Loops of interconnected benzene rings have long fascinated chemists, who have now developed a more flexible way to string the rings together.

Kenichiro Itami and his co-workers at Nagoya University in Japan created the loop, or cycloparaphenylene (CPP, pictured below left), by first coupling L-shaped and linear molecules to form U-shaped ones. They then combined two of these molecules to form the desired O-shaped CPP.

This modular approach has potential for producing specific CPPs of any size greater than 13 benzene rings. The loops could be useful for fabricating single-walled carbon nanotubes of specific diameter, by growing the loops horizontally (pictured right).

Credit: WILEY

Angew. Chem. Int. Edn doi:10.1002/anie.201005734 (2010)