Frontier orbital interactions in the hetero Diels–Alder cycloaddition of diazadienes

2008 ◽  
Vol 86 (5) ◽  
pp. 384-394 ◽  
Author(s):  
Pratibha Sharma ◽  
Ashok Kumar ◽  
Vinita Sahu ◽  
Jitendra Singh
Keyword(s):  
Chemical Potential ◽  
Molecular Orbital Calculation ◽  
Diels Alder ◽  
Reaction Pathways ◽  
Electronic Charge ◽  
Chemical Hardness ◽  
Frontier Orbital ◽  
Electrophilicity Index ◽  
Reactivity Pattern ◽  
Orbital Interactions

This work deals with the molecular orbital calculation studies performed on different diazadienes to assess their reactivity pattern. The interaction of these diazadienes with various electron-poor and electron-rich dienophiles leads to the formation of diazines and tetrazines as the cycloadducts. The results from frontier orbital interactions were used to rationalize the reactivity and predictability of NDAC and IEDDAC reaction pathways. Correlation studies were also performed to predict reactivity sequence using a number of electronic descriptors, such as electrophilicity index (ω), chemical potential (µ), electronic charge ΔNmax, and chemical hardness η. Moreover, these studies exhibit good compatibility with experimental observations.Key words: AM1, MNDO, PM3, diazadienes, tetrazines, electrophilicity index, chemical potential.

scholarly journals Effects of Solvent Polarity on Solvation Free Energy, Dipole Moment, Polarizability, Hyperpolarizability and Molecular Properties of Metronidazole

2016 ◽  
Vol 19 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Mohammad Firoz Khan ◽  
Ridwan Bin Rashid ◽  
Md Yeunus Mian ◽  
Mohammad S Rahman ◽  
Mohammad A Rashid
Keyword(s):  
Free Energy ◽  
Dipole Moment ◽  
Gas Phase ◽  
Chemical Potential ◽  
Solvent Polarity ◽  
Solvation Free Energy ◽  
Molecular Properties ◽  
Chemical Hardness ◽  
Electrophilicity Index ◽  
Polar Solvents

A computational study of medium effect on solvation free energy, dipole moment, polarizability, hyperpolarizability and different molecular properties like chemical hardness & softness, chemical potential, electronegativity and electrophilicity index of metronidazole have been reported in this paper. Becke, 3-parameter, Lee-Yang-Parr (B3LYP) level of theory with 6-31G (d,p) basis set was applied for gas phase and solution. The effect of solvent polarity on solvation free energy, dipole moment, polarizability, hyperpolarizability and molecular properties were calculated by employing Solvation Model on Density (SMD). The solvation free energies and dipole moment of metronidazole were found to be increased in nonpolar to polar solvents. The dipole moment of metronidazole was higher in different solvent than that of the gas phase. Moreover, from non-polar to polar solvents the chemical potential, electronegativity and electrophilicity index were increased. On the other hand, opposite relation was found in the case of chemical hardness and softness. The results obtained in this study may lead to understand the stability and reactivity of metronidazole and the results will be of assistance to use the title molecule as reaction intermediates and pharmaceuticals.Bangladesh Pharmaceutical Journal 19(1): 9-14, 2016

scholarly journals Study on the chemical potential of apigenin, luteolin, quercetin, and myricetin using the molecular modeling

2021 ◽  
Vol 44 (1) ◽  
pp. 63-66
Author(s):  
Steluta Gosav ◽  
Adriana Hodorogea ◽  
Dan Maftei
Keyword(s):  
Gas Phase ◽  
Chemical Potential ◽  
Chemical Compounds ◽  
Molecular Structures ◽  
Basis Set ◽  
Chemical Hardness ◽  
Equilibrium Geometry ◽  
Hybrid Functional ◽  
Electrophilicity Index ◽  
Quantum Molecular Descriptors

In the present paper, the chemical potential of four flavonoids i.e. apigenin, luteolin, quercetin, and myricetin, of interest in the pharmaceutical industry was investigated using molecular modelling. The equilibrium geometry of molecular structures was calculated in the gas phase and ground state by using B3LYP hybrid functional in conjunction with a 6-311G(d,p) basis set. In order to assess the chemical potential of investigated flavonoids, the main quantum molecular descriptors, such as the dipole moment, the energy of the highest/lowest occupied/unoccupied molecular orbital, the gap energy, the electronegativity, the chemical hardness/softness, and the electrophilicity index have been computed. Also, the influence of the hydroxylation degree of chemical compounds on the chemical potential is discussed.

scholarly journals Spin-Orbit Coupling Effect on the Electrophilicity Index, Chemical Potential, Hardness and Softness of Neutral Gold Clusters: A Relativistic Ab-initio Study

2021 ◽  
Vol 2 (1) ◽  
pp. 38-50
Author(s):  
Mahnaz Jabbarzadeh Sani
Keyword(s):  
Chemical Potential ◽  
Coupling Effect ◽  
Gold Clusters ◽  
Orbit Coupling ◽  
Basis Set ◽  
Structure Stability ◽  
Chemical Hardness ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Electrophilicity Index

Electrophilicity index (𝜔) is related to the energy lowering associated with a maximum amount of electron flow between a donor and an acceptor and possesses adequate information regarding structure, stability, reactivity and interactions. Chemical potential (μ) measures charge transfer from a system to another having a lower value of μ, while chemical hardness (η) is a measure of characterizing relative stability of clusters. The main purpose of the present research work is to examine the Spin-Orbit Coupling (SOC) effect on the behavior of the electrophilicity index, chemical potential, hardness and softness of neutral gold clusters Aun (n=2-6). Using the second-order Douglas-Kroll-Hess Hamiltonian, geometries are optimized at the DKH2-B3P86/DZP-DKH level of theory. Spin-orbit coupling energies are computed using the fourth-order Douglas-Kroll-Hess Hamiltonian, generalized Hartree-Fock method and all-electron relativistic double-ζ level basis set. Then, spin-orbit coupling (SOC) corrections to the electrophilicity index, chemical potential, hardness and softness are calculated. It is revealed that spin-orbit correction to the vertical chemical hardness has important effect on Au3 and Au6, i.e. SOC decreases (increases) the hardness of gold trimer (hexamer). Due to the relationship between hardness and softness, σ = , inclusion of spin-orbit coupling increases (decreases) the softness of Au3 (Au6) and thus destabilizes (stabilizes) it. Spin-orbit coupling (SOC) also has more important effect on the chemical potential of Au3 by decreasing its value. It is found that spin-orbit coupling has considerable effect on the electrophilicity index of gold trimer and greatly increases its value. Furthermore, SOC increases the maximal charge acceptance of Au3 more and thus destabilizes it more. As a result, spin-orbit coupling effect appears to be important in calculating the electrophilicity index of the gold trimer. Doi: 10.28991/HIJ-2021-02-01-05 Full Text: PDF

scholarly journals Computational Study of Geometry, Solvation Free Energy, Dipole Moment, Polarizability, Hyperpolarizability and Molecular Properties of 2-Methylimidazole

2016 ◽  
Vol 21 (2) ◽  
pp. 89
Author(s):  
Mohammad Firoz Khan ◽  
Ridwan Bin Rashid ◽  
Shahidul M. Islam ◽  
Mohammad A. Rashid
Keyword(s):  
Free Energy ◽  
Dipole Moment ◽  
Chemical Potential ◽  
Computational Study ◽  
Solvation Free Energy ◽  
Molecular Properties ◽  
Chemical Hardness ◽  
Electrophilicity Index ◽  
Reactivity Descriptors ◽  
Solvent Systems

Ab initio calculations were carried out to study the geometry, solvation free energy, dipole moment, molecular electrostatic potential (MESP), Mulliken and Natural charge distribution, polarizability, hyperpolarizability, Natural Bond Orbital (NBO) energetic and different molecular properties like global reactivity descriptors (chemical hardness, softness, chemical potential, electronegativity, electrophilicity index) of 2-methylimidazole. B3LYP/6-31G(d,p) level of theory was used to optimize the structure both in the gas phase and in solution. The solvation free energy, dipole moment and molecular properties were calculated by applying the Solvation Model on Density (SMD) in four solvent systems, namely water, dimethylsulfoxide (DMSO), n-octanol and chloroform. The computed bond distances, bond angles and dihedral angles of 2-methylimidazole agreed reasonably well with the experimental data except for C(2)-N(1), C(4)-C(5) and N(1)-H(7) bond lengths and N(1)-C(5)-C(4) bond angle. The solvation free energy, dipole moment, polarizability, first order hyperpolarizability, chemical potential, electronegativity and electrophilicity index of 2-methylimidazole increased on going from non-polar to polar solvents. Chemical hardness also increased with increasing polarity of the solvent and the opposite relation was found in the case of softness. These results provide better understanding of the stability and reactivity of 2-methylimidazole in different solvent systems.  

scholarly journals EFFECTS OF SOLVENT POLARITY ON SOLVATION FREE ENERGY, DIPOLE MOMENT, POLARIZABILITY, HYPERPOLARIZABILITY AND MOLECULAR REACTIVITY OF ASPIRIN

2017 ◽  
Vol 9 (2) ◽  
pp. 217 ◽  
Author(s):  
Mohammad Firoz Khan ◽  
Ridwan Bin Rashid ◽  
Muhammed Mahfuzur Rahman ◽  
Md. Al Faruk ◽  
Md. Mustafezur Rahman ◽  
...  
Keyword(s):  
Free Energy ◽  
Dipole Moment ◽  
Chemical Potential ◽  
Solvent Polarity ◽  
Solvation Free Energy ◽  
Molecular Properties ◽  
Chemical Hardness ◽  
Electrophilicity Index ◽  
First Order ◽  
Solvent Systems

<p><strong>Objective: </strong>The aim of the study is to explore the effects of solvent polarity on solvation free energy, dipole moment, polarizability, first order hyperpolarizability and different molecular properties like chemical hardness and softness, chemical potential, electronegativity, electrophilicity index of aspirin which may lead to better understand the reactivity and stability of aspirin in different solvent systems.</p><p><strong>Methods: </strong>Becke, 3-parameter, Lee-Yang-Parr (B3LYP) level of theory with 6-31G(d,p) basis set was employed to conduct all type of calculations for both in the gas phase and in solution. The solvation free energy, dipole moment and molecular properties were calculated by applying the Solvation Model on Density (SMD) in four solvent systems namely water, methanol, ethanol and <em>n</em>-octanol.</p><p><strong>Results: </strong>The solvation energies steadily increased as the dielectric constant was decreased i.e. free energy increases with decreasing polarity of the solvent. The dipole moment of aspirin was found to be increased when going from non-polar to polar solvents. The dipole moment of aspirin was higher in different solvents than that of the gas phase. The polarizability and first order hyperpolarizability were also increased with the increasing dielectric constant of the solvent. Moreover, ongoing from non-polar to polar solvent the chemical potential, electronegativity and electrophilicity index were increased except in <em>n</em>-octanol. The chemical potential, electronegativity and electrophilicity index of aspirin in <em>n</em>-octanol was higher than that of ethanol. On the other hand, chemical hardness was increased with decreasing polarity of the solvent and the inverse relation was found in the case of softness.</p><p><strong>Conclusion: </strong>The calculated solvation free energy, dipole moment, polarizability, first order hyperpolarizability and molecular properties found in this study may lead to the understanding of stability and reactivity of aspirin in different solvent systems.</p>

HETEROATOM EFFECTS ON THE TRIAFLUAVENE AND HEAVIER ANALOGUES, XC5H4 AND XC5H3 (X = C, Si, Ge, N, P, AND As): DFT CALCULATIONS

2011 ◽  
Vol 10 (06) ◽  
pp. 769-788 ◽  
Author(s):  
ESMAIL VESSALLY ◽  
SAMANEH FATEH BASHARZAD ◽  
MARYAM MOTALLEBZADEH ◽  
LADAN EDJLALI
Keyword(s):  
Dft Calculations ◽  
Chemical Potential ◽  
Electronic Charge ◽  
Chemical Hardness ◽  
Geometrical Parameters ◽  
Aromatic Character ◽  
Gibbs Energies ◽  
Nics Calculations ◽  
Homo And Lumo

DFT calculations were carried out on molecular structure of triafluavenes and their heavier analogues, X C 5 H 4 and X C 5 H 3; 1X and 2X (X = C , Si , Ge , N , P , and As ); by using B3LYP/6-311++G** and MP2/6-311++G** //B3LYP/6-311++G** levels of theory with the Gaussian 03 program. The thermal energies (E), enthalpies (H), and free Gibbs energies (G) of 1X and 2X were calculated. The geometrical parameters, natural bonding orbital charge at atoms HOMO and LUMO, the chemical hardness (η), chemical potential (μ), electrophilicity (ω), and the maximum amount of electronic charge, ΔN max , were obtained. The NICS calculations were preformed for both rings of 1X as well as 2X due to determination of the aromatic character of each rings. Molecular electrostatic potential maps were plotted and the infrared and ultraviolet spectra were calculated for 1X and 2X.

scholarly journals Computational Study of Solvation Free Energy, Dipole Moment, Polarizability, Hyperpolarizability and Molecular Properties of Betulin, a Constituent of Corypha taliera (Roxb.)

2017 ◽  
Vol 16 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Mohammad Firoz Khan ◽  
Ridwan Bin Rashid ◽  
Md Aslam Hossain ◽  
Mohammad A Rashid
Keyword(s):  
Free Energy ◽  
Dipole Moment ◽  
Electrostatic Potential ◽  
Molecular Electrostatic Potential ◽  
Chemical Potential ◽  
Solvation Free Energy ◽  
Molecular Properties ◽  
Mulliken Charge ◽  
Chemical Hardness ◽  
Electrophilicity Index

Ab initio calculations were carried out to studysolvation free energy, dipole moment, molecular electrostatic potential (MESP), Mulliken charge distribution, polarizability, hyperpolarizability and different molecular properties like global reactivity descriptors (chemical hardness, softness, chemical potential, electronegativity, electrophilicity index) of betulin. B3LYP/6-31G(d,p) level of theory was used to optimize the structure both in gas phase and in solution. The solvation free energy, dipole moment and molecular properties were calculated by applying the Solvation Model on Density (SMD) in six solvent systems namely water, dimethyl sulfoxide (DMSO), acetonitrile, n-octanol, chloroform and carbontetrachloride. The solvation free energy of betulin increases with decreasing polarity of the solvent. No systematic trend of hyperpolarizability with solvent polarity is found. Molecular electrostatic potential (MESP) and Mulliken population analysis (MPA) reveal that the most possible sites for nucleophilic attack are C30, H76 and H77 and electrophilic attack are O1 and O2 among the atoms in betulin. However, the dipole moment, polarizability, chemical potential, electronegativity and electrophilicity index of betulin increase on going from non-polar to polar solvents. Chemical hardness was also increased with decreasing polarity of the solvent and opposite relation was found in the case of softness. These results provide better understanding of the stability and reactivity of betulin in different solvent systems.Dhaka Univ. J. Pharm. Sci. 16(1): 1-9, 2017 (June)

Characteristics of the Two Frontier Orbital Interactions in the Diels−Alder Cycloaddition

2004 ◽  
Vol 69 (3) ◽  
pp. 757-764 ◽  
Author(s):  
Claude Spino ◽  
Hadi Rezaei ◽  
Yves L. Dory
Keyword(s):  
Diels Alder ◽  
Frontier Orbital ◽  
Orbital Interactions
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