VO2+ complexation by bioligands showing keto-enol tautomerism: A potentiometric, spectroscopic, and computational study

Daniele Sanna, K. Várnagy, Sarolta Timári, Giovanni Micera, Eugenio Garribba

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

The interaction of VO2+ ion with ligands of biological interest that are present in important metabolic pathways-2-oxopropanoic acid (pyruvic acid, pyrH), 3-hydroxy-2-oxopropanoic acid (3-hydroxypyruvic acid, hydpyrH), oxobutanedioic acid (oxalacetic acid, oxalH2), (S)-hydroxybutanedioic acid (l-malic acid, malH2), and 2,3-dihydroxy-(E)-butanedioic acid (dihydroxyfumaric acid, dhfH2)-was described. Their complexing capability was compared with that of similar ligands: 3-hydroxy-2-butanone (hydbut) and 3,4-dihydroxy-3-cyclobutene-1,2-dione (squaric acid, squarH 2). All of these ligands (except l-malic acid) exhibit keto-enol tautomerism, and the presence of a metal ion can influence such an equilibrium. The different systems were studied with electron paramagnetic resonance (EPR) and UV-vis spectroscopies and with pH potentiometry. Density functional theory (DFT) methods provide valuable information on the relative energy of the enol and keto forms of the ligands both in the gas phase and in aqueous solution, on the geometry of the complexes, and on EPR and electronic absorption parameters. The results show that most of the ligands behave like α- hydroxycarboxylates, forming mono- and bis-chelated species with (COO -, O-) coordination, demonstrating that the metal ion is able to stabilize the enolate form of some ligands. With dihydroxyfumaric acid, the formation of a non-oxidovanadium(IV) complex, because of rearrangement of dihydroxyfumaric to dihydroxymaleic acid (dhmH2), can be observed. With 3-hydroxy-2-butanone and 3,4-dihydroxy-3-cyclobutene-1,2-dione, complexation of VO2+ does not take place and the reason for this behavior is explained by chemical considerations and computational calculations.

Original languageEnglish
Pages (from-to)10328-10341
Number of pages14
JournalInorganic Chemistry
Volume50
Issue number20
DOIs
Publication statusPublished - Oct 17 2011

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Complexation
Ligands
acids
Acetoin
Metal ions
Paramagnetic resonance
ligands
Oxaloacetic Acid
Acids
Succinic Acid
Ultraviolet spectroscopy
Pyruvic Acid
Dione
Density functional theory
Gases
metal ions
electron paramagnetic resonance
Ions
Geometry
potentiometric analysis

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

Cite this

VO2+ complexation by bioligands showing keto-enol tautomerism : A potentiometric, spectroscopic, and computational study. / Sanna, Daniele; Várnagy, K.; Timári, Sarolta; Micera, Giovanni; Garribba, Eugenio.

In: Inorganic Chemistry, Vol. 50, No. 20, 17.10.2011, p. 10328-10341.

Research output: Contribution to journalArticle

Sanna, Daniele ; Várnagy, K. ; Timári, Sarolta ; Micera, Giovanni ; Garribba, Eugenio. / VO2+ complexation by bioligands showing keto-enol tautomerism : A potentiometric, spectroscopic, and computational study. In: Inorganic Chemistry. 2011 ; Vol. 50, No. 20. pp. 10328-10341.
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