Experimental and computational thermochemical studies of 9-R-xanthene derivatives (ROH, COOH, CONH2)

Freitas, Vera L.S.; Gomes, José R. B.; Silva, Manuel A.V. Ribeiro da

doi:10.1016/j.jct.2012.03.017

Cited by 19 publications

(6 citation statements)

References 35 publications

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“…Those results differ 13 to 20 kJ mol −1 from the ones obtained in our study ( Table 6 ). We feel confident with our results, since the composite method applied in the development of the present study has been already tested for similar heteropolycyclic molecules, with the inherent validation of the methodology used [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”

Section: Resultssupporting

confidence: 63%

“…The reliability of selected gas-phase enthalpies of formation is powerfully influenced by the computational method and a suitable set of chemical reactions. For polycyclic aromatic compounds such as the ones studied in this work, the isodesmic and homodesmotic reactions appear to be most appropriate [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. These theoretical chemical reactions rely upon the similarity of the bonding environment of the reactants and products and lead to cancellation of systematic errors.…”

Section: Resultsmentioning

confidence: 99%

“…A literature survey showed the scarcity of thermodynamic data for heteropolycyclic compounds that motivated our involvement in a systematic study of compounds structurally formed by two benzene rings fused to a pentagonal or hexagonal central ring, containing oxygen, sulfur or nitrogen as heteroatoms [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. This work has been developed in a “duo dynamic” between the experimental and computational studies of those species, with the main goal of determining their thermodynamic properties, among others.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Hydroxyl Functional Group on the Structure and Stability of Xanthone: A Computational Approach

Freitas

Silva

2018

Molecules

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The present work addresses computational research focused on the energetic and structural properties of four isomers monohydroxyxanthone, using the G3(MP2)//B3LYP method, in order to evaluate the influence of the hydroxyl (—OH moiety) functional group on the xanthone molecule. The combination of these computational results with previous experimental data of these compounds enabled the determination of their enthalpies, entropies and Gibbs energies of formation, in the gaseous phase, and consequently to infer about the relative thermodynamic stability of the four isomers. Other issues were also addressed for the hydroxyxanthone isomers, namely the conformational and the tautomeric equilibrium analysis of the optimized molecular structures, the frontier orbitals, and the electrostatic potential energy maps. Complementarily, an energetic study of the intramolecular normalO—normalH⋯normalO hydrogen bond for 1-hydroxanthone was also performed.

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Section: Resultssupporting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Hydroxyl Functional Group on the Structure and Stability of Xanthone: A Computational Approach

Freitas

Silva

2018

Molecules

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“…The computational study of the three o -acetylnaphthol isomers ( Figure 1 ) was performed using the G3(MP2)//B3LYP approach [ 18 ]. The good agreement obtained between the experimental and the computational values for the gas-phase enthalpy of formation in previous studies of compounds with a similar structural typology, give us confidence for the use of the G3(MP2)//B3LYP approach in this study [ 17 , 28 , 29 , 30 ].…”

Section: Resultssupporting

confidence: 76%

Structural and Energetic Insights on Two Dye Compounds: 1-Acetyl-2-Naphthol and 2-Acetyl-1-Naphthol

Freitas

Silva

2020

Molecules

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The energy involved in the structural switching of acyl and hydroxyl substituents in the title compounds was evaluated combining experimental and computational studies. Combustion calorimetry and Knudsen effusion techniques were used to determine the enthalpies of formation, in the crystalline state, and of sublimation, respectively. The gas-phase enthalpy of formation of both isomers was derived combining these two experimental data. Concerning the computational study, the G3(MP2)//B3LYP composite method was used to optimize and determine the energy of the isomers in the gaseous state. From a set of hypothetical reactions it has been possible to estimate the gas-phase enthalpy of formation of the title compounds. The good agreement between the experimental and computational gas-phase enthalpies of formation of the 1-acetyl-2-naphthol and 2-acetyl-1-naphthol isomers, provided the confidence for extending the computational study to the 2-acetyl-3-naphthol isomer. The structural rearrangement of the substituents in position 1 and 2 in the naphthalene ring and the energy of the intramolecular hydrogen bond are the factors responsible for the energetic differences exhibited by the isomers. The gas phase tautomeric keto « enol equilibria of the o-acetylnaphthol isomers were analyzed using the Boltzmann’s distribution.

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“…The properties of these compounds caught also our attention since they can be used to provide additional understanding of the energetic and structural effects caused by the substitution of an oxygen atom by a sulfur atom in heterocyclic compounds. This understanding constitutes one of our research objectives, and for that purpose we have been performing a systematic investigation of such effects on several heterocycles. − …”

Section: Introductionmentioning

confidence: 99%

Energetics and Reactivity of Morpholine and Thiomorpholine: A Joint Experimental and Computational Study

2014

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The influence of the heteroatoms in the conformational, energetic, and reactivity trends exhibited by morpholine and thiomorpholine isosteres was obtained from computational and experimental thermochemical studies. For those purposes, the gas-phase standard (p° = 0.1 MPa) molar enthalpies of formation of the compounds, at T = 298.15 K, were determined from the experimental values of the standard molar enthalpies of formation, in the liquid phase, and of the standard molar enthalpies of vaporization, obtained by calorimetric techniques, and also from composite G3(MP2)//B3LYP calculations making use of appropriate working reactions. A very good agreement was found between the calculated and the experimental gas-phase enthalpies of formation. The computational study was further extended to the calculation of other gas-phase thermodynamic properties of these compounds, namely, the N–H or C–H bond dissociation enthalpies, gas-phase acidities and basicities, proton affinities and adiabatic ionization enthalpies, and the energies and structures of the conformational stereoisomers of morpholine and thiomorpholine.

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Experimental and computational thermochemical studies of 9-R-xanthene derivatives (ROH, COOH, CONH2)

Cited by 19 publications

References 35 publications

Influence of Hydroxyl Functional Group on the Structure and Stability of Xanthone: A Computational Approach

Influence of Hydroxyl Functional Group on the Structure and Stability of Xanthone: A Computational Approach

Structural and Energetic Insights on Two Dye Compounds: 1-Acetyl-2-Naphthol and 2-Acetyl-1-Naphthol

Energetics and Reactivity of Morpholine and Thiomorpholine: A Joint Experimental and Computational Study

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