Dependence of the Fe(II)-Gallic Acid Coordination Compound Formation Constant on the pH

One important property of tannins involves their ability to form coordination compounds with metal ions, which is vital for the bioavailability of these ions, as well as for the antibacterial and antioxidative activities of tannins. In this study, the pH dependence of interactions between gallic aci...

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Auteurs principaux:	Franjo Frešer, Gregor Hostnik, Jelena Tošović, Urban Bren
Format:	article
Langue:	EN
Publié:	MDPI AG 2021
Sujets:	UV/Vis spectra gallic acid Fe(II) ions coordination compounds modeling Job diagrams Chemical technology TP1-1185
Accès en ligne:	https://doaj.org/article/33d37f019015401d94aa2a163a9a8fcb
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spelling	oai:doaj.org-article:33d37f019015401d94aa2a163a9a8fcb2021-11-25T17:34:11ZDependence of the Fe(II)-Gallic Acid Coordination Compound Formation Constant on the pH10.3390/foods101126892304-8158https://doaj.org/article/33d37f019015401d94aa2a163a9a8fcb2021-11-01T00:00:00Zhttps://www.mdpi.com/2304-8158/10/11/2689https://doaj.org/toc/2304-8158One important property of tannins involves their ability to form coordination compounds with metal ions, which is vital for the bioavailability of these ions, as well as for the antibacterial and antioxidative activities of tannins. In this study, the pH dependence of interactions between gallic acid, one of the basic building blocks of tannins, and Fe(II) ions, was investigated using UV/Vis spectroscopy, in conjunction with density functional theory (DFT) calculations. Moreover, two models were developed to explain the processes taking place in the solution. The first model treated the reaction as a simple bimolecular process while the second also considered the protolytic equilibrium, which was proven very successful in discerning the pH dependence of formation constants, and whose assumptions were well supported by DFT calculations. We showed that the two-time deprotonated gallic acid species forms the coordination compound with Fe(II) ions in a 1:1 molar ratio. To gain better insight into the process, the coordination compound formation was also studied using various DFT functionals, which further supported the model results. Furthermore, due to the relatively low sample amounts needed, the methodology developed here will be useful to study compounds that are more difficult to isolate.Franjo FrešerGregor HostnikJelena TošovićUrban BrenMDPI AGarticleUV/Vis spectragallic acidFe(II) ionscoordination compoundsmodelingJob diagramsChemical technologyTP1-1185ENFoods, Vol 10, Iss 2689, p 2689 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	UV/Vis spectra gallic acid Fe(II) ions coordination compounds modeling Job diagrams Chemical technology TP1-1185
spellingShingle	UV/Vis spectra gallic acid Fe(II) ions coordination compounds modeling Job diagrams Chemical technology TP1-1185 Franjo Frešer Gregor Hostnik Jelena Tošović Urban Bren Dependence of the Fe(II)-Gallic Acid Coordination Compound Formation Constant on the pH
description	One important property of tannins involves their ability to form coordination compounds with metal ions, which is vital for the bioavailability of these ions, as well as for the antibacterial and antioxidative activities of tannins. In this study, the pH dependence of interactions between gallic acid, one of the basic building blocks of tannins, and Fe(II) ions, was investigated using UV/Vis spectroscopy, in conjunction with density functional theory (DFT) calculations. Moreover, two models were developed to explain the processes taking place in the solution. The first model treated the reaction as a simple bimolecular process while the second also considered the protolytic equilibrium, which was proven very successful in discerning the pH dependence of formation constants, and whose assumptions were well supported by DFT calculations. We showed that the two-time deprotonated gallic acid species forms the coordination compound with Fe(II) ions in a 1:1 molar ratio. To gain better insight into the process, the coordination compound formation was also studied using various DFT functionals, which further supported the model results. Furthermore, due to the relatively low sample amounts needed, the methodology developed here will be useful to study compounds that are more difficult to isolate.
format	article
author	Franjo Frešer Gregor Hostnik Jelena Tošović Urban Bren
author_facet	Franjo Frešer Gregor Hostnik Jelena Tošović Urban Bren
author_sort	Franjo Frešer
title	Dependence of the Fe(II)-Gallic Acid Coordination Compound Formation Constant on the pH
title_short	Dependence of the Fe(II)-Gallic Acid Coordination Compound Formation Constant on the pH
title_full	Dependence of the Fe(II)-Gallic Acid Coordination Compound Formation Constant on the pH
title_fullStr	Dependence of the Fe(II)-Gallic Acid Coordination Compound Formation Constant on the pH
title_full_unstemmed	Dependence of the Fe(II)-Gallic Acid Coordination Compound Formation Constant on the pH
title_sort	dependence of the fe(ii)-gallic acid coordination compound formation constant on the ph
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/33d37f019015401d94aa2a163a9a8fcb
work_keys_str_mv	AT franjofreser dependenceofthefeiigallicacidcoordinationcompoundformationconstantontheph AT gregorhostnik dependenceofthefeiigallicacidcoordinationcompoundformationconstantontheph AT jelenatosovic dependenceofthefeiigallicacidcoordinationcompoundformationconstantontheph AT urbanbren dependenceofthefeiigallicacidcoordinationcompoundformationconstantontheph
_version_	1718412215356227584

Dependence of the Fe(II)-Gallic Acid Coordination Compound Formation Constant on the pH

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