Enforced Folding of Oligo(phenylene ethynylenes)

苯环由乙烯基（苯乙烯）连接组成的非天然低聚物和聚合物被设计成折叠成多孔的螺旋结构，由局部分子内氢键强制。具有足够长的主链的低聚物可以折叠起来，形成左旋和右旋螺旋。这种基于主干的螺旋规划提供了稳定的螺旋结构，而不考虑决定外表面性质的侧基的结构变化。由此产生的螺旋的内部由芳香氢原子排列，使这些管状腔相当疏水。螺旋的内径是可调节的（8埃到40埃甚至更大），这使得新型的非自然折叠纳米管具有可调节的内部空腔。此外，这些不自然的文件夹具有螺旋和不饱和的骨架，这些特征可能赋予不寻常和有用的物理和化学性质。设计和合成具有超疏水（氟化）或两亲性内腔的螺旋，拆分对映体，并通过手性侧链和手性溶剂诱导螺旋扭曲感也进行了讨论。纳米空腔和通道在催化、分离、纳米器件（传感器、流体等）、用于构建更大结构的纳米支架以及其他纳米多孔材料的设计等方面具有许多潜在的应用。在有机和大分子化学项目的支持下，纽约州立大学布法罗分校化学系的龚兵教授和内布拉斯加州林肯大学化学系的曾晓成教授正在研究碳基分子的合成和性质，这些碳基分子被设计成选择性和有效地折叠成螺旋结构。这些螺旋结构包含纳米级的通道，这些通道的大小和功能都是可调节的，允许调整它们的性质以及它们与其他分子的相互作用。这些研究还提供了关于其他大分子折叠的基本信息，包括自然的和非自然的。学生进行这些跨学科的研究可以获得有机合成、生物有机和超分子有机化学以及理论化学的技能。

Unnatural oligomers and polymers consisting of benzene rings linked by ethynyl groups (phenyleneethynylenes) are designed to fold into porous helical structures, enforced by localized intramolecular hydrogen bonds. An oligomer with a sufficiently long backbone folds back on itself, leading to left- and right-handed helices. Such a backbone-based helical programming affords stable helical structures regardless of structural variation of the side groups that determine the outside surface properties. The interior of the resulting helices is lined by aromatic hydrogen atoms, making these tubular cavities rather hydrophobic. The internal diameters of the helices are adjustable (8 angstrom to 40 angstrom and larger), providing access to novel unnatural folding nanotubes with adjustable interior cavities. Furthermore, these unnatural foldamers have backbones that are both helical and unsaturated, features that may endow unusual and useful physical and chemical properties. The design and synthesis of helices with superhydrophobic (fluorinated) or amphiphilic interior cavities, resolution of enantiomers, and induction of helical twist sense by chiral side chains and chiral solvents are also addressed.Nanosized cavities and channels have numerous potential applications in catalysis, separations, nanodevices (sensors, fluidics, etc.), nanoscaffolds for building larger structures, and design of other nanoporous materials. With the support of the Organic and Macromolecular Chemistry Program, Professor Bing Gong, of the Department of Chemistry at the State University of New York - Buffalo and Professor Xiao Cheng Zeng, of the Department of Chemistry at the University of Nebraska - Lincoln, are studying the synthesis and properties of carbon-based molecules designed to fold selectively and efficiently into helical structures. These helical structures contain nanosized channels of adjustable size and functionality, allowing tuning of their properties and their interactions with other molecules. These studies also provide fundamental information about the folding of other large molecules, both natural and unnatural, Students carrying out these interdisciplinary studies gain skills in organic synthesis, bioorganic and supramolecular organic chemistry, and theoretical chemistry.