Tritopic ion-pair receptors based on anion-π interactions for selective CaX2 binding.

Selective ion-pair binding of CaX2 (X = Br-, I-) was realized by a tritopic receptor containing homoditopic anion-π binding sites and a pentaethylene glycol site. The receptor formed an unusual solvent-separated ion-pair complex with CaI2 and a contact one with CaBr2, and can be applied to selectively dissolve calcium halides in organic solvents.