Electrochemical Reduction of Quinones in Different Media: A Review

Guin, Partha Sarathi; Das, Saurabh; Mandal, P. C.

doi:10.4061/2011/816202

Cited by 346 publications

(281 citation statements)

References 220 publications

(327 reference statements)

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“…As described in [19,20,27], the stabilization of the electrode reaction products of redox reactions 2) and 3) can be achieved by hydrogen bonding with water molecules. Alternatively, the observed behavior of Q could be partially explained via a radical reaction mechanism [24][25][26]. However, from the stability of the cyclic voltammograms obtained by consecutive cycling we conclude that no radical reaction mechanism takes place under such conditions.…”

Section: Coq Oxidizedmentioning

confidence: 90%

“…The redox features of many hydrophilic and lipophilic Q and HQ have been intensively studied by various electrochemical methods [4,19,20,[24][25][26][27][28][29], but surprisingly, there are only few reports related to the electrochemical features of the simplest CoQ member, i.e. CoQ-0 [21][22][23].…”

Section: Voltammetry Of Coenzyme Q-0 In Buffered Water Solutionmentioning

confidence: 99%

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New insights into the chemistry of Coenzyme Q-0: A voltammetric and spectroscopic study

Gulaboski

Bogeski

Kokoškarova

et al. 2016

Bioelectrochemistry

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Coenzyme Q-0 (CoQ-0) is the only Coenzyme Q lacking an isoprenoid group on the quinoid ring, a feature important for its physico-chemical properties. Here, the redox behavior of CoQ-0 in buffered and non-buffered aqueous media was examined. In buffered aqueous media CoQ-0 redox chemistry can be described by a 2-electron-2-proton redox scheme, characteristic for all benzoquinones. In non-buffered media the number of electrons involved in the electrode reaction of CoQ-0 is still 2; however, the number of protons involved varies between 0 and 2. This results in two additional voltammetric signals, attributed to 2-electrons-1H + and 2-electrons-0H + redox processes, in which mono-and di-anionic compounds of CoQ-0 are formed. In addition, CoQ-0 exhibits a complex chemistry in strong alkaline environment. The reaction of CoQ-0 and OH − anions generates several hydroxyl derivatives as products. Their structures were identified with HPLC/MS. The prevailing radical reaction mechanism was analyzed by electron paramagnetic resonance spectroscopy. The hydroxyl derivatives of CoQ-0 have a strong antioxidative potential and form stable complexes with Ca 2+ ions. In summary, our results allow mechanistic insights into the redox properties of CoQ-0 and its hydroxylated derivatives and provide hints on possible applications.

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Section: Coq Oxidizedmentioning

confidence: 90%

Section: Voltammetry Of Coenzyme Q-0 In Buffered Water Solutionmentioning

confidence: 99%

New insights into the chemistry of Coenzyme Q-0: A voltammetric and spectroscopic study

Gulaboski

Bogeski

Kokoškarova

et al. 2016

Bioelectrochemistry

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“…The entropy contributions to the total free energies of reaction have been neglected because the entropies of reduction of quinones are found to be very similar 22,23 , and the E 0 of the oxidation-reduction system is linearly expressed as (−nF) −1 H f + b, where b is a constant. It was also assumed that the reduction of quinones takes place in a single-step reaction involving a two-electron twoproton process 9,24 . The total free energies of molecules were obtained from first-principles quantum chemical calculations within density functional theory (DFT) at the level of generalized gradient approximation (GGA) using the PBE functional 25 .…”

Section: Theory and Methodsmentioning

confidence: 99%

A metal-free organic–inorganic aqueous flow battery

Huskinson

Marshak

Suh

et al. 2014

Nature

1,401

1,331

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This paper can be cited as: B. Huskinson, M.P. Marshak, C. Suh, S. Er, M.R. Gerhardt, C.J. Galvin, X. Chen, A. Aspuru-Guzik, R.G. Gordon and M.J. Aziz, "A metal-free organicinorganic aqueous flow battery", Nature 505, 195-198 (2014).The formatted version of this manuscript can be found at the following link: http://www.nature.com/nature/journal/v505/n7482/full/nature12909.html A metal-free organic-inorganic aqueous flow batteryBrian Huskinson 1 *, Michael P. Marshak 1,2 *, Changwon Suh 2 , Süleyman Er 2,3 , Michael R. *These authors contributed equally to this work.As the fraction of electricity generation from intermittent renewable sources-such as solar or wind-grows, the ability to store large amounts of electrical energy is of increasing importance. Solid-electrode batteries maintain discharge at peak power for far too short a time to fully regulate wind or solar power output 1,2 . In contrast, flow batteries can independently scale the power (electrode area) and energy (arbitrarily large storage volume) components of the system by maintaining all of the electro-active species in fluid form 3-5 . Wide-scale utilization of flow batteries is, however, limited by the abundance and cost of these materials, particularly those using redox-active metals and precious metal electrocatalysts 6,7 . Here we describe a class of energy storage materials that exploits the favourable chemical and electrochemical properties of a family of molecules known as quinones. The example we demonstrate is a metal-free flow battery based on the redox chemistry of 9,10-anthraquinone-2,7-disulphonic acid (AQDS). AQDS undergoes extremely rapid and reversible two-electron two-proton reduction on a glassy carbon electrode in sulphuric acid. An aqueous flow battery with inexpensive carbon electrodes, combining the quinone/hydroquinone couple with the Br 2 /Br  redox couple, yields a peak galvanic power density exceeding 0.6 W cm Solutions of AQDS in sulphuric acid (negative side) and Br 2 in HBr (positive side) were pumped through a flow cell as shown schematically in Fig. 1a. The quinone-bromide flow battery (QBFB) was constructed using a Nafion 212 membrane sandwiched between Toray carbon paper electrodes (six stacked on each side) with no catalysts; it is similar to a cell described elsewhere (see figure 2 in ref. 7). We report the potential-current response (Fig. 1b) and the potential-power relationship ( measured with respect to the quinone side of the cell). As the SOC increased from 10% to 90%, the open-circuit potential increased linearly from 0.69 V to 0.92 V. In the galvanic direction, peak power densities were 0.246 W cm 2 and 0.600 W cm 2 at these same SOCs, respectively ( Fig. 1c). In order to avoid significant water splitting in the electrolytic direction, we used a cutoff voltage of 1.5 V, at which point the current densities observed at 10% and 90% SOCs were −2.25 A cm −2 and −0.95 A cm −2 , respectively, with corresponding power densities of −3.342 W cm −2 and −1.414 W cm −2 .In Fig. 2 we report the results of initial cy...

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“…Many of these natural CoQ-like compounds have immense importance in pharmaceutical and chemical industry [47,82]. Although there are numerous voltammetric studies already reported on some of these naturally occurring quinones [83], there is still much work to be done in order to recognize much closer the chemical features and the mechanisms of redox transformation of these compounds. For example, even recently it has been recognized that Coenzyme Q10 can undergo structural changes in the presence of the membrane-bound Cytochrome P450 enzyme [42].…”

Section: Future Perspectivesmentioning

confidence: 99%

Redox chemistry of coenzyme Q—a short overview of the voltammetric features

Gulaboski

Markovski

Zhu

2016

J Solid State Electrochem

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Quinones constitute a big family of organic redox active compounds that are overwhelmingly involved in important physiological processes. The most important members in the class of quinones are, indeed, the plastoquinones and the coenzyme Q (CoQ) derivatives. Voltammetry of coenzyme Q family members attracts significant attention since 50 years ago. In this work, we refer to some of the most important voltammetric features of coenzyme Qs studied in aprotic and in aqueous media. While the redox chemistry of coenzyme Q members in non-aqueous aprotic organic solvents can be described by two consecutive one-electron transfer steps, more complex situation exists in the voltammetry of coenzyme Qs performed in aqueous media. Although it has been claimed for a while that the voltammetric processes of coenzyme Qs in aqueous solutions proceed via formation of semiquinone radical intermediate species, it has been recently proven that this can be not completely true. Intensive voltammetric and spectroscopic studies of coenzyme Q systems in buffered and non-buffered aqueous media revealed that hydrogen bonding between electrochemically created CoQ species and the water molecules plays an important role in stabilizing electrochemically generated species of these systems. We also pay attention to the amazing redox chemistry of coenzyme Qs in strong alkaline media, while we refer to the chemical features of novel coenzyme Q derivatives obtained under such conditions. Hints are presented about the antioxidant capacity of some of the novel hydroxylated coenzyme Q systems. Also, the possibility of these systems to bind and transfer earth-alkaline cations across biomimetic membranes is shortly elaborated. In the end, we refer to some relevant theoretical works that describe closely the voltammetric behavior of various coenzyme Q systems. We believe that this short review will contribute towards better understanding of the amazing chemistry of coenzyme Q derivatives.

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Electrochemical Reduction of Quinones in Different Media: A Review

Cited by 346 publications

References 220 publications

New insights into the chemistry of Coenzyme Q-0: A voltammetric and spectroscopic study

New insights into the chemistry of Coenzyme Q-0: A voltammetric and spectroscopic study

A metal-free organic–inorganic aqueous flow battery

Redox chemistry of coenzyme Q—a short overview of the voltammetric features

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