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Jun 2019 DOI 10.14302/issn.2377-2549.jndc-19-2765
Tetrodotoxin (TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an order that includes pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin. Although tetrodotoxin was discovered in these fish and found in several other aquatic animals (e.g., in blue–ringed octopuses, rough–skinned newts, and moon snails), it is actually produced by certain infecting or symbiotic bacteria like Pseudoalteromonas, Pseudomonas, and Vibrio as well as other species found in animals. Parameters such as FT–IR and Raman vibrational wavelengths and intensities for single crystal Tetrodotoxin (TTX)are calculated using density functional theory and were compared with empirical results. The investigation about vibrational spectrum of cycle dimers in crystal with carboxyl groups from each molecule of acid was shown that it leads to create Hydrogen bounds for adjacent molecules. The current study aimed to investigate the possibility of simulating the empirical values. Analysis of vibrational spectrum of Tetrodotoxin (TTX) is performed based on theoretical simulation and FT–IR empirical spectrum and Raman empirical spectrum using density functional theory in levels of F/6–31G*, HF/6–31++G**, MP2/6–31G, MP2/6–31++G**, BLYP/6–31G, BLYP/6–31++G**, B3LYP/6–31G and B3LYP6–31–HEG**. Vibration modes of methylene, carboxyl acid and phenyl cycle are separately investigated. The obtained values confirm high accuracy and validity of results obtained from calculations. Molecular structure of Tetrodotoxin (TTX) 1–42.
Aug 2017 DOI 10.14302/issn.2377-2549.jndc-17-1645
The structure of the newly synthesized hydrazone derivative 2 - 6 – oxo - 2-thioxotetrahydropyrimidin – 4 1H - ylidene hydrazine carbothioamide (OTTHPYHCT)compound is determined by using spectral information and elemental study. Density functional theory (DFT) studies were performed using the B3LYP/6-31G (d, p) basis set to expand imminent into their structural properties. Frontier molecular orbital (FMO’s) analysis of title compoundwas computed at the same level of theory to get knowledge about their kinetic stability of the molecule by the energy gap value obtained. Global reactivity descriptors are determined to explain the biological activity of the molecule. NBO analysis provides information about charge transfer, delocalization effect, hyperconjugative interactions and the energy responsible for the stabilization of the compound. First hyperpolarizability analysis nonlinear optical response was simulated at the B3LYP/6-31G d, p level of theory as well. Thermodynamic parameters explain vibrational intensity of the molecule.
Apr 2017 DOI 10.14302/issn.2377-2549.jndc-17-1488
The compound 2-(4-methoxyphenyl)-2, 3-dihydro-1H-perimidine (MPDP) was synthesized. The molecular structure and its functional groups were characterized with the help of Fourier Transform Infrared: FTIR/ Fourier Transform FT-Raman spectra in the regions of 400-4000/50-4000cm-1, respectively. The geometrical parameters, harmonic vibrational wavenumbers, Infrared (IR) & Raman scattering intensities, Nuclear Magnetic Resonance (NMR) chemical shift and Ultraviolet-Visible (UV-Vis) spectra were computed using B3LYP/6-311++G(d,p) level of theory. The complete vibrational analysis were made on the basis of Potential energy distribution (PED) calculation with the help of VEDA4 programme. The Highest occupied molecular orbital (HOMO) – Lowest unoccupied molecular orbital (LUMO) energy gap and intra-molecular charge transfer (ICT) were studied using NBO analysis. The first order hyperpolarizability (β0) and other related properties (β, α0, Δα) of MPDP were computed. The molecular electrostatic potential (MEP), Mulliken atomic charges were calculated using the same level of theory. In addition, the various thermodynamic parameters were also calculated.
Sep 2016 DOI 10.14302/issn.2377-2549.jndc-16-1119
The FT-IR, FT-Raman and UV-Vis spectra of E-[1-(3'-methylthienyl)-5-Phenyl-2,4-Pentadiene-3-one (MPPO) were recorded. The optimized molecular bond parameters, harmonic frequencies were calculated using B3LYP method with 6-311++G (d,p) basis set.The various normal modes were precisely assigned with thehelp ofTED calculation. The theoretical spectrograms for FT-IR, FT-Raman and Ultra Violet visible. Spectra of the title molecule had been constructed. The ICT was calculated by means of Natural Bond Orbital analysis. The Non Linear Optical properties related to polarizability and hyperpolarizability based on the finite-field approach were calculated.The band gap energy was calculated using HOMO-LUMO analysis. Furthermore, the Molecular Electrostatic Potential, Mulliken atomic charges and thermodynamic properties of MPPO were also calculated.
Apr 2016 DOI 10.14302/issn.2377-2549.jndc-16-949
Vibrational spectral analysis and first order hyperpolarizability calculations on (E)-N′-(furan-2- ylmethylene) nicotinohydrazide (F2CNH), a novel, organic, hydrozone Schiff base compound was synthesized and its structure was characterized by FT-IR, FT-Raman and UV-visible spectrum. The optimized molecular structure, vibrational frequencies and corresponding vibrational assignments of F2CNH were performed on the basis of TED analysis using SQM method. Natural boding orbital (NBO) assessment has been carried out to clarify the charge transfer or conjugative interaction and delocalization of electron density within the molecule. Electronic transitions were studied employing UV-visible spectrum and the observed values were compared with theoretical values. The first order hyperpolarizability and related properties of F2NH were calculated. Besides FMO’s MEP, mulliken atomic charge and various thermodynamic paramefress such as Zero-point energy, rotational constant and enthalpy were also calculated and analyzed.
Feb 2018 DOI 10.14302/issn.2377-2549.jndc-18-1933
The organic molecule (E)-1-(4-bromobenzylidene)thiourea (BBTU) have been synthesized and characterized using FT-IR and FT-Raman spectral studies. The quantum chemical calculations of BBTU have been studied using DFT/B3LYP/6-31G(d,p) level of theory. The stable conformer is identified by the potential energy surface scan. The complete vibrational assignments were performed on the basis of PED analysis with the help of SQM method. NBO analysis was carried out to explore the various conjucative/hyperconjucative interactions within the molecule and their second order stabilization energy. The NLO activity of BBTU is calculated and compared with the standard Urea molecule. The energies of the FMOs are used for the determination of global reactivity descriptors. The electrophilic and nucleophilic charge sites were identified by the molecular electrostatic potential mapped surface. The molecular docking of BBTU is carried out with the receptors of 3U2D and 1JIJ to screen the bacterial activity.
May 2017 DOI 10.14302/issn.2377-2549.jndc-17-1459
A combined experimental and theoretical study on molecular and vibrational structure of E-N¢ (ICINH) had been carried out. The FTIR, FT-Raman and UV-Vis spectra of ICINH were recorded in the solid phase. The optimized geometry was calculated by B3LYP method with 6-311++G(d,p) level of basis set. The harmonic vibrational frequencies, IR intensities and Raman scattering activities of the title compound were calculated at same level of theory. The scaled theoretical wavenumber showed very good agreement with the experimental values. The mulliken charges and thermodynamic functions of the ICINH were also performed at same level of theory. NLO and a study on the electronic properties such as excitation energies and wavelength, were performed by TD-DFT approach. HOMO–LUMO energy gap was also calculated and interpreted.