A versatile synthesis of electroactive stilbenoprismands for effective binding of metal cations

A versatile synthesis of a new class of polyaromatic receptors (stilbenoprismands) containing a Delta-shaped cavity similar to that of the pi-prismand together with an intimately coupled electroactive stilbenoid moiety was accomplished via an efficient intramolecular McMurry coupling reaction. The presence of the Delta-shaped cavity in stilbenoprismands allows an efficient binding of a single silver cation as probed by (1)H NMR spectroscopy. Electron-rich stilbenoprismands undergo a ready oxidation to their highly robust cation-radical and dicationic salts. X-ray structure determination of a representative dicationic stilbenoprismand showed that the charges were largely localized on the tetraarylethylene moiety, which results in a twisting of the ethylenic C=C bond by approximately 35 degrees. Moreover, the electronic coupling among the stilbenoid and pi-prismand moieties in various stilbenoprismands was briefly probed by optical methods.