Pd(II) complexes bearing chromone based Schiff bases: Synthesis, characterisation and biological activity studies

Pd(II) complexes of 3-formyl chromone Schiff bases such as 3-((2-hydroxyphenylimino) methyl)-4H-chromen-4-one (HL1), 2-((4-oxo-4H-chromen-3-yl)methylneamino)benzoic acid (HL2), 3-((3-hydroxypyridin-2-ylimino)methyl)-4H-chromen-4-one (HL3), 3-((2-mercaptophenylimino) methyl)-4H-chromen-4-one (HL4) and 3-((pyridine-2-ylimino)methyl)-4H-chromen-4-one (L5) have been synthesised and characterised by elemental analysis, molar conductivity, IR, electronic, magnetic, TG–DTA, powder XRD and fluorescence spectral data. From the analytical, electronic and magnetic data square-planar geometry has been proposed for all the Pd(II) complexes. Powder XRD studies indicate the crystalline state of the Pd(II) complexes. The antimicrobial activity of Pd(II) complexes was performed against two Gram(−ve), two Gram(+ve) and fungal microorganisms and the results indicate that, complexes show better microbial inhibition activity than the ligands. Pd(II) complex of HL1 displayed comparable antioxidant activity with reference to the standard drug (BHT). Agarose gel electrophoresis assay demonstrates the ability of complexes to cleave the pUC19 plasmid DNA. The cytotoxicity was tested by the MTT assay. The results indicate that the complexes exert cytotoxic effects against tested cell lines but their cytotoxicity is less than that of cisplatin.