A hexaamine cage was synthesised in good yield by a [2+3] Schiff-base condensation followed by sodium borohydride reduction to be used as a receptor for the selective binding of anionic species. The protonation constants of the receptor, as well as its association constants with Cl⁻, I⁻, NO₃ ⁻, AcO⁻, ClO₄ ⁻, H₂PO₄ ⁻, SO₄ ²⁻, SeO₄ ²⁻ and S₂O₃ ²⁻ were determined by potentiometry at 298.2 ± 0.1 K in H₂O–MeOH (50 : 50 v/v) and at ionic strength 0.10 ± 0.01 mol dm⁻³ in KTsO. These studies revealed a remarkable selectivity for dianionic tetrahedral anions by the protonated receptor, with association constants ranging 5.03–5.30 log units for the dianionic species and 1.49–2.97 log units for monoanionic ones. Single crystal X-ray determination of [(H₆xyl)(SO₄)(H₂O)₆](SO₄)₂·9.5H₂O showed that one sulfate anion is encapsulated into the receptor cage sited between the two 2,4,6-triethylbenzene caps establishing three N–H⋯O hydrogen bonds with two adjacent N–H binding sites and additional O–H⋯O hydrogen bonding interactions with six water of crystallization molecules. Four water molecules of the (SO₄)(H₂O)₆cluster interact with [H₆xyl]⁶⁺ through N–H⋯O hydrogen bonds. Molecular dynamics simulations (MD) carried out with SO₄ ²⁻ and Cl⁻ anions in H₂O–MeOH (50 : 50 v/v) allowed the full understanding of anion molecular recognition, the selectivity of the protonated receptor for SO₄ ²⁻ and the role played by the methanol and water solvent molecules.

The recognition of either homomeric or heteromeric pairs of pentoses in an aromatic oligoamide double helical foldamer capsule was evidenced by circular dichroism (CD), NMR spectroscopy, and X‐ray crystallography. The cavity of the host was predicted to be large enough to accommodate simultaneously two xylose molecules and to form a 1:2 complex (one container, two saccharides). Solution and solid‐state data revealed the selective recognition of the α‐⁴C₁‐d‐xylopyranose tautomer, which is bound at two identical sites in the foldamer cavity. A step further was achieved by sequestering a heteromeric pair of pentoses, that is, one molecule of α‐⁴C₁‐d‐xylopyranose and one molecule of β‐¹C₄‐d‐arabinopyranose despite the symmetrical nature of the host and despite the similarity of the guests. Subtle induced‐fit and allosteric effects are responsible for the outstanding selectivities observed.