Biotin[6]uril hexaesters represent a new class of anionophores which operate solely through C-H···anion interactions. The use of soft H-bond donors favors the transport of less hydrophilic anions (e.g., Cl(-), NO3(-)) over hard, stongly hydrated anions (e.g., HCO3(-) and SO4(2-)). Especially relevant is the selectivity between chloride and bicarbonate, the major inorganic anions in biological systems.

The discovery of receptors using templated synthesis enables the selection of strong receptors from complex mixtures.

The combination of a pyrenyl tetraamine with an isophthaloyl spacer has led to two new water‐soluble carbohydrate receptors (“synthetic lectins”). Both systems show outstanding affinities for derivatives of N‐acetylglucosamine (GlcNAc) in aqueous solution. One receptor binds the methyl glycoside GlcNAc‐β‐OMe with K a≈20 000 m −1, whereas the other one binds an O‐GlcNAcylated peptide with K a≈70 000 m −1. These values substantially exceed those usually measured for GlcNAc‐binding lectins. Slow exchange on the NMR timescale enabled structural determinations for several complexes. As expected, the carbohydrate units are sandwiched between the pyrenes, with the alkoxy and NHAc groups emerging at the sides. The high affinity of the GlcNAcyl–peptide complex can be explained by extra‐cavity interactions, raising the possibility of a family of complementary receptors for O‐GlcNAc in different contexts.