Enforced Folding of Oligo(phenylene ethynylenes)

非天然低聚物和由乙炔基团(苯乙炔)连接的苯环组成的聚合物被设计成折叠成多孔螺旋结构，通过局部分子内氢键加强。具有足够长主链的低聚物自身折叠，导致左旋和右旋螺旋。这种基于骨架的螺旋编程提供稳定的螺旋结构，而不考虑决定外表面性质的侧基的结构变化。形成的螺旋内部排列着芳香族氢原子，使这些管状空腔相当疏水。螺旋的内径是可调节的(8埃到40埃或更大)，提供了新的具有可调节内腔的非自然折叠纳米管。此外，这些非天然的折叠体具有螺旋和不饱和的骨架，这些特征可能赋予它们不寻常和有用的物理和化学特性。此外，还讨论了具有超疏水(含氟)或两亲性内腔的螺旋的设计和合成、对映体的拆分以及手性侧链和手性溶剂诱导的螺旋扭转感。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孔材料的设计中具有广泛的潜在应用。在有机化学和高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-林肯大学化学系的肖承曾教授正在研究碳基分子的合成和性质，这些分子旨在选择性和高效地折叠成螺旋结构。这些螺旋结构包含大小和功能可调的纳米通道，允许调节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，包括自然和非自然的，进行这些跨学科研究的学生获得了有机合成、生物有机化学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.