Specific tetramethylammonium recognition drives general anion positioning in tandem sites of a deep cavitand

A new cavitand bearing four 2-benzylbenzimidazole moieties binds tetramethylammonium, surrounding it in a synthetic binding site with a single opening that comprises a second binding site. Ion pairing couples the binding sites, driving general anion positioning in this second site, which is defined by geometry rather than specific anion-recognition motifs.