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 S_NAr 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 K_1:1 values up to (3.98 ± 0.08) × 10⁴ M^–1 in toluene.