Fluorine-studded nanohoops assembled in 1 pot

Chemists have come up with a new twist on cycloparaphenylenes—carbon nanohoops made up of benzene rings strung together at their para positions. By replacing all the nanohoops’ hydrogens with fluorines, researchers led by Nagoya University’s Kenichiro Itami and Yasutomo Segawa have created perfluorocycloparaphenylenes (PFCPPs). These nanohoops feature aromatic rings that twist out of alignment because of steric repulsion between their fluorine atoms. Itami and Segawa’s team made PFCPPs using a one-pot procedure that starts with deprotonation of octafluorobiphenyl. The chemists then added a macrocyclic nickel catalyst, which pulled the fluorinated biphenyl molecules together. Oxidant-promoted reductive elimination stitched the C–C bonds together to produce a mixture of PFCPPs with 10 (shown), 12, 14, and 16 aromatic rings (Nat. Commun. 2022, DOI: 10.1038/s41467-022-31530-x). The fluorinated nanohoops have several potential applications. They can act as hosts for host-guest chemistry and be used for electron transport or as light-emitting materials. Also, Itami says in an email, “By taking advantage of reactive C–F bonds, these can be starting materials for longer carbon nanobelts or even longer carbon nanotubes.”