Vol 23 No 6

Asian Journal of Physics Vol. 23, No 6 (2014) 861-874

Vibrational assignments, theoretical calculations, structural parameters and conformer stability

determinations of cyclobutyldichlorosilane

James R Durig^a^*, Ikhlas D Darkhalil^1a, Bhushan S Deodhar^2a, Gamil A Guirgis^b, Justin K Wyatt^b,Carson W Reed^b and Joshua J Klaassen^a

^aDepartment of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110 USA

^bDepartment of Chemistry and Biochemistry, College of Charleston, Charleston, SC 29424, USA

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The infrared spectra of the gas (3500 to 80 cm^–1) and Raman spectra of the liquid (1500 to 1100 cm^–1) of cyclobutyldichlorosilane (c-C₄H₇SiHCl₂) have been recorded and complete vibrational assignments are given for all four conformers. To support the spectroscopic study, ab initio calculations by the Møller-Plesset perturbation method to second order MP2 (full) and density functional theory calculations by the B3LYP method have been carried out. The infrared intensities, Raman activities, vibrational frequencies and band contours have been predicted from MP2 (full)/6-31G(d) calculations and these theoretical values are compared to the experimental ones when available. The conformational stabilities (t-Eq > g-Eq > t-Ax > g-Ax) have been predicted from theoretical calculations with basis sets up to 6-311+G(2d,2p) from both MP2(full) and density functional theory calculations by the B3LYP method. The results are discussed and compared to the corresponding properties of some related molecules.© Anita Publications. All rights reserved.

Keywords: cyclobutyldichlorosilane; vibration; conformations.

Total Refs : 21

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Asian Journal of Physics Vol. 23, No 6 (2014) 875-882

Surface enhanced Raman scattering study of monolayers of 2-mercaptopurine at the gold surface

Xiaoyu Guo, Yali Pu and Haifeng Yang*

Department of Chemistry, Key Laboratory of Resource Chemistry of Ministry of Education,Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, 100 Guilin Road, Shanghai 200234, People’s Republic of China.

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The monolayers of 2-mercaptopurine (2MP) were self-assembled at the roughened polycrystalline gold surface in acid and alkaline media. The interpretation of SERS mapping spectral data aided by the calculations for the vibrational modes using BLYP/6-31G method suggested that the resulted 2MP monolayers under acid condition through the S and N₃ atoms of pyrimidine moiety anchoring at the gold surface in a tilted fashion and in basic solution, formation of 2MP molecules by the interaction of the C=S bond and N₁ atom with the surface. In-situ SERS spectroelectrochemical experiment was conducted to examine the stability of the SAMs, and it was found the detaching process of the 2MP SAMs formed under acid media had happened around -1.6 V vs SCE. The monolayers of 2MP formed at pH 13 were detached from the Au surface at ca. −1.2 V vs SCE.© Anita Publications. All rights reserved.

Keywords: 2-mercaptopurine; SERS mapping; spectral assignments.

Total Refs : 20

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Asian Journal of Physics Vol. 23, No 6 (2014) 883-890

Lattice dynamics and normal coordinate analysis of HTSCGdBa₂Cu₃O₇

Sujin P Jose¹, V Arjunan², K Sanghamitra³ and S Mohan³*

¹Department of Computational Physics, School of Physics, Madurai Kamaraj University, Madurai-625 021, India.

¹Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry-605 008, India.

³ School of Sciences and Humanities, Vel Tech University, Avadi, Chennai-600 062, India

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Knowledge about the phonons in high temperature superconductors is essential to understand the strong electron-phonon coupling which may be one of the possible origins of the high T_c superconductor. It is not possible to obtain all the phonon frequencies experimentally through Raman and infrared spectra due to the nature of high temperature superconducting materials. Hence, a theoretical evaluation of phonon frequencies of high temperature superconductors assumes importance. The normal coordinate analysis and lattice dynamical calculations of the optically active lattice vibrations are useful for the theoretical interpretation of Raman and infrared spectra at the center of Brillouin zone in high temperature superconductors. Therefore an attempt is made in the present work to evaluate all phonon frequencies using two different methods namely lattice dynamics studies and normal coordinate analysis. The results obtained by these two methods are discussed in detail.© Anita Publications. All rights reserved.

Keywords: GdBa₂Cu₃O₇, Phonon frequencies, Lattice dynamics, Normal coordinate analysis

Total Refs : 19

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Asian Journal of Physics Vol. 23, No 6 (2014) 891-908

Synthesis, structure, biological properties and DFT investigations of 3,4-dihydropyrimidin-2(1H)-ones

T K Shabeer¹, V Arjunan^2* and E Vinoth Kumar¹

¹Post–Graduate and Research Department of Chemistry, The New College (Autonomous), Chennai-600 014. India.

¹Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry-605 008, India.

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The 3,4-dihydropyrimidinones namely ethyl-4-(4-N,N-dimethylaminophenyl)-6-methyl-2-oxo-3,4-dihydropyrimidine-5-carboxylate (C1) and 5-acetyl-4-(4-N,N-dimethylaminophenyl)-6-methyl-2-oxo-3,4–dihydropyrimidine (C2) were synthesized using acetoacetic ester/acetylacetone, urea and 4-N,N-dimethylaminobenzaldehyde by grindstone technique. The purity of the compounds were determined by elemental analysis, TLC, FTIR and ¹H–NMR spectroscopic methods. The in vitro antibacterial and antifungal activities of the compounds were studied. The structural parameters for the optimised structure of the compounds were determined by B3LYP method. The molecular electrostatic potential, charges of the atoms and the HOMO–LUMO energies of the compounds were determined.© Anita Publications. All rights reserved.

Keywords: FTIR; NMR; 3,4–dihydropyrimidin–2(1H)–ones; DFT; antimicrobial.

Total Refs : 45

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Asian Journal of Physics Vol. 23, No 6 (2014) 909-913

Optical properties of galvanostatically synthesized hydrophilic Fe doped ZnSe thin films

G M Lohar^a, J V Thombare^a, S K Shinde^a, B P Relekar^a, M C Rath^b, V J Fulari^a

^a Thin Film Physics and Holography Laboratory, Department of Physics,Shivaji University, Kolhapur-416 004 (MH), India

^b Radiation and Photochemistry Division, BARC, Mumbai-400 085, India.

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The present investigation describes the iron (Fe) doped ZnSe thin films were successfully synthesised via galvanostatic mode of electrodeposition. These crystalline Fe doped ZnSe thin films are characterised by X-ray diffraction (XRD), Raman spectroscopy, UV-Vis spectroscopy, reflectance spectroscopy, and surface wettability. Transmittance observed to be decreases as Fe doping percent increases in the ZnSe. The reflectance, refractive index and extinction coefficient observed to be increases as percent on Fe content increases in the ZnSe thin film. Fe doped ZnSe thin films are hydrophilic in nature.© Anita Publications. All rights reserved.

Keywords: Galvanostatic, Raman spectroscopy, Reflectance, Surface wettability

Total Refs : 12

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Asian Journal of Physics Vol. 23, No 6 (2014) 915-932

Experimental and theoretical quantum chemical investigations of 2-cis-4-trans-hexadiene and 2-trans-4-trans-hexadiene

V Arjunan¹, R. Durgadevi², and S Thillai Govindaraja²

¹Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry- 605 008, India.

²Research and Development Centre, Bharathiar University, Coimbatore- 641 046, India.

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A detailed conformational, vibrational, NMR and DFT studies of 2-cis-4-trans-hexadiene and 2-trans-4-trans-hexadiene have been carried out. In DFT, B3LYP method has been used with 6–311++G** and cc–pVTZ basis sets. The vibrational frequencies were calculated resulting in IR and Raman frequencies together with intensities and Raman depolarization ratios. The dipole moment derivatives were computed analytically. Isoelectronic molecular electrostatic potential surface and electron density surface were examined. ¹H and ¹³C NMR isotropic chemical shifts were calculated and the assignments made are compared with the experimental values. The energies of important MO’s of the compound were also determined from TD–DFT method. The stabilisation energies of the delocalization of electrons are determined. © Anita Publications. All rights reserved.

Keywords: 2-cis-4-trans-hexadiene; 2-trans-4-trans-hexadiene; DFT; FTIR; FT-Raman; NMR.

Total Refs : 35

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Asian Journal of Physics Vol. 23, No 6 (2014) 933-944

Vibrational spectroscopic studies, electronic structure calculations and normal coordinate analysis

of 2,3,6-trichlorobenzaldehyde

C S Hiremath

P C Jabin Science College (Autonomous) Hubli-580031, Karanataka, India

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FTIR (4000–450 cm⁻¹) spectral measurement of 2,3,6-trichlorobenzaldehyde (236CBZ) has been done. DFT (B3LY/6-311G*) calculations have been performed giving optimized structures, energies, harmonic vibrational wavenumbers, infrared intensities, and atomic displacements. Furthermore, force field calculations have been performed by normal coordinate analysis. Force field calculations showed that several normal modes are mixed in terms of the internal coordinates. A complete assignment of the observed spectra, based on spectral correlations, electronic structure and normal coordinate analysis, has been proposed. Optimization leads to CS symmetry with 7Cl-trans and 7Cl-cis forms, with 7Cl-cis-form as the low energy stable form. The energy difference between the two forms is 0.050549 kcal/mol. The results of the calculations have been used to simulate IR spectra. The SQM method, which implies multiple scaling of DFT force fields has been shown superior to the uniform scaling approach. The computed HOMO-LUMO orbitals show that charge transfer occurs within the molecule. © Anita Publications. All rights reserved.

Keywords: 2,3,6-trichlorobenzaldehyde; DFT; vibration; SQM.

Total Refs : 41

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Asian Journal of Physics Vol. 23, No 6 (2014) 945-952

Phonon spectral studies of high temperature superconductor TmBa₂Cu₃O₇

V Arjunan¹, Sujin P Jose², R Jothilakshmi³ and S Mohan³

¹Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry- 605 008, India.

³School of Physics, Madurai Kamaraj University, Madurai- 625 021

³School of Sciences and Humanities, Vel Tech University, Avadi, Chennai- 600 062, India

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One of the possible origins to explain high T_c superconductor is the strong electron phonon coupling. Therefore, a knowledge of phonon frequencies is essential to understand the mechanism of high temperature superconductors. In order to investigate phonon spectra, Raman and infrared spectra of these systems have been studied. Unfortunately there is a little information available in the literature for complete Raman and infrared absorption spectra. The nature of the superconductivity materials does not yield all the phonon frequencies experimentally through Raman and infrared spectra. Alternatively, a theoretical evaluation of phonon frequencies of high temperature superconductors assumes importance. The calculations of lattice dynamics using the modified three body force shell model yields the required phonon frequencies. The present approach leads to a better understanding of phonon frequency of high T_c superconductor TmBa₂Cu₃O_7. The phonon frequencies of TmBa₂Cu₃O₇ are evaluated by normal coordinate analysis by using Wilson’s FG matrix method due to the strong covalent bonding nature of high temperature superconductors. The normal coordinate analysis of optically active lattice vibrations will be useful for the theoretical interpretation of vibrational spectrum at the center of Brillouin zone for TmBa₂Cu₃O₇ high T_c superconductor. Further, the evaluated potential energy distribution helps to identify the pure and mixed frequencies. Hence, the present approach is useful not only to obtain all the phonon frequencies of high temperature superconductor TmBa₂Cu₃O₇ reasonably but also to characterize it. This gives further support in understanding the phonon spectra of the high temperature superconductors. © Anita Publications. All rights resrved.

Keywords: TmBa₂Cu₃O₇, Phonon frequencies, Lattice dynamics, Normal coordinate analysis

Total Refs : 18

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Asian Journal of Physics Vol. 23, No 6 (2014) 953-958

Scaling equation method vs single scale factor for vibrational spectra – the case of 1,4–H2–1,2,4–triazolium ion

M Daszkiewicz

Institute of Low Temperature and Structure Research, Polish Academy of Sciences,
Okólna str. 2, P.O. Box 1410, 50–950 Wrocław, POLAND

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Scaling equation method for the assignment of vibrational spectra is discussed. The root–mean–square deviation for single scale factor, linear equation and quadratic equation is calculated for 1,4–H2–1,2,4–triazolium ion. When the single scale factor is applied, large RMS is obtained. Since the difference between RMS for linear and quadratic equation is comparable with the resolution of the experimental data, a linear equation a·x + b is satisfactory for scaling the calculated wavenumbers. Thus, further using of the single scale factor is not recommended.© Anita Publications. All rights reserved.

Keywords: Scaling Factor, Theoretical Spectra, Triazole, DFT, Hybrid Materials.

Total Refs : 28

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Asian Journal of Physics Vol. 23, No 6 (2014) 959-972

Experimental and theoretical quantum chemical investigations of trans-methylcrotonate

V Arjunan¹, L Devi², P Remya² and S Senthilkumari¹

¹Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry-605 008. India
²Research and Development Centre, Bharathiar University, Coimbatore-641 046, India.

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A detailed conformational, vibrational, NMR and DFT studies of trans-methylcrotonate have been carried out. In DFT, B3LYP method has been used with 6-311++G** and cc-pVTZ basis sets. The vibrational wavenumbers were calculated together with intensities and Raman depolarization ratios. The dipole moment derivatives were computed analytically. Isoelectronic molecular electrostatic potential surface and electron density surface were examined. 1H and 13C NMR isotropic chemical shifts were calculated and the assignments made are compared with the experimental values. The energies of important MO’s of the compound were also determined from TD–DFT method. © Anita Publications. All rights reserved.

Keywords: trans-methylcrotonate; DFT; FTIR; FT-Raman; NMR.

Total Refs : 32

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Asian Journal of Physics Vol. 23, No 6 (2014) 973-988

Quantum chemical investigations of carbamoylazide and its deuterated derivative

V Arjunan¹, R Anitha¹, S Thillai Govindaraja² and R Santhanam²

¹Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry-605 008. India.

²Research and Development Centre, Bharathiar University, Coimbatore 641 046, India.

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A detailed conformational, vibrational and DFT studies of carbamoylazide and its deuterated derivatives have been carried out. In DFT, B3LYP method has been used with 6-311++G** and cc-pVTZ basis sets. The vibrational wavenumbers were calculated resulting in IR and Raman wavenumbers together with intensities and Raman depolarization ratios. The dipole moment were computed analytically. Isoelectronic molecular electrostatic potential surface and electron density surface were examined. The energies of important MO’s of the compound were also determined from TD–DFT method. The isotopic effect on the vibrational frequencies were discussed.© Anita Publications. All rights reserved.

Keywords: carbamoylazide; DFT; FTIR; FT-Raman; NMR.

Total Refs : 53

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Asian Journal of Physics Vol. 23, No 6 (2014) 989-998

Investigation of induction period, nucleation parameters and microhardness studies of

solution grown thiosemicarbazone of benzophenone

G V Pandian¹ and P Anbusrinivasan²

¹Department of chemistry, T.B.M.L College, Porayar-609 307, India

²Department of Chemistry, A.V.C College (Autonomous), Mannampandal, Mayiladuthurai-609 305, India

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Thiosemicarbazone of benzophenone (TSCBP) is grown by solution growth technique by adopting slow evaporation method from the solvent methanol. The crystal dimension up to 14 × 6.5 × 4 mm³ is obtained. The harvested crystal was purified by repeated recrystallization. The induction period was measured at various super saturations and hence the interfacial energies were evaluated. Using the interfacial tension value, the nucleation parameters such as radius of the critical nuclei (r*), the Gibbs free energy for the formation of a critical nucleus (ΔG*) and the number of molecules in the critical nucleus (i*) were also calculated for various concentration of solvent at two different temperatures. The effect of surface tension, viscosity and density of these solvents are correlated with interfacial tension. These crystals were characterized by FTIR spectra to identify the functional group present in the compound. The optical transparency was examined by UV-spectral analysis. © Anita Publications. All rights reserved.

Keywords: Solution growth, slow evaporation technique, Induction period, Interfacial energy, spectral characterization.

Total Refs : 30

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Asian Journal of Physics Vol. 23, No 6 (2014) 999-1012

Monomer and dimer structural stability, experimental and theoretical spectroscopic

investigations (FTIR, FT-Raman and UV-Vis),

MEP, DOS and NLO studies of Niacin

P B Nagabalasubramanian^a and S Periandy^b

^aDepartment of Physics, Arignar Anna Govt Arts & Science College, Karaikal, Puducherry, India
^bDepartment of Physics, Tagore Arts College, Puducherry, India

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The FTIR, FT-Raman and UV-Visible spectra of niacin (C6H5NO2) were studied. The molecular geometry and vibrational frequencies of the Niacin (NA) in the ground state were calculated using B3LYP method invoking 6-311++G(d,p) basis set. The fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The stability of the molecule was confirmed by calculating the energies at B3LYP/6-311++G(d,p) level. Based on the position of the carboxyl group in NA, four conformers are possible among which C1 form is more stable than others. The vibrational wavenumbers of Cs conformer with monomer and dimer structures were studied. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were performed by time-dependent density functional theory. In addition, the dipole moment, linear polarizability and first hyperpolarizability values were computed. The linear polarizabilities and first hyper polarizabilities of the studied molecule indicate that the compound is a good candidate for nonlinear optical materials. © Anita Publications. All rights reserved.

Keywords: Niacin, FTIR, FT-Raman, UV-Visible, HOMO–LUMO, NLO.

Total Refs : 49

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