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An electrochemical analysis strategy based on the Marcus–Hush approximation is presented to analyze the kinetic component of organic redox flow battery (RFB) electrolytes. The procedure was applied to aqueous solutions of methyl viologen (MV) and 2,2′-bipyridyl (diquat, DQ) derivatives as model redox-active electrolytes; although these systems are promising negolyte candidates in organic RFBs, their electrode kinetics continues to be unclear. For compound MV, the voltammetric analysis revealed an adsorption process of electrogenerated species to the glassy carbon electrode surface, so its electron transfer rate constant k s should not be estimated by applying outer sphere electron transfer formulations. For the remaining compounds studied, experimental k s values were obtained and they range from 0.22 to 0.62 cm s–1. Quantum chemical modeling was applied not only to decipher properties of the adsorption process of the MV structure but also to rationalize the kinetic differences in compounds studied through their total and inner reorganization energies. This experimental and theoretical approach allowed elucidation of the kinetic component of compounds studied, revealing that k s values for MV and DQ compound derivatives should not exhibit the reported differences of at least one order of magnitude. Finally, the experimental k s value (0.62 cm s–1) obtained for compound 5,5′-DMDQ is the largest value reported to date in the literature of aqueous organic RFBs, which makes it a strong anolyte candidate.

We study the influence of the interparticle and confining potentials on statistical correlation via the correlation coefficient and mutual information in ground and some excited states of the Moshinsky atom in position and momentum space. The magnitude of the correlation between positions and between momenta is equal in the ground state. In excited states, the correlation between the momenta of the particles is greater than between their positions when they interact through an attractive potential whereas for repulsive interparticle potentials the opposite is true. Shannon entropies, and their sums (entropic formulations of the uncertainty principle), are also analyzed, showing that the one-particle entropy sum is dependent on the interparticle potential and thus able to detect the correlation between particles.

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Shannon entropies of the pair density, conditional entropies, and mutual information are studied in position and in momentum space for ground state neutral atoms and selected excited states at the Hartree-Fock level. We show that the mutual information, a measure of correlation, is larger in position space than in momentum space. This result also holds for a mutual information defined in terms of the exchange density; however, these quantities display much more structure than the corresponding ones based on the pair densities. The interpretation of this behavior is that exchange effects are smaller in momentum space than in position space in these systems.