氢键诱导的人工二级结构及其分子识别性能研究

This project focuses on the development of new aromatic artificial secondary structures (foldamers) and hydrid helical structures, and their binding to multi-acetylene or multi-hydroxyl guests. Benzene and pyrazine or pyrimidine-linked triazole oligomers will be prepared. Intramolecular C-H…X (X = F, N, Cl) hydrogen bonding will be used to induce the oligomers to adopt folded or extended conformations. Intramolecular hydrogen bonding-free triazole oligomers will be prepared. Intermolecular N…H-O hydrogen bonding between the 2,3-N atoms of the triazole units and the OH groups of guest molecules will be used to induce them to form compact folded conformations. Particularly, hybrid sequences will be constructed from one F…H-N hydrogen bonding-induced arylamide-based folded segment and one or two identical or different, structurally flexible triazole, m-phenylene ethynylene or N-methyl arylamide oligomeric segment(s). Intramolecular stacking between the folded arylamide segment and the flexible segment(s) will be utilized to induce the flexible segment(s) to form folded conformations. Nine hybrid sequences with varying length and discrete segments will be prepared and investigated to reveal the rules behind this folding- inducing-folding phenomenon in synthetic molecular systems. Chiral proline group will be introduced to one end of the hydrogen bonding-induced folded arylamide segment to exploit the possobility of chirality transfer from the proline group to the whole hybrid helicates. The folded conformation of the trizole oligomers will also be utilized to facilitate the formation of nano-scaled triazole macrocycles. Their binding to multi- acetylene and hydroxyl guests will also be investigated.

本项目提出构筑新的芳香骨架人工二级结构，发展新的杂交螺旋结构，研究折叠结构对多炔和多醇的结合性质。设计合成由苯环或二嗪连接的三氮唑寡聚体，利用分子内C-H…X(X = F,N,Cl)氢键控制其骨架形成折叠和扩展型二级结构。利用三氮唑2，3位氮形成的分子间N…H-O氢键诱导柔性三氮唑寡聚体形成折叠结构。把一个或两个相同或不同的柔性的寡聚三氮唑、间-苯乙炔或N-甲基芳香酰胺片段连接到分子内氢键稳定的寡聚芳酰胺折叠体上，通过折叠片段与柔性片段的分子内堆积作用诱导后者形成折叠构象，从而构筑复合型人工螺旋结构。共计设计9种线性分子序列，以系统研究这种复合序列螺旋二级结构的形成规律。在芳香酰胺折叠体一端引入手性脯氨酸基团，进一步探索酰胺/间-苯乙炔寡聚体杂交螺旋体内的手性传递效应。利用三氮唑折叠构象促进纳米尺度大环的合成，研究新的大环对多炔、多醇等客体的结合性质，并比较其与三氮唑折叠体之间的性质差异。

本项目通过分子内氢键和疏溶剂作用产生的芳环堆积作用构筑l了一系列芳香酰胺和酰肼聚合物螺旋二级结构，通过分子内氢键诱导构建了一类芳香三氮唑寡聚体折叠二级结构，，通过共轭正离子自由基堆积驱动构建了若干系列褶皱型聚合物人工二级结构，实现了聚合物螺旋管结构通过手性客体络合诱导的螺旋手性偏差。螺旋管结构内径在0.6-1.2nm，深度平均达到4.5nm，为进一步研究螺旋单分子管结构的包结和催化功能提供了结构平台。通过对螺旋芳香酰肼纳米管结构修饰，在其外侧引入两亲性的短肽链，构建了一类单个大分子聚合物跨膜通道，可以选择性输送K+离子。另外，我们还成功把芳香酰胺氢键折叠片段并入到三稳态轮烷分子梭内，通过折叠片段的折叠与去折叠实现了三稳态轮烷双向分子梭运动调控。