Reaction of 1,5-diphenyl-3-arylverdazyles with СН-acids

Tanaseichuk, B. S.; Томилин, О. Б.; Pryanichnikova, M. K.; Tsebulaeva, Yu. V.; Boyarkina, O. V.

doi:10.1134/s1070428017050189

Cited by 3 publications

(5 citation statements)

References 14 publications

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“…The verdazyl cation 5 is present as the oxidized form, confirmed by ESI-MS in connection to the literature. 4,23 This form was proposed as oxidized species after the disproportionation by Kuhn and Trischmann and used by Tanaseichuk et al for their quantumchemical consideration of the disproportionation. 4,23 Reduction of the oxidized species 5 by a total of two electrons with two additional protons leads to reduced species 7.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…4,23 This form was proposed as oxidized species after the disproportionation by Kuhn and Trischmann and used by Tanaseichuk et al for their quantumchemical consideration of the disproportionation. 4,23 Reduction of the oxidized species 5 by a total of two electrons with two additional protons leads to reduced species 7. The reduced species is positively charged due to protonation in the acidic electrolytes.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The presumed disproportionation prevents the straight-forward use of verdazyl radicals in RFBs with acidic electrolytes. Follow-up studies investigated the disproportionation reaction further by evaluation of the kinetics with dimedone and acetylacetone, as well as the pH dependency of water-soluble verdazyl radicals. , However, a detailed understanding of the reaction after disproportionation and the electrochemical processes of the material class of verdazyl species in aqueous systems is still lacking.…”

Section: Introductionmentioning

confidence: 99%

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Unraveling the Electrochemistry of Verdazyl Species in Acidic Electrolytes for the Application in Redox Flow Batteries

et al. 2022

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Verdazyl radicals are a promising class of materials for the potential application in organic redox flow batteries. Although studies on the redox behavior of verdazyl radicals in organic solvents exist, only the disproportionation in aqueous acidic electrolytes is known. Herein, we address this knowledge gap by analyzing the verdazyl species after disproportionation with a series of electrochemical measurements, quantum-chemical calculations, and chemical characterizations to evaluate the redox chemistry. We thereby focused on the parent 1,3,5triphenylverdazyl radical to potentially expand the findings to other verdazyl derivatives. Two electrons participate in the investigated electrochemical reaction in acidic electrolytes, compared to the two distinguishable single-electron transfers in organic electrolytes. Participation of two protons in the reaction leads to a pH-dependent potential in the investigated pH window. The oxidized and reduced forms were investigated separately and exhibit reaction rate constants in the range of 10 −2 cm/s. Based on the obtained results, a detailed description of the redox behavior of verdazyl radicals is proposed. The high rate constants for the reaction connected with the utilization of two electrons pave the way to apply this material class in aqueous redox flow batteries, pending further structural modifications of the verdazyl radical.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Unraveling the Electrochemistry of Verdazyl Species in Acidic Electrolytes for the Application in Redox Flow Batteries

et al. 2022

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“…The high radical stability is attributed to the delocalization of the unpaired electron between the N1-N2 and N4-N5 atoms [122]. There is no spin delocalization at the C3 positions found because the SOMO has a nodal plane there [122,123]. Additional stabilizing resonances are obtained for the oxo-and thio-verdazyl radicals by the carbonyl and thiocarbonyl groups, respectively.…”

Section: Verdazyl Radicalsmentioning

confidence: 93%

“…Koivisto and Hicks [122] speculated that the lack of spin density at the C3 group would dampen the effect of substituents at C3 on the spin distribution. However, a combined experimental and theoretical study by Tanaseichuk et al [123] showed that substituents at C3 have strong effects on the SOMO energy and reaction barriers. The calculations were performed at B3LYP/6-31G(d) level of theory and focused on the determination of orbital energies and spin densities.…”

Section: Verdazyl Radicalsmentioning

confidence: 99%

Static theoretical investigations of organic redox active materials for redox flow batteries

Zaichenko,

Achazi,

Kunz

et al. 2023

Prog. Energy

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New efficient redox flow batteries (RFBs) are currently of great interest for large-scale renewable energy storage. Further development requires improvement of the redox active materials. Quantum chemical methods allow to screen large numbers of redox active molecules for required molecular properties. Especially the redox potentials are calculated in high-throughput studies. In addition, calculations of other properties such as solubility or stability and in-depth analysis of the electronic structure are performed on smaller number of molecules. This review provides an overview of various known classes of active material molecules and their results in quantum chemical calculations. We will focus on electronic structure methods such as density functional theory and wave function-based methods. Significant theoretical results are presented and discussed for each considered class of redox-active molecules. In addition, the various quantum chemical approaches are also examined, specifically with regard to their advantages and limitations. Another focus of this review is on comparing theoretically predicted results with experimental studies, which are discussed using various examples. Finally, further challenges and trends in the theoretical development of active materials are highlighted.

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