New Chemical Insights Using Weakly Supported Voltammetry: Ion Pairing in the EC₂ Reduction of 2,6‐Diphenylpyrylium in Acetonitrile

Abstract

Pairing effect: Varying the concentration of support electrolyte in the electrochemical EC(2) reduction of 2,6-diphenylpyrylium reveals the presence of ion pairing between the electroactive species and BF(4)(-). Experiment and theory are shown to be in good agreement only if ion pairing is included in the simulations. This previously unanticipated effect is only observable if voltammetry is performed under conditions of weak support.

Recent Advances in Voltammetry

“…This boundary condition may then be used with the Nernst–Planck–Poisson system of equations to numerically generate a potential profile and species concentration profiles across the solution. This method has been shown to be successful in simulating diverse experimental data, at both micro and macro electrodes,– and is used to obtain theoretical results discussed in sections 5.2 to 5.4.…”

“…The literature reports a large range of values for k dim from 2.5×10 7 dm 3 mol −1 s −1 to 2.5×10 9 dm 3 mol −1 s −1 . Barnes et al . investigated this reduction at a range of concentrations of tetrabutylammonium tetrafluoroborate supporting electrolyte, and using simulation, were unable to reproduce experimental data across the whole range of supporting electrolyte concentration used.…”

Steady-state voltammetry at a microdisc electrode in the absence of excess supporting electrolyte for reversible, quasi-reversible and irreversible electrode kinetics

“…[10][11][12][13][14][15][16] The added complexity can be used, for example, to investigate mechanistic pathways invisible to conventional, 'diffusion-only', techniques. 17,18 Despite both techniques providing useful scientific insight, the use of both simultaneously has been limited by a need for accurate theoretical methods. [19][20][21] In general, chemical systems are most thoroughly investigated by means of a combination of theoretical and experimental techniques.…”