Synthesis, structural characterization, CT-DNA interaction study and antithrombotic activity of new ortho-vanillin-based chiral (Se,N,O) donor ligands and their Pd complexes

Abstract

Two new selenated ligands: (S)-BnSeCH2CH(Bn)N = CH-C6H3-3-OCH3-2-OH ((S)-L1H) and (S)-BnSeCH2CH(Bn)NH-CH2-C6H3-3-OCH3-2-OH ((S)-L2H) incorporating ortho-vanillin moiety and their respective palladium(II) complexes (S)-1 and (S)-2 were synthesized in a high-yielding procedures. All compounds were characterized by various spectroscopic techniques such as 1H, 13C{1H} NMR, FT-IR, and UV–Visible. Further, the elemental and single crystal X-ray diffraction analyses of complexes showed that the deprotonated ligands ((S)-L1 and (S)-L2) coordinated to central palladium as tridentate (Se,N,O−) chelates of composition [PdCl(L1-2)]. In crystalline state the molecules of complexes were found to held by a moderate to strong intermolecular hydrogen bonds like CH⋯Cl and CH⋯O in both and OH⋯O, OH⋯Cl, NH⋯Cl in (S)-2∙H2O. In addition, there exists rare CH⋯Se and Se⋯O types of secondary bonding interactions between the molecules of (S)-1 and (S)-2∙H2O respectively. The interactions of ligands and complexes with CT-DNA have been studied by absorption, fluorescence and viscosity measurements. These determinants showed efficient binding interaction with DNA through ‘intercalation’ mode. The reduced Schiff base showed a higher binding capacity than the parent Schiff base. Further, the DNA binding affinity of complexes is higher than the corresponding ligands. The anticoagulant and non-haemolytic activities have also been investigated for these compounds. The human blood clotting time found to be enhanced from 150 to 200 sec in both PPP and PRP cases on coordination of ligands to palladium.