ABSTRACT
The reversibility of a signaling system is essential for many applications, for ex ample, those involving continuous monitoring. Nevertheless, such reversibility of signaling requires genuine receptors in the supramolecular [137] sense, that
is, those with reversibility of analyte binding over relatively short timescales operating via noncovalent interactions. This requirement becomes a burden in many cases when we step beyond atomic analytes. The palette of suitably re versible receptors, while expanding all the time, still has not built up to the point of designating many important molecular analytes. One reason is the relatively short history of supramolecular chemistry [137] vis-a-vis inorganic coordination chemistry.
