Facile Synthesis of Nitrogen-Doped [(6.)<sub><i>m</i></sub>8]<sub><i>n</i></sub>Cyclacene Carbon Nanobelts by a One-Pot Self-Condensation Reaction
Zhu Jun, Yi Han, Yong Ni, Guangwu Li, Jishan Wu
Abstract
Synthesis of fully conjugated carbon nanobelts (CNBs) remains one of the biggest challenges in organic chemistry. Herein, we report a facile synthesis of four nitrogen-doped [(6.)m8]ncyclacene CNBs (m = 1–3; n = 3,4) with different sizes by a one-pot self-condensation reaction of three bis(o-aminobenzophenone) precursors. The belt-shaped structure was confirmed by X-ray crystallographic analysis. The existence of eight-membered [1,5]diazocine rings releases the strain while maintaining weak π-conjugation throughout the belt backbone, which is supported by electronic absorption spectra and frontier molecular orbital analysis. NMR measurements and magnetic shielding calculations suggest an alternating aromatic–nonaromatic ring structure, with a slightly more shielded chemical environment in the cavity. Our method opens the opportunities to access more sophisticated π-conjugated 2D/3D belt-/cage-like molecules in a simple way.