Catalytic catechol oxidation by copper complexes: development of a structure–activity relationship

Ording-Wenker, Erica C.M.; Siegler, Maxime A.; Lutz, Martin; Bouwman, Elisabeth

doi:10.1039/c5dt01041a

Cited by 41 publications

(29 citation statements)

References 42 publications

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“…In order to understand the activation of dioxygen by metalloenzymes, a large number of dinuclear copper(II) complexes, as biomimetic models of catechol oxidase, have been investigated. [49][50][51][52][53] Nevertheless, very few studies report the catechol oxidase activity of copper(II)-peptide complexes, 21,54,55 and for this purpose tripodal peptides have been studied only by us. 27 The reaction was followed by the formation of the product 3,5-di-tert-butyl-o-benzoquinone (DTBQ) spectrophotometrically at 400 nm in a 50% EtOH/H 2 O solvent, in order to enhance the solubility of DTBQ.…”

Section: Oxidation Of 35-di-tert-butylcatechol (H 2 Dtbc)mentioning

confidence: 99%

On the copper(ii) binding of asymmetrically functionalized tripodal peptides: solution equilibrium, structure, and enzyme mimicking

et al. 2018

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Our aim is to combine the preorganized structure of tripodal scaffolds and the advantageous metalbinding ability of histidine subunits. To this end, recently we have studied the copper(II) complexes of the tris(L-histidyl)-functionalized tren derivative, tren3his. Here we report the copper(II)-binding properties of the mono-and bis(L-histidyl)-functionalized tren ligands (tren1his (L 1 ) and tren2his (L 2 )), and thus explore the impact of increasing histidine 'density' on the copper(II) binding of these tripodal peptides. Our solution equilibrium study was supplemented by several (UV-vis, CD, ESR, and NMR) spectroscopic and MS methods. The mono-His derivative L 1 forms only mononuclear complexes. Above pH 4, the tren-like subunit is the main binding site, which is supplemented by an imidazole coordination. In the case of L 2 , both mono-and dinuclear copper(II) species are formed. In the acidic-neutral pH range, the highly stable bis-histamine-type binding mode dominates in the equimolar solution, while at a higher pH amide coordinated complexes are present. The bis-histamine coordination in CuHL 2 creates a preorganized structure, which promotes the binding of a second metal at the tren-like binding site with {N À ,N tert ,N À } coordination in Cu 2 H À1 L 2 /Cu 2 H À2 L 2 . Only the dinuclear Cu 2 H À2 L 2 complex was found to efficiently catalyze the oxidation of H 2 DTBC. The kinetic data resulted in a very high k cat /K M ratio (4360 M À1 s À1 ), which is due to the exceptionally strong substrate-binding ability of the dinuclear complex. However, the oxidation of the substrate within this adduct, which is a common feature of catalytically active dicopper(II) complexes, does not occur in the absence of dioxygen. This finding implies that the role of dioxygen is the oxidation of the substrate activated by the dinuclear complex. We assume a Cu(II)Cu(II)-catecholate-Cu(II)Cu(I)-semiquinone valence tautomer (VT) equilibrium. The semiquinone formed in small quantities reacts with dioxygen in a rate-determining step, which eventually results in DTBQ and H 2 O 2 products. The Cu(II)-L 2 complexes also exhibit efficient superoxide dismutase-like activity, supporting the versatility of tripodal peptide complexes in redox enzyme mimicking.

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Section: Oxidation Of 35-di-tert-butylcatechol (H 2 Dtbc)mentioning

confidence: 99%

On the copper(ii) binding of asymmetrically functionalized tripodal peptides: solution equilibrium, structure, and enzyme mimicking

et al. 2018

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“…13 In order to understand the activation of dioxygen by metalloenzymes a large number of biomimetic models of catechol oxidase have been studied. 14,43 Catechol oxidases are type 3 copper enzymes; 44,45 therefore mainly dinuclear complexes were used, [46][47][48][49][50][51] but several mono- 52,53 and trinuclear 13,41,54 species were also reported to have important catechol oxidase activity. Table 3 Spectroscopic parameters of the different copper(II) complexes observed, with estimated errors in parentheses (last digit) a Trinuclear complex spectra were described as the sum of mononuclear and broad singlet type spectra for which only g o values could be determined.…”

Section: Kinetic Studiesmentioning

confidence: 99%

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

et al. 2017

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“…Copper compounds were introduced as catalyst for oxidative alkane dehydrogenation . Also, copper complexes were used as catalyst for many organic reactions . In this work, six Cu(II)‐triazolophthalazine complexes were synthesized by reaction of the hydrazonophthalazines L 1 and L 2 shown in Scheme with copper (II) salts.…”

Section: Introductionmentioning

confidence: 99%

Cu(II)‐promoted cyclization of hydrazonophthalazine to triazolophthalazine; Synthesis and structure diversity of six novel Cu(II)‐triazolophthalazine complexes

Soliman

Albering

El‐Faham

2019

Applied Organom Chemis

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A novel route for the synthesis of Cu(II)-triazolophthalazine complexes using the Cu(II)-promoted cyclization dehydrogenation reactions of hydrazonophthalazines under reflux was presented. Two hydrazonophthalazines were cyclized to the corresponding triazolophthalazine ligands, 3-pyridin-2-yl-3,10b-dihydro- [1,2,4]triazolo[3,4-a]phthalazine (TPP) and 3-(3,10b-dihydro-[1,2,4]triazolo[3,4-a]phthalazin-3-yl)-benzoic acid (TP3COOH), followed by in situ complexation with Cu(II) yielding six novel Cu(II)-triazolophthalazine complexes depending on the reaction conditions. The molecular and supramolecular structures of the Cu(II)-triazolophthalazine complexes were discussed. The metal sites have rectangular pyramidal geometry in the [Cu(TPP)Cl 2 ] 2 ; 1 and [Cu(TP3COOEt)Cl 2 (H 2 O)] 2 ; 4 dinuclear complexes, distorted square planar in [Cu(TP3COOMe) 2 Cl 2 ]; 3, [Cu(TP3COOH) 2 Cl 2 ]; 5 and [Cu(TP3COOH) 2 Cl 2 ]·H 2 O; 6 and a distorted octahedral in [Cu(TPP)(H 2 O) 2 (NO 3 ) 2 ]; 2. Hirshfeld analysis showed that the O…H, C…H, Cl…H (except TP3COOH and 2), N…H and π-π stacking interactions are the most important intermolecular contacts. The π-π stacking interactions are the maximum for TP3COOH and complex 6 with net C…C/C…N contacts of 19.4% and 15.4%, respectively. The orbital-orbital interaction energies of the Cu-N/Cu-Cl bonds correlated inversely with the corresponding Cu-N/Cu-Cl distances, respectively. The charge transfer processes between Cu(II) and ligand groups were also discussed. The charge densities of the Cu(II) centers are reduced to 0.663-0.995 e due to the interactions with the ligand groups coordinating it.

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Catalytic catechol oxidation by copper complexes: development of a structure–activity relationship

Cited by 41 publications

References 42 publications

On the copper(ii) binding of asymmetrically functionalized tripodal peptides: solution equilibrium, structure, and enzyme mimicking

On the copper(ii) binding of asymmetrically functionalized tripodal peptides: solution equilibrium, structure, and enzyme mimicking

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

Cu(II)‐promoted cyclization of hydrazonophthalazine to triazolophthalazine; Synthesis and structure diversity of six novel Cu(II)‐triazolophthalazine complexes

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