Supramolecular Chemistry with Heavy Main-Group Elements

超分子化学寻求对分子间力的理解和应用。超分子系统的终极例子是一个生命实体，其中大量分子被组织成精美的自组装结构，并执行化学和物理过程的惊人交响乐。化学家在实验室中研究的更温和的系统主要基于少数超分子相互作用，即氢键，金属离子的配位，以及由碳原子组成的平面结构的堆叠。然而，其他分子间的相互作用才刚刚开始被详细研究。我在麦克马斯特的研究小组在加拿大率先对“硫属元素键合”（ChB）进行了系统研究，这是富电子原子与硫属元素（元素周期表中氧族的重元素）原子之间的相互作用。）渴望负电荷。典型的ChB原子间距离比“常规共价”键长得多，并且可以可逆地形成和断裂，相互作用分子的结构变化最小。这种现象类似于氢键，但由于重原子的性质而更加复杂。值得注意的是，ChB相互作用具有独特的功能，有助于调整与技术应用相关的材料的结构和物理性质。我们小组的前期工作表明，ChB相互作用导致宏观光学性质，如向色性，并可以诱导具有非线性光学性质的晶体生长。与其他分子间相互作用相反，ChB使分子间电子迁移率成为可能，这是一种可以实现半导体特性并可用于构建自组装分子线的特征。这种导电的单分子厚结构对于构建集成电路很有吸引力，因为与全硅元件相比，它们应该不太容易发生电流泄漏。在这里，自组装分子有一个特别的优势：热力学使错误自我校正成为可能，这解决了在合成低聚噻吩和其他大有机分子时不可避免的偶然缺陷的问题，这些分子通常用于纳米技术中的分子电子学部分。我们的首要目标是定义在功能性超分子结构中利用ChB的方法。在下一个资助期间，我们将扩大ChB构建模块和自组装结构的曲目。虽然我们的调查追求一个基本的理解，从这项工作中获得的知识是高度相关的应用在不同的精细化学合成，光学信息技术和电子行业。由于该研究计划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，国家实验室和学术界培养高素质人才的优秀工具。

Supramolecular chemistry seeks understanding and application of the forces between molecules. The ultimate example of a supramolecular system is a living entity, in which a multitude of molecules are organized into exquisitely self-assembled structures and perform an astonishing symphony of chemical and physical processes. The more modest systems studied by chemists in the laboratory have been primarily based on a handful of supramolecular interactions, namely hydrogen bonding, coordination of metal ions, and stacking of flat structures made from carbon atoms. However, other intermolecular interactions are just beginning to be investigated in detail. My research group at McMaster has pioneered in Canada the systematic investigation of "Chalcogen Bonding" (ChB), which is the interaction between electron-rich atoms and atoms of the chalcogens (the heavy members of the oxygen family of the periodic table) that are avid for negative electric charge. Typical ChB interatomic distances are much longer than "regular covalent" bonds and can be reversibly formed and broken with minimal structural changes of the interacting molecules. This phenomenon is analogous to hydrogen bonding, but more complex due to the nature of heavy atoms. Notably, ChB interactions have unique features that help tune the structure and physical properties of materials relevant to technological applications. Previous work by our group showed that ChB interactions lead to macroscopic optical properties such as chromotropism and can induce the growth of crystals with nonlinear optical properties. In contrast to other intermolecular interactions, ChB enables intermolecular electron mobility, a feature that can enable semiconductor properties and could be applied to build self-assembled molecular wires. Such conducting one-molecule thick structures are appealing to construct integrated circuits because, compared to all-silicon components, they should be less prone to current leaks. Here self-assembling molecules have a particular advantage: thermodynamics enables error self-correction, which solves the problem of occasional defects that are inevitable in the synthesis of oligothiophenes and other large organic molecules commonly used in the part of nanotechnology known as molecular electronics. Our overarching goal is to define methods to utilize ChBs in functional supramolecular structures. During the next grant period, we will expand the repertoire of ChB building blocks and self-assembled structures. While our investigations pursue a fundamental understanding, knowledge derived from this work is highly relevant to applications in industries as diverse as fine-chemical synthesis, optical information technologies, and electronics. Because 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, national laboratories, and academia.