Estimation of individual Gibbs energies of cation transfer employing the insertion electrochemistry of solid Prussian blue

Electroanalytical chemistry for the analysis of solids: Characterization and classification (IUPAC Technical Report)

“…Solid state voltam metric techniques permit determination of the thermodynamic properties of compounds [150] and individual guest species entrapped into microporous solid systems [144,151]. Recent approaches involve measurement of individual Gibbs free energies of anion [153] and cation [154] transfer between two solvents. The study of size selectivity and the determination of diffusion coefficients for electrons and ions in solid materials can also be obtained from solid state electrochemical experiments [155]; in particular, for processes involving cation [156,157] and anion [158] diffusion in micro-and mesoporous aluminosilicates, as well as metal-organic frameworks [159,160].…”

Solvent-Independent Electrode Potentials of Solids Undergoing Insertion Electrochemical Reactions: Part I. Theory

“…Accordingly, only the partial electron-transfer process described by eq would be solvent-independent. The solvent-independent redox potential E L m +/( m – n )+ ⊖ could be calculated under voltammetric conditions from the voltammetric midpeak potentials provided that the equilibrium constant of the partial process described by eq and the thermochemical activities of the oxidized and reduced forms of the solid and M + ions in the electrolyte bulk could be estimated as: In principle, K could be estimated as described in the precedent section, while a M solution + could be obtained from experimental E mp versus log a M solution + plots assuming that the coefficients of activity tends to unit at low concentrations, as already described. − …”

“…In several instances, however, the formation of bilayered structures has been reported. , Obviously, experimental testing is needed with this regard. On first examination, the aforementioned Prussian blue and alkynyl–diphosphine dinuclear Au­(I) complexes and heterometallic Au­(I)–Cu­(I) cluster complexes containing ferrocenyl units , could be plausible solids usable as solvent-independent redox systems. Among others, possible candidates could also be hybrid inorganic–organic materials consisting of electroactive species entrapped into inert supports such as zeolites , or Maya Blue. − Interestingly, the use of different L, S, and so on systems could be used to test the self-consistency of the proposed approach: constant E L m + /L ( m – n )+ ⊖ – E S m + S ( m – n )+ ⊖ differences should be obtained regardless the solvent.…”

“…In prior works the voltammetry of microparticles (VMP) methodology, a solid-state technique developed by Scholz et al, , has been applied to determine individual Gibbs energies of transfer of cation and anion , between two miscible solvents. In this report, a theoretical modeling is proposed that is potentially usable to define solvent-independent redox systems combining voltammetric and chronoamperometric measurements on selected ion-insertion solids.…”

“…Application of this method to define solvent-independent potentials involves two extra-thermodynamic assumptions: (i) there is no accumulation of net charge in the solid complex/electrolyte boundary and (ii) the structures of the solid and the ion binding to the solid are not affected by the solvent. Prior data on the solid-state electrochemistry of Prussian Blue and alkynyl–diphosphine dinuclear Au­(I) complexes and heterometallic Au­(I)–Cu­(I) cluster complexes containing ferrocenyl units , make such systems reasonable candidates for making the proposed method operative.…”