Degree: Doctor

Affiliation(s):

CIQUP - FCUP

Bio

Vera Freitas is a researcher and professor in the field of Physical Chemistry. She obtained her PhD in Thermochemistry from Porto University, Portugal, in 2011. After completing her PhD, she conducted a scientific project in Thermochemistry under a post-doctoral grant for seven years at the Chemistry Research Center of the University of Porto (CIQUP). She currently holds a research position at CIQUP & The Institute of Molecular Sciences Research Center within the Department of Chemistry and Biochemistry at the University of Porto.

At the research center, she is a key member of the Molecular Thermodynamics for Sustainability research group. Her work primarily involves experimental (thermochemical and thermophysical) and computational studies of organic compounds, with a particular emphasis on those relevant to the pharmaceutical industry and the development of sustainable new materials.

In addition to her research, she actively participates in teaching courses focused on molecular energetics, leveraging her extensive expertise in thermodynamics to enhance the education and training of students in this field.

Projects
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Publications
Showing 5 latest publications. Total publications: 53
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1. Thermochemical study to assess the energetical and structural effects of nitro substituents in methyl benzoate isomers, Ledo, JM; Flores, H; Ramos, F; Freitas, VLS da Silva, MDMCR in JOURNAL OF CHEMICAL THERMODYNAMICS, 2022, ISSN: 0021-9614,  Volume: 173, 
Article,  Indexed in: crossref, scopus, wos  DOI: 10.1016/j.jct.2022.106837 P-00W-PP6
Abstract Combined experimental and computational studies were performed aiming the analysis of energetic properties vs structural characteristics of three methyl nitrobenzoate isomers (methyl 2-nitrobenzoate, M2NB, methyl 3-nitro benzoate, M3NB, methyl 4-nitrobenzoate, M4NB). The experimental studies include the determination of the enthalpy of formation in the condensed state (crystal and liquid) of the compounds by static combustion, and the determination of enthalpies of phase transition, using Differential Scanning Calorimetry, high temperature Calvet microcalorimetry and the Knudsen effusion method. These data were combined to derive the enthalpy of formation of the methyl nitrobenzoate isomers in the gaseous phase, at T = 298.15 K. At the computational level, the gas-phase enthalpy of formation of the methyl nitrobenzoate isomers were estimated using theoretical approaches, resorting to the G3(MP2)//B3LYP composite method and to appropriate hypothetical gas-phase reactions. The enthalpies of formation obtained experimental and computationally will be discussed and the energetic structural synergies for the three methyl nitrobenzoate, along with other analogous isomers, will be also analyzed.

2. Thermochemical study of anthranilate derivatives: Effect of the size of the alkyl substituent, Freitas, VLS Silva, CAO; da Silva, MDMCR in JOURNAL OF CHEMICAL THERMODYNAMICS, 2021, ISSN: 0021-9614,  Volume: 158, 
Article,  Indexed in: crossref, scopus, wos  DOI: 10.1016/j.jct.2021.106441 P-00T-N9Z
Abstract The gas-phase enthalpies of formation of two fragrance compounds, methyl anthranilate and butyl anthranilate, at T = 298.15 K, were determined from the combination of the corresponding enthalpies of vaporisation and energies of combustion, obtained from Calvet microcalorimetry and combustion calorimetry measurements, respectively. Additionally, theoretical calculations were performed, using the G3(MP2)//B3LYP composite method, to estimate the gas-phase enthalpies of formation of the two fragrance compounds. The good agreement between the experimental and computational gas-phase enthalpies of formation of the methyl anthranilate and butyl anthranilate, provided the confidence for extending the theoretical study to propyl anthranilate. Furthermore, the results were interpreted in terms of enthalpic increments, aiming to evaluate and understand the energetic effect inherent to the alkyl group (methyl, ethyl, propyl or butyl) present in the ester functional group of the anthranilate derivatives. (c) 2021 Elsevier Ltd.

3. The Relative Thermodynamic Stability of Diamond and Graphite, White, MA; Kahwaji, S; Freitas, VLS Siewert, R; Weatherby, JA; da Silva, MDMCR Verevkin, SP; Johnson, ER; Zwanziger, JW in ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 2021, ISSN: 1433-7851,  Volume: 60, 
Article,  Indexed in: crossref, scopus, wos  DOI: 10.1002/anie.202009897 P-00S-ZNF
Abstract Recent density-functional theory (DFT) calculations raised the possibility that diamond could be degenerate with graphite at very low temperatures. Through high-accuracy calorimetric experiments closing gaps in available data, we reinvestigate the relative thermodynamic stability of diamond and graphite. For T400 K, graphite is always more stable than diamond at ambient pressure. At low temperatures, the stability is enthalpically driven, and entropy terms add to the stability at higher temperatures. We also carried out DFT calculations: B86bPBE-25X-XDM//B86bPBE-XDM and PBE0-XDM//PBE-XDM results overlap with the experimental -T Delta S results and bracket the experimental values of Delta H and Delta G, displaced by only about 2x the experimental uncertainty. Revised values of the standard thermodynamic functions for diamond are Delta H-f(o)=-2150 +/- 150 J mol(-1), Delta S-f(o)=3.44 +/- 0.03 J K-1 mol(-1) and Delta(f)G(o)=-3170 +/- 150 J mol(-1).

4. Benzocaine: A comprehensive thermochemical study, Manuel Ledo, JM; Flores, H; Freitas, VLS Solano Altamirano, JM; Hernandez Perez, JM; Adriana Camarillo, EA; Ramos, F; Ribeiro da Silva, MDMCR in JOURNAL OF CHEMICAL THERMODYNAMICS, 2020, ISSN: 0021-9614,  Volume: 147, 
Article,  Indexed in: crossref, scopus, wos  DOI: 10.1016/j.jct.2020.106119 P-00R-Z4Z
Abstract In the present work, a detailed thermochemical, experimental and theoretical, study of benzocaine is presented. The enthalpy of formation in crystalline state at T = 298.15 K was obtained from combustion calorimetry experiments [ΔfHm°cr=-415.2±1.7kJ∙mol-1], within an oxygen atmosphere, using a static bomb calorimeter. The phase transition enthalpies (fusion, vaporization, and sublimation) were obtained by different techniques, namely differential scanning calorimetry, Calvet microcalorimetry, thermogravimetry, and the Knudsen effusion method. The results obtained by the different techniques are as follows: ΔcrlHm°298.15 K=21.4±0.1 kJ⋅mol−1; ΔlgHm°298.15 K=84.9±1.0 kJ⋅mol−1; ΔcrgHm°298.15 K=106.8±0.4 kJ⋅mol−1. From the experimental results, the enthalpy of formation of the aforesaid compound, in the gas phase, was calculated at T = 298.15 K as: ΔfHm°g=-308.4±1.8kJ∙mol-1. Theoretical enthalpies were computed using the Gaussian G4 composite method, atomization reactions, and the weighted Boltzmann average method. For the latter, the conformational diversity of the molecular structure of the compound was considered. Using the above data and using a similar approach, the theoretical entropy of benzocaine was computed as well. The experimental and theoretical values obtained were compared and an excellent accordance was found. Using the experimental and theoretical results, Gibbs energy of formation in crystalline and gaseous states of benzocaine, at T = 298.15 K were calculated as: ΔfGm°cr=-164.4kJ∙mol-1 and ΔfGm°g=-123.9kJ∙mol-1, respectively. Finally, the results obtained from the enthalpies of phase change are compared with those previously reported in the literature, in order to propose an exact value for these properties. © 2020 Elsevier Ltd

5. Structural and Energetic Insights on Two Dye Compounds: 1-Acetyl-2-Naphthol and 2-Acetyl-1-Naphthol, Freitas, VLS Ribeiro da Silva, MDMCR in MOLECULES, 2020, ISSN: 1420-3049,  Volume: 25, 
Article,  Indexed in: crossref, scopus, wos  DOI: 10.3390/molecules25173827 P-00S-KE5
Abstract 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 theo-acetylnaphthol isomers were analyzed using the Boltzmann's distribution.