A Möbius Carbon Nanobelt Accomplished

Key words

Möbius ring - carbon nanobelts - Z-selective Wittig reaction - molecular topology

Significance

Molecular structures with novel topological features are appealing targets to both synthetic and materials chemistry researchers. For the first time, a fully conjugated, all-sp²-carbon nanobelt­ with the topology of a Möbius band is accomplished. The achievement relies on a smart design of incorporating and stitching an odd number of all Z-configured stilbene moieties into continually fused phenanthrene groups. The topological chirality manifested by the Möbius nanobelt is proven by circular dichroism spectroscopy after resolving the enantiomers with chiral HPLC.

Comment

Using a stepwise chain-extension strategy, a large macrocycle comprising five repeated units of hexabromo-substituted bis(phenanthrenylvinyl)benzene is synthesized. By virtue of the Z-selective Wittig protocol facilitated stereochemistry control, the Möbius topology is realized in the ring-closure step. Upon subsequent nickel-catalyzed intramolecular aryl coupling to avail ring fusion, (25,25)MCNB (Möbius carbon nanobelt) is successfully obtained.