O6‑Corona[6]arenes with Expanded Cavities for Specific Complexation with C70

O6-Corona­[3]­arene­[3]­tetrazines with expanded cavities were synthesized by one-pot SNAr reaction between 3,6-dichlorotetrazine and aromatic diols. The macrocycle-to-macrocycle transformation involving IEDDA of tetrazine moieties with an enamine followed by denitrogenative aromatization afforded O6-corona­[3]­arene­[3]­pyridazines. O6-Corona­[6]­arenes adopted coronary conformations yielding hexagonal cavities of varied sizes. While O6-corona­[3]­arene­[3]­pyridazines complexed both C60 and C70 in a virtually nonselective manner, O6-corona­[3]­arene­[3]­tetrazines behaved as selective receptors to complex C70 with K1:1 values up to (3.98 ± 0.08) × 104 M–1 in toluene.