A 2:1 receptor/C60 complex as a nanosized universal joint.

Buckycatcher II, a C51 H24 hydrocarbon with two corannulene pincers on a dibenzonorbornadiene tether, exhibits an affinity toward C60 in organic solvents that is dramatically higher than the original buckycatcher C60 H28 and other corannulene-based molecular receptors for fullerenes. In addition to the formation of an usual 1:1 C60 @catcher inclusion complex, a trimeric C60 @(catcher)2 assembly is detected in solutions and in the solid state. X-ray structure determination reveals a remarkable "universal joint" solvent-free crystal arrangement of the trimer, with a single fullerene cage wrapped by four corannulene subunits of two cooperating catcher receptors.