Y. Shyma Mary

FT-IR, FT-Raman spectroscopy and computational study of (E)-4-((anthracen-9-ylmethylene)amino)-N-carbamimidoylbenzene sulfonamide.

The infrared and Raman spectra of (E)-4-((anthracen-9-ylmethylene)amino)-N-carbamimidoylbenzene sulfonamide have been recorded and analysed. Geometry and harmonic vibrational wavenumbers were calculated theoretically using Gaussian03 set of quantum chemistry codes. The data obtained from vibrational wavenumber calculations are used to assign vibrational bands found in infrared and Raman spectra of the studied molecule. The red-shift of the NH stretching band in the infrared spectrum from the computed wavenumber indicates the weakening of the NH bond. The NH stretching band has split into a doublet in the IR spectrum owing to the Davydov coupling between neighbouring units. The geometrical parameters of the title compound are in agreement with the reported similar derivatives. The calculated first hyperpolarizability is comparable with the reported value of similar structures and may be an attractive object for further studies on non-linear optics. The important thermodynamical parameters are also reported.

Vibrational spectroscopic studies (FT-IR, FT-Raman, SERS) and quantum chemical calculations on cyclobenzaprinium salicylate

FT-IR, FT-Raman and surface enhanced Raman scattering spectra of cyclobenzaprinium salicylate were recorded and analyzed. The vibrational wavenumbers were examined theoretically using the Gaussian09 set of quantum chemistry codes, and the normal modes were assigned by potential energy distribution calculations. The downshift of the OH stretching frequency is due to strong hydrogen bonded system present in the title compound as given by XRD results. The presence of CH3, CH2 and CO2 modes in the SERS spectrum indicates the nearness of the methyl group to the metal surface which affects the orientation and metal molecule interaction. The presence of phenyl ring modes in the SERS spectrum indicates a tilted orientation with respect to the metal surface. The geometrical parameters of the title compound are in agreement with XRD results. A computation of the first hyperpolarizability indicates that the compound may be a good candidate as a NLO material.

Theoretical investigations on the molecular structure, vibrational spectra, HOMO-LUMO and NBO analysis of 5-chloro-2-((4-chlorophenoxy)methyl)benzimidazole

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 5-chloro-2-((4-chlorophenoxy)methyl)benzimidazole have been investigated experimentally and theoretically using Gaussian09 software package. The energy and oscillator strength calculated by time dependent density functional theory results almost compliments with experimental findings. Gauge-including atomic orbital (1)H NMR chemical shifts calculations were carried out and compared with experimental data. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. Molecular electrostatic potential was performed by the DFT method and the infrared intensities and Raman activities are reported. Mullikens net charges have been calculated and compared with the atomic natural charges. Fist hyperpolarizability is calculated in order to find its role in non-linear optics.

Vibrational spectroscopic (FT-IR, FT-Raman, SERS) and quantum chemical calculations of 3-(10,10-dimethyl-anthracen-9-ylidene)-N,N,N-trimethylpropanaminiium chloride (Melitracenium chloride)

FT-IR, FT-Raman spectra of Melitracenium chloride were recorded and analyzed. SERS spectrum was recorded in silver colloid. The vibrational wavenumbers were computed using DFT quantum chemical calculations. The data obtained from wavenumber calculations are used to assign vibrational bands obtained in infrared and Raman spectra as well as in SERS of the studied molecule. Potential energy distribution was done using GAR2PED program. The geometrical parameters (SDD) of the title compound are in agreement with the XRD results. The presence anthracene ring modes in the SERS spectrum suggest a tilted orientation with respect to the metal surface. The methyl groups in the title molecule are also close to the metal surface. The first hyperpolarizability, NBO analysis and molecular electrostatic potential results are also reported.

Vibrational spectra, NBO analysis, HOMO-LUMO and first hyperpolarizability of 2-{[(2-Methylprop-2-en-1-yl)oxy]methyl}-6-phenyl-2,3,4,5-tetrahydro-1,2,4-triazine-3,5-dione, a potential chemotherapeutic agent based on density functional theory calculations.

The experimental FT-IR and FT-Raman spectra of 2-{[(2-Methylprop-2-en-1-yl)oxy]methyl}-6-phenyl-2,3,4,5-tetrahydro-1,2,4-triazine-3,5-dione were recorded. The optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of the compound have been examined by means of density functional theory. Reliable vibrational assignments and molecular orbital have been investigated by the potential energy distribution and natural bonding orbital analyses, respectively. The calculated first hyperpolarizability of the title compound is 2.82×10(-30) esu which is 21.69 times that of the standard NLO material urea. MEP was performed by the B3LYP level and the predicted infrared intensities and Raman activities have also been reported. Quantum chemical parameters were arrived from the frontier molecular orbital theory. The calculated geometrical parameters are in agreement with experimental results. From the MEP it is evident that the negative charge covers the CO groups and the positive region is over the rings and NH group.

Quantum mechanical and spectroscopic (FT-IR, FT-Raman, 1H NMR and UV) investigations of 2-(phenoxymethyl)benzimidazole

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 2-(phenoxymethyl)benzimidazole have been investigated experimentally and theoretically using Gaussian09 software package. The energy and oscillator strength calculated by time dependent density functional theory results almost compliments with experimental findings. Gauge-including atomic orbital (1)H NMR chemical shifts calculations were carried out and compared with experimental data. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. Molecular Electrostatic Potential was performed by the DFT method and the infrared intensities and Raman activities have also been reported. Mullikens net charges have been calculated and compared with the atomic natural charges. First hyperpolarizability is calculated in order to find its role in non-linear optics.

Molecular structure and vibrational spectra of 2-Ethoxymethyl-6-ethyl-2,3,4,5-tetrahydro-1,2,4-triazine-3,5-dione, a potential chemotherapeutic agent, by density functional methods

In this work, the vibrational spectral analysis was carried out using FT-IR and FT-Raman spectroscopy for 2-Ethoxymethyl-6-ethyl-2,3,4,5-tetrahydro-1,2,4-triazine-3,5-dione, which is a potential chemotherapeutic agent derivative. Theoretical calculations were performed by density functional methods. The complete vibrational assignments of the wavenumbers were made on the basis of potential energy distribution. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with the observed spectra. The frontier orbital energy gap and related properties of the molecule illustrates the high reactivity of the title compound. The first order hyperpolarizability, dipole moment and polarizability are also calculated. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. Molecular electrostatic potential map is also constructed. The calculated geometrical parameters are in agreement with the XRD results.