Tunable van der Waals interactions in low-dimensional nanostructures.

Non-covalent van der Waals interactions play a major role at the nanoscale, and even a slight change in their asymptotic decay could produce a major impact on surface phenomena, self-assembly of nanomaterials, and biological systems. By a full many-body description of vdW interactions in coupled carbyne-like chains and graphenic structures, here, we demonstrate that both modulus and a range of interfragment forces can be effectively tuned, introducing mechanical strain and doping (or polarizability change). This result contrasts with conventional pairwise vdW predictions, where the two-body approximation essentially fixes the asymptotic decay of interfragment forces. The present results provide viable pathways for detailed experimental control of nanoscale systems that could be exploited both in static geometrical configurations and in dynamical processes.

Haemostatic effects of latex from Croton sparsiflorus Morang, in vitro, in vivo, in silico approaches.

The present investigations are phytochemical screening of Latex aqueous (Laq) extract of C. sparsiflorus and study its role in homeostasis. It is being traditionally used for fresh cuts to stop bleeding immediately. To know the contents of extract, the quantitative phytochemical analysis were performed it showed the contents such as saponins (15.2%), alkaloids (7.61%), phenols (0.62%), tannins (1.1%), and flavonoids (0.224%). The in vitro and in vivo blood clotting mechanism was observed in Wister albino rats to understand the blood clotting activity. The in vitro cytotoxicity assay was performed by 3T3L1 cell lines evaluated by Laq extract of C. sparsiflorus to determine the toxic effects of the extract. The gas chromatographic and liquid chromatographic mass spectra (GCMS and LCMS) were observed there were three compounds obtained namely, 1) methyl-hexafuranoside, 2) cumarandione, and 3) crotonosine, in addition to that the NMR (1H and 13C) elemental analysis, FT-IR (4000-400 cm-1) and UV-vis (800-200 nm) spectra were also recorded in aqueous solution. The molecular docking studies performed, in which the blood clotting factors have a potential interaction with crotonosine. This in-silico study demonstrates the interactions of active components of C. sparsiflorus with blood clotting factors. Furthermore, since the crotonosine compound has more blood clotting factor the molecular structure was treated with density functional theory calculation (DFT) to understand the optimized geometry, vibrational behaviour and electronic excitation states.

Synthesis and spectral characterization of bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)propane.

Bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)propane (BAMTP) was synthesized and characterized by FT-IR and FT-Raman spectra. Gas phase structure of BAMTP was examined under density functional theory B3LYP/6-311++G(d, p) level of basis set, wherein the molecule was subjected to conformational analysis. Thus the identified stable structure utilized for the calculations such as geometry optimization, vibrational behavior, hyperpolarizability analysis, natural bond orbital analysis, band gap, chemical hard/softness and stability. Geometry of BAMTP has been discussed elaborately with related crystal data. The results found from experimental and theoretical methods were reported herewith.

Structural and vibrational studies on 1-(5-methyl-[1,3,4] thiadiazol-2-yl)-pyrolidin-2-ol.

FT-Raman and FT-IR spectra were recorded for1-(5-methyl-[1,3,4]thiadiazol-2-yl)-pyrolidin-2-ol (MTPN) sample in solid state. The equilibrium geometries, harmonic vibrational frequencies, IR and the Raman scattering intensities were computed using DFT/6-311++G (d,p) level. Results obtained at this level of theory were used for a detailed interpretation of the IR and Raman spectra, based on the TED of the normal modes. Molecular parameters such as bond lengths, bond angles and dihedral angles were calculated. The intra-molecular charge transfer was calculated by means of NBO. Hyperconjugative interaction energy was more during the π-π(∗) transition. Energy gap of the molecule has been found using HOMO and LUMO calculation, hence the less band gap, which seems to be more stable.

Crystal structure of ethyl (2S)-9-meth-oxy-2-methyl-4-oxo-3,4,5,6-tetra-hydro-2H- 2,6-methano-benzo[g][1,3,5]oxa-diazocine-11-carboxyl-ate.

In the title compound, C15H18N2O5, the meth-oxy-phenyl ring makes a dihedral angle of 84.70 (12)° with the mean plane of the tetra-hydro-pyrimidin-2(1H)-one ring. Both the pyran and tetra-hydro-pyrimidin-2(1H)-one rings have distorted envelope conformations with the carboxyl-ate-substituted C atom as the flap. In the crystal, mol-ecules are linked via pairs of N-H⋯O hydrogen bonds, forming zigzag chains propagating along [010], which enclose R (2) 2(8) ring motifs. The chains are linked by C-H⋯π inter-actions, forming a two-dimensional network parallel to (100).

Synthesis and spectroscopical study of rhodanine derivative using DFT approaches.

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of (E)-5-benzylidene-2-thioxothiazolidine-4-one (E5BTTO) have been investigated experimentally and theoretically based on Density Functional Theory (DFT) approach. The FT-Raman and FT-IR spectra of E5BTTO were recorded in solid phase. Theoretical calculations were performed at the DFT level using the Gaussian 03 program. The experimental bands were assigned and characterized on the basis of the scaled theoretical wavenumber by their Total Energy Distribution (TED). The results of the calculation were applied to simulate infrared and raman spectra of the title compound which showed good agreement with the observed spectra. The calculated HOMO and LUMO energies show that charge transfer occur within the molecule. Stability arising from hyperconjugative interactions leading to its NLO activity and charge delocalization were analyzed using Natural Bond Orbital (NBO) analysis.

Vibrational spectroscopy investigation and density functional theory calculations on (E)-N'-(4-methoxybenzylidene) benzohydrazide.

The FT-IR, FT-Raman and UV-Vis spectra of the Schiff base compound (E)-N'-(4-methoxybenzylidene) benzohydrazide (MBBH) have been recorded and analyzed. The optimized geometrical parameters were calculated. The complete vibrational assignments were performed on the basis of TED of the vibrational modes, calculated with the help of SQM method. NBO analysis has been carried out to explore the hyperconjugative interactions and their second order stabilization energy within the molecule. The molecular orbitals (MO's) and its energy gap were studied. The first order hyperpolarizability (ß0) and related properties (ß, α0, Δα) of MBBH are also calculated. All theoretical calculations were performed on the basis of B3LYP/6-311++G(d,p) level of theory.

Synthesis and spectral characterization of hydrazone derivative of furfural using experimental and DFT methods.

The Spectral Characterization of (E)-1-(Furan-2-yl) methylene)-2-(1-phenylvinyl) hydrazine (FMPVH) were carried out by using FT-IR, FT-Raman and UV-Vis., Spectrometry. The B3LYP/6-311++G(d,p) level of optimization has been performed on the title compound. The conformational analysis was performed for this molecule, in which the cis and trans conformers were studied for spectral characterization. The recorded spectral results were compared with calculated results. The optimized bond parameters of FMPVH molecule was compared with X-ray diffraction data of related molecule. To study the intra-molecular charge transfers within the molecule the Lewis (bonding) and Non-Lewis (anti-bonding) structural calculation was performed. The Non-linear optical behavior of the title compound was measured using first order hyperpolarizability calculation. The atomic charges were calculated and analyzed.

FT-IR, FT-Raman spectral and conformational studies on (E)-2-(2-hydroxybenzylidenamino)-3-(1H-indol-3yl) propionic acid.

The (E)-2-(2-hydroxybenzylidenamino)-3-(1H-indol-3yl) propionic acid ((E)-2HBA3IPA) was synthesized. The theoretical conformational analysis was performed to identify the stable structure. Optimized molecular bond parameters were calculated by using B3LYP/6-31G(d,p) basis set. The hyperconjugative interaction energy (E(2)) and electron densities of donor (i) and acceptor (j) bonds were calculated using NBO analysis. First order hyperpolarizability (ß0) was calculated. The band gap energy was analyzed by UV-Visible recorded spectra and compared with theoretical band gap TD-DFT/B3LYP/6-31G(d,p) values. The intra-molecular hydrogen bonding interaction was identified between nitrogen and hydroxyl hydrogen (N⋯H-O).

Structural, vibrational and hyperpolarizability calculation of (E)-2-(2-hydroxybenzylideneamino)-3-methylbutanoic acid.

The (E)-2-(2-hydroxybenzylideneamino)-3-methylbutanoic acid (E)-2HBAMBA was synthesized. The FT-IR, FT-Raman and UV-vis spectra have been recorded and characterized. Theoretical wavenumbers along with IR and Raman intensities were calculated using B3LYP/6-31G(d,p) level and total energy distribution (TED) of the various normal mode of vibrations were also studied. The conformational analysis was performed for a stable conformer by selecting the dihedral angles and the optimized bond parameters were calculated for the stable structure. Effect of intramolecular interactions is calculated by changing the orientation of hydroxyl hydrogen. To know the charge transfer while changing the hydroxyl group hydrogen orientation, the NBO analysis was performed. Using the same level of calculation, the electronic charge transfers were calculated and compared.

FT-Raman, FT-IR spectral and DFT studies on (E)-1-4-nitrobenzylidenethiocarbonohydrazide.

Quantum mechanical calculation of optimized parameters, vibrational wavenumbers and energies of (E)-1-4-nitrobenzylidenethiocarbonohydrazide ((E)-1-4-NBTCH) was carried out using Hatree Fock (HF) with 6-31G(d,p), 6-311G(d,p) basis sets and density functional theory (DFT) with 6-31G(d,p) basis set. The optimized geometrical parameters obtained by HF and DFT are in better agreement with analogues single XRD data. The vibrational wavenumbers were calculated and the complete assignments were performed on the basis of total energy distribution (TED), calculated with scaled quantum mechanical (SQM) method. The electrical dipole moment (µ) and first hyperpolarizability (ß(0)) values have been computed using ab initio and DFT quantum mechanical calculation. The calculated results (ß(0)) show that the title molecule might have nonlinear optical (NLO) behaviour. The total energy, dipole moment and rotational constant are reported for the title molecule. The HOMO-LUMO energies were calculated and natural bonding orbital (NBO) analysis has also been carried out.

FT-Raman, FT-IR spectra and total energy distribution of 3-pentyl-2,6-diphenylpiperidin-4-one: DFT method.

FT-Raman and FT-IR spectra were recorded for 3-pentyl-2,6-diphenylpiperidin-4-one (PDPO) sample in solid state. The equilibrium geometries, harmonic vibrational frequencies, infrared and the Raman scattering intensities were computed using DFT/6-31G(d,p) level. Results obtained at this level of theory were used for a detailed interpretation of the infrared and Raman spectra, based on the total energy distribution (TED) of the normal modes. Molecular parameters such as bond lengths, bond angles and dihedral angles were calculated and compared with X-ray diffraction data. This comparison was good agreement. The intra-molecular charge transfer was calculated by means of natural bond orbital analysis (NBO). Hyperconjugative interaction energy was more during the π-π* transition. Energy gap of the molecule was found using HOMO and LUMO calculation, hence the less band gap, which seems to be more stable. Atomic charges of the carbon, nitrogen and oxygen were calculated using same level of calculation.

Molecular structure, vibrational spectroscopic (FT-IR, FT-Raman), UV and NBO analysis of 2-chlorobenzonitrile by density functional method.

In this work, we will report a combined experimental and theoretical study on molecular structure, vibrational spectra, NBO and UV spectral analysis of 2-chlorobenzonitrile (2-ClBN). The FT-IR solid phase (4000-400 cm(-1)), and FT-Raman spectra (3500-50 cm(-1)) of 2-ClBN was recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of 2-ClBN in the ground state have been calculated by using the density functional methods (BLYP, B3LYP) with 6-31G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ* and π* anti bonding orbitals and E2 energies confirms the occurrence of ICT (Intra molecular Charge Transfer) within the molecule. The UV spectrum was measured in ethanol solution. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) results complements with the experimental findings. The calculated HOMO and LUMO energies also confirm that charge transfer occurs within the molecule. Finally calculated results were applied to simulated Infrared and Raman spectra of the title compound which show good agreement with observed spectra.

Vibrational spectroscopic study and NBO analysis on bis(4-amino-5-mercapto-1,2,4-triazol-3-yl) methane using DFT method.

In this work, we report a combined experimental and theoretical study on molecular structure, vibrational spectra, NBO analysis of bis(4-amino-5-mercapto-1,2,4-triazol-3-yl) methane (BAMTM). The FT-Raman and FT-IR spectra of BAMTM were recorded in the solid phase. The molecular geometry, harmonic vibrational frequencies and bonding features of BAMTM in the ground state have been calculated by using density functional method (B3LYP) with standard 6-31G(d, p) basis set. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally the theoretical spectrograms for FT-IR and FT-Raman spectra of the title molecule have been constructed which show good agreement with recorded spectra.