Electrochemical study of lithium(I) interactions with radical anions derived from 9,10-anthraquinone and 1-hydroxy-9,10-anthraquinone by cathodic reduction in N,N-dimethylformamide solutions

Electrochemical ESR and Voltammetric Studies of Lithium Ion Pairing with Electrogenerated 9,10-Anthraquinone Radical Anions Either Free in Acetonitrile Solution or Covalently Bound to Multiwalled Carbon Nanotubes

“…37 A simulated spectrum using these hyperfine couplings and a Gaussian line width of 0.015 mT is shown in Figure 4b and displays good qualitative agreement in terms of relative line intensities. It should be noted that hyperfine The spectrum obtained upon electrolysis of 0.25 mM anthraquinone at the same flow rate and potential as above, but in the presence of 0.25 mM LiClO 4 , was found to be qualitatively very similar to that observed in the absence of any Li + , demonstrating no further hyperfine splitting due to coupling with magnetic 6 Li and 7 Li nuclei, nor any alternating line width effects. The two measured proton hyperfine coupling constants (0.032 and 0.099 mT) were also unchanged within experimental error.…”

“…The importance of electrolyte identity and the influence of ion pairing on the voltammetric reduction of quinones has been the focus of much investigation, particularly in aprotic solvents where the electrochemical reduction takes place in two single electron steps [1][2][3][4][5][6][7][8][9][10][11][12] Cations present in the supporting electrolyte interact with radical anions and dianions formed, the level of their association depending on the identity of both ions and the solvent employed. In the presence of tetraalkylammonium cations in aprotic solvents, for example, it is often assumed that the degree of ion pairing is small enough to be neglected and, hence, their widespread use in electrolyte solutions.…”

“…The importance of electrolyte identity and the influence of ion pairing on the voltammetric reduction of quinones has been the focus of much investigation, particularly in aprotic solvents where the electrochemical reduction takes place in two single electron steps − Cations present in the supporting electrolyte interact with radical anions and dianions formed, the level of their association depending on the identity of both ions and the solvent employed. In the presence of tetraalkylammonium cations in aprotic solvents, for example, it is often assumed that the degree of ion pairing is small enough to be neglected and, hence, their widespread use in electrolyte solutions. , However, alkali metal cations have a tendency to form complexes with organic anions, which can have a dramatic effect on the observed voltammetry and is manifested in the shifting of voltammetric reduction peaks to less negative potentials as the anions are thermodynamically stabilized by the ion pairing interaction.…”

Electrochemical lithiation-induced polymorphism of anthraquinone derivatives observed by operando X-ray diffraction

“…In general, such applications treat the anthraquinone (AQ) moiety as a single molecule, capable of undergoing two one-electron reductions, one at each carbonyl, while structural considerations are largely neglected. While some work notes the impact lithium ion pairing has on anthraquinone's voltammetric response, [16][17][18] there is no characterization of the ion pair's identity. Other work notes that the AQ crystal structure reforms reversibly when recharged in a lithium battery, 19 but any demonstration of structural transformations during the charge/discharge processes is glaringly omitted/absent.…”

Association Reactions of the Anion Radicals of Some Hydroxyquinones: Evidence for Formation of π- and σ-Dimers As Well As a Neutral−Anion Radical Complex

“…Hydroxyquinones are of significant interest owing to their important biological functions. There have been numerous electrochemical studies of the reduction of a variety of hydroxyquinones, − studies which have revealed several effects of hydroxyl substituents including self-protonation, in which the initially formed anion radical is protonated by the neutral quinone, and stabilization of reduced forms of the quinone by intramolecular hydrogen bonding between the hydroxylic proton and a quinoidal oxygen.…”