| Abstract
| - The electrochemical oxidation of lutetium bis(tetra-tert-butylphthalocyaninato) (LBPC) and decamethylferrocene(DMFC), as well as the reduction of LBPC, lutetium bis(phthalocyaninato) (LPC), and lutetium (tetra-tert-butylphthalocyaninato hexadecachlorphthalocyaninato) (LBPCl), has been studied in a thin nitrobenzene (NB) filmdeposited on the surface of a graphite electrode (GE) bymeans of square-wave voltammetry (SWV). The organicfilm-modified electrode was immersed in an aqueous (W)electrolyte solution and used in a conventional three-electrode configuration. When the aqueous phase contains ClO4-, NO3-, or Cl- (ClO4-, or NO3- only, in thecase of DMFC), both LBPC and DMFC are oxidized tostable monovalent cations in the organic phase. Theelectron transfer at the GE | NB interface is accompaniedby a simultaneous anion transfer across the W | NBinterface to preserve the electroneutrality of the organicphase. LBPC, LPC, and LBPCl are reduced to stablemonovalent anions accompanied by expulsion of the anionof the electrolyte from the organic into the aqueous phase.In all cases, the overall electrochemical process comprises simultaneous electron and ion transfer across twoseparate interfaces. Under conditions of SWV, the overallelectrochemical process is quasireversible, exhibiting awell-formed “quasireversible maximum” that is an intrinsic property of electrode reactions occurring in a limitingdiffusion space. For all the redox compounds that havebeen studied, the kinetics of the overall electrochemicalprocess is controlled by the rate of the ion transfer acrossthe liquid | liquid interface. Based on the quasireversiblemaximum, a novel and simple methodology for measuringthe rate of ion transfer across the liquid | liquid interfaceis proposed. A theoretical background explaining the roleof the ion-transfer kinetics on the overall electrochemicalprocess at the thin organic film modified electrode underconditions of SWV is presented. Comparing the positionsof the theoretical and experimental quasireversible maximums, the kinetics of ClO4-, NO3-, and Cl- across theW | NB interface was estimated. The kinetics of the overallprocess at the thin organic film modified electrode,represented by the second-order standard rate constant,is 91 ± 8, 90 ± 4, and 133 ± 10 cm4 s-1 mol-1, for thetransfer of ClO4-, NO3-, and Cl- respectively.
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