Density functional theory calculations and vibrational spectral analysis of 3,5-(dinitrobenzoic acid)

The FT-IR and Raman spectra of 3,5-dinitrobenzoic acid (DNBA) have been recorded and analyzed. The equilibrium geometry, various bonding and harmonic vibrational wavenumbers have been calculated with the help of density functional theory (DFT) method. Most of the vibrational modes are observed in the expected range. Mulliken population analysis shows the interactions C–N–O⋯H–C and C–O⋯H–C. The most possible interaction is explained using natural bond orbital (NBO) analysis. The strengthening and polarization of the CO bond increases due to the degree of conjugation. HOMO–LUMO energy and the thermodynamic properties are also evaluated.

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► Density functional theory computational methods have proved to be an essential tool for interpreting and predicting the various molecular properties of biologically active molecules.
► The bio activity of the 3,5-(dinitrobenzoic acid) was confirmed by the density functional theoretical calculation and the vibrational spectra.