Interlocked host rotaxane and catenane structures for sensing charged guest species via optical and electrochemical methodologies

The potential of interlocked host rotaxane and catenane structures as innovative optical and electrochemical sensors is highlighted. Interlocked structures can be engineered to bind specific guests within the topologically constrained three dimensional cavities created during their template-driven syntheses. This binding ability, when coupled to the signal transduction capabilities associated with appended reporter groups and their dynamic structures, make catenanes and rotaxanes highly promising candidates for the development of molecular sensors. With the ultimate challenge of fabricating highly selective anion sensing configurations, a three-staged strategy has been followed. First, we developed a general anion templation methodology for the construction of a variety of interpenetrated and interlocked molecular structures. [2]Rotaxanes and [2]catenanes synthesised using this novel protocol show, after template removal, favourable selective anion binding characteristics distinct from their separate components. At the second stage, the incorporation of redox- and photo-active groups into these interlocked frameworks converts them into electrochemical/optical molecular sensors. In the final third stage, the confinement of interlocked anion receptors at surfaces results in the fabrication of devices exhibiting highly selective binding and electrochemical and/or optical sensing behaviour.