Iso-Tellurazole N-Oxides Assemble Adaptively Folded Macrocyclic Dodecamers.

Self-assembled macrocyclic dodecamers were found in the crystals of new pseudo-polymorphs of iso-tellurazole N-oxides. These structures are formed by molecules connected by NTe…O chalcogen bonds and are folded in a pattern that defines 89-153 Å3 cavities, which are large enough to host solvent molecules. These crystals only grow in the presence of molecular species that can act as guests alone (cyclohexane) or in combination with sodium cations (1,4-dioxane, tetrahydrofuran, and pyrazine). A solution rich in a sodium salt yielded a crystal featuring a cage-like aggregate of three tetramers bridged by sodium cations, suggesting a plausible route for the formation of the new macrocycles by reorganization of the chalcogen bonds.