ortho-Phenylenes in Complex Foldamer Architectures

化学学部的大分子、超分子和纳米化学项目支持迈阿密大学化学与生物化学系C. Scott Hartley教授的工作。在自然界中，大分子（如蛋白质）的结构复杂性及其最终功能是由较小分子块（低聚物和聚合物）的折叠产生的。这一事实激发了许多研究非生物“折叠体”的努力，这些折叠体是指以明确的方式折叠的小分子片段。哈特利小组的研究重点是邻苯乙烯，这是一种由直接连接的芳香环形成的简单折叠物。在这个项目中，哈雷集团开发了控制邻苯乙烯折叠的方法，并将环纳入更复杂的结构中。该项目涉及研究生、本科生和高中教师，他们利用有机合成、计算化学和各种表征方法来理解分子折叠、自组装和分子识别的基本概念。邻苯乙烯结合了几个特点，使其成为“下一代”文件夹的吸引力。它们很容易合成。它们的折叠行为很容易用简单、廉价的方法建模。它们精确的溶液相折叠状态可以用核磁共振光谱来表征。这个项目有三个利用这些特性的具体目标。首先，利用手性端基控制邻苯折叠的扭转感。虽然这种对低聚物折叠的控制已经在其他系统中得到证明，但它对于邻苯乙烯的更高级用途至关重要。如果成功，可用于测试邻苯的自旋选择性电子输运。其次，邻苯亚基连接在一起形成大环。这个简单的系统代表了将邻苯二烯二级结构（即螺旋结构）纳入高阶结构的第一步，并提供了一个框架来测试桥接文件夹亚基之间的构象相互作用。最后，邻苯乙烯被大环功能化，在其侧面形成结合位点。这些结构代表了邻苯基分子识别的第一步。

The Macromolecular, Supramolecular, and Nanochemistry Program of the Chemistry Division supports the work of Prof. C. Scott Hartley in the Department of Chemistry & Biochemistry at Miami University. In nature, the structural complexity of large molecules (e.g., proteins), and ultimately their function, is generated by the folding of smaller molecular pieces (oligomers and polymers). This fact has inspired many efforts to study non-biological "foldamers" smaller molecular pieces that fold in well-defined ways. Research in the Hartley group focuses on the ortho-phenylenes, a simple class of foldamers formed from directly connected aromatic rings. In this project, the Harley group develops methods to control the folding of o-phenylenes and incorporates the rings into more complex structures. The project involves graduate students, undergraduates, and high-school teachers working to understand fundamental concepts of molecular folding, self-assembly, and molecular recognition, using the techniques of organic synthesis, computational chemistry, and various characterization methods.The ortho-phenylenes combine several features that make them attractive as "next-generation" foldamers. They are straightforward to synthesize. Their folding behavior is easily modeled using simple, inexpensive methods. Their exact, solution-phase folding state can be characterized by NMR spectroscopy. This project has three specific aims that take advantage of these features. First, the twist-sense of o-phenylene folding is controlled using chiral end groups. While this sort of control over oligomer folding has been demonstrated in other systems, it is critical for more advanced uses of o-phenylenes. If successful, may be used to test o-phenylenes for spin-selective electron transport. Second, o-phenylene subunits are linked together into macrocycles. This simple system represents a first step toward incorporating o-phenylene secondary structures (i.e., helices) into higher-order structures, and provides a framework to test the conformational interaction between bridged foldamer subunits. Finally, o-phenylenes are functionalized with macrocycles to create binding sites along their sides. The architectures represents a first step toward o-phenylene-based molecular recognition.