Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany.
J Am Chem Soc. 2010 Aug 18;132(32):11119-24. doi: 10.1021/ja101523v.
In this paper we report on the synthesis of a new family of nonionic dendritic amphiphiles that self-assemble into defined supramolecular aggregates. Our approach is based on a modular architecture consisting of different generations of hydrophilic polyglycerol dendrons [G1-G3] connected to hydrophobic C(11) or C(16) alkyl chains via mono- or biaromatic spacers, respectively. All amphiphiles complex hydrophobic compounds as demonstrated by solubilization of Nile Red or pyrene. The structure of the supramolecular assemblies as well as the aggregation numbers are strongly influenced by the type of the dendritic headgroup. While the [G1] amphiphiles form different structures such as ringlike and fiberlike micelles, the [G2] and [G3] derivatives aggregate toward spherical micelles of low polydispersity clearly proven by transmission electron microscopy (TEM) measurements. In the case of the biaromatic [G2] derivative, the structural persistence of the micelles allowed a three-dimensional structure determination from the TEM data and confirmed the aggregation number obtained by static light scattering (SLS) measurements. On the basis of these data, molecular packing geometries indicate a drastic mass deficit of alkyl chains in the hydrophobic core volume of spherical micelles. It is noteworthy that these highly defined micelles contain as little as 15 molecules and possess up to 74% empty space. This behavior is unexpected as it is very different from classical detergent micelles such as sodium dodecyl sulfate (SDS), where the hydrophobic core volume is completely filled by alkyl chains.
在本文中，我们报告了一类新型的非离子型树枝状两亲分子的合成，这些分子可以自组装成特定的超分子聚集体。我们的方法基于一种模块化的结构，由不同代的亲水性聚甘油树枝[G1-G3]组成，通过单或双芳基间隔物分别与疏水性 C(11)或 C(16)烷基链连接。所有的两亲分子都能络合疏水性化合物，如尼罗红或芘的溶解实验所证明的。超分子组装体的结构和聚集数强烈受到树枝状头基类型的影响。虽然[G1]两亲分子形成了不同的结构，如环状和纤维状胶束，但[G2]和[G3]衍生物则聚集形成低多分散性的球形胶束，这一点通过透射电子显微镜（TEM）测量得到了明确证明。对于双芳基[G2]衍生物，胶束的结构稳定性允许从 TEM 数据中确定三维结构，并证实了静态光散射（SLS）测量得到的聚集数。基于这些数据，分子堆积几何形状表明，在球形胶束的疏水性核心体积中，烷基链的质量严重不足。值得注意的是，这些高度确定的胶束仅包含 15 个分子，却拥有高达 74%的空空间。这种行为出乎意料，因为它与传统的去污剂胶束（如十二烷基硫酸钠（SDS））非常不同，在 SDS 中，疏水性核心体积完全被烷基链填满。
