Functionalized O₆–Corona[6]arenes: Synthesis, Structure, and Fullerene Complexation Property

The synthesis, structure, and fullerene complexation property of novel and functionalized On–corona­[n]­arenes were reported. Based on the fragment coupling strategy, ester-containing On–corona­[n]­arenes (n = 6, 8) were obtained readily starting from 1,4-hydroquinone and diethyl 2,5-difluoroterephthalate. Reduction of esters with LiAlH4 produced almost quantitatively hydroxymethylated On–corona­[n]­arenes, which underwent etherification with MeI to afford methoxymethyl-substituted On–corona­[n]­arenes (n = 6, 8) in good yields. The macrocycles adopt unique corona-type conformation with a large cylindroid cavity. They are strong macrocyclic host molecules to form 1:1 complexes with fullerenes C60 and C70 in toluene with an associate constant up to (1.59 ± 0.04) × 105 M–1.