scholarly journals Geometries, Reactivity and Binding Energy of Urea on Mg9O9

2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Antonio Luiz Almeida ◽  
João Batista Lopes Martins
Keyword(s):  
Binding Energy ◽  
Gas Phase ◽  
Chemical Potential ◽  
Function Analysis ◽  
Binding Energies ◽  
Chemical Hardness ◽  
Atomic Charges ◽  
Quantum Chemical Descriptors ◽  
Site Selectivity ◽  
Global And Local

In this paper we present global and local reactivity results of the urea gas phase molecule and gas phase (MgO)18 agglomerated for understand charge distribution and binding energy (MgO)-UREA. We analyze the quantum chemical descriptors, ionization potential (I), electron affinity (A), chemical hardness (ɳ), chemical potential (μ) and Global Philicity Index (ω) and site reactivity or site selectivity condensed Fukui function analysis of the distribution of atomic charges investigated with  methods of Mulliken, Merz-Kolman and Natural Atomic Charges. For instance, the binding energies of MgO-Urea systems are.

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

X-Ray photoelectron spectroscopy of monosubstituted perfluorobenzenes

1977 ◽  
Vol 55 (8) ◽  
pp. 1279-1284 ◽  
Author(s):  
Barry C. Trudell ◽  
S. James W. Price
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Atomic Charges ◽  
X Ray ◽  
Sophisticated Analysis ◽  
Charge Calculations

The gas phase X-ray photoelectron spectra, XPS, were observed for the series C6F5X (X = F, Cl, I, Br, H). Binding energies were determined from the spectra using the ESCAPLOT Program. Charge calculations were carried out using Equalization of Electronegativity, CNDO/2, and ACHARGE approaches on each molecule. The more sophisticated analysis leads to the following equation correlating the (C 1s) binding energies and the atomic charges qi[Formula: see text]

Probing Intramolecular Interaction of Stereoisomers Using Computational Spectroscopy

2020 ◽  
Vol 73 (8) ◽  
pp. 813
Author(s):  
Feng Wang ◽  
Shawkat Islam ◽  
Frederick Backler
Keyword(s):  
Hydrogen Bonding ◽  
Binding Energy ◽  
Gas Phase ◽  
Intramolecular Interaction ◽  
Dipole Moments ◽  
Energy Difference ◽  
Binding Energies ◽  
Intramolecular Interactions ◽  
Computational Spectroscopy ◽  
Ionic States

Several model stereoisomers such as ferrocene (Fc), methoxyphenol, and furfural conformers are discussed. It was discovered that the Fc IR spectroscopic band(s) below 500cm−1 serve as fingerprints for eclipsed (splitting 17 (471–488)cm−1) and staggered Fc (splitting is ~2 (459–461)cm−1) in the gas phase. It is revealed that in the gas phase the dominance of the eclipsed Fc (D5h) at very low temperatures changes to a mixture of both eclipsed and staggered Fc when the temperature increases. However, in solvents such as CCl4, eclipsed Fc dominates at room temperature (300K) due to the additional solvation energy. Intramolecular interactions of organic model compounds such as methoxyphenols (guaiacol (GUA) and mequinol (MEQ)) and furfural, ionization energies such as the carbon 1s (core C1s), as well as valence binding energy spectra serve this purpose well. Hydrogen bonding alters the C1s binding energies of the methoxy carbon (C(7)) of anti-syn and anti-gauche conformers of GUA to 292.65 and 291.91eV, respectively. The trans and cis MEQ conformers, on the other hand, are nearly energy degenerate, whereas their dipole moments are significantly different: 2.66 Debye for cis and 0.63 Debye for trans-MEQ. Moreover, it is found that rotation around the Cring–OH and the Cring–OCH3 bonds differ in energy barrier height by ~0.50 kcal⋅mol−1. The Dyson orbital momentum profiles of the most different ionic states, 25a′ (0.35eV) and 3a′ (−0.33eV), between cis and trans-MEQ in outer valence space (which is measurable using electron momentum spectroscopy (EMS)), exhibit quantitative differences. Finally, the molecular switch from trans and cis-furfural engages with a small energy difference of 0.74 kcal mol−1, however, at the calculated C(3)(–H⋅⋅⋅O=C) site the C1s binding energy difference is 0.105eV (2.42 kcal mol−1) and the NMR chemical shift of the same carbon site is also significant; 7.58ppm from cis-furfural without hydrogen bonding.

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.

An ESCA Investigation of some Halogeno(methyl)-Silane and -Germane Series

1975 ◽  
Vol 53 (23) ◽  
pp. 3602-3612 ◽  
Author(s):  
John E. Drake ◽  
Chris Riddle ◽  
L. Coatsworth
Keyword(s):  
Binding Energy ◽  
Chemical Shifts ◽  
Binding Energies ◽  
Core Level ◽  
Atomic Charges ◽  
Electronegativity Equalization

Core-level binding energies of all atoms are reported for two series of compounds; MenMCl4−n and Me3MX (n = 0 → 4, M = Si or Ge, X = F, Cl, Br, I and (for M = Ge) CN, N3, and NCS ). Binding energy shifts are discussed using a 'whole-molecule' approach and are correlated with estimated atomic charges derived from an electronegativity-equalization procedure. Carbon 1s binding energies are also correlated to 13C n.m.r. chemical shifts.

scholarly journals Segregation effect and N2 binding energy reduction in CO-N2 systems adsorbed on water ice substrates

2018 ◽  
Vol 619 ◽  
pp. A111 ◽  
Author(s):  
T. Nguyen ◽  
S. Baouche ◽  
E. Congiu ◽  
S. Diana ◽  
L. Pagani ◽  
...  
Keyword(s):  
Binding Energy ◽  
Gas Phase ◽  
Adsorption Energy ◽  
High Vacuum ◽  
Amorphous Solid ◽  
Abundant Species ◽  
Binding Energies ◽  
Ultra High Vacuum ◽  
Pure Species ◽  
Water Ice

Context. CO and N2 are two abundant species in molecular clouds. CO molecules are heavily depleted from the gas phase towards the centre of pre-stellar cores, whereas N2 maintains a high gas phase abundance. For example, in the molecular cloud L183, CO is depleted by a factor of ≈400 in its centre with respect to the outer regions of the cloud, whereas N2 is only depleted by a factor of ≈20. The reason for this difference is not yet clear, since CO and N2 have identical masses, similar sticking properties, and a relatively close energy of adsorption. Aims. We present a study of the CO-N2 system in sub-monolayer regimes, with the aim to measure, analyse and elucidate how the adsorption energy of the two species varies with coverage, with much attention to the case where CO is more abundant than N2. Methods. Experiments were carried out using the ultra-high vacuum (UHV) set-up called VENUS. Sub-monolayers of either pure 13CO or pure 15N2 and 13CO:15N2 mixtures were deposited on compact amorphous solid water ice, and crystalline water ice. Temperature-programmed desorption experiments, monitored by mass spectrometry, are used to analyse the distributions of binding energies of 13CO and 15N2 when adsorbed together in different proportions. Results. The distribution of binding energies of pure species varies from 990 K to 1630 K for 13CO, and from 890 K to 1430 K for 15N2. When a CO:N2 mixture is deposited, the 15N2 binding energy distribution is strongly affected by the presence of 13CO, whereas the adsorption energy of CO is unaltered. Conclusions. Whatever types of water ice substrate we used, the N2 effective binding energy was significantly lowered by the presence of CO molecules. We discuss the possible impact of this finding in the context of pre-stellar cores.

scholarly journals Global chemical reactivity parameters for several chiral beta-blockers from Density Functional Theory Viewpoint

2016 ◽  
Vol 89 (4) ◽  
pp. 513-518 ◽  
Author(s):  
Mona Maria Talmaciu ◽  
Ede Bodoki ◽  
Radu Oprean
Keyword(s):  
Quantum Chemical ◽  
Density Functional ◽  
Chemical Potential ◽  
Chemical Reactivity ◽  
Beta Blockers ◽  
Chemical Hardness ◽  
Quantum Chemical Descriptors ◽  
Chemical Structures ◽  
Coronary Syndrome ◽  
Chemical Descriptors

Background and aim.  Beta-adrenergic antagonists have been established as first line treatment in the medical management of hypertension, acute coronary syndrome and other cardiovascular diseases, as well as for the prevention of initial episodes of gastrointestinal bleeding in patients with cirrhosis and esophageal varices, glaucoma, and have recently become the main form of treatment of infantile hemangiomas.The aim of the present study is to calculate for 14 beta-blockers several quantum chemical descriptors in order to interpret various molecular properties such as electronic structure, conformation, reactivity, in the interest of determining how such descriptors could have an impact on our understanding of the experimental observations and describing various aspects of chemical binding of beta-blockers in terms of these descriptors.Methods. The 2D chemical structures of the beta-blockers (14 molecules with one stereogenic center) were cleaned in 3D, their geometry was preoptimized using the software MOPAC2012, by PM6 method, and then further refined using standard settings in MOE; HOMO and LUMO descriptors were calculated using semi-empirical molecular orbital methods AM1, MNDO and PM3, for the lowest energy conformers and the quantum chemical descriptors (HLG, electronegativity, chemical potential, hardness and softness, electrophilicity) were then calculated.Results. According to HOMO-LUMO gap and the chemical hardness the most stable compounds are alprenolol, bisoprolol and esmolol. The softness values calculated for the study molecules revolve around 0.100. Propranolol, sotalol and timolol have among the highest electrophilicity index of the studied beta-blocker molecules. Results obtained from calculations showed that acebutolol, atenolol, timolol and sotalol have the highest values for the electronegativity index. Conclusions. The future aim is to determine whether it is possible to find a valid correlation between these descriptors and the physicochemical behavior of the molecules from this class. The HLG could be correlated to the experimentally recorded electrochemical properties of the molecules. HOMO could be correlated to the observed oxidation potential, since the required voltage is related to the energy of the HOMO, because only the electron from this orbital is involved in the oxidation process.

X-ray photoelectron spectra of C6F5X compounds (X = CH3, CF3, CN, CHO, OH, OCH3, NH2, NO2)

1978 ◽  
Vol 56 (4) ◽  
pp. 538-542 ◽  
Author(s):  
Barry C. Trudell ◽  
S. James W. Price
Keyword(s):  
Gas Phase ◽  
Curve Fitting ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Atomic Charges ◽  
X Ray ◽  
Wide Range ◽  
Charge Calculations

The gas phase photoelectron spectra, XPS, were observed for the series C6F5X (X = CH3, CF3, OCH3, OH, CHO, NO2, NH2, CN). Binding energies were determined from the spectra by using computer curve fitting. Charge calculations were carried out using CNDO/2 and ACHARGE techniques. The CNDO/2 analysis led to the following correlation for the C 1s binding energies and the atomic charges, qi[Formula: see text]Correlations were also obtained for O 1s and N 1s:[Formula: see text]These equations are based on only four and three points respectively. However, the N 1s values cover a wide range (Ei, 402 to 419 eV; qi, −0.2 to 0.5) and show a better correlation than those for oxygen.

Spectroscopic and Quantum Chemical Investigations of Hypothetical m-Diacetylaminoazopyrimidine and Its Photovoltaic Properties

2021 ◽  
Vol 14 (2) ◽  
pp. 139-154
Keyword(s):  
Excited State ◽  
Quantum Chemical ◽  
Density Functional ◽  
Chemical Potential ◽  
Energy Gap ◽  
Dye Sensitized Solar Cells ◽  
Chemical Hardness ◽  
Quantum Chemical Descriptors ◽  
Photovoltaic Properties ◽  
Chemical Descriptors

Abstract: Here, an attempt is made to theoretically study and predict the electronic and spectroscopic (UV-Vis and IR) and structural properties, quantum chemical descriptors and subsequent application of diacetylaminoazopyrimidine in dye-sensitized solar cells (DSSCs). Ground- and excited-state time-dependent density functional theory (TD-DFT) calculations were carried out using material studio and ORCA software, respectively. The computed ground-state energy gap, chemical hardness, chemical softness, chemical potential, electronegativity and electrophilicity index are: 3.60 eV, 1.80 eV, 0.56 eV, 4.49 eV, -4.49 eV and 5.68, respectively. Conversely, the DFT-predicted excited-state quantum chemical descriptors are: 1.67 eV, 0.83 eV, 1.20 eV, 4.71 eV and -4.71 eV, corresponding to the energy gap, chemical hardness, chemical softness, chemical potential and electronegativity, respectively. Furthermore, vibrational frequency calculations confirm the presence of some key functional groups (N=N, C=O, C-H) present in the dye molecules. The computed optoelectronic parameters, such as light-harvesting efficiency, electron injection and open-circuit voltage are 0.06 eV, -8.59 eV and -5.75 eV, respectively. Overall, the dye possesses a relatively good current conversion efficiency as compared to other dyes studied in the literature; hence, it could be used as a novel material for photovoltaic technological applications. Keywords: Diacetylaminoazopyrimidine, DFT, Excited state, Spectroscopy, DSSCs.

scholarly journals Modeling the Structures and Electronic Properties of Uracil and Thymine in Gas Phase and Water

2017 ◽  
Vol 11 (12) ◽  
pp. 1
Author(s):  
Lawan Sani Taura ◽  
Chifu Ebenezer Ndikilar ◽  
Aminu Muhammad
Keyword(s):  
Electronic Properties ◽  
Gas Phase ◽  
Density Functional ◽  
Chemical Potential ◽  
Dipole Moments ◽  
Chemical Hardness ◽  
Quadrupole Moments ◽  
Bond Lengths ◽  
Total Energies ◽  
Average Bond

The molecular geometries and electronic properties of Uracil and Thymine are studied at the Restricted Hatree-Fock (RHF) and Density Functional Theory (DFT) levels of theory in gas phase and water. The optimized structures, dipole moments, total energies, charge transfer, quadrupole moments and other electronic properties of the two molecules were computed in gas and water. The two molecules showed higher polarity, stability and band gap in water. The average bond lengths of Thymine are greater than those of Uracil in gas. Thymine has significantly lower bond lengths than Uracil in solution. The average bond lengths of C-C and N-H are respectively the longest and shortest. Thymine molecule has lower total energies compared to Uracil at both levels of theory and in both media. The polarity of both molecules increases in solution. HOMO and LUMO energy values decrease slightly in solution for both molecules at both levels of theory. The Ionization Potential (IP) and Electron Affinity (EA) decreases for both molecules in solution. The chemical potential and electrophilicity of both molecules increase in solution. The chemical hardness of Uracil increases slightly in solution while that of Thymine decreases slightly in solution.

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