Research Center for Analytical Sciences, College of Chemistry, Nankai University, 94 Weijin Road, Tianjin 300071 (China), Fax: (+86) 22-23506075.
Chemistry. 2010 Apr 19;16(15):4639-49. doi: 10.1002/chem.200903188. Epub 2010 Mar 23.
Strategies for exploring anionic templates to direct sophisticated supramolecular assembly have attracted attention. Herein, a series of new anion receptors 1-3 containing two indole-based binding sites bridged by linking spacer pyrazino[2.3-g]quinoxaline (PQ) have been rationally designed and prepared from the precursors 2,3-diindol-3'-yl quinoxaline (DIQ) and 5,6-dihydrodiindolo[3,2-a:2',3'-c]phenazine (DIPZ). X-ray analyses showed a self-connected network and dimeric packing through hydrogen bonding and π-π stacking interaction in the solid state in the structures of 1 and 2, respectively. All three receptors exhibited a series of prominent absorption bands from the expanded π system. The indole-based expanded receptors were found to strongly and selectively bind F(-), AcO(-), and H2PO4(-) among the tested anions (F(-), Cl(-), Br(-), AcO(-), H2PO4(-), HSO4(-), NO3(-), and ClO4(-)), and operated as efficient colorimetric sensors for naked-eye detection of fluoride anions in DMSO. These tailored building blocks captured two anions located at far-spaced binding sites, and adopted noninterfering anion-binding processes to guarantee the anion-binding affinity, topology, and dimensionality. Solid-state studies elucidated that the neutral 1-3 interacted with the tetrahedral dihydrogen phosphate anion in proper proportions and designed topologies, thus leading to the formation of a series of multidimensional networks by self-assembly in the solid state. The observations showed a well-characterized phosphate-directed assembly of multidimensional metal-free coordination polymers in the solid state, in which the formed phosphate aggregates, including dimer encapsulated in an indole-mediated hydrogen-bonded pocket and an infinite chain, behaved as anionic templates to direct the self-assembly. However, no evidence proved the presence of such phosphate-directed infinite coordination polymers in solution.
探索阴离子模板以指导复杂超分子组装的策略引起了人们的关注。在此，我们从 2,3-二吲哚-3'-基喹喔啉（DIQ）和 5,6-二氢二吲哚并[3,2-a：2',3'-c]吩嗪（DIPZ）前体出发，合理设计并制备了一系列含有两个吲哚基结合位点且由连接间隔基吡嗪并[2,3-g]喹喔啉（PQ）桥接的新型阴离子受体 1-3。X 射线分析表明，在结构 1 和 2 中，在固态下通过氢键和 π-π 堆积相互作用分别表现出自连接网络和二聚体堆积。所有三个受体都表现出一系列来自扩展的π体系的显著吸收带。基于吲哚的扩展受体被发现可以强烈且选择性地结合测试阴离子（F(-)、Cl(-)、Br(-)、AcO(-)、H2PO4(-)、HSO4(-)、NO3(-)和 ClO4(-)）中的 F(-)、AcO(-)和 H2PO4(-)，并作为用于 DMSO 中氟阴离子的肉眼检测的高效比色传感器。这些定制的构建基块捕获位于远间隔结合位点的两个阴离子，并采用非干扰阴离子结合过程来保证阴离子结合亲和力、拓扑结构和维度。固态研究表明，中性 1-3 与四氢磷酸二氢盐阴离子以适当的比例和设计的拓扑相互作用，从而导致在固态下通过自组装形成一系列多维网络。观察结果表明，在固态中形成了一系列无金属配位聚合物的多维度磷酸盐导向组装，其中形成的磷酸盐聚集体，包括在吲哚介导的氢键口袋中封装的二聚体和无限链，作为阴离子模板来指导自组装。然而，没有证据表明在溶液中存在这种磷酸盐导向的无限配位聚合物。
