Probing carboxylate Gibbs transfer energies via liquid|liquid transfer at triple phase boundary electrodes: ion-transfer voltammetry versus COSMO-RS predictions

S M MacDonald, M Opallo, A Klamt, F Eckert, Frank Marken

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)

Abstract

Understanding liquid\liquid ion transfer processes is important in particular for naturally occurring species such as carboxylates. In this study electrochemically driven mono-, di-, and tri-carboxylate anion transfer at the 4-(3-phenylpropyl) pyridine\aqueous electrolyte interface is investigated experimentally for a triple phase boundary system at graphite electrodes. The tetraphenylporphyrinato-Mn(III/II) redox system (Mn(III/II)TPP) dissolved in the water-immiscible organic phase (4-(3-phenylpropyl) pyridine) is employed for the quantitative study of the structure-Gibbs transfer energy correlation and the effects of the solution pH on the carboxylate transfer process. For di- and tri-carboxylates the partially protonated anions are always transferred preferentially even at a pH higher than the corresponding pK(a). COSMO-RS computer simulations are shown to provide a quantitative rationalisation as well as a powerful tool for predicting Gibbs free energy of transfer data for more complex functionalised carboxylate anions. It is shown that the presence of water in the organic phase has a major effect on the calculated Gibbs free energies.
Original languageEnglish
Pages (from-to)3925-3933
Number of pages9
JournalPhysical Chemistry Chemical Physics
Volume10
Issue number26
Early online date21 May 2008
DOIs
Publication statusPublished - 14 Jul 2008

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