Synthesis and spectroscopic and thermogravimetric characterization of heterobimetallic complexes with Sn(IV) and Pd(II); DNA binding, alkaline phosphatase inhibition and biological activity studies

Abstract

A palladium complex, [KLCSS]₂Pd (1), has been prepared by stirring sarcosine (HLH), KOH and CS₂ in methanol and subsequently treating with palladium(II) chloride. Six heterobimetallic derivatives of the type [R₂(Cl)SnLCS₂]₂Pd (R = Me: 2; Bu: 3; Ph: 4)/[R₃SnLCS₂]₂Pd (R = Me: 5; Bu: 6; Ph: 7) were also synthesized by stirring sarcosine (HLH) with KOH and CS₂ in methanol followed by an addition of R₂SnCl₂/R₃SnCl and then PdCl₂. FT-IR data demonstrated bidentate binding of dithiocarbamate and carboxylate with four- and five-coordinate environments around Pd(II) and Sn(IV) centers, respectively, in the solid state. UV–visible studies verified the square planar arrangement around Pd(II) in solution. The magnitude of ²J(¹¹⁹Sn-¹H) demonstrates a distorted trigonal bipyramidal geometry around tin(IV) in solution. Elemental analysis (C, H, N, and S), mass spectroscopic (EI-MS and ESI), and thermogravimetric analyses verified the chemical composition of products. Complexes 1–7 exhibited interaction with salmon sperm DNA (SS-DNA). The palladium complex 1 had shown higher potential to bind with SS-DNA and to inhibit the alkaline phosphatase when compared to the heteronuclear products (2–7). However, the antifungal/antibacterial activities of the bimetallic complexes (2–7) were significantly higher than the palladated derivative 1. The in vitro hemolytic activity investigations on human red blood cells showed that bimetallic derivative 2 with chlorodimethyltin(IV) exhibited the lowest hemolytic effects (17.55%), while 5 having trimethyltin(IV) center exhibited the highest hemolytic activity (78.64%).

A palladium complex and its heterobimetallic (Sn, Pd) derivatives were synthesized and characterized by spectroscopic and thermogravimetric analyses. The palladium complex showed higher potential to bind with SS-DNA and to inhibit the alkaline phosphatase (ALPs) relative to the heteronuclear products (2–7). However, the bimetallic derivatives displayed significantly higher antifungal/antibacterial activities than the palladium complex 1.

Keywords:

• Heterobimetallic
• Sarcosine
• Spectroscopic
• TGA
• Geometry
• SS-DNA
• Alkaline phosphatase
• Antifungal/antibacterial
• Hemolytic

Acknowledgements

SH thanks the Higher Education Commission, Islamabad, Pakistan, for the financial support under the PhD Fellowship Scheme Batch-IV (PIN Code: 074-3160-ps4-362).