Supramolecular Main-Group Chemistry

合成化学家已经在原子尺度上实现了对物质结构的精细控制。举几个例子，它们选择性地在原子之间形成和重新排列键的能力，是开发新的药物和先进技术材料的壮观进展的背后。然而，操纵强原子间键往往会导致不必要的副作用；化学反应很少是100%有效的。即使在获得少量且容易去除的副产物时，当必须在多个步骤中进行合成以形成大而复杂的结构时，这种方法的有限效率被极大地放大。在许多情况下，自然界通过使用很容易断裂和重新连接的弱键来绕过这个问题；这一性质允许热力学自发地“纠正”结构中的错误。将这一概念应用于控制分子的组织和结构是超分子化学的基础。这一领域的大部分工作都依赖于分子间的联系，如氢桥和金属离子与富含电子的分子的结合。近年来，碘等元素的原子对含有孤对电子的原子的亲和力受到了极大的关注，国际理论与应用化学联合会正式采用了“卤键”一词来描述这种亲和力。其他重元素，也来自元素周期表的p-块，具有类似的形成超分子链的能力。

Synthetic chemists have achieved exquisite control of the structure of matter at atomic scale. Their ability to selectively form and rearrange bonds between atoms is behind spectacular advances in the development of new medicinal drugs and materials for advanced technologies, to name a couple of examples. However, manipulating strong interatomic bonds often leads to unwanted side processes; chemical reactions seldom are 100% efficient. Even when by-products are obtained in small amounts and are easily removed, the limited efficiencies of such methods are greatly amplified when a synthesis must be carried out in multiple steps in order to form a large and complex structure. In many instances nature gets around such a problem by using weak bonds, which are easy to break and reconnect; this property allows thermodynamics to spontaneously “correct errors” in the structure. The adaptation of this concept to the control of molecular organization and structure is the basis of supramolecular chemistry. Most work in this area has relied on intermolecular links like hydrogen bridges and the binding of metal ions to electron-rich molecules. In recent years, the affinity of atoms of elements like iodine for atoms bearing lone pairs of electrons has received much attention and the term “halogen bond” has formally been adopted by the International Union of Pure and Applied Chemistry to describe it. Other heavy elements, also from the p-block of the periodic table, have analogous abilities to form supramolecular links.