Crystal Structure of a Cyclotetraicosaphenylene

The biggest known quasi-rigid macrocycle is the cyclotetraicosaphenylene 1. Determining the X-ray crystal structure was a challenge which took more than a year. The three-dimensional packing shows the molecules to be piled up like coins or more precisely like garden chairs, giving rise to potentially endless tubes with diameters of ca. 28 Å. In the crystal these channels are filled with liquid solvent which is amorphously frozen during data collection at 133 K. In principle, it should be possible to replace the solvent molecules in the channels by metal atoms forming quantum wires.