Mechanisms for forming methylglyoxal complexes with benzene and ethanol molecules. Nonempirical calculations

The formation mechanism of methylglyoxal monomers, dimers, trimers, methylglyoxal+benzene, and methylglyoxal+ethanol complexes was investigated using the density functional theory (DFT) approach and the B3LYP/6-311++G(d, p) functional set. Methylglyoxal has two C=O stretching vibrations, and in solvents, the intensity of the first C=O vibration band increased sharply, and the intensity of the second C=O vibration band decreased. This is due to the C=O···H hydrogen bond formed between methylglyoxal+benzene/ethanol solvents. Also, the calculations showed that among the molecules of methyglyoxal+benzene/ethanol mainly weak interactions, i.e. Van der Waals interactions, play a dominant role. Calculations are shown the complex formation energy increases as the number of molecules increases, but the average hydrogen bond energy corresponding to each bond remains unchanged. Also, the DFT method was used to study molecular structure, quantum chemical parameters such as Mulliken atomic charge distribution, atoms in molecules (AIM), reduced density gradient (RDG) and noncovalent interaction (NCI), electron localization functions (ELF), and localized orbital locator (LOL).