DFT and Ab initio computational study on the reactivity sites of the GABA and its agonists, such as CACA, TACA, DABA, and muscimol: In the gas phase and dielectric media

2010 ◽  
Vol 111 (14) ◽  
pp. 3938-3948
Author(s):  
Goncagül Serdaroğlu
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Computational Study ◽  
Dielectric Media

scholarly journals A ‘bottom up’, ab initio computational approach to understanding fundamental photophysical processes in nitrogen containing heterocycles, DNA bases and base pairs

2016 ◽  
Vol 18 (30) ◽  
pp. 20007-20027 ◽  
Author(s):  
Barbara Marchetti ◽  
Tolga N. V. Karsili ◽  
Michael N. R. Ashfold ◽  
Wolfgang Domcke
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Radiative Decay ◽  
Computational Study ◽  
Computational Approach ◽  
Dna Bases ◽  
Base Pairs ◽  
Bottom Up ◽  
Photophysical Processes ◽  
Uv Excitation

A systematic computational study of non-radiative decay pathways following UV excitation of selected heterocycles, DNA bases, nucleosides and base-pairs in the gas phase.

An ab initio study of model triazene-based anticancer agents

2010 ◽  
Vol 88 (8) ◽  
pp. 709-715 ◽  
Author(s):  
Katherine G. Doucet ◽  
Julie F. Glister ◽  
Cory C. Pye
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Anticancer Agents ◽  
Computational Study ◽  
Transition States ◽  
Ab Initio Study

A computational study of a series of model triazene-based anticancer agents based on methyl- and amidyl-substituted 5-(1-triazenyl)imidazoles has been carried out, including the drugs Dacarbazine, Temozolomide, and Mitozolomide. A number of different conformers are analyzed. The transition states for the gas-phase and water-mediated triazene tautomerization reaction are found and the barriers are determined.

Explaining the magnetism of gold

2017 ◽  
Author(s):  
Robson de Farias
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Formation Enthalpy ◽  
Gold Atom ◽  
Orbital Energy ◽  
Knudsen Effusion ◽  
Energy Diagram ◽  
Unpaired Electrons ◽  
The Difference ◽  
Good Agreement

<p>In the present work, a computational study is performed in order to clarify the possible magnetic nature of gold. For such purpose, gas phase Au<sub>2</sub> (zero charge) is modelled, in order to calculate its gas phase formation enthalpy. The calculated values were compared with the experimental value obtained by means of Knudsen effusion mass spectrometric studies [5]. Based on the obtained formation enthalpy values for Au<sub>2</sub>, the compound with two unpaired electrons is the most probable one. The calculated ionization energy of modelled Au<sub>2</sub> with two unpaired electrons is 8.94 eV and with zero unpaired electrons, 11.42 eV. The difference (11.42-8.94 = 2.48 eV = 239.29 kJmol<sup>-1</sup>), is in very good agreement with the experimental value of 226.2 ± 0.5 kJmol<sup>-1</sup> to the Au-Au bond<sup>7</sup>. So, as expected, in the specie with none unpaired electrons, the two 6s<sup>1</sup> (one of each gold atom) are paired, forming a chemical bond with bond order 1. On the other hand, in Au<sub>2</sub> with two unpaired electrons, the s-d hybridization prevails, because the relativistic contributions. A molecular orbital energy diagram for gas phase Au<sub>2</sub> is proposed, explaining its paramagnetism (and, by extension, the paramagnetism of gold clusters and nanoparticles).</p>

2-Deoxyribose Radicals in the Gas Phase and Aqueous Solution. Transient Intermediates of Hydrogen Atom Abstraction from 2-Deoxyribofuranose

2005 ◽  
Vol 70 (11) ◽  
pp. 1769-1786 ◽  
Author(s):  
Luc A. Vannier ◽  
Chunxiang Yao ◽  
František Tureček
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Atom ◽  
Gas Phase ◽  
Computational Study ◽  
Hydrogen Atom Abstraction ◽  
Oh Radical ◽  
Free Energies ◽  
Intramolecular Hydrogen ◽  
Solvation Free Energies ◽  
Transient Intermediates

A computational study at correlated levels of theory is reported to address the structures and energetics of transient radicals produced by hydrogen atom abstraction from C-1, C-2, C-3, C-4, C-5, O-1, O-3, and O-5 positions in 2-deoxyribofuranose in the gas phase and in aqueous solution. In general, the carbon-centered radicals are found to be thermodynamically and kinetically more stable than the oxygen-centered ones. The most stable gas-phase radical, 2-deoxyribofuranos-5-yl (5), is produced by H-atom abstraction from C-5 and stabilized by an intramolecular hydrogen bond between the O-5 hydroxy group and O-1. The order of radical stabilities is altered in aqueous solution due to different solvation free energies. These prefer conformers that lack intramolecular hydrogen bonds and expose O-H bonds to the solvent. Carbon-centered deoxyribose radicals can undergo competitive dissociations by loss of H atoms, OH radical, or by ring cleavages that all require threshold dissociation or transition state energies >100 kJ mol-1. This points to largely non-specific dissociations of 2-deoxyribose radicals when produced by exothermic hydrogen atom abstraction from the saccharide molecule. Oxygen-centered 2-deoxyribose radicals show only marginal thermodynamic and kinetic stability and are expected to readily fragment upon formation.

A vibrational spectroscopic and computational study of the structures of protonated imidacloprid and its fragmentation products in the gas phase

2021 ◽  
Vol 23 (5) ◽  
pp. 3377-3388
Author(s):  
Kelsey J. Menard ◽  
Jonathan Martens ◽  
Travis D. Fridgen
Keyword(s):  
Computational Chemistry ◽  
Gas Phase ◽  
Vibrational Spectroscopy ◽  
Computational Study ◽  
Unimolecular Decomposition ◽  
Decomposition Products

Vibrational spectroscopy and computational chemistry studies were combined with the aim of elucidating the structures of protonated imidacloprid (pIMI), and its unimolecular decomposition products.

scholarly journals Density Functional Theory and Complete Basis Set Ab Initio Computational Study of Five-, Six-, Seven- and Eight-hydrogen Coordinated Carbon Cations

1999 ◽  
Vol 23 (8) ◽  
pp. 502-503
Author(s):  
Branko S. Jursic
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Computational Study ◽  
Basis Set ◽  
Functional Theory ◽  
Complete Basis ◽  
Complete Basis Set ◽  
High Level

High level ab initio and density functional theory studies are performed on highly protonated methane species.

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