Institute for Complex Molecular Systems and Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
J Org Chem. 2010 Feb 5;75(3):598-610. doi: 10.1021/jo902053t.
A series of oligo(ethylene oxide) (oligoEO) substituted 2-ureido-pyrimidinones (UPy), differing in the number of ethylene oxide units and the length of the aliphatic spacer connecting the oligoEO side chain with the UPy group, have been prepared. It was found that variation in these structural parameters strongly influences the dimerization constant (K(dim)) of the UPy dimer and the association constant (K(a)) of UPy with 2,7-diamido-1,8-naphthyridine (NaPy) in chloroform. By analyzing the relation between dimerization strength, length of aliphatic spacer, and the number of EO units in the oligoEO chain, we present strong evidence that the reduction in hydrogen bond strength is caused by competitive intramolecular hydrogen bonding of the ether atoms of the oligoEO chain to the hydrogen bond donors of the UPy unit.
一系列聚（环氧乙烷）（oligoEO）取代的 2-脒基嘧啶酮（UPy）已被制备，其在聚氧乙烯单元的数量和连接聚氧乙烯侧链与 UPy 基团的脂肪族间隔物的长度上有所不同。结果发现，这些结构参数的变化强烈影响 UPy 二聚体的二聚常数（K(dim)）和 UPy 与 2,7-二氨基-1,8-萘啶（NaPy）在氯仿中的缔合常数（K(a)）。通过分析二聚强度、脂肪族间隔物的长度和聚氧乙烯链中的环氧乙烷单元数之间的关系，我们提供了强有力的证据表明，氢键强度的降低是由聚氧乙烯链的醚原子与 UPy 单元的氢键供体之间的竞争分子内氢键引起的。
