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.

Carbohydrate receptors with a chiral framework have been generated by combining a tetra-aminopyrene and a C₃-symmetrical triamine via isophthalamide spacers bearing water-solubilising groups. These “synthetic lectins” are the first to show enantiodiscrimination in aqueous solution, binding N-acetylglucosamine (GlcNAc) with 16 : 1 enantioselectivity. They also show exceptional affinities. GlcNAc is bound with K_a up to 1280 M⁻¹, more than twice that measured for previous synthetic lectins, and three times the value for wheat germ agglutinin, the lectin traditionally employed to bind GlcNAc in glycobiological research. Glucose is bound with K_a = 250 M⁻¹, again higher than previous synthetic lectins. The results suggest that chirality can improve complementarity to carbohydrate substrates and may thus be advantageous in synthetic lectin design.

Dendritic side chains have been used to modify the binding environment in anthracene‐based synthetic carbohydrate receptors. Control of length, charge, and branching enabled the positioning of side‐chain carboxylate groups in such a way that they assisted in binding substrates rather than blocking the cavity. Conformational degeneracy in the dendrimers resulted in effective preorganization despite the flexibility of the system. Strong binding was observed to glucosammonium ions in water, with K_a values up to 7000 M⁻¹. Affinities for uncharged substrates (glucose and N‐acetylglucosamine) were also enhanced, despite competition from solvent and the absence of electrostatic interactions.

Biomimetic carbohydrate receptors (“synthetic lectins”) have potential as agents for biological research and medicine. However, although effective strategies are available for “all‐equatorial” carbohydrates (glucose, etc.), the recognition of other types of saccharide under natural (aqueous) conditions is less well developed. Herein we report a new approach based on a pyrene platform with polar arches extending from aryl substituents. The receptors are compatible with axially substituted carbohydrates, and also feature two identical binding sites, thus mimicking the multivalency observed for natural lectins. A variant with negative charges forms 1:2 host/guest complexes with aminosugars, with K₁>3000 m⁻¹ for axially substituted mannosamine, whereas a positively charged version binds the important α‐sialyl unit with K₁≈1300 m⁻¹.