Gillies Elizabeth R, Fréchet Jean M J
Center for New Directions in Organic Synthesis, Department of Chemistry, University of California, Berkeley, California 94720-1460, USA.
J Org Chem. 2004 Jan 9;69(1):46-53. doi: 10.1021/jo035329s.
Self-assembled polyester dendritic bow-ties with various peripheral groups were prepared, and their association constants were measured by (1)H NMR in CDCl(3). The two complementary dendrons were prepared by attachment of either a bis(adamantylurea) or a glycinylurea to the focal point of the dendron. The parent self-assembled system with benzylidene acetals on one periphery and isopropylidene acetals on the other had an association constant of 520 M(-)(1). Upon deprotection of one dendron, the association constant is increased by more than an order of magnitude as the solubility of the hydroxyl-terminated dendron in CDCl(3) is decreased. In contrast, attachment of tri(ethylene oxide) units to the periphery of one dendron lowers the association constant by almost an order of magnitude. The causes of these relatively large changes in complex strength are discussed in terms of solubility, steric effects, competitive hydrogen bonding, and the structure of the dendritic scaffold.
制备了带有各种外围基团的自组装聚酯树枝状领结，并通过在CDCl₃中的¹H NMR测量其缔合常数。通过将双（金刚烷基脲）或甘氨酰脲连接到树枝状分子的焦点上制备了两种互补的树枝状分子。一种外围带有亚苄基缩醛而另一种带有异亚丙基缩醛的母体自组装体系的缔合常数为520 M⁻¹。当一个树枝状分子脱保护时，随着羟基封端的树枝状分子在CDCl₃中的溶解度降低，缔合常数增加了一个多数量级。相反，将三（环氧乙烷）单元连接到一个树枝状分子的外围会使缔合常数降低近一个数量级。从溶解度、空间效应、竞争性氢键和树枝状支架的结构方面讨论了这些复合物强度相对较大变化的原因。
