Synthesis, spectroscopic, thermal decomposition, DFT studies and antibacterial activity of uracil cobalt(III)dimethylglyoximato complexes

Three new mixed-ligand complexes of the type [Co(Hdmg)(2)(Ura)X], where Hdmg = dimethylglyoximato anion, Ura = uracil, and X = Cl, Br, or I, were synthesized and characterized using elemental analyses, molar conductance, IR and UV?visible spectroscopies. The molar conductance values indicate that the compounds are not electrolytes. The thermal decomposition was studied using TG and DSC techniques. It is shown that the decomposition process of all complexes occurs in three steps. The IR spectra of the complexes show that the four nitrogen atoms of oxime functions of the two Hdmg mono-anions are linked to the central atom, the whole moiety forming an equatorial plane. Uracil (-N) and halogen occupy the apical sites in the trans position in an octahedral arrangement. The absorption bands observed in the UV-visible spectra are due either to intra-ligand transitions, ligand-metal charge transfer transitions or D-d transitions. Density Functional Theory (DFT) calculations have been successfully used to investigate the nature of the bonding in the complexes. The antibacterial activities of the complexes and their combinations were tested against Escherichia coli, pseudomonas aeruginosa, klebsiella pneumonia, proteus mirabilis, staphylococcus aureus, and bacillus cereus. The combination of iodo and bromo complexes showed a strong inhibitory power compared to the other combinations and to the free complexes. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Three new mixed-ligand complexes of [Co(Hdmg)(2)(Ura)X] type were synthesized and characterized. The thermal decomposition process was found to occur in three steps, with the complexes showing specific structural and bonding characteristics observed through IR and UV-visible spectroscopies. Antibacterial activity tests revealed that the combination of iodo and bromo complexes exhibited stronger inhibitory power compared to other combinations and free complexes.