Systematic size mediated trapping of anions of varied dimensionality within a dimeric capsular assembly of a flexible neutral bis-urea platform.

A rationally designed ortho-phenylenediamine based trifluoromethyl meta-disubstituted bis-urea receptor (L) exhibits effective, consistent and systematic binding in its neutral form towards smaller spherical halides (fluoride, chloride, bromide and iodide), and relatively larger planar carbonate and tetrahedral sulphate oxyanions. All the complexes are well characterized both in the solid-state and solution phase. In the presence of excess fluoride anions, the receptor L encapsulates a hydrated cyclic fluoride-water [F