Supramolecular Main-Group Chemistry

合成化学家已经在原子尺度上精确地控制了物质的结构。它们有选择性地形成和重新排列原子间化学键的能力，在新药物和先进技术材料的开发中取得了惊人的进展，仅举几个例子。然而，操纵强原子间键通常会导致不必要的副过程；化学反应很少是100%有效的。即使获得的副产物数量很少，而且很容易去除，但当合成过程必须分多个步骤进行才能形成一个大而复杂的结构时，这种方法的有限效率就会大大提高。在许多情况下，大自然通过使用弱键来解决这个问题，这些弱键很容易断开并重新连接；这种性质允许热力学自发地“纠正结构中的错误”。将这一概念应用于分子组织和结构的控制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连接，比如氢桥和金属离子与富电子分子的结合。近年来，碘等元素的原子对带有孤对电子的原子的亲和力受到了广泛的关注，国际纯粹与应用化学联合会正式采用“卤素键”一词来描述它。其他重元素，同样来自元素周期表的p区，也具有类似的形成超分子连接的能力。

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.