Synthesis and spectroscopic characterization on 4-(2,5-di-2-thienyl-1H-pyrrol-1-yl) benzoic acid: A DFT approach.

A complete structural and vibrational analysis of the 4-(2,5-di-2-thienyl-1H-pyrrol-1-yl) benzoic acid (TPBA), was carried out by ab initio calculations, at the density functional theory (DFT) method. Molecular geometry, vibrational wavenumbers and gauge including atomic orbital (GIAO) (13)C NMR and (1)H NMR chemical shift values of (TPBA), in the ground state have been calculated by using ab initio density functional theory (DFT/B3LYP) method with 6-311G(d,p) as basis set for the first time. Comparison of the observed fundamental vibrational modes of (TPBA) and calculated results by DFT/B3LYP method indicates that B3LYP level of theory giving yield good results for quantum chemical studies.

Vibrational spectra (FT-IR and FT-Raman), molecular structure, natural bond orbital, and TD-DFT analysis of L-Asparagine Monohydrate by Density Functional Theory approach.

In this work we report the vibrational spectral analysis of l-Asparagine Monohydrate (LAM) molecule by using FT-IR and FT-Raman spectroscopic techniques. The equilibrium geometry, harmonic vibrational wavenumbers, various bonding features have been computed using density functional B3LYP method with 6-311G(d,p) as basis set. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis.

Molecular structure, Normal Coordinate Analysis, harmonic vibrational frequencies, Natural Bond Orbital, TD-DFT calculations and biological activity analysis of antioxidant drug 7-hydroxycoumarin.

In this work, we report harmonic vibrational frequencies, molecular structure, NBO and HOMO, LUMO analysis of Umbelliferone also known as 7-hydroxycoumarin (7HC). The optimized geometric bond lengths and bond angles obtained by computation (monomer and dimmer) shows good agreement with experimental XRD data. Harmonic frequencies of 7HC were determined and analyzed by DFT utilizing 6-311+G(d,p) as basis set.

Vibrational spectra, UV and NMR, first order hyperpolarizability and HOMO-LUMO analysis of 2-amino-4-chloro-6-methylpyrimidine.

The solid phase FTIR and FT-Raman spectra of 2-amino-4-chloro-6-methylpyrimidine (2A4Cl6MP) have been recorded in the regions 400-4000 and 50-4,000 cm(-1), respectively. The spectra have been interpreted interms of fundamentals modes, combination and overtone bands. The structure of the molecule has been optimized and the structural characteristics have been determined by density functional theory (B3LYP) method with 6-311++G(d,p) as basis set.

Experimental (FT-IR, FT-Raman and UV-Vis) spectra and theoretical DFT investigations of 2,3-diaminophenazine.

Vibrational analysis of the planar electron-rich heterocyclic 2,3-diaminophenazine (DAP) molecule was carried out using FT-IR and FT-Raman spectroscopic techniques. The equilibrium geometry, harmonic vibrational wavenumbers, various bonding features have been computed using density functional method. The calculated molecular geometry parameters have been compared with XRD data.