Structural, electronic, and thermodynamic insights into Zn(II), Cd(II), and Hg(II) kojate systems: combined spectroscopic and DFT analysis

Metal complexes of kojic acid have been analyzed through the use of elemental analysis, thermogravimetry, and density functional theory (DFT). The results of the elemental analysis showed that metal ratios other than 1:2 had been obtained, and therefore, it cannot be concluded that the composition of the products is known. The results of thermal analysis determined that all products had T 50 > 400°C. The use of the DFT method showed that M–O bond length increased from Zn to Hg and that there was a significant attraction between metals and molecules in gas phase. M=O vibrations were calculated for Zn and Cd and were found to be in reasonable agreement with experimental data while those for Hg showed different results. Overall, there are strong M–kojate interactions evidenced in the study, although additional studies are needed to comprehend the nature of the metal complex.