Structural and vibrational studies of the potential anticancer agent, 5-difluoromethyl-1,3,4-thiadiazole-2-amino by DFT calculations
Autor: | María Florencia Ladetto, Silvia Antonia Brandán, Elida Romano |
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Rok vydání: | 2013 |
Předmět: |
Chemistry
Atoms in molecules Condensed Matter Physics Biochemistry NMR spectra database Molecular geometry Atomic orbital Computational chemistry Physics::Atomic and Molecular Clusters Molecule Physical chemistry Density functional theory Physics::Chemical Physics Physical and Theoretical Chemistry HOMO/LUMO Natural bond orbital |
Zdroj: | Computational and Theoretical Chemistry. 1011:57-64 |
ISSN: | 2210-271X |
Popis: | The structural and vibrational properties of a potential anticancer agent, the 5-difluoromethyl-1,3,4 thiadiazole-2- amino derivative and its tautomeric forms were studied by using the available experimental infrared and 1H, 13C and 19F NMR spectra and theoretical calculations based the density functional theory (DFT). The bonds order, atomic charges, charge-transfers and topological properties were studied by means of the Natural Bond Orbital (NBO) and the Atoms in Molecules theory (AIM) calculations. The harmonic vibrational wavenumbers for the optimized geometries were calculated at B3LYP/6-31G∗ and B3LYP/6-311++G∗∗ levels. For a complete assignment of the compound infrared spectrum, the DFT calculations were combined with Pulay’s scaled quantum mechanical force field (SQMFF) methodology in order to fit the theoretical wavenumbers values to the experimental ones. The results were then used to predict the Raman spectra, for which there are no experimental data. An agreement between theoretical and available experimental results was found and a complete assignment of all the observed bands in the vibrational spectra was performed. The theoretical vibrational calculations allowed us to obtain a set of scaled force constants fitting the observed wavenumbers. Additionally, the frontier molecular HOMO and LUMO orbitals for the compound were analyzed and compared with those calculated for the 2-amino-1,3,4 thiadiazole molecule. The calculated 1H, 13C and 19F chemicals shifts are in good agreement with the corresponding experimental NMR spectra of the compound in solution. |
Databáze: | OpenAIRE |
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