Apoorva Dwivedi

VIBRATIONAL DYNAMICS AND POTENTIAL ENERGY DISTRIBUTION OF TWO WELL-KNOWN NEUROTRANSMITTER RECEPTORS: TYRAMINE AND DOPAMINE HYDROCHLORIDE

This work deals with the theoretical study on the molecular structure of two well-known neurotransmitter receptors tyramine hydrochloride and dopamine hydrochloride. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities, and Raman scattering activities were calculated by the density functional B3LYP method employing 6-311G(d,p) as the basis set and the vibrational studies were interpreted in terms of the potential energy distribution (P.E.D.). The internal coordinates were optimized repeatedly to maximize the P.E.D. contributions. A detailed interpretation of the infrared and Raman spectra of tyramine and dopamine hydrochloride is reported in the present work. The similarities and differences between the vibrational spectra of the two molecules studied have been highlighted. The scaled theoretical wave numbers are in perfect agreement with the experimental values. The thermodynamic calculations related to the title compounds were also performed at B3LYP/6-311G(d,p) level of theory. The FT-Raman and FT-IR spectra of tyramine and dopamine hydrochloride have been taken from literature.

Comparative Study of Vibrational Spectra of Two Bioactive Natural Products Lupeol and Lupenone Using MM/QM Method

This work deals with the theoretical study on the molecular structure and vibrational spectra of two well-known natural products: lupeol and lupenone. The spectra were interpreted with the aid of normal mode analysis following full-structure optimization carried out with the hybrid two-level ONIOM (B3LYP/6-31G: PM3) method. A detailed interpretation of the infrared spectra of Lupeol and Lupenone is also reported in the present work. The similarities and differences between the vibrational spectra of the two molecules studied have been highlighted. The scaled theoretical wave numbers are in perfect agreement with the experimental values. The thermodynamic calculations related to the title compounds were also performed at B3LYP/6-31G: PM3 level of theory. Quantum chemical calculations have been carried out to understand the dynamical behavior of the bioactive molecules Lupeol and Lupenone.

Structural, Electronic, and Vibrational Properties of Isoniazid and Its Derivative N-Cyclopentylidenepyridine-4-carbohydrazide: A Quantum Chemical Study

Isoniazid (Laniazid, Nydrazid), also known as isonicotinylhydrazine (INH), is an organic compound that is the first-line medication in prevention and treatment of tuberculosis. The optimized geometry of the isoniazid and its derivative N-cyclopentylidenepyridine-4-carbohydrazide molecule has been determined by the method of density functional theory (DFT). For both geometry and total energy, it has been combined with B3LYP functionals having LANL2DZ and 6-311 G (d, p) as the basis sets. Using this optimized structure, we have calculated the infrared wavenumbers and compared them with the experimental data. The calculated wavenumbers by LANL2DZ are in an excellent agreement with the experimental values. On the basis of fully optimized ground-state structure, TDDFT//B3LYP/LANL2DZ calculations have been used to determine the low-lying excited states of isoniazid and its derivative. Based on these results, we have discussed the correlation between the vibrational modes and the crystalline structure of isoniazid and its derivative. A complete assignment is provided for the observed FTIR spectra. The molecular HOMO, LUMO composition, their respective energy gaps, and MESP contours/surfaces have also been drawn to explain the activity of isoniazid and its derivative.

Density functional theory study on the molecular structure of loganin

The computational Quantum Chemistry (QC) has been used for different types of problems, for example: structural biology, surface phenomena and liquid phase. In this paper we have employed the density functional method for the study of molecular structure of loganin. The equilibrium geometry, harmonic vibrational frequencies and infrared intensities were calculated by B3LYP/6-311G (d, p) method and basis set combinations. It was found that the optimized parameters obtained by the DFT/B3LYP method are very near to the experimental ones. A detailed conformational analysis was carried out. A detailed interpretation of the infrared spectra of loganin is also reported in the present work. The FT-IR spectra of loganin were recorded in solid phase. The thermodynamic calculations related to the title compound were also performed at B3LYP/6-311G (d, p) level of theory.

Quantum Mechanical Study on the Structure and Vibrational Spectra of Cyclobutanone and 1,2-Cyclobutanedione

For 1,2-cyclobutanedione and cyclobutanone, we have carried out a comparative study of different methods like B3LYP, LSDA, and B3PW91 of DFT using 6-31G (d, p) basis set and MP2 method. On comparing these methods we find that B3PW91 method is closer to the experimental one. So by using B3PW91 method, we have made a comparative study of their structures, normal mode analysis, and other properties of the two derivatives of cyclobutane. The molecular HOMO, LUMO composition, their respective energy gaps, and MESP contours/surfaces have also been drawn to explain the activity of 1,2-cyclobutanedione and cyclobutanone.

Vibrational analysis and electronic properties of 2-Decenoic acid and its derivative by first principles

Royal jelly is the mixture of acids like 2-Decenoic acid (DA), 10-Hydroxy 2-Decenoic acid and many others. 10-HDA possesses strong inhibition to the growth of cancer cells, namely transferable AKR leukaemia, TA3 breast cancer, etc. The equilibrium geometry of 2-Decenoic acid and its derivative 10-Hydroxy 2-Decenoic acid in the ground state have been determined and analyzed by Density functional theory (DFT) employing 6-311 G (d, p) as the basis set. The harmonic frequencies of 2-DA and 10-HDA have also been calculated to understand its complete vibrational dynamics. The study of simulated spectra provides important information about the ability of the computational method to describe the vibrational modes.

Fukui Function Analysis and Optical, Electronic, and Vibrational Properties of Tetrahydrofuran and Its Derivatives: A Complete Quantum Chemical Study

The spectroscopic, optical, and electronic properties of tetrahydrofuran and its derivatives were investigated by FTIR techniques. We have done a comparative study of tetrahydrofuran and its derivatives with B3LYP with 6-311 G (d, p) as the basis set. Here we have done a relative study of their structures, vibrational assignments, and thermal, electronic, and optical properties of ttetrahydrofuran and its derivatives. We have plotted frontier orbital HOMO-LUMO surfaces and molecular electrostatic potential surfaces to explain the reactive nature of tetrahydrofuran and its derivatives.

Vibrational Spectra of Two Narcotics-A DFT Study

This work deals with the theoretical study of the molecular structure and vibrational spectra of two well known narcotics-heroin and morphine. The spectra were interpreted with the aid of normal mode analysis following full structure optimization based on the density functional theory and the 6-311G (d, p) basis set combination. A detailed interpretation of the infrared spectra of morphine and heroin is also reported in the present work. The similarities and differences between the vibrational spectra of the two molecules studied have been highlighted. The scaled theoretical wave numbers are in perfect agreement with the experimental values. The thermodynamical calculations related to the two narcotics, namely heroi n and morphine, were also performed at the B3LYP/6-311G (d, p) theoretical level.

Isolation, Identification, Molecular and Electronic Structure, Vibrational Spectroscopic Investigation, and Anti-HIV-1 Activity of Karanjin Using Density Functional Theory

“Karanjin” (3-methoxy furano-2,3,7,8-flavone) is an anti-HIV drug, and it is particularly effective in the treatment of gastric problems. The method of isolation of “Karanjin” followed the Principles of Green Chemistry (eco-friendly and effortless method). The optimized geometry of the “Karanjin” molecule has been determined by the method of density functional theory (DFT). Using this optimized structure, we have calculated the infrared wavenumbers and compared them with the experimental data. The calculated wavenumbers are in an excellent agreement with the experimental values. On the basis of fully optimized ground-state structure, TDDFT//B3LYP/LANL2DZ calculations have been used to determine the low-lying excited states of Karanjin. Based on these results, we have discussed the correlation between the vibrational modes and the crystalline structure of “Karanjin.” A complete assignment is provided for the observed FTIR spectra. This is the first report of the isolation, molecular and electronic structure using vibrational spectroscopic investigation, density functional theory, and anti-HIV-1 activity of “Karanjin.”

Ab Initio Study of the Endohedral Fullerene PbH4@C60

The structure, electronic property and vibrational spectroscopy of the endohedral fullerene PbH4@C60 have been systematically studied by the Hartree Fock theory using 6-31 G as the basis set. In the first step, geometrical optimization of the PbH4, C60 and C60-PbH4 have been carried out. In the next step, these optimized geometries are used to calculate the inclusion energy and HOMO-LUMO gap (band gap). It is found that the PbH4 molecule is more compact when the PbH4 is seated in the center of the C60 cage, and the C60 cage may stabilize the PbH4 molecule. The formation of PbH4@C60 from the free C60 and Td PbH4 is endothermic with inclusion energy of 203.6616 kcal/mol. In addition, the IR active modes and harmonic vibrational frequencies of PbH4@C60 are also discussed.