Synthesis, physico-chemical and antimicrobial screening studies of some transition metal complexes with O:O donor ligands

The solid complexes of MnII, FeIII, CoII, NiII and CuII with 3-(3-furan-2yl-acryloyl)-6-methyl-pyran-2,4-dione(L1) and 3-(3-thiophene-2yl-acryloyl)-6-methyl-pyran-2,4-dione (L2) have been synthesized and characterized by elemental analysis, conductometry, thermal analysis, magnetic, i.r., P-n.m.r., u.v.–vis, X-ray diffraction and antimicrobial study. From the analytical and spectral data, the stoichiometry of the complexes has been found to be 1:2 (metal:ligand). I.r. spectral data suggest that the ligand behaves as a dibasic bidentate ligand with O:O donor sequence towards metal ions. The physico-chemical data suggests distorted octahedral geometry for CuII complexes and octahedral geometry for all other complexes. The X-ray diffraction suggests an Orthorhombic crystal system for the CuII complex and Monoclinic crystal system for CoII and NiII complexes of ligand L1. The ligands and their metal complexes were screened for antibacterial activity against Staphylococcus aureus and Escherichia coli, and the fungicidal activity against Aspergillus flavus, Curvularia lunata and Penicillium notatum.