Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, USA.
Acc Chem Res. 2009 Oct 20;42(10):1554-63. doi: 10.1021/ar900077c.
Self-assembly allows for the preparation of highly complex molecular and supramolecular systems from relatively simple starting materials. Typically, self-assembled supramolecules are constructed by combining complementary pairs of two highly symmetric molecular components, thus limiting the chances of forming unwanted side products. Combining asymmetric molecular components or multiple complementary sets of molecules in one complex mixture can produce myriad different ordered and disordered supramolecular assemblies. Alternatively, spontaneous self-organization phenomena can promote the formation of specific product(s) out of a collection of multiple possibilities. Self-organization processes are common throughout much of nature and are especially common in biological systems. Recently, researchers have studied self-organized self-assembly in purely synthetic systems. This Account describes our investigations of self-organization in the coordination-driven self-assembly of platinum(II)-based metallosupramolecules. The modularity of the coordination-driven approach to self-assembly has allowed us to systematically study a wide variety of different factors that can control the extent of supramolecular self-organization. In particular, we have evaluated the effects of the symmetry and polarity of ambidentate donor subunits, differences in geometrical parameters (e.g., the size, angularity, and dimensionality) of Pt(II)-based acceptors and organic donors, the influence of temperature and solvent, and the effects of intermolecular steric interactions and hydrophobic interactions on self-organization. Our studies have shown that the extent of self-organization in the coordination-driven self-assembly of both 2D polygons and 3D polyhedra ranges from no organization (a statistical mixture of multiple products) to amplified organization (wherein a particular product or products are favored over others) and all the way to the absolute self-organization of discrete supramolecular assemblies. In many cases, inputs such as dipolar interactions, steric interactions, and differences in the geometric parameters of subunits, used either alone or as multiple factors simultaneously, can achieve absolute self-organization of discrete supramolecules. We have also observed instances where self-organization is not absolute and varies in its deviation from statistical results. Steric interactions are particularly useful control factors for driving such amplified self-organization because they can be subtly tuned through small structural variations. Having the ability to fully understand and control the self-organization of complex mixtures into specific synthetic supramolecules can provide a better understanding of analogous processes in biological systems. Furthermore, self-organization may allow for the facile synthesis of complex multifunctional, multicomponent systems from simply mixing a collection of much simpler, judiciously designed individual molecular components.
自组装允许从相对简单的起始材料中制备高度复杂的分子和超分子体系。通常，自组装超分子是通过将两个高度对称的分子组件的互补对组合而成，从而限制形成不需要的副产物的机会。将不对称分子组件或多个互补的分子集合在一个复杂混合物中可以产生无数不同的有序和无序超分子组装体。或者，自发的自组织现象可以促进从多种可能性中形成特定产物。自组织过程在自然界中很常见，在生物系统中尤为常见。最近，研究人员研究了纯合成系统中自发的自组装。本说明描述了我们对基于铂(II)的金属超分子配位驱动自组装中的自组织的研究。配位驱动自组装方法的模块化使我们能够系统地研究可以控制超分子自组织程度的各种不同因素。特别是，我们评估了配位驱动自组装中 ambidentate 给体亚基的对称性和极性、基于 Pt(II)的受体和有机给体的几何参数（例如大小、角度和维度）的差异、温度和溶剂的影响、以及分子间空间位阻和疏水相互作用对自组织的影响。我们的研究表明，在基于 Pt(II)的 2D 多边形和 3D 多面体的配位驱动自组装中，自组织的程度从没有组织（多种产物的统计混合物）到放大的组织（其中特别的产物或产物优先于其他产物），再到离散超分子组装体的绝对自组织。在许多情况下，单独使用或同时使用诸如偶极相互作用、空间位阻相互作用和亚基几何参数的差异等输入，可以实现离散超分子的绝对自组织。我们还观察到自组织不是绝对的情况，并且其偏离统计结果的程度也不同。空间位阻相互作用是驱动这种放大自组织的特别有用的控制因素，因为它们可以通过微小的结构变化进行微妙地调整。完全理解和控制复杂混合物自组装成特定的合成超分子的能力，可以更好地理解生物系统中类似的过程。此外，自组织可能允许从简单地混合收集的许多更简单、精心设计的单个分子组件，轻松合成复杂的多功能、多组分系统。
