Large N-Doped Zigzag Hydrocarbon Belts from Calixarenes: Synthesis, Structure, and Properties

Zigzag hydrocarbon belts and heteroatom-doped analogs have captivated chemists because of their unique structures, tantalizing properties, and potential applications. Despite synthetic breakthroughs, the diversity, especially, the size of belts synthesized by fjord-stitching approach is limited by resorcin[n]arenes (n = 4, 6). We report herein the synthesis, structure and properties of large belts starting from conventional calix[8]arenes. The synthesis features multiple C─N cross-coupling reactions of per-brominated calix[8]arenes with anilines and ammonia, and selective transformation of 1,4-dihydroquinoline into quinolin-4(1H)-one segments. The molecules in question adopt a unique zigzag belt structure with nitrogen atoms and functional groups located around both portals, yielding a large octagonal prism cavity. They are able to accommodate fullerene C₆₀ or C₇₀ with high affinity driven by lone-pair electron/π interactions and steric complementarity between host and guest.