An Acyclic Aminonaphthyridine‐Based Receptor for Carbohydrate Recognition: Binding Studies in Competitive Solvents

Abstract 1 H NMR spectroscopic and microcalorimetric titrations revealed that receptor 3b , consisting of three protonated 2‐amino‐1,8‐naphthyridine units, binds N ‐acetylneuraminic acid (Neu5Ac), the most commonly occurring sialic acid, with high affinity in competitive solvents such as water/dimethyl sulfoxide. Receptor 3b is able to form neutral/charge‐reinforced hydrogen bonds and ion pairs with Neu5Ac, similar to sialic acid‐binding proteins. Furthermore, indications for weak binding of neutral sugars, such as methyl β‐ D ‐glucopyranoside, D ‐maltose and D ‐cellobiose were provided by NMR spectroscopy. Molecular modelling calculations, synthesis and binding studies in aqueous media are described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)