Examples of Regioselective Anion Recognition among a Family of Two‑, Three‑, and Four-“Armed” Bis‑, Tris‑, and Tetrakis(thioureido) [<i>n</i>]Polynorbornane hosts

A family of conformationally preorganized, [<i>n</i>]­polynorbornane-based anion hosts <b>1a</b>,<b>b</b>–<b>6a</b>,<b>b</b> have been synthesized. The series includes receptors with 4, 8, and 12 H-bond donors. Using ¹H NMR titration techniques, evaluation of the new hosts against a series of alkyl and aryl dicarboxylates as well as a range of phosphoanionic species has revealed that the tris­(thioureido) hosts (in particular <b>3a</b>) are capable of regioselectively binding dicarboxylates and pyrophosphate (H₂PPi^2–)