Synthesis and characterization of a redox-active ion channel supporting cation flux in lipid bilayers.

The synthesis, cation binding and transmembrane conductive properties of a novel synthetic ion channel containing a redox-active ferrocene unit are described. Fluorescence spectroscopy was used to demonstrate that the channel supports multiple ion coordination and association constants for 1:1 and 1:2 (channel:cation) coordination for both Na+ and K+ were evaluated. Experiments using a black lipid membrane preparation revealed that this compound functioned effectively as an ion channel for both Na+ and K+. Concomitant 23Na NMR spectroscopy studies supported this finding and revealed a Na+ flux, at least 5 times higher than ion transport rates by monensin. Furthermore, oxidation of the redox-active centre (Fe2+ to Fe3+) effectively inhibited ion transport.