Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic/Water Mixtures. Determination of the Thermodynamic pKa Values by UV/Visible Spectroscopy and DFT Calcula...

Autores
Davila, Yamina Andrea; Sancho, Matias Israel; Almandoz, María C.; Blanco, Sonia Encarnacion
Año de publicación
2013
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
The acid dissociation constants (pKa) of 7-hydroxyflavone, 3-hydroxyflavone and 5-hydroxyflavone, which are practically insoluble compounds in water but of great biological and physicochemical interest, were determined by UV–visible spectroscopy in ethanol–water and acetonitrile–water solutions, varying the solvent relative permittivity in the interval of 61 to 75, at constant ionic strength (0.050 mol·kg–1) and temperature (298.15 K). The pKa values of the compounds increase as the permittivity of the reaction medium decreases. Correlations were established between the pKa values and empirical parameters of the solvents, such as the relative permittivity and hydrogen-bond donor capacity. These equations allow the interpretation of the solvent effect on the acid–base equilibria and the determination of pKa values at 298.15 K in pure water. The ordering of the pKa values was 7-hydroxyflavone (7.28) < 3-hydroxyflavone (8.68) < 5-hydroxyflavone (11.75). In addition, the dissociation constants were also calculated by means of DFT methods (B3LYP/6-311+G(2d,p) level of theory), employing several thermodynamic cycles. The solvent effect on the optimized structures in the gas-phase was evaluated using the polarizable continuum model. A good agreement was observed between the theoretical and experimental pKa values. Finally, the experimental ordering in the acidity of the hydroxyflavones was explained using natural bond orbital analysis.
Fil: Davila, Yamina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigación Biológica de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Catedra de Quimica Fisica; Argentina
Fil: Sancho, Matias Israel. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Catedra de Quimica Fisica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina
Fil: Almandoz, María C.. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Catedra de Quimica Fisica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina
Fil: Blanco, Sonia Encarnacion. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigación Biológica de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Catedra de Quimica Fisica; Argentina
Materia
Pka
Solvent-Effect
Flavonoids
Dft
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repositorio
CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identificador
oai:ri.conicet.gov.ar:11336/4390
Acceder
id CONICETDig_48fefc5f33d62327685c2fbe683626eb
oai_identifier_str oai:ri.conicet.gov.ar:11336/4390
network_acronym_str CONICETDig
repository_id_str 3498
network_name_str CONICET Digital (CONICET)
spelling Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic/Water Mixtures. Determination of the Thermodynamic pKa Values by UV/Visible Spectroscopy and DFT CalculationsDavila, Yamina AndreaSancho, Matias IsraelAlmandoz, María C.Blanco, Sonia EncarnacionPkaSolvent-EffectFlavonoidsDfthttps://purl.org/becyt/ford/1.4https://purl.org/becyt/ford/1The acid dissociation constants (pKa) of 7-hydroxyflavone, 3-hydroxyflavone and 5-hydroxyflavone, which are practically insoluble compounds in water but of great biological and physicochemical interest, were determined by UV–visible spectroscopy in ethanol–water and acetonitrile–water solutions, varying the solvent relative permittivity in the interval of 61 to 75, at constant ionic strength (0.050 mol·kg–1) and temperature (298.15 K). The pKa values of the compounds increase as the permittivity of the reaction medium decreases. Correlations were established between the pKa values and empirical parameters of the solvents, such as the relative permittivity and hydrogen-bond donor capacity. These equations allow the interpretation of the solvent effect on the acid–base equilibria and the determination of pKa values at 298.15 K in pure water. The ordering of the pKa values was 7-hydroxyflavone (7.28) < 3-hydroxyflavone (8.68) < 5-hydroxyflavone (11.75). In addition, the dissociation constants were also calculated by means of DFT methods (B3LYP/6-311+G(2d,p) level of theory), employing several thermodynamic cycles. The solvent effect on the optimized structures in the gas-phase was evaluated using the polarizable continuum model. A good agreement was observed between the theoretical and experimental pKa values. Finally, the experimental ordering in the acidity of the hydroxyflavones was explained using natural bond orbital analysis.Fil: Davila, Yamina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigación Biológica de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Catedra de Quimica Fisica; ArgentinaFil: Sancho, Matias Israel. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Catedra de Quimica Fisica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Almandoz, María C.. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Catedra de Quimica Fisica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Blanco, Sonia Encarnacion. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigación Biológica de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Catedra de Quimica Fisica; ArgentinaAmerican Chemical Society2013-06info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfapplication/pdfapplication/pdfapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/4390Davila, Yamina Andrea; Sancho, Matias Israel; Almandoz, María C.; Blanco, Sonia Encarnacion; Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic/Water Mixtures. Determination of the Thermodynamic pKa Values by UV/Visible Spectroscopy and DFT Calculations; American Chemical Society; Journal of Chemical and Engineering Data; 58; 6; 6-2013; 1706-17160021-9568enginfo:eu-repo/semantics/altIdentifier/url/http://pubs.acs.org/doi/abs/10.1021/je400153rinfo:eu-repo/semantics/altIdentifier/doi/DOI:10.1021/je400153rinfo:eu-repo/semantics/altIdentifier/issn/0021-9568info:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-10-22T11:42:33Zoai:ri.conicet.gov.ar:11336/4390instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982025-10-22 11:42:33.893CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic/Water Mixtures. Determination of the Thermodynamic pKa Values by UV/Visible Spectroscopy and DFT Calculations
title Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic/Water Mixtures. Determination of the Thermodynamic pKa Values by UV/Visible Spectroscopy and DFT Calculations
spellingShingle Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic/Water Mixtures. Determination of the Thermodynamic pKa Values by UV/Visible Spectroscopy and DFT Calculations
Davila, Yamina Andrea
Pka
Solvent-Effect
Flavonoids
Dft
title_short Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic/Water Mixtures. Determination of the Thermodynamic pKa Values by UV/Visible Spectroscopy and DFT Calculations
title_full Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic/Water Mixtures. Determination of the Thermodynamic pKa Values by UV/Visible Spectroscopy and DFT Calculations
title_fullStr Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic/Water Mixtures. Determination of the Thermodynamic pKa Values by UV/Visible Spectroscopy and DFT Calculations
title_full_unstemmed Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic/Water Mixtures. Determination of the Thermodynamic pKa Values by UV/Visible Spectroscopy and DFT Calculations
title_sort Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic/Water Mixtures. Determination of the Thermodynamic pKa Values by UV/Visible Spectroscopy and DFT Calculations
dc.creator.none.fl_str_mv Davila, Yamina Andrea
Sancho, Matias Israel
Almandoz, María C.
Blanco, Sonia Encarnacion
author Davila, Yamina Andrea
author_facet Davila, Yamina Andrea
Sancho, Matias Israel
Almandoz, María C.
Blanco, Sonia Encarnacion
author_role author
author2 Sancho, Matias Israel
Almandoz, María C.
Blanco, Sonia Encarnacion
author2_role author
author
author
dc.subject.none.fl_str_mv Pka
Solvent-Effect
Flavonoids
Dft
topic Pka
Solvent-Effect
Flavonoids
Dft
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.4
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv The acid dissociation constants (pKa) of 7-hydroxyflavone, 3-hydroxyflavone and 5-hydroxyflavone, which are practically insoluble compounds in water but of great biological and physicochemical interest, were determined by UV–visible spectroscopy in ethanol–water and acetonitrile–water solutions, varying the solvent relative permittivity in the interval of 61 to 75, at constant ionic strength (0.050 mol·kg–1) and temperature (298.15 K). The pKa values of the compounds increase as the permittivity of the reaction medium decreases. Correlations were established between the pKa values and empirical parameters of the solvents, such as the relative permittivity and hydrogen-bond donor capacity. These equations allow the interpretation of the solvent effect on the acid–base equilibria and the determination of pKa values at 298.15 K in pure water. The ordering of the pKa values was 7-hydroxyflavone (7.28) < 3-hydroxyflavone (8.68) < 5-hydroxyflavone (11.75). In addition, the dissociation constants were also calculated by means of DFT methods (B3LYP/6-311+G(2d,p) level of theory), employing several thermodynamic cycles. The solvent effect on the optimized structures in the gas-phase was evaluated using the polarizable continuum model. A good agreement was observed between the theoretical and experimental pKa values. Finally, the experimental ordering in the acidity of the hydroxyflavones was explained using natural bond orbital analysis.
Fil: Davila, Yamina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigación Biológica de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Catedra de Quimica Fisica; Argentina
Fil: Sancho, Matias Israel. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Catedra de Quimica Fisica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina
Fil: Almandoz, María C.. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Catedra de Quimica Fisica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina
Fil: Blanco, Sonia Encarnacion. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigación Biológica de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Catedra de Quimica Fisica; Argentina
description The acid dissociation constants (pKa) of 7-hydroxyflavone, 3-hydroxyflavone and 5-hydroxyflavone, which are practically insoluble compounds in water but of great biological and physicochemical interest, were determined by UV–visible spectroscopy in ethanol–water and acetonitrile–water solutions, varying the solvent relative permittivity in the interval of 61 to 75, at constant ionic strength (0.050 mol·kg–1) and temperature (298.15 K). The pKa values of the compounds increase as the permittivity of the reaction medium decreases. Correlations were established between the pKa values and empirical parameters of the solvents, such as the relative permittivity and hydrogen-bond donor capacity. These equations allow the interpretation of the solvent effect on the acid–base equilibria and the determination of pKa values at 298.15 K in pure water. The ordering of the pKa values was 7-hydroxyflavone (7.28) < 3-hydroxyflavone (8.68) < 5-hydroxyflavone (11.75). In addition, the dissociation constants were also calculated by means of DFT methods (B3LYP/6-311+G(2d,p) level of theory), employing several thermodynamic cycles. The solvent effect on the optimized structures in the gas-phase was evaluated using the polarizable continuum model. A good agreement was observed between the theoretical and experimental pKa values. Finally, the experimental ordering in the acidity of the hydroxyflavones was explained using natural bond orbital analysis.
publishDate 2013
dc.date.none.fl_str_mv 2013-06
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/11336/4390
Davila, Yamina Andrea; Sancho, Matias Israel; Almandoz, María C.; Blanco, Sonia Encarnacion; Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic/Water Mixtures. Determination of the Thermodynamic pKa Values by UV/Visible Spectroscopy and DFT Calculations; American Chemical Society; Journal of Chemical and Engineering Data; 58; 6; 6-2013; 1706-1716
0021-9568
url http://hdl.handle.net/11336/4390
identifier_str_mv Davila, Yamina Andrea; Sancho, Matias Israel; Almandoz, María C.; Blanco, Sonia Encarnacion; Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic/Water Mixtures. Determination of the Thermodynamic pKa Values by UV/Visible Spectroscopy and DFT Calculations; American Chemical Society; Journal of Chemical and Engineering Data; 58; 6; 6-2013; 1706-1716
0021-9568
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/url/http://pubs.acs.org/doi/abs/10.1021/je400153r
info:eu-repo/semantics/altIdentifier/doi/DOI:10.1021/je400153r
info:eu-repo/semantics/altIdentifier/issn/0021-9568
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
eu_rights_str_mv openAccess
rights_invalid_str_mv https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.format.none.fl_str_mv application/pdf
application/pdf
application/pdf
application/pdf
application/pdf
application/pdf
dc.publisher.none.fl_str_mv American Chemical Society
publisher.none.fl_str_mv American Chemical Society
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
instname:Consejo Nacional de Investigaciones Científicas y Técnicas
reponame_str CONICET Digital (CONICET)
collection CONICET Digital (CONICET)
instname_str Consejo Nacional de Investigaciones Científicas y Técnicas
repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
repository.mail.fl_str_mv dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar
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score 12.982451

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