Molecular structures, FT-IR and FT-Raman spectra, NBO analysis, NLO properties, reactive sites and quantum chemical calculations of keto–enol tautomerism (2-amino-4-pyrimidinol and 2-amino-pyrimidine-4(1H)-one) (original) (raw)
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Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2014
FT-IR and the effect of various organic solvents on the UV-vis spectras were compared with X-ray and DFT results. NBO, NPA, Mulliken population method and Fukui function analysis were performed. HOMO, LUMO, local reactivity and chemical reactivity were performed. g r a p h i c a l a b s t r a c t
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Keto-enol tautomerism in some N-arylsalicylaldimine derivatives has been evaluated from spectroscopic data. The effect of substituents on the hydrogen bonded ortho-hydroxyl Schiff bases were studied using different psubstituents with varying nucleophilicity. The N-aryl salicylaldimine derivatives were characterized with elemental analysis, infrared, NMR and UV/Visible spectral data. The Schiff bases exist mainly as the phenol-imine tautomers. However, keto-amine tautomers were observed in methanol which is a protic solvent. The extent of the intra-molecular hydrogen bonding in the Schiff bases was evaluated from Hammett substituents’ constant. There was a positive correlation between the band intensity and the substituents nucleophilicity; and consequently with the basicity of the imine nitrogen.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
The FT-IR and Laser-Raman spectra of the title compound were recorded in solid phase. The optimized geometry and vibrational frequencies were calculated for the first time. The HOMO-LUMO energies and related molecular properties were evaluated. g r a p h i c a l a b s t r a c t a b s t r a c t In this study the experimental and theoretical vibrational frequencies of a newly synthesized anti-tumor and anti-inflammatory agent namely, methyl 4-(trifluoromethyl)-1H-pyrrole-3-carboxylate have been investigated. The experimental FT-IR (4000-400 cm À1 ) and Laser-Raman spectra (4000-100 cm À1 ) of the molecule in solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters (bond lengths, bond angles and torsion angles) have been calculated using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr and DFT/M06-2X: highly parameterized, empirical exchange correlation function) with 6-311++G(d,p) basis set by Gaussian 03 software, for the first time. The assignments of the vibrational frequencies have been done by potential energy distribution (PED) analysis using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data and results in the literature. In addition, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy and the other related molecular energy values of the compound have been investigated using the same theoretical calculations.
Vibrational Spectral Studies and Thermodynamic Functions of 4,6-DIHYDROXY-5-NITRO Pyrimidine
1998
A b stra ct The vibrational spectra of 4,6-dihydroxy-.'S-nilro pyrimidine have been reported alongwilh their assignments Hydrogen bonding and tautomeric forms have been discussed Thermodynamic functions have also been computed using the vibrational frequencies of the said molecule and the results discussed. K eyw ords Infra re d>and Raman spectroscopy, vibrational frequencies, thermodynamic functions