Electrochemical and 1H NMR studies on the complexation of hexacyanoferrate(II) anions by aminocyclodextrins

Luis A. Godínez, James Lin, Marc Muñoz, Anthony W. Coleman, Angel E. Kaifer

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Abstract

The complexation of the hexacyanoferrate(II) anion by three modified cyclodextrins [hexakis(6-deoxy-6-amino-)-α-CD (1), heptakis(6-deoxy-6-amino)-β-CD (2), and octakis(6-deoxy-6-amino)-γ-CD (3)] has been studied by cyclic voltammetry and 1H NMR in moderately acidic aqueous media. The binding constants of hexacyanoferrate(ii) with the three hosts were estimated by computer simulation of the voltammetric data, and were found to fall in the ranges 3 × 105-106 dm3 mol-1 and 2-5 × 103 dm3 mol-1 for the reduced and oxidized forms of the anion, respectively. The reduced form (-4 charge) of the guest is always more strongly bound to any of the positive charged aminocyclodextrins than the oxidized form (-3 charge). This finding, along with the magnitude of the Gibbs energies of complexation, suggests that the binding interactions are essentially electrostatic in nature. Based on the 1H NMR spectroscopic data, complexation seems to take place by partial inclusion of the anionic guest inside the cavity of the CD receptors.

Original languageEnglish (US)
Pages (from-to)645-650
Number of pages6
JournalJournal of the Chemical Society - Faraday Transactions
Volume92
Issue number4
DOIs
StatePublished - Jan 1 1996

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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