TetrazineBox: A Structurally Transformative Toolbox
TetrazineBox: A Structurally Transformative Toolbox
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DOI：
10.1021/jacs.0c01114
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发表时间：
2020-03-18
影响因子：
15
通讯作者：
Stoddart, J. Fraser
中科院分区：
文献类型：
--
作者：
Guo, Qing-Hui;Zhou, Jiawang;Stoddart, J. Fraser
能够通过响应多种外部刺激来进行变构调节的合成大环化合物是超分子科学中越来越受到关注的主题。在此，我们报道了一种结构转变的四阳离子环烷，含有两个 3,6-双(4-吡啶基)-l,2,4,5-四嗪 (4-bptz) 单元，它们通过两个对亚二甲苯桥连接在一起。环芳烷具有模块化的氧化还原态和结构后修饰，可以经历两次可逆的连续双电子还原，首先提供其双自由基双键对应物，然后提供完全还原的物质。此外，利用还原或逆电子需求狄尔斯-阿尔德（IEDDA）反应，一种单亲环烷可以通过盒到盒级联转化有效地提供三种其他新类似物。虽然所有四种新型四阳离子环烷均采用刚性且对称的盒状构象，但它们与尺寸、形状、电子特性以及对多环芳烃的结合亲和力相关的几何形状可以很容易地调节。这种结构上具有变革性的四阳离子环烷由于结构后修饰而执行多种新任务，因此可作为探索自由基性质并通过有效的发散合成快速生成一系列结构多样的环烷的工具箱。这项研究为将结构转变的四阳离子环烷引入机械连锁分子领域奠定了坚实的基础，并将提供构建和操作智能分子机器的工具箱。
Synthetic macrocycles capable of undergoing allosteric regulation by responding to versatile external stimuli are the subject of increasing attention in supramolecular science. Herein, we report a structurally transformative tetracationic cyclophane containing two 3,6-bis(4-pyridyl)-l,2,4,5-tetrazine (4-bptz) units, which are linked together by two p-xylylene bridges. The cyclophane, which possesses modular redox states and structural post-modifications, can undergo two reversibly consecutive two- electron reductions, affording first its bisradical dicationic counterpart, and then subsequently the fully reduced species. Furthermore, one single-parent cyclophane can afford effectively three other new analogs through box-to-box cascade transformations, taking advantage of either reductions or an inverse electron-demand Diels-Alder (IEDDA) reaction. While all four new tetracationic cyclophanes adopt rigid and symmetric box-like conformations, their geometries in relation to size, shape, electronic properties, and binding affinities toward polycyclic aromatic hydrocarbons can be readily regulated. This structurally transformative tetracationic cyclophane performs a variety of new tasks as a result of structural post-modifications, thus serving as a toolbox for probing the radical properties and generating rapidly a range of structurally diverse cyclophanes by efficient divergent syntheses. This research lays a solid foundation for the introduction of the structurally transformative tetracationic cyclophane into the realm of mechanically interlocked molecules and will provide a toolbox to construct and operate intelligent molecular machines.