³SnBu₃ (4) were produced by refluxing sodium but-2-ynedioate (Na₂L₃) with Ph₃SnCl and Bu₂SnCl₂ or Ph₃SnCl and Bu₃SnCl in methanol. A heteronuclear (Sn,Pd) product, [(Bu₃Sn)₂L²CSS]₂Pd (5) was synthesized by the reaction of 5-aminoisophthalic acid (H₂L⁴H), KOH, CS₂, PdCl_2(aq) with Bu₃SnCl. The products were characterized by elemental analysis, FT-IR, UV-Vis, ¹H NMR and EIMS. A square planar geometry of Pd(II) and a penta-coordinated environment around Sn(IV) were verified in solid state. The complexes maintain their solid state geometries around Pd(II) even in solutions. Pd(II) complexes 1 and 2 exhibited a significant intercalating mode of binding with salmon sperm DNA. ALPs were inhibited in a concentration dependent manner. Sn(IV) complexes (3 and 4) were inactive against ALPs. Pd(II) complexes (1 and 2) were potent ALPs inhibitors, while the heteronuclear complex 5 was comparatively less active. Organotin(IV) products demonstrated significant antibacterial/ antifungal potential while Pd(II) products were inactive. The heteronuclear (Sn,Pd) product demonstrated moderate inhibition. Among all products, Pd(II) derivative 1 exhibited the highest hemolytic effect.