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 (23)Na 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 (Fe(2+) to Fe(3+)) effectively inhibited ion transport.