Synthesis, Characterization, Thermal Stability and Photocatalytic Activity of Hg(II) and Co(II) Complexes of Vanillin

Hg(II) and Co(II) complexes of vanillin VanH, namely, [Hg(van)₂]. 1.5H₂O and [Co(van)₂]. 5.5H₂O were prepared. The complexes were characterized by elemental analyses, Fourier transform infrared spectra and thermal techniques. The molecular geometries of the compounds were fully optimized with density functional theory computations using the B3LYP/LANL2DZ method. To determine the reactivity and possible electrophilic and nucleophilic sites, frontier molecular orbital energies, global reactivity, molecular electrostatic potential, Mullikan and NBO charges were calculated using the same method. The obtained results indicate that the compound possesses good kinetic stability. The thermal decomposition kinetics of the complexes were studied by the TG and DTG methods. The kinetic parameters, activation entropy, and activation free energy were also calculated using the Coats Redfern method. The photocatalytic activity was evaluated by the degradation of methyl orange aqueous solution under UV irradiation.