Roy & Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
J Am Chem Soc. 2009 Dec 2;131(47):17500-21. doi: 10.1021/ja907882n.
The synthesis of 4'-hydroxy-4-biphenylpropionic, 3',4'-dihydroxy-4-biphenylpropionic, 3',5'-dihydroxy-4-biphenylpropionic, and 3',4',5'-trihydroxy-4-biphenylpropionic methyl esters via three efficient and modular strategies including one based on Ni-catalyzed borylation and sequential cross-coupling is reported. These building blocks were employed in a convergent iterative approach to the synthesis of one library of 3,4,5-trisubstituted and two libraries of constitutional isomeric 3,4- and 3,5-disubstituted biphenylpropyl ether dendrons. Structural and retrostructural analysis of supramolecular dendrimers revealed that biphenylpropyl ether dendrons self-assemble and self-organize into the same periodic lattices and quasi-periodic arrays observed in previously reported libraries, but with larger dimensions, different mechanisms of self-assembly, and improved solubility, thermal, acidic, and oxidative stability. The different mechanisms of self-assembly led to the discovery of two new supramolecular structures. The first represents a new banana-like lamellar crystal with a four layer repeat. The second is a giant vesicular sphere self-assembled from 770 dendrons that exhibits an ultrahigh molar mass of 1.73 x 10(6) g/mol. Thus, the enhanced size of the self-assembled structures constructed from biphenylpropyl ether dendrons permitted for the first time discrimination of various molecular mechanisms of spherical self-assembly and elaborated a continuum between small filled spheres and very large hollow spheres that is dictated by the primary structure of the dendron. The comparative analysis of libraries of biphenylpropyl ether dendrons with the previously reported libraries of benzyl-, phenylpropyl-, and biphenyl-4-methyl ether dendrons demonstrated biomimetic self-assembly wherein the primary structure of the dendron and to a lesser extent the structure of its repeat unit determines the supramolecular tertiary structure. A "nanoperiodic table" of self-assembling dendrons and supramolecular dendrimers that allows the prediction of the general features of tertiary structures from primary structures was elaborated.
通过三种高效且模块化的策略，包括一种基于 Ni 催化的硼化和顺序交叉偶联的策略，合成了 4'-羟基-4-联苯丙酸、3'，4'-二羟基-4-联苯丙酸、3'，5'-二羟基-4-联苯丙酸和 3'，4'，5'-三羟基-4-联苯丙酸甲酯。这些构建块被用于合成一个 3,4,5-三取代的和两个 3,4-和 3,5-取代的联苯丙基醚树枝状大分子的构象异构库的收敛迭代方法。超分子树状大分子的结构和反结构分析表明，联苯丙基醚树枝状大分子自组装并自组织成与以前报道的库中观察到的相同的周期性晶格和准周期性阵列，但具有更大的尺寸、不同的自组装机制和提高的溶解度、热稳定性、酸稳定性和氧化稳定性。不同的自组装机制导致发现了两种新的超分子结构。第一种代表具有四层重复的新型香蕉状层状晶体。第二种是由 770 个树枝状大分子自组装而成的巨型囊泡球体，其摩尔质量高达 1.73 x 10(6) g/mol。因此，由联苯丙基醚树枝状大分子构建的自组装结构的增强尺寸首次允许区分球形自组装的各种分子机制，并详细阐述了由树枝状大分子的主链结构决定的从小填充球体到非常大的空心球体的连续体。与先前报道的苄基、苯基丙基和联苯-4-甲醚树枝状大分子的库进行的联苯丙基醚树枝状大分子库的比较分析表明，存在仿生自组装，其中树枝状大分子的主链结构和在较小程度上其重复单元的结构决定了超分子三级结构。从主链结构预测三级结构的一般特征的自组装树枝状大分子和超分子树状大分子的“纳米周期性表”被详细阐述。
