Expanded aromatic carboxylate anion induced molecular sandwich construction via a tetracationic imidazolium macrocycle conversion from molecular box to molecular tweezer

The molecular box, namely cyclo[2](2,6-di(1H-imidazol-1-yl)pyridine)-[2](1,4-dimethylene benzene) (1⁴⁺; as PF₆^? salt), fold its conformation as molecular tweezer to clip the specific carboxylates with expanded aromatic plane. The binding modes between 1⁴⁺ and carboxylate, namely pseudorotaxane, outside or clipping (i.e., sandwich like), also depend on the location of carboxylate on the large conjugated moiety. These finding develop the usability of 1⁴⁺ and carboxylates as important building block pairs to create non-covalent self-assembly structures.