RESUMEN
In this work we analyzed the vibrational spectra of 3,5-dinitrosalicylic acid (3,5DNSA) molecule. The total energy of eight possible conformers can be calculated by Density Functional Theory with 6-31G(d,p) as basis set to find the most stable conformer. Computational result identify the most stable conformer of 3,5DNSA is C6. The assignments of the vibrational spectra have been carried out by computing Total Energy Distribution (TED). The molecular geometry, second order perturbation energies and Electron Density (ED) transfer from filled lone pairs of Lewis base to unfilled Lewis acid sites for 3,5-DNSA molecular analyzed on the basis of Natural Bond Orbital (NBO) analysis. The formation of inter and intramolecular hydrogen bonding between OH and COOH group gave the evidence for the formation of dimer formation for 3,5-DNSA molecule. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincides with the experimental spectra.
Asunto(s)
Electrones , Modelos Moleculares , Conformación Molecular , Teoría Cuántica , Salicilatos/química , Vibración , Enlace de Hidrógeno , Espectrofotometría Ultravioleta , Espectroscopía Infrarroja por Transformada de Fourier , Espectrometría Raman , Electricidad Estática , TermodinámicaRESUMEN
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. The results show that charge in electron density (ED) in σ(*) and π(*) antibonding orbitals and second order delocalization energies E((2)) confirms the occurrence of Intramolecular Charge Transfer (ICT) within the molecule. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincide with the experimental spectra.
Asunto(s)
Asparagina/química , Modelos Moleculares , Teoría Cuántica , Espectroscopía Infrarroja por Transformada de Fourier , Espectrometría RamanRESUMEN
Vibrational spectral analysis of 4-amino-3-hydroxy-1-naphthalenesulfonicacid (4A3HNSA) molecule were 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 B3LYP method with 6-31G(d,p) as basis set. The Non-Linear Optical (NLO) behavior of 4A3HNSA has been studied by determination of the electric dipole moment (µ) and hyperpolarizability ß using HF/6-31G(d,p) method. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in σ(*) and π(*) antibonding orbitals and second order delocalization energies (E2) confirms the occurrence of Intramolecular Charge Transfer (ICT) within the molecule. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincide with the experimental spectra.
Asunto(s)
Naftalenosulfonatos/química , Modelos Moleculares , Teoría Cuántica , Espectroscopía Infrarroja por Transformada de Fourier , Espectrometría Raman , TermodinámicaRESUMEN
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. The assignments of the vibrational spectra have been carried out with the help of Normal Coordinate Analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). The change in electron density (ED) in the σ* and π* antibonding orbitals and stabilization energies E(2) have been calculated by Natural Bond Orbital (NBO) analysis to give clear evidence of stabilization originating in the hyperconjugation of hydrogen-bonded interaction. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincides with the experimental spectra. Microbial activity of studied compounds was tested against Staphylococcus aureus, Streptococcus pyogenes, Bacillus subtilis, Escherichia coli, Psuedomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Shigella flexneri, Salmonella typhi and Enterococcus faecalis.
Asunto(s)
Antibacterianos/química , Antibacterianos/farmacología , Antioxidantes/química , Antioxidantes/farmacología , Umbeliferonas/química , Umbeliferonas/farmacología , Bacterias/efectos de los fármacos , Infecciones Bacterianas/tratamiento farmacológico , Humanos , Modelos Moleculares , Conformación Molecular , Espectrofotometría Ultravioleta , Espectroscopía Infrarroja por Transformada de Fourier , Espectrometría RamanRESUMEN
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. The detailed interpretation of the vibrational spectra has been carried out. The first order hyperpolarizability (ß(0)) of the molecular system and related properties (ß, α(0) and Δα) of DAP are calculated using HF/6-31G(d,p) method on the basis of finite-field approach. Vibrational analysis reveals that the simultaneous IR and Raman activation of the C-C stretching mode in the molecule provide the evidence for the charge transfer interaction takes place from electron donating group to the ring. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. The simulated spectra satisfactorily coincide with the experimental spectra.