scholarly journals Structural Preferences and Vibrational Analysis of 2-Hydroxy-2-methyl-1-phenylpropan-1-one: A Computational and Infrared Spectroscopic Research

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
O. Belaidi ◽  
T. Bouchaour ◽  
U. Maschke
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Energy Gap ◽  
Density Functional Theory Calculation ◽  
Vibrational Analysis ◽  
Molecular Geometry ◽  
Basis Set ◽  
Potential Energy Distribution ◽  
Stable Conformation

The Fourier transform infrared (FTIR) spectrum of 2-hydroxy-2-methyl-1-phenylpropan-1-one has been measured in the region 4000–700 . The most stable conformation of title molecule was found after a careful potential energy surfaces study. The molecular geometry, vibrational frequencies, and infrared intensities have been calculated by using ab initio HF and density functional theory calculation B3LYP with 6-311+ basis set. Scaled frequencies and potential energy distribution were calculated for band assignment. We found an excellent agreement between the experimental and the simulated spectra. Energy gap between HOMO and LUMO explains the eventual charge transfer interactions taking place within the molecule.

scholarly journals Molecular Structure, Homo-Lumo and Vibrational Analysis Of Ergoline By Density Functional Theory

2021 ◽  
Vol 14 (14) ◽  
pp. 21-30
Author(s):  
Bhawani Datt Joshi ◽  
Ghanshyam Thakur ◽  
Manoj Kumar Chaudhary
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical ◽  
Density Functional ◽  
Graphical Representation ◽  
Energy Gap ◽  
Quantum Chemical Study ◽  
Vibrational Analysis ◽  
Basis Set ◽  
Potential Energy Distribution ◽  
Functional Theory

In this work, quantum chemical study on a natural product ergoline has been presented using density functional theory (DFT) employing 6-311++G(d,p) basis set. A complete vibrational assignment has been performed for the theoretical FT-IR and Raman wavenumbers along with the potential energy distribution (PED) with the result of quantum chemical calculations. The structure–activity relationship has been interpreted by mapping electrostatic potential surface (MEP). Graphical representation of frontier molecular orbitals with their energy gap have been analyzed theoretically for both the gaseous and solvent environment employing time dependent density functional theory (TDDFT) employing 6-31G basis set.

Potential Energy Surface Calculations of Alanine Dipeptide using BVWN Density Functional Approach and 6-311G Basis Set

2009 ◽  
Vol 1219 ◽  
Author(s):  
Jyoti Singh ◽  
Subhash Chandra Singh ◽  
Narsingh Bahadur Singh
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Basis Set ◽  
Reaction Coordinates ◽  
Conformational Properties ◽  
Energy Surfaces ◽  
Polypeptide Chains ◽  
Alanine Dipeptide

AbstractThis work is devoted to a study of the conformational properties of alanine dipeptide. We have studied potential energy surfaces of alanine dipeptide molecule using density functional theoretical approach with 6-311G basis set. For this purpose potential energies of this molecule are calculated as a function of Ramachandran angles φ and ψ, which are important factors for the characterizations of polypeptide chains. These degrees of freedoms φ and ψ are important for the characterization of protein folding systems. Stable conformations, energy barriers and reaction coordinates of this important dipeptide molecule are calculated. Energy required for the transition of one conformation into other are also discussed.

scholarly journals Structural and Vibrational Studies (FT-IR, FT-Raman) of Voglibose Using DFT Calculation

2016 ◽  
Vol 64 ◽  
pp. 45-62 ◽  
Author(s):  
R. Solaichamy ◽  
J. Karpagam
Keyword(s):  
Charge Transfer ◽  
Density Functional ◽  
Energy Gap ◽  
Chemical Shifts ◽  
Nbo Analysis ◽  
Biological Properties ◽  
Basis Set ◽  
Potential Energy Distribution ◽  
Charge Delocalization ◽  
Ft Raman

In the present study, we report on the Molecular structure and infrared (IR) and FT-Raman studies of Voglibose (VGB) as well as by calculations based on the density functional theory (DFT) approach; utilizing B3LYP/6-31G(d,p) basis set. The targeted interpretation of the vibrational spectra intended to the basis of calculated potential energy distribution matrix (PED) utilizing VEDA4 program. Stability of the molecule arising from hyperconjugative interactions and charge delocalization was studied using natural bond orbital (NBO) analysis. The results show that change in electron density in the σ∗and π∗antibonding orbitals and E2energies confirm the occurrence of intramolecular charge transfer within the molecule. The UV-Visible and NMR spectral analysis were reported by using TD-DFT and gauge GIAO approach respectively and their chemical shifts related to TMS were compared. The lowering of HOMO and LUMO energy gap appears to be the cause for its enhanced charge transfer interactions. Besides, molecular electrostatic potential (MEP) analysis was reported. Due to different potent biological properties, the molecular docking results are also reported.

scholarly journals Comprehensive spectroscopic (FT-IR, FT-Raman, 1H and 13C NMR) identification and computational studies on 1-acetyl-1H-indole-2,3-dione

2017 ◽  
Vol 15 (1) ◽  
pp. 225-237 ◽  
Author(s):  
Maha S. Almutairi ◽  
S. Muthu ◽  
Johanan C. Prasana ◽  
B. Chandralekha ◽  
Alwah R. Al-Ghamdi ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Density Functional ◽  
Energy Gap ◽  
Solid Phase ◽  
Atomic Orbital ◽  
Basis Set ◽  
Potential Energy Distribution ◽  
Charge Delocalization ◽  
Ft Ir ◽  
Ft Raman

AbstractFourier transform infrared (FT-IR) and FT-Raman spectra of 1-acetyl-1H-indole-2,3-dione (N-acetylisatin) were recorded in the solid phase and analyzed. The molecular geometry, vibrational frequencies, infrared intensities, Raman activities and atomic charges were calculated using density functional theory (DFT/B3LYP) calculations with a standard 6-311++G(d,p) basis set. The fundamental vibrational modes of N-acetylisatin were analyzed and fully assigned with the aid of the recorded FT-IR and FT-Raman spectra. The simulated FT-IR and FT-Raman spectra showed good agreement with the experimental spectra. The stability of the molecule, arising from hyper-conjugative interactions and charge delocalization, was analyzed using natural bond orbital (NBO) analysis. The dipole moment (µ), polarization (α) and hyperpolarization (β) values of N-acetylisatin were also computed. The potential energy distribution (PED) was computed for the assignment of unambiguous vibrational fundamental modes. The HOMO and LUMO energy gap illustrated the chemical activity of N-acetylisatin. The energy and oscillator strength were calculated by DFT. Gauge–including atomic orbital NMR (1H and 13C) chemical shift calculations were performed and compared with the experimental values. Thermodynamic properties (heat capacity, entropy and enthalpy) of the compound at different temperatures were also calculated.

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

2009 ◽  
Vol 08 (03) ◽  
pp. 433-450 ◽  
Author(s):  
SHAMOON AHMAD SIDDIQUI ◽  
APOORVA DWIVEDI ◽  
P. K. SINGH ◽  
TANVEER HASAN ◽  
SUDHA JAIN ◽  
...  
Keyword(s):  
Potential Energy ◽  
Energy Distribution ◽  
Density Functional ◽  
Basis Set ◽  
Potential Energy Distribution ◽  
Neurotransmitter Receptors ◽  
Equilibrium Geometry ◽  
Perfect Agreement ◽  
Dopamine Hydrochloride ◽  
Detailed Interpretation

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.

scholarly journals Structure, MESP and HOMO-LUMO study of 10-Acetyl- 10H-phenothiazine 5-oxide using vibrational spectroscopy and quantum chemical methods

BIBECHANA ◽  
2012 ◽  
Vol 9 ◽  
pp. 38-49
Author(s):  
Bhawani Datt Joshi ◽  
Poonam Tandon ◽  
Sudha Jain
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Geometry Optimization ◽  
Basis Set ◽  
Orbital Energy ◽  
Potential Energy Distribution ◽  
Hartree Fock ◽  
Quantum Chemical Methods ◽  
B3lyp Method

In this communication, we have presented the geometry optimization, complete vibrational study with potential energy distribution (PED) and frontier orbital energy gap for the 10-Acetyl-10H-phenothiazine 5-oxide (APTZ) molecule using ab initio Hartree-Fock (HF) and density functional theory (DFT/B3LYP) method employing 6-311++G(d,p) basis set. The calculated IR and Raman spectra with their intensities, molecular electrostatic potential (MESP) surface and highest occupied molecular orbital (HOMO) - lowest unoccupied molecular orbital (LUMO) plot have been given. DOI: http://dx.doi.org/10.3126/bibechana.v9i0.7151 BIBECHANA 9 (2013) 38-49

scholarly journals Synthesis, Characterization and Theoretical Studies of New Organotellurium Compounds Based on (4-(((1S,E)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene)amino)phenyl)mercury(II) Chloride

2021 ◽  
Vol 21 (6) ◽  
pp. 1443
Author(s):  
Nuha Hussain Al-Saadawy
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Condensation Reaction ◽  
Geometry Optimization ◽  
Molecular Geometry ◽  
Basis Set ◽  
Chemical Structures ◽  
Lower Case ◽  
Donor And Acceptor ◽  
Organotellurium Compounds

The current study aimed to prepare new organomercury and organotellurium compounds based on the condensation reaction of 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one (camphor) and p-aminophenyl mercuric(II) chloride. All the prepared compounds were characterized using different methods such as infrared spectrum, nuclear magnetic resonance, and CHN analysis. The analysis results concurred with the suggested chemical structures of the prepared compounds. Density functional theory has been applied with the basis set 3-21G to investigate the molecular structure of the prepared organotellurium compounds. Geometrical structure, HOMO surfaces, LUMO surfaces, and energy gap have been produced throughout the geometry optimization. The molecular geometry and contours for organotellurium compounds have been investigated throughout the geometrical optimization. Also, the donor and acceptor have been studied by comparing the HOMO energies of the prepared organotellurium compounds. Finally, the electronegativity, electrophilicity, ionization potential, electron affinity, and lower case of organotellurium compounds have been calculated and discussed.

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.

Spectroscopic investigations and DFT studies of synthesized 4-acetamidophenyl 3,4,5-trimethoxybenzoate and 4-acetyl phenyl 3,4,5-trimethoxybenzoate a novel conjugate of gallic acid

2020 ◽  
Vol 17 ◽  
Author(s):  
Sangeeta Srivastava ◽  
Nadeem Ahmad Ansari ◽  
Sadaf Aleem
Keyword(s):  
Gallic Acid ◽  
Density Functional ◽  
Energy Gap ◽  
Basis Set ◽  
Major Constituent ◽  
Orbital Energy ◽  
Reactivity Descriptors ◽  
Homo And Lumo ◽  
Electrophilic Reactivity ◽  
Global And Local

: Gallic acid is abundantly found in amla (Phyllanthus emblica), a deciduous of the family phyllanthaceae. Gallic acid, the major constituent of the plant was methylated to 3,4,5 trimethoxy gallic acid, which then underwent steglich esterification first with paracetamol and then with 4-hydroxy acetophenone to yield 4-acetamidophenyl 3,4,5-trimethoxybenzoate and 4-acetyl phenyl 3,4,5-trimethoxybenzoate “respectively”. 1H NMR, 13C NMR, UV, FT-IR and mass spectroscopy were used to characterize the synthesized compounds. Density functional theory (B3YLP) using 6-31G (d,p) basis set have been used for quantum chemical calculations. AIM (Atom in molecule) approach depicted weak molecular interactions within the molecules whereas the reactive site and reactivity within the molecule were examined by global and local reactivity descriptors. The HOMO and LUMO energies and frontier orbital energy gap were calculated by time dependant DFT approach using IEFPCM model. Small value for HOMO–LUMO energy gap indicated that easier charge transfer occurs within compound 4. The nucleophilic and electrophilic reactivity were determined by MEP (molecular electrostatic potential) experiment. Polarizability, dipole moment, and first hyperpolarizability values were calculated to depict the NLO (nonlinear optical) property of both the synthesized compounds. The antimicrobial activity was also carried out and broad spectrum antibacterial activity against several strains of bacteria and certain unicellular fungi were exhibited by synthesized compound 3.

THE H2NO POTENTIAL ENERGY SURFACE EXPLORED WITH HIGH LEVEL AB INITIO AND DENSITY FUNCTIONAL THEORY METHODS

2007 ◽  
Vol 06 (03) ◽  
pp. 549-562
Author(s):  
ABRAHAM F. JALBOUT
Keyword(s):  
Density Functional Theory ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Density Functional ◽  
Energy Surface ◽  
Hybrid Methods ◽  
Transition States ◽  
Basis Set ◽  
Functional Theory ◽  
High Level

The transition states for the H 2 NO decomposition and rearrangements mechanisms have been explored by the CBS-Q method or by density functional theory. Six transition states were located on the potential energy surface, which were explored with the Quadratic Complete Basis Set (CBS-Q) and Becke's one-parameter density functional hybrid methods. Interesting deviations between the CBS-Q results and the B1LYP density functional theory lead us to believe that further study into this system is necessary. In the efforts to further assess the stabilities of the transition states, bond order calculations were performed to measure the strength of the bonds in the transition state.

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