Conformational and Spectroscopic Analysis of the Tyrosyl Radical Dipeptide Analogue in the Gas Phase and in Aqueous Solution by a Density Functional/Continuum Solvent Model

2002 ◽  
Vol 124 (38) ◽  
pp. 11531-11540 ◽  
Author(s):  
Emma Langella ◽  
Roberto Improta ◽  
Vincenzo Barone
Keyword(s):  
Aqueous Solution ◽  
Gas Phase ◽  
Density Functional ◽  
Spectroscopic Analysis ◽  
Tyrosyl Radical ◽  
Continuum Solvent Model ◽  
Solvent Model

Conformational analysis of the tyrosine dipeptide analogue in the gas phase and in aqueous solution by a density functional/continuum solvent model

2002 ◽  
Vol 23 (6) ◽  
pp. 650-661 ◽  
Author(s):  
Emma Langella ◽  
Nadia Rega ◽  
Roberto Improta ◽  
Orlando Crescenzi ◽  
Vincenzo Barone
Keyword(s):  
Aqueous Solution ◽  
Conformational Analysis ◽  
Gas Phase ◽  
Density Functional ◽  
Continuum Solvent Model ◽  
Solvent Model

A Density Functional Study of the Addition of Water to SO3in the Gas Phase and in Aqueous Solution

1998 ◽  
Vol 102 (17) ◽  
pp. 2893-2898 ◽  
Author(s):  
Evert Jan Meijer ◽  
Michiel Sprik
Keyword(s):  
Aqueous Solution ◽  
Gas Phase ◽  
Density Functional ◽  
Functional Study ◽  
Density Functional Study

scholarly journals Computational Evidence Suggests That 1-chloroethanol May Be an Intermediate in the Thermal Decomposition of 2-chloroethanol into Acetaldehyde and HCl

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Oscar Ventura ◽  
Vincenzo Barone
Keyword(s):  
Aqueous Solution ◽  
Water Molecule ◽  
Gas Phase ◽  
Density Functional ◽  
Water Molecules ◽  
Functional Theory ◽  
Direct Transformation ◽  
The Density Functional Theory ◽  
Successive Step ◽  
The One

<p>The dehalogenation of 2-chloroethanol (2ClEtOH) in gas phase with and without participation of catalytic water molecules has been investigated using methods rooted into the density functional theory. The well-known HCl elimination leading to vinyl alcohol (VA) was compared to the alternative elimination route towards oxirane and shown to be kinetically and thermodynamically more favorable. However, the isomerization of VA to acetaldehyde in the gas phase, in the absence of water, was shown to be kinetically and thermodynamically less favorable than the recombination of VA and HCl to form the isomeric 1-chloroethanol (1ClEtOH) species. This species is more stable than 2ClEtOH by about 6 kcal mol<sup>-1</sup>, and the reaction barrier is 22 kcal mol<sup>-1</sup> vs 55 kcal mol<sup>-1</sup> for the direct transformation of VA to acetaldehyde. In a successive step, 1ClEtOH can decompose directly to acetaldehyde and HCl with a lower barrier (29 kcal mol<sup>-1</sup>) than that of VA to the same products (55 kcal mol<sup>-1</sup>). The calculations were repeated using a single ancillary water molecule (W) in the complexes 2ClEtOH_W and 1ClEtOH_W. The latter adduct is now more stable than 2ClEtOH_W by about 8 kcal mol<sup>-1</sup>, implying that the water molecule increased the already higher stability of 1ClEtOH in the gas phase. However, this catalytic water molecule lowers dramatically the barrier for the interconversion of VA to acetaldehyde (from 55 to 6 kcal mol<sup>-1</sup>). This barrier is now smaller than the one for the conversion to 1ClEtOH (which also decreases, but not so much, from 22 to 12 kcal mol<sup>-1</sup>). Thus, it is concluded that while 1ClEtOH may be a plausible intermediate in the gas phase dehalogenation of 2ClEtOH, it is unlikely that it plays a major role in water complexes (or, by inference, aqueous solution). It is also shown that neither in the gas phase nor in the cluster with one water molecule, the oxirane path is competitive with the VA alcohol path.</p>

scholarly journals Kinetics and thermodynamics of the hydroxylation products in the photodegradation of the herbicide Metolachlor

2020 ◽  
Vol 92 (3) ◽  
pp. 473-484
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Oscar N. Ventura
Keyword(s):  
Aqueous Solution ◽  
Gas Phase ◽  
Density Functional ◽  
Electronic Structure Calculations ◽  
Kinetic Characteristics ◽  
Kinetics And Thermodynamics ◽  
Composite Methods ◽  
Herbicide Metolachlor ◽  
Kinetics Of ◽  
Structure Calculations

AbstractElectronic structure calculations have been performed to determine the thermochemistry and kinetics of the reaction between OH and the radicals of the S enantiomer of the herbicide Metolachlor, 2-chloro-N-(2-methyl-6-ethylphenyl)-N(2-methoxy-1-methylethyl) acetamide (MC), produced by photoinduced breaking of the C–Cl bond. Both density functional and ab initio composite methods were employed to calculate the structure of reactants, intermediates, transition states and products, in gas phase and in aqueous solution. The expected relative abundance of each product was calculated and compared to the experimentally observed concentrations. It is shown that a combination of thermodynamic and kinetic characteristics interplay to produce the expected theoretical abundances, which turn out to be in agreement with the experimentally observed distribution of products.

Density functional study of the Hoffmann elimination of (N-Cl),N-methylethanolamine in gas phase and in aqueous solution

2006 ◽  
Vol 429 (4-6) ◽  
pp. 425-429 ◽  
Author(s):  
D.R. Ramos ◽  
R. Castillo ◽  
M. Canle L. ◽  
M.V. García ◽  
J. Andrés ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Gas Phase ◽  
Density Functional ◽  
Functional Study ◽  
Density Functional Study

scholarly journals Computational Evidence Suggests That 1-chloroethanol May Be an Intermediate in the Thermal Decomposition of 2-chloroethanol into Acetaldehyde and HCl

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Oscar Ventura ◽  
Vincenzo Barone
Keyword(s):  
Aqueous Solution ◽  
Water Molecule ◽  
Gas Phase ◽  
Density Functional ◽  
Water Molecules ◽  
Functional Theory ◽  
Direct Transformation ◽  
The Density Functional Theory ◽  
Successive Step ◽  
The One

<p>The dehalogenation of 2-chloroethanol (2ClEtOH) in gas phase with and without participation of catalytic water molecules has been investigated using methods rooted into the density functional theory. The well-known HCl elimination leading to vinyl alcohol (VA) was compared to the alternative elimination route towards oxirane and shown to be kinetically and thermodynamically more favorable. However, the isomerization of VA to acetaldehyde in the gas phase, in the absence of water, was shown to be kinetically and thermodynamically less favorable than the recombination of VA and HCl to form the isomeric 1-chloroethanol (1ClEtOH) species. This species is more stable than 2ClEtOH by about 6 kcal mol<sup>-1</sup>, and the reaction barrier is 22 kcal mol<sup>-1</sup> vs 55 kcal mol<sup>-1</sup> for the direct transformation of VA to acetaldehyde. In a successive step, 1ClEtOH can decompose directly to acetaldehyde and HCl with a lower barrier (29 kcal mol<sup>-1</sup>) than that of VA to the same products (55 kcal mol<sup>-1</sup>). The calculations were repeated using a single ancillary water molecule (W) in the complexes 2ClEtOH_W and 1ClEtOH_W. The latter adduct is now more stable than 2ClEtOH_W by about 8 kcal mol<sup>-1</sup>, implying that the water molecule increased the already higher stability of 1ClEtOH in the gas phase. However, this catalytic water molecule lowers dramatically the barrier for the interconversion of VA to acetaldehyde (from 55 to 6 kcal mol<sup>-1</sup>). This barrier is now smaller than the one for the conversion to 1ClEtOH (which also decreases, but not so much, from 22 to 12 kcal mol<sup>-1</sup>). Thus, it is concluded that while 1ClEtOH may be a plausible intermediate in the gas phase dehalogenation of 2ClEtOH, it is unlikely that it plays a major role in water complexes (or, by inference, aqueous solution). It is also shown that neither in the gas phase nor in the cluster with one water molecule, the oxirane path is competitive with the VA alcohol path.</p>

scholarly journals Theoretical DFT Studies on Free Base, Cationic and Hydrochloride Species of Narcotic Tramadol Agent in Gas Phase and Aqueous Solution

2021 ◽  
Vol 11 (5) ◽  
pp. 13064-13088
Keyword(s):  
Aqueous Solution ◽  
Gas Phase ◽  
Density Functional ◽  
Solid Phase ◽  
Free Base ◽  
Uv Spectrum ◽  
Reaction Field ◽  
Vibrational Assignments ◽  
Cationic Species ◽  
The Density Functional Theory

Theoretical studies based on the density functional theory (DFT) have been performed to study structural and vibrational properties of the free base, cationic, and hydrochloride species of narcotic tramadol agent in the gas phase and aqueous solution. In both media, B3LYP/6-31G* calculations were used while in solution, the self-consistent reaction field (SCRF) method together with the integral equation formalism variant polarised continuum (IEFPCM) and universal solvation model density (SMD) models have been employed because these models consider the solvent effects. The vibrational studies have revealed that the species cationic is present in the solid phase because the most intense band predicted for the hydrochloride in infrared and Raman spectra is not observed in the experimental spectra. The harmonic force fields, together with the normal internal coordinates and scaling factors, have allowed the complete vibrational assignments of 126, 129, and 132 vibration modes expected for the free base, cationic, and hydrochloride species, respectively, by using the SQMFF methodology. The cationic species evidence the most negative solvation energy and higher hydration in solution in agreement with its lower stability, while the hydrochloride species is the most reactive in solution. MK charges and NBO and AIM studies support cationic species' instability due to the positive charge on N atom. Comparisons of the experimental UV spectrum of hydrochloride tramadol with the predicted for the three species suggest that the free base, cationic, and hydrochloride species can be present in solution. Comparisons of predicted infrared, Raman, 1H, and 13C NMR and electronic spectra for the free base, cationic, and hydrochloride species of tramadol with the corresponding experimental ones have evidenced reasonable correlations for the cationic species showing that this species present in the solid phase and in solution.

Modelling the reaction OH-+ CO2→ HCO-3in the gas phase and in aqueous solution: a combined density functional continuum approach

1994 ◽  
Vol 83 (2) ◽  
pp. 327-333 ◽  
Author(s):  
Mark M. Davidson ◽  
Ian H. Hillier ◽  
Richard J. Hall ◽  
Neil A. Burton
Keyword(s):  
Aqueous Solution ◽  
Gas Phase ◽  
Density Functional ◽  
Continuum Approach

scholarly journals Theoretical prediction of coordination environments and stability constants of lanthanum lactate complexes in solution

2016 ◽  
Vol 45 (39) ◽  
pp. 15517-15522 ◽  
Author(s):  
Lindsay E. Roy ◽  
Leigh R. Martin
Keyword(s):  
Density Functional Theory ◽  
Theoretical Prediction ◽  
Stability Constants ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Coordination Environment ◽  
Continuum Solvent Model ◽  
Explicit Solvent ◽  
Solvent Model

Using Density Functional Theory calculations in combination with explicit solvent and a continuum solvent model, this work sets out to understand the coordination environment and relevant thermodynamics of La(iii)-lactate complexes.

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