Synthesis, spectral, thermal and biological studies of transition metal complexes of 4-hydroxy-3-[3-(4-hydroxyphenyl)-acryloyl]-6-methyl-2H-pyran-2-one

The solid complexes of Mn(II), Fe(III), Co(II), Ni(II), and Cu(II) with 4-hydroxy-3-[(2E)-3-(4-hydroxyphenyl)prop-2-enoyl]-6-methyl-2H-pyran-2-one, derived from 3-acetyl-6-methyl-2H-pyran-2,4(3H)-dione (dehydroacetic acid) and 4-hydroxybenzaldehyde, were synthesized and characterized by elemental analysis, conductometry, thermal analysis, magnetic measurements, IR, 1H-NMR and UV–Vis spectroscopy and a biological study. From the analytical and spectral data, the stoichiometry of the complexes was found to be 1:2 (metal:ligand). The physico–chemical data suggest a distorted octahedral geometry for the Cu(II) complexes and an octahedral geometry for all the other complexes. The thermal decomposition of all the complexes was studied by the TG–DTA method. The synthesized ligand and its metal complexes were screened for their in vitro antibacterial activity against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacterial strains and for in vitro antifungal activity against Aspergillus flavus, Curvularia lunata and Penicillium notatum. The results of these studies showed the metal complexes to be more antibacterial/antifungal against one or more species as compared with the non-complexed ligand