Molecular structure, vibrational spectroscopic (FT-IR, FT-Raman), UV–vis spectra, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis, thermodynamic properties of benzophenone 2,4-dicarboxylic acid by ab initio HF and density functional

The FT-IR (4000–450 cm−1) and FT-Raman spectra (3500–100 cm−1) of benzophenone 2,4-dicarboxylic acid (2,4-BDA) have been recorded in the condensed state. Density functional theory calculation with B3LYP/6-31G(d,p) basis set have been used to determine ground state molecular geometries (bond lengths and bond angles), harmonic vibrational frequencies, infrared intensities, Raman activities and bonding features of the title compounds. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (β0) and related properties (β, α0 and Δα) of 2,4-BDA is calculated using HF/6-31G(d,p) method on the finite-field approach. The stability of molecule has been analyzed by using NBO analysis. The calculated first hyperpolarizability shows that the molecule is an attractive molecule for future applications in non-linear optics. The calculated HOMO and LUMO energies show that charge transfer occurs within these molecules. Mulliken population analysis on atomic charges is also calculated. Because of vibrational analyses, the thermodynamic properties of the title compound at different temperatures have been calculated. Finally, the UV–vis spectra and electronic absorption properties were explained and illustrated from the frontier molecular orbitals.

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► The detailed vibrational assignments of Benzophenone 2,4-dicarboxylic acid.
► The vibrational frequencies are calculated using Density functional theory.
► The thermodynamic properties of the title molecule is calculated theoritically.
► The redistribution of electron density (ED) in various bonding, antibonding orbitals and E(2) energies had been calculated by natural bond orbital (NBO).
► The electronic absorption properties were explained and illustrated from the frontier molecular orbitals.