[n]Cycloparahenylenes ([n]CPPs), or “nanohoops”, are unique among curved aromatic molecules in that they exhibit an inherent electron-rich pore reminiscent of the inner channel of a carbon nanotube (CNT). However, the utility of [n]CPPs as a porous solid-state material is limited by their tendency to adopt a herringbone-like packing motif in the solid state. Recently, we have found that, through judicious fluorination of the [n]CPP backbone, weak arene-perfluoroarene interactions can be invoked to afford columnar arrays of these fluorinated nanohoops in the solid state. Based on a highly modular synthetic route, we believe this general approach will allow for the construction of porous solids with sub-nanometer control over channel widths. Exploiting the well-established host-guest chemistry between [n]CPPs and fullerenes, we have demonstrated that the fluorinated analog of [10]CPP can encapsulate C60 and align it linearly in the solid state, not unlike CNT@C60 peapods. Moreover, fluorescence quenching experiments have shown that solution-cast thin films of this fluorinated nanohoop are capable of uptaking C60 from solution, a phenomenon not observed with the all-hydrocarbon [10]CPP. Current work is focused on further exploring the guest templating capabilities of these fluorinated nanohoops as well as studying the effects of extended fluorination on the properties of [n]CPPs.

Controlling the solid-state self-assembly of [n]cycloparaphenylenes through weak organofluorine interactions

255th National Meeting (2018)

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