Control of structure, stability and catechol oxidase activity of copper(II) complexes by the denticity of tripodal platforms

Ferenc Matyuska, Nóra V. May, A. Bényei, T. Gajda

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3 Citations (Scopus)

Abstract

Copper(ii) complexes of a new polydentate tripodal ligand trenpyz (L, tris[2-(5-pyrazolylmethyl)aminoethyl]amine) were characterized in both solution and solid states. A combined evaluation of potentiometric UV-Vis and EPR data provided both thermodynamic and structural information on the complexes formed in solution. In equimolar solution the highly stable square pyramidal CuHL and trigonal bipyramidal CuL are the dominant species at around pH 3 and 5-8, respectively. Above pH 8 further deprotonation was observed (pK = 9.56), which is related to the formation of a copper(ii)-bound pyrazolate anion. This creates the possibility for the formation of oligonuclear complexes, through pyrazolate bridges, and at a 3/2 Cu(ii)/L ratio three trinuclear complexes were identified, similar to the copper(ii)-tachpyz (N,N′,N′′-tris(5-pyrazolylmethyl)-1,3,5-cis,cis-triamino-cyclohexane) system studied earlier. The trinuclear complexes of the two ligands have considerably different speciations, due to the different denticities of tripodal platforms. At the optimal pH the catechol oxidase activities of the triply deprotonated trinuclear complexes of trenpyz and tachpyz are similar, but the pH-rate constant profiles are significantly different, as a consequence of the deviations in their speciation. Consequently, the H2dtbc oxidation promoted by these trinuclear complexes can be easily controlled by the denticity of the tripodal ligands, since it affects the coordination environment of the central metal ion, which is proposed to be the main actor during the reaction.

Original languageEnglish
Pages (from-to)11647-11660
Number of pages14
JournalNew Journal of Chemistry
Volume41
Issue number20
DOIs
Publication statusPublished - Jan 1 2017

Fingerprint

Catechol Oxidase
Copper
Ligands
Deprotonation
Cyclohexane
Amines
Anions
Metal ions
Paramagnetic resonance
Rate constants
Negative ions
Thermodynamics
Oxidation
Oxidoreductases

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Materials Chemistry

Cite this

Control of structure, stability and catechol oxidase activity of copper(II) complexes by the denticity of tripodal platforms. / Matyuska, Ferenc; May, Nóra V.; Bényei, A.; Gajda, T.

In: New Journal of Chemistry, Vol. 41, No. 20, 01.01.2017, p. 11647-11660.

Research output: Contribution to journalArticle

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