Vpliv pH in strukture flavonoidov na njihove interakcije s Fe(II) ioni

diplomsko delo univerzitetnega študijskega programa I. stopnje

Iza Vodenik (Author), Gregor Hostnik (Mentor), Franjo Frešer (Co-mentor)

Abstract

V diplomskem delu smo raziskovali vpliv vrednosti pH in strukture flavonoidov na njihove interakcije s Fe(II) ioni. Osredotočili smo se na analizo koordinacijskih spojin, ki so nastale pri reakciji med Fe(II) ioni in izbranimi flavonoidi (FL; katehin (C), epigalokatehin (EGC) in epigalokatehin galat (EGCG)). Z uporabo spektroskopije UV-Vis smo spremljali tvorbo koordinacijskih spojin pri treh različnih vrednostih pH (3,5, 4,5 in 5,5) in tako izrisali Jobove diagrame, s pomočjo katerih smo določili stehiometrijo tvorjenih koordinacijskih spojin. Stehiometrija koordinacijskih spojin (flavonoid:Fe(II)) pri C in EGC je enaka 1:1, pri EGCG pa 1:2. Rezultati so pokazali, da pH ne vpliva na stehiometrijo tvorjenih koordinacijskih spojin, medtem ko vpliva na količino koordinacijskih spojin, ki se tvorijo pri rekaciji med FL in Fe(II) ioni, saj se pri višjih vrednostih pH tvori več koordinacijske spojine. Pokazali smo, da strukturne razlike med proučevanimi FL pomembno vplivajo na njihovo sposobnost kelacije Fe(II) ionov. Vsak aromatski obroč z dvema fenolnima skupinama v poziciji orto namreč omogoča kelacijo enega Fe(II) iona. Eksperimentalnim podatkom Jobovega diagrama smo prilegali modelne funkcije. Model za C in EGC smo izpeljali na podlagi predpostavke, da C in EGC kelirata en Fe(II) ion, medtem ko smo pri izpeljavi modela za EGCG predpostavili, da EGCG kelira dva Fe(II) iona. S prileganjem modela smo določili konstante formacije in molarne absorpcijske koeficiente za proučevane koordinacijske spojine. Izračunali smo tudi, kako se množinska koncetracija nevezanega železa spreminja s sestavo raztopin.

Keywords

flavonoidi;Fe(II) ioni;koordinacijska spojina;Jobov diagram;spektroskopija UV-Vis;modeliranje;diplomske naloge;

Data

Language:	Slovenian
Year of publishing:	2025
Typology:	2.11 - Undergraduate Thesis
Organization:	UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher:	[I. Vodenik]
UDC:	547.972:544.152.3(043.2)
COBISS:	248314371
Views:	0
Downloads:	7
Average score:	0 (0 votes)
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Other data

Secondary language:	English
Secondary title:	Effect of pH and structure of flavonoids on their interactions with Fe(ii) ions
Secondary abstract:	In this thesis, we investigated the influence of pH and flavonoid structure on their interactions with Fe(II) ions. The focus was placed on the analysis of coordination compounds formed in reactions between Fe(II) ions and selected flavonoids (FL; catechin (C), epigallocatechin (EGC), and epigallocatechin gallate (EGCG)). Using UV-Vis spectroscopy, we monitored the formation of coordination compounds at three different pH values (3.5, 4.5, and 5.5), and constructed Job plots to determine the stoichiometry of the formed complexes. The stoichiometry of the coordination compounds (flavonoid:Fe(II)) was found to be 1:1 for C and EGC, and 1:2 for EGCG. Results showed that pH does not influence the stoichiometry of the coordination compounds, but it does affect the amount of coordination compound formed: higher pH values led to increased formation of coordination compounds. We demonstrated that structural differences between the studied flavonoids significantly influence their Fe(II)-chelating abilities. Specifically, each aromatic ring containing two hydroxyl groups in ortho-position enables chelation of one Fe(II) ion. Model functions were fitted to the experimental Job plot data. For C and EGC, the model was based on the assumption that each molecule chelates one Fe(II) ion, whereas for EGCG, the model assumed chelation of two Fe(II) ions per molecule. Through model fitting, we determined the formation constants and molar absorptivity coefficients for the studied coordination compounds. We also showed and compared how the molar concentration of unbound iron varies with the composition of the prepared solutions.
Secondary keywords:	flavonoids;Fe(II) ions;coordination compound;Job’s plot;UV-Vis spectroscopy;modelling;
Type (COBISS):	Bachelor thesis/paper
Thesis comment:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages:	1 spletni vir (1 datoteka PDF (59 str.))
ID:	27128882