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确控制。它们选择性地形成和重新排列原子之间的键的能力是开发新药物和先进技术材料的巨大进步的背后，仅举几个例子。然而，操纵强的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。即使当副产物以少量获得并且容易去除时，当合成必须在多个步骤中进行以形成大的和复杂的结构时，这些方法的有限效率被极大地放大。在许多情况下，自然界通过使用容易断裂和重新连接的弱键来解决这样的问题;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。这一领域的大多数工作都依赖于分子间的连接，如氢桥和金属离子与富电子分子的结合。近年来，碘等元素的原子与带有孤对电子的原子之间的亲和力受到了广泛关注，国际纯粹与应用化学联合会正式采用了“卤键”一词来描述它。其他重元素，也是周期表中的p区元素，也具有类似的形成超分子键的能力。 在NSERC的支持下，麦克马斯特大学的Vargas小组在加拿大率先系统研究了由硫、硒和碲原子（统称为“硫属元素”）形成的超分子相互作用，以构建功能性超分子结构。例如，含碲分子的无限超分子链的结构已经被操纵以设计具有特殊光学性质的晶体。最近的另一项成就是首次证明了碲-氧“硫族元素键”诱导几个分子的离散、明确定义的聚集体自发组装的能力，这些分子一起拥有新分子实体的性质并执行新分子实体的功能。 在新的资助期内的研究将建立在这些成功的基础上，扩大超分子积木和自组装结构的剧目。这些调查追求对这种组装的基本理解，但从这项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。由于该研究项目结合了现代化学的各种实验和计算方法，因此它构成了为加拿大工业界和学术界培养高素质人才的优秀工具。

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.