DFT electronic structure calculations, spectroscopic studies, and normal coordinate analysis of 2-[(5-nitro-1,3-thiazol-2-yl)carbamoyl]phenyl acetate

• Spectroscopic properties were examined by FT-IR, and FT-Raman techniques.
• The detailed interpretation of the vibrational spectra has been carried out with aid of NCA.
• The NBO, HOMO and LUMO analysis were also performed by DFT approach.
• Thermodynamic properties of the molecule were calculated.

The solid phase FTIR and FT-Raman spectra of 2-[(5-nitro-1,3-thiazol-2-yl)carbamoyl]phenyl acetate (25N2LCPA) have been recorded 450–4000 cm−1 and 100–4000 cm−1 respectively. The normal coordinate analysis was carried out to confirm the precision of the assignments. DFT calculations have been performed giving energies, optimized structures, harmonic vibrational frequencies and IR intensities. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (DFT) using B3LYP method with 6-31+G(d,p) basis set. The detailed interpretation of the vibrational spectra has been carried out with aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology. The Vibrational frequencies are calculated in the above method and are compared with experimental frequencies which yield good agreement between observed and calculated frequencies. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. In addition, Frontiers molecular orbital and molecular electrostatic potential were computed by using Density Functional Theory (DFT) B3LYP/6-31+G(d,p) basis set. The calculated HOMO and LUMO energies show that charge transfer occurs in the molecule.

2-[(5-Nitro-1,3-thiazol-2-yl)carbamoyl]phenyl acetate (25N2LCPA) is prescribed for treatment of diseases caused by Giardia-intestinalis and Cryptosporidium like diarrhea, chronic hepatitis B, rotavirus disease, and immune-compromised patients, including those with AIDS or HIV infection. The equilibrium geometry harmonic vibrational frequencies, infrared intensities and Raman scattering activities were calculated by with the help DFT method with 6-31+G(d,p) basis set using Gaussian 03W program. Based on Pulay’s recommendations a complete set of internal coordinates has been defined to calculate potential energy distribution (PED) for each normal mode with aid of NCA.Figure optionsDownload as PowerPoint slide