scholarly journals Structure Conformation, Vibrational Properties, NLO Activity, HOMO-LUMO and Thermodynamic Parameters of Dinicotinic Acid Using Experimental and Theoretical Approach

2021 ◽  
Vol 12 (3) ◽  
pp. 2752-2761
Keyword(s):  
Thermodynamic Parameters ◽  
Zero Order ◽  
Least Square ◽  
Geometrical Parameters ◽  
Vibrational Modes ◽  
Force Field Calculations ◽  
Valence Force Field ◽  
Fundamental Frequencies ◽  
Homo Lumo ◽  
Ft Raman

In the present study, the Dinicotinic acid was characterized by FTIR and FT-Raman spectra in the range of 4000-450 and 4000-50 cm-1. The most stable molecular structure and optimized geometrical parameters are calculated using DFT studies. Normal Co-ordinate Analysis (NCA) was studied out by solving Inverse Vibrational Problem using 74-valence force field calculations using overlay least square technique. It reproduces into 35 fundamental frequencies with an rms error of 9.28 cm-1 in the zero-order calculations. Based on PED, vibrational modes are assigned for this molecule. The energy of HOMO & LUMO, NLO parameters, and thermodynamic parameters were computed.

Structural, vibrational (FTIR and FT-Raman), NMR, UV–vis spectral analysis, and DFT study of 2-(6-oxo-2-thioxotetrahydropyrimidin-4(1H)-ylidene) hydrazine carboxamide

2017 ◽  
Vol 95 (5) ◽  
pp. 580-589 ◽  
Author(s):  
N. Kalaiarasi ◽  
S. Manivarman
Keyword(s):  
Density Functional ◽  
Nbo Analysis ◽  
Basis Set ◽  
Geometrical Parameters ◽  
Mulliken Population ◽  
Functional Theory ◽  
Charge Delocalization ◽  
Homo Lumo ◽  
Spectral Characterizations ◽  
Ft Raman

Vibrational and spectral characterizations of 2-(6-oxo-2-thioxo tetrahydro pyrimidin-4(1h)-ylidene) hydrazine carboxamide (OTHHPYHC) were experimentally presented for the ground state using FTIR and FT-Raman and theoretically presented by density functional theory (DFT) using B3LYP correlation function with the basis set 6-31G(d,p). The geometrical parameters, energies, and wavenumbers have been obtained. The fundamental assignments were performed on the basis of total energy distribution. The first order hyperpolarizability (β0) and relative properties (β, α0, and Δα) were calculated using B3LYP/6-31G(d, p) method. Solidity of the molecule due to hyperconjugative interactions and charge delocalization has been analysed using natural bond orbital (NBO) analysis. The charge distribution and electron transfer from bonding to antibonding orbitals and electron density in the σ* and π* antibonding orbitals confirms interaction within the molecule. In addition to this, Mulliken population and HOMO–LUMO analysis have been used to support the information of structural properties.

Valence Force Constants and Normal Vibrations of Methanol

1970 ◽  
Vol 25 (11) ◽  
pp. 1729-1731 ◽  
Author(s):  
A. Timidei ◽  
G. Zerbi
Keyword(s):  
Force Field ◽  
Molecular Spectroscopy ◽  
Harmonic Approximation ◽  
Force Constants ◽  
Least Square ◽  
Vibrational Modes ◽  
Normal Vibrations ◽  
Valence Force ◽  
Valence Force Field

Abstract The possibility of reproducing the normal vibrations of methanol, CH3OH, and its deutero-derivatives CH3OD, CD3OH, CD3OD using a valence force field has been critically analyzed. A 13 parameter valence force field has been determined by least square calculations. The meaning of the obtained numbers and their validity in molecular spectroscopy are discussed and compared with the information already available in the literature. It is concluded that the vibrational modes of this molecule are fairly well known within the harmonic approximation.

Density functional theory, Comparative vibrational spectroscopic studies, HOMO-LUMO, and NBO analysis of Trichloro isocyanuric acid and Trithio cyanuric acid

2015 ◽  
Vol 8 (3) ◽  
pp. 2197-2221
Author(s):  
Theraviyum Chithambarathanu ◽  
M. Darathi ◽  
J. DaisyMagdaline ◽  
S. Gunasekaran
Keyword(s):  
Density Functional ◽  
Cyanuric Acid ◽  
Nbo Analysis ◽  
Basis Set ◽  
Potential Energy Distribution ◽  
Point Energy ◽  
Isocyanuric Acid ◽  
Ft Ir ◽  
Homo Lumo ◽  
Ft Raman

The molecular vibrations of Trichloro isocyanuric acid (C3Cl3N3O3) and Trithio cyanuric acid (C3H3N3S3) have been investigated in polycrystalline sample at room temperature by Fourier Transform Infrared (FT-IR) and FT-Raman spectroscopies in the region 4000-450 cm-1 and 4000-50 cm-1 respectively, which provide a wealth of structural information about the molecules. The spectra are interpreted with the aid of normal co-ordinate analysis following full structure optimization and force field calculations based on density functional theory   (DFT) using standard B3LYP / 6-311++ G (d, p) basis set for investigating the structural and spectroscopic properties. The vibrational frequencies are calculated and the scaled values are compared with experimental FT-IR and FT-Raman spectra. The scaled theoretical wave numbers shows very good agreement with experimental ones. The complete vibrational assignments are performed on the basis of potential energy distribution (PED) of vibrational modes, calculated with scaled quantum (SQM) method. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that change in electron density (ED) in σ* and π* anti-bonding orbitals and second order delocalization   energy (E2) confirm the occurrence of Intra molecular Charge Transfer (ICT) within the molecule. The thermodynamic properties like heat capacity, entropy, enthalpy and zero point energy have been calculated for the molecule. The frontier molecular orbitals have been visualized and the HOMO-LUMO energy gap has been calculated. The Molecular Electrostatic Potential (MEP) analysis reveals the sites for electrophilic attack and nucleophilic reactions in the molecule.

Complex formation and kinematic coupling: C2H4.PtCl3

1988 ◽  
Vol 53 (10) ◽  
pp. 2377-2384 ◽  
Author(s):  
Roman Řeřicha ◽  
Björg N. Cyvin ◽  
Jon Brunvoll ◽  
Sven J. Cyvin
Keyword(s):  
Complex Formation ◽  
Crystallographic Data ◽  
System Modelling ◽  
Vibrational Modes ◽  
Normal Coordinate ◽  
Kinematic Coupling ◽  
Fundamental Frequencies

Normal coordinate analyses including calculations of PED's were performed for C2H4.PtCl3 system modelling Zeise's anion, [(C2H4)PtCl3]-. The wedgewise distorsion of the C2H4 ligand known from the crystallographic data for Zeise's salt, was taken into account. Under these circumstances it was found that the kinematic couplings between the internal ligand and complex framework vibrational modes are rather small. The reliability of some existing assignments of the fundamental frequencies of Zeise's anion is discussed.

A Theoretical Study of Substituted Stepwise Fluorinated Cyclopropanone Keto-Enol System

2003 ◽  
Vol 58 (12) ◽  
pp. 749-755
Author(s):  
Abdullah El-Alali ◽  
Ali A. Marashdeh ◽  
Salim M. Khalil
Keyword(s):  
Theoretical Study ◽  
Dipole Moments ◽  
Heats Of Formation ◽  
Geometrical Parameters ◽  
Free Energies ◽  
Isodesmic Reactions ◽  
Orbital Energies ◽  
Substantial Concentration ◽  
Homo Lumo ◽  
Complete Optimization

MINDO-Forces calculations have been performed with complete optimization of the geometries on stepwise fluorinated cyclopropanones and their enols. Increase in the number of fluorine atoms causes destabilization of cyclopropanone. Perfluorinated enol was found to be present in substantial concentration, as was mentioned in previous work. This is supported by calculations of Gibbs free energies and isodesmic reactions. Geometrical parameters, heats of formation, electron densities, dipole moments and orbital energies (HOMO-LUMO) are reported.

scholarly journals Computational and Spectral Discussion of Some Substituted Chalcone Derivatives

2021 ◽  
Vol 12 (6) ◽  
pp. 7159-7176
Keyword(s):  
Geometry Optimization ◽  
Spectroscopic Characterization ◽  
Diffusion Method ◽  
Geometrical Parameters ◽  
1H And 13C Nmr ◽  
Chalcone Derivatives ◽  
Ft Ir ◽  
Experimental Values ◽  
Antibacterial And Antifungal ◽  
Homo Lumo

The substituted chalcone derivatives 1–7 have been synthesized, and spectroscopic characterization were done as done using the experimental FT-IR, UV-Vis, GC-MS, 1D NMR spectroscopy. The favored conformation of substituted chalcone 3 was predicted theoretically by geometry optimization structure selected geometrical parameters and molecular properties such as NBO, AIM, HOMO-LUMO, MEP surface, and atomic charges were derived from optimized structures. The 1H and 13C NMR spectral data had been additionally computed using the Gaussian-09 package and compared with the experimental values. The antibacterial and antifungal activity was derived by the disc diffusion method.

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