Fully conjugated chrysaorene. Redox-coupled anion binding in a tetraradicaloid macrocycle.
Chrysaorene, a fully conjugated carbocyclic coronoid, is shown to be a low-bandgap π-conjugated system with a distinct open-shell character. The system shows good chemical stability and can be oxidized to well-defined radical cation and dication states. The cavity of chrysaorene acts as an anion receptor toward halide ions with a particular selectivity toward iodides (Ka = 207 ± 6 M–1). The interplay between anion binding and redox chemistry is demonstrated using a 1H NMR analysis in solution. In particular, a well-resolved, paramagnetically shifted spectrum of the chrysaorene radical cation is observed, providing evidence for the inner binding of the iodide. The radical cation–iodide adduct can be generated in thin solid films of  chrysaorene by simple exposure to diiodine vapor.