有机有序空穴结构的可控自组装及其功能 (一)

This project focuses on the controlled self-assembly of cyclic, tubular, 2D and 3D porous organic supramolecular architectures. Non-covalent forces (mainly hydrogen bonding) will be utilized to induce rationally designed building blocks to adopt specific conformation or orientation to achieve multivalent and cooperative binding. New helical and macrocyclic systems will be further exploited to stack in membranes to form column-styled architectures, which will be investigated as transmembrane channels for biologically active species. Rigid planar triangular and square building blocks, which bear three or four viologen or tetrathiafulvalene (TTF) units, will be synthesized. The viologen and TTF units will be reduced or oxidized to their monocationic radicals, respectively. The related stable radical dimers will be used to drive the building blocks to generate 2D honeycomb- and square-styled architectures. Rigid tetrahedron-styled building blocks, which bear four viologen or TTF units, will also be prepared. These monomers will be used to assemble 3D ordered porous architectures. Curcubituril[8] will be further used to enhance the stability of the 2D and 3D architectures by complexing the radical dimers and also to assemble other similar porous architectures by complexing the 1:1 complex of viologen and TTF. The function of the cationic 3D porous architectures as "supramolecular sponges" in absorbing anionic conjugated molecules, polyelectrolytes and nucleic acids will be investigated. The controlled electron and energy transfer between the assembled architectures and the absorbed conjugated molecules will be exploited. The function of the new 3D self-assembled systems in promoting rationally designed photocatalyzed reactions will also be exploited.

本项目提出基于单体结构预组织构筑环状、柱状、二维及三维有机有序空穴组装体。通过氢键等诱导单体形成特定构象，以实现结合作用的加合性和协同性，以高效构筑大环。利用大环结构在膜内堆积形成通道，实现跨膜输送。设计刚性平面三角型和正方形单体，分别引入三个或四个紫精或四硫富瓦烯（TTF）片段。还原紫精或氧化TTF为正离子自由基，通过堆积作用形成正离子自由基二聚体，从而构筑二维蜂窝型和方格形组装体。在四面体型刚性骨架上引入紫精或TTF等片段，同样基于自由基二聚体模块，构筑金刚石型的三维有机有序空穴组装体。通过葫芦脲[8](CB[8])等的主体络合增强作用提高二维和三维组装体的稳定性。通过CB[8]对紫精和TTF络合物的包结作用构筑类似二维和三维组装体。探索正离子型三维组装体作为“超分子海绵”吸收负离子型分子和聚电解质及核酸的功能，探索新的组装体在控制电子转移和能量传递及促进光催化反应方面的功能。

本项目建立了水相二维和三维超分子有机框架结构（Supramolecular Organic Framework, SOF）全新自组装结构体系。我们通过葫芦脲[8]对4,4'-联二吡啶单正离子的1：2包结作用，从刚性共平面三角形前体出发，构筑了第一例二维单层SOF组装体，该蜂窝型框架结构具有约3.7nm的内经。基于葫芦脲[8]对4-苯基吡啶正离子的1：2包结作用，从四面体形前体出发构筑黎第一例三维SOF组装体，这类金刚石型框架结构具有1.7nm的孔内经。基于4，4‘-联二吡啶正离子自由基堆积二聚作用，构筑了另一类二维蜂窝型单层SOF。我们利用溶液相小角X-射线闪射和衍射实验证明了二维和三维SOF结构的周期性，通过原子力显微镜证明了二维SOF结构的单层性，通过高分辨透射电镜观察到三维SOF结构的周期性孔结构。新的二维和三维SOF在固相也能保持其周期性结构特征。三维SOF作为一类新的自组装周期性框架结构可以在水相和固相高效吸收负离子性客体，包括有机染料，药物，肽，核酸和树枝状分子等，并能实现pH调控下的可逆释放。本项目建立的SOF能够体现金属有机框架的空穴和周期性结构特征，但能够在均相和非均相两种相态下保持结构周期性。