The electrochemistry of the ferri/ferrocyanide redox couple has been studied at An electrodes modified with calix[4]resorcinarenetetrathiol. Cyclic voltammetry in Fe(CN)(6)(3-) solutions yields three separate pairs of faradaic peaks. Evidence is given for these redox couples corresponding to the reduction of Fe(CN)(6)(3-) and the subsequent re-oxidation of Fe(CN)(6)(4-) in three differing steric arrangements. One pair of peaks suggest that when the Fe(CN)(6)(3-) ion resides within the calix[4]resorcinarene bowl, electron transport is facilitated by the calix[4]resorcinarene acting as a charge transfer mediator; in this arrangement the activation energy is found to be lowered by similar to24 kJ mol(-1). Another pair of peaks is thought to correspond to the reduction of Fe(CN)(6)(3-) as it approaches the An electrode by packing itself in-between adjacent calix[4]resorcinarene molecules. The third pair of redox peaks is attributed to the reduction and subsequent re-oxidation of Fe(CN)(6)(3-)/Fe(CN)(6)(4-) when the ion resides above a saturated calix[4]resorcinarene coating; in this case the activation energy was raised by similar to45 kJ mol(-1). FTIR spectroscopy of calix[4]resorcinarene-coated An electrodes and calix[4]resorcinarene-coated An electrodes exposed to Fe(CN)(6)(3-) lends further support to this argument, by demonstrating that the Fe(CN)(6)(3-) ion resides within at least two and possibly three differing environments. Calix[4]resorcinarene modified electrodes previously exposed to ferricyanide lose the calix[4]resorcinarene coating together with a surface layer of gold when subsequently scanned in a phosphate buffer. It therefore appears that the calix[4]resorcinarene/Fe(CN)(6)(3-) association is stronger than the An binding to the underlying glass material. (C) 2003 Elsevier Science B.V. All rights reserved.