Dipartimento di Chimica, Università di Firenze, I-50019 Sesto Fiorentino, Firenze, Italy.
J Org Chem. 2012 Sep 7;77(17):7548-54. doi: 10.1021/jo301341c. Epub 2012 Aug 20.
The carbohydrate recognition properties of synthetic tripodal receptors relying on H-bonding interactions have highlighted the crucial role played by the functional groups matching saccharidic hydroxyls. Herein, pyrrole and pyridine, which emerged as two of the most effective H-bonding groups, were quantitatively compared through their isostructural substitution within the architecture of a shape-persistent bicyclic cage receptor. NMR and ITC binding studies gave for the pyrrolic receptor a 20-fold larger affinity toward octyl-β-d-glucopyranoside in CDCl(3), demonstrating the superior recognition properties of pyrrole under conditions in which differences would depend on the intrinsic binding ability of the two groups. The three-dimensional structures of the two glucoside complexes in solution were elucidated by combined NMR and molecular mechanics computational techniques, showing that the origin of the stability difference between the two closely similar complex structures resides in the ability of pyrrole to establish shorter/stronger H-bonds with the glucosidic ligand compared to pyridine.
基于氢键相互作用的合成三脚架受体的碳水化合物识别特性突出了与糖基羟基相匹配的官能团所起的关键作用。在此，吡咯和吡啶作为两种最有效的氢键供体，通过在结构上保持一致的双环笼受体的架构内进行等结构取代，进行了定量比较。NMR 和 ITC 结合研究表明，在 CDCl(3) 中，吡咯受体对辛基-β-d-吡喃葡萄糖苷的亲和力大 20 倍，证明在依赖于两个基团内在结合能力的条件下，吡咯具有更好的识别性能。通过结合 NMR 和分子力学计算技术，阐明了两种葡萄糖苷配合物在溶液中的三维结构，表明两种非常相似的配合物结构之间稳定性差异的根源在于吡咯与糖苷配体形成更短/更强氢键的能力优于吡啶。
