A Computational Study (TDDFT and RICC2) of the Electronic Spectra of Pyranoanthocyanins in the Gas Phase and Solution

2011 ◽  
Vol 7 (4) ◽  
pp. 1073-1081 ◽  
Author(s):  
Angelo Domenico Quartarolo ◽  
Nino Russo
Keyword(s):  
Gas Phase ◽  
Electronic Spectra ◽  
Computational Study

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>

A contribution to evaluation of effects of medium on electronic spectra

1986 ◽  
Vol 51 (4) ◽  
pp. 746-752 ◽  
Author(s):  
Vojtěch Bekárek ◽  
Juraj Ševčík
Keyword(s):  
Gas Phase ◽  
Electronic Spectra ◽  
Cross Term

Efficiency has been compared of the Bayliss-McRae-Ooshika, Bakhshiev, and cross term methods in evaluation of the effect of medium on electronic spectra of nine indicators of polarity of medium using also the data obtained in gas phase and in perfluorinated hydrocarbons.

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.

Computational study of the concerted gas-phase triple dissociations of 1,3,5-triazacyclohexane and its 1,3,5-trinitro derivative (RDX)

1991 ◽  
Vol 95 (20) ◽  
pp. 7699-7702 ◽  
Author(s):  
Dariush Habibollahzadeh ◽  
Michael Grodzicki ◽  
Jorge M. Seminario ◽  
Peter Politzer
Keyword(s):  
Gas Phase ◽  
Computational Study

A computational study on the gas phase reaction of Os+ with N2O

2009 ◽  
Vol 20 (8) ◽  
pp. 1010-1014 ◽  
Author(s):  
Tao Hong Li ◽  
Chuan Ming Wang ◽  
Shi Wen Yu ◽  
Xiang Yi Liu ◽  
Hui Fu ◽  
...  
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Phase Reaction ◽  
Gas Phase Reaction
Sign in / Sign up

Export Citation Format

Share Document