Synthesis,spectroscopic characterization and biological studies of schiff base complexes derived from di & tripeptides and aromatic aldehydes

Three schiff base ligands have been produced by condensation of dipeptide (i.e.,glycylglycine) with benzaldehyde and salicyaldehyde (namely l-1,l-2,respectively) and tripeptide (i.e.,glycylglycylglycine) with benzaldehyde (namely l-3),then their complexes with cu(ii),pd(ii) and pt(ii) were prepared and characterized by ftir,uv-vis,chn and thermal analyses. the analytical data revealed that the ligand l-1 can coordinate as tridentate species resulting in the formation of 1:2 [metal: ligand] complexes. water soluble schiff base l-1 (glycylglycinebenzaldehyde) with molecular formula k(c11h11n2o3).h2o was coordinated to the central metal ion via azomethine nitrogen,deprotonated peptide nitrogen and carboxylate-oxygen atoms. the infrared data showed the tetra dentate binding of the water soluble schiff base ligands l-2 (glycylglycine-salicyaldehyde),and l-3 (glycylglycylglycine-benzaldehyde) with metallic ions (cu(ii),pd(ii) and pt(ii)),through-onno-atoms,resulting in the formation of 1:1 [metal: ligand] complexes. thermal analyses explained the general decomposition pattern of the prepared compounds. the in vitro antibacterial activity of the prepared ligands and complexes were also evaluated against four bacterial strains e.g.,staphylococcus aureus,bacillus subtilis,escherichia coli and proteus mirabilis,by the well-diffusion method. anti-bacterial activities of the prepared schiff bases and their complexes were determined in terms of inhibition zones. the ligands l-1 and l-2 showed no antibacterial activity against staphylococcus aureus,bacillus subtilis,escherichia coli and proteus mirabilis. l-3 was active compound in staphylococcus aureus strain while it showed no activity against bacillus subtilis,escherichia coli and proteus mirabilis strains. the results of the antibacterial assay showed that the complexes have potential antibacterial activity. the l-3 cu(ii) complex showed excellent antibacterial activities against bacillus subtilis relative to the l-3 and l-4 complexes.