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。在NSERC的支持下，麦克马斯特大学的瓦尔加斯小组在加拿大率先系统地研究了硫、硒和碲(统称为“硫族”)原子形成的超分子相互作用的应用，以构建功能性的超分子结构。例如，含碲分子的无限大超分子链的结构已经被操纵来设计具有特殊光学性质的晶体。另一项最近的成就是首次证明了碲-氧“硫族键”能够诱导由几个分子组成的离散的、定义明确的聚集体的自发组装，这些聚集体一起具有新的分子实体的性质和功能。*在新的授权期内的研究将建立在这些成功的基础上，扩大超分子构件和自组装结构的保留范围。这些研究追求对此类组件的基本了解，但从这些工作中获得的知识与化学合成、光学技术、电子和无机聚合物等领域的应用高度相关。由于这个研究项目结合了现代化学的各种实验和计算方法，它构成了为加拿大工业界和学术界培养高素质人才的绝佳工具。

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.***With NSERC support, the Vargas group at McMaster University has pioneered in Canada the systematic study of the application of the supramolecular interactions formed by atoms of sulfur, selenium and tellurium (collectively called “the chalcogens”) to construct functional supramolecular structures. For example, the structure of infinite supramolecular chains of tellurium-containing molecules have been manipulated to engineer crystals with especial optical properties. Another recent achievement is the first demonstration of the ability of tellurium-oxygen “chalcogen bonds” to induce of the spontaneous assembly of discrete, well-defined, aggregates of a few molecules that together possess properties and perform the functions of new molecular entities.***Research during the new grant period will build on these successes, expanding the repertoire of supramolecular building blocks and self-assembled structures. These investigations pursue a fundamental understanding of such assemblies but knowledge derived from this is work is highly relevant to applications in areas as diverse as chemical synthesis, optical technologies, electronics and inorganic polymers. As this research program combines a wide variety of experimental and computational methods of modern chemistry, it constitutes an excellent vehicle to train highly qualified personnel for Canadian industry and academia.