Redox processes of 2,6-dichlorophenolindophenolate in different solvents. A combined electrochemical, spectroelectrochemical, photochemical, and theoretical study

Dvoranová, Dana; Barbieriková, Zuzana; Dorotíková, Sandra; Malček, Michal; Brincko, Adam; Rišpanová, Lucia; Bučinský, Lukáš; Staško, Andrej; Brezová, Vlasta; Rapta, Peter

doi:10.1007/s10008-015-2823-x

Cited by 8 publications

(11 citation statements)

References 38 publications

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“…Note that, in a proton-donating solvent, the potentials of both reduction and oxidation processes were shifted to the more positive values versus the internal potential standard Fc + /Fc, and additionally, a broad reduction peak appeared during the reverse scan in the cyclic voltammogram at a strongly negatively shifted potential (Figure c). A distinct oxidation pattern of the corresponding voltammograms in protic media is caused by the involvement of protons in the process in accordance with chemical oxidations discussed previously and the well-known reaction mechanism proposed for the quinone-like systems. , …”

Section: Solution Equilibrium Studiessupporting

confidence: 85%

“…A distinct oxidation pattern of the corresponding voltammograms in protic media is caused by the involvement of protons in the process in accordance with chemical oxidations discussed previously and the well-known reaction mechanism proposed for the quinone-like systems. 70,71 Similar redox behavior was observed for the anodic oxidation of HL 1a ′ in DMSO with several new redox-active species, which appeared upon the first and the second voltametric scans (Figure S12a). However, the oxidized 1,4benzoquinone imine species HL 1a ″can be reversibly reduced in the cathodic part (Figure S12b) with a voltammetric pattern characteristic for the electrochemistry of quinones in aprotic media.…”

Section: ■ Solution Equilibrium Studiessupporting

confidence: 66%

“…After the complexes were mixed with GSH, a well-detectable change is observed due to the formation of ternary complexes via the coordination of GSH as it was reported for several TSC complexes. 70 , 71 Then the spectral changes show the absorbance decrease at the λ max of the S → Cu charge transfer band of the complexes. The final spectra show a strong similarity to those of HL 1 and HL 3 at λ > 310 nm suggesting the release of the TSCs.…”

Section: Solution Equilibrium Studiesmentioning

confidence: 99%

Section: Solution Equilibrium Studiesmentioning

confidence: 99%

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Triapine Analogues and Their Copper(II) Complexes: Synthesis, Characterization, Solution Speciation, Redox Activity, Cytotoxicity, and mR2 RNR Inhibition

et al. 2021

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Three new thiosemicarbazones (TSCs) HL 1 – HL 3 as triapine analogues bearing a redox-active phenolic moiety at the terminal nitrogen atom were prepared. Reactions of HL 1 – HL 3 with CuCl 2 ·2H 2 O in anoxic methanol afforded three copper(II) complexes, namely, Cu(HL 1 )Cl 2 ( 1 ), [ Cu(L 2 )Cl] ( 2′ ), and Cu(HL 3 )Cl 2 ( 3 ), in good yields. Solution speciation studies revealed that the metal-free ligands are stable as HL 1 – HL 3 at pH 7.4, while being air-sensitive in the basic pH range. In dimethyl sulfoxide they exist as a mixture of E and Z isomers. A mechanism of the E/Z isomerization with an inversion at the nitrogen atom of the Schiff base imine bond is proposed. The monocationic complexes [Cu(L 1 – 3 )] + are the most abundant species in aqueous solutions at pH 7.4. Electrochemical and spectroelectrochemical studies of 1 , 2′ , and 3 confirmed their redox activity in both the cathodic and the anodic region of potentials. The one-electron reduction was identified as metal-centered by electron paramagnetic resonance spectroelectrochemistry. An electrochemical oxidation pointed out the ligand-centered oxidation, while chemical oxidations of HL 1 and HL 2 as well as 1 and 2′ afforded several two-electron and four-electron oxidation products, which were isolated and comprehensively characterized. Complexes 1 and 2′ showed an antiproliferative activity in Colo205 and Colo320 cancer cell lines with half-maximal inhibitory concentration values in the low micromolar concentration range, while 3 with the most closely related ligand to triapine displayed the best selectivity for cancer cells versus normal fibroblast cells (MRC-5). HL 1 and 1 in the presence of 1,4-dithiothreitol are as potent inhibitors of mR2 ribonucleotide reductase as triapine.

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Section: Solution Equilibrium Studiessupporting

confidence: 85%

Section: ■ Solution Equilibrium Studiessupporting

confidence: 66%

Section: Solution Equilibrium Studiesmentioning

confidence: 99%

Section: Solution Equilibrium Studiesmentioning

confidence: 99%

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Triapine Analogues and Their Copper(II) Complexes: Synthesis, Characterization, Solution Speciation, Redox Activity, Cytotoxicity, and mR2 RNR Inhibition

et al. 2021

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“…The irreversible oxidation wave at E pa = 0.1 V vs. Fc + /Fc (Figure 2b) can be only seen for complex 3 with potentially redox-active 2,6-dimethyl-4-aminophenol unit. A similar response was observed for the corresponding proligand HL 3 (Figure S4b, ESI †), likely indicating oxidation of the 2,6-dimethyl-4-aminophenol moiety [65,66]. In situ spectroelectrochemistry in 0.1 M nBu 4 NPF 6 /DMSO solution provides further evidence for chemical irreversibility of the reduction process, as shown for 2 in Figure 3.…”

Section: Electrochemistry and Spectroelectrochemistrysupporting

confidence: 65%

Coumarin-Based Triapine Derivatives and Their Copper(II) Complexes: Synthesis, Cytotoxicity and mR2 RNR Inhibition Activity

et al. 2021

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A series of thiosemicarbazone-coumarin hybrids (HL1-HL3 and H2L4) has been synthesised in 12 steps and used for the preparation of mono- and dinuclear copper(II) complexes, namely Cu(HL1)Cl2 (1), Cu(HL2)Cl2 (2), Cu(HL3)Cl2 (3) and Cu2(H2L4)Cl4 (4), isolated in hydrated or solvated forms. Both the organic hybrids and their copper(II) and dicopper(II) complexes were comprehensively characterised by analytical and spectroscopic techniques, i.e., elemental analysis, ESI mass spectrometry, 1D and 2D NMR, IR and UV–vis spectroscopies, cyclic voltammetry (CV) and spectroelectrochemistry (SEC). Re-crystallisation of 1 from methanol afforded single crystals of copper(II) complex with monoanionic ligand Cu(L1)Cl, which could be studied by single crystal X-ray diffraction (SC-XRD). The prepared copper(II) complexes and their metal-free ligands revealed antiproliferative activity against highly resistant cancer cell lines, including triple negative breast cancer cells MDA-MB-231, sensitive COLO-205 and multidrug resistant COLO-320 colorectal adenocarcinoma cell lines, as well as in healthy human lung fibroblasts MRC-5 and compared to those for triapine and doxorubicin. In addition, their ability to reduce the tyrosyl radical in mouse R2 protein of ribonucleotide reductase has been ascertained by EPR spectroscopy and the results were compared with those for triapine.

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Light‐Driven NADPH Cofactor Recycling by Photosystem I for Biocatalytic Reactions

et al. 2023

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Biocatalytic asymmetric reduction of C=C and C=O bonds is highly attractive to produce valuable (chiral) chemicals for the fine and pharmaceutical industry, yet occurs at the expense of reduced nicotinamide adenine dinucleotide coenzyme NADPH that requires recycling. Established methods each have their challenges. Here we developed a light‐driven approach based on photosystem I (PSI) by mimicking the natural electron transfer from PSI via ferredoxin (Fd) towards ferredoxin NADP+ reductase (FNR) in vitro. Illumination with red light led to reduction of NADP+ to NADPH with a turnover frequency of 2.55 s−1 (>9000 h−1) at pH 7.5. Light‐driven NADPH regeneration by PSI‐Fd‐FNR was coupled with three oxidoreductases for asymmetric reduction of C=C and C=O bonds, reaching up to 99 % conversion with a turnover number of 3035, and retaining enantioselectivity. This study demonstrates the capacity of a PSI system to drive continuous NADPH‐dependent biocatalytic conversions with light.

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Redox processes of 2,6-dichlorophenolindophenolate in different solvents. A combined electrochemical, spectroelectrochemical, photochemical, and theoretical study

Cited by 8 publications

References 38 publications

Triapine Analogues and Their Copper(II) Complexes: Synthesis, Characterization, Solution Speciation, Redox Activity, Cytotoxicity, and mR2 RNR Inhibition

Triapine Analogues and Their Copper(II) Complexes: Synthesis, Characterization, Solution Speciation, Redox Activity, Cytotoxicity, and mR2 RNR Inhibition

Coumarin-Based Triapine Derivatives and Their Copper(II) Complexes: Synthesis, Cytotoxicity and mR2 RNR Inhibition Activity

Light‐Driven NADPH Cofactor Recycling by Photosystem I for Biocatalytic Reactions

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