Electronic Structure of Toluic Acid Isomers

Abstract— Spatial, vibrational, and electronic structures of ortho-, meta-, and para-isomers of toluic acid are calculated by density functional theory methods. Energies and locations of molecular orbitals are obtained. The Mulliken atomic charge distribution is analyzed. The valence and core spectra of electronic levels of p-toluic acid are measured for the first time by X-ray photoelectron spectroscopy techniques and interpreted. Optical absorption spectra are recorded in solutions with different ethanol concentrations. The unit cell parameters are determined by X-ray diffraction techniques. The effect of the methyl group on the electronic structure and excited states is revealed together with reactivity. The applicability of toluic acid isomers as the ligand environment in REE complexes is shown.