A macrocyclic receptor containing two viologen species connected by conjugated terphenyl groups.
A macrocyclic receptor containing two viologen species connected by conjugated terphenyl groups.
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DOI：
10.1039/c8ob00919h
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发表时间：
2018-07
影响因子：
3.2
通讯作者：
Longqi Chen;Kate J. C. Lim;T. S. Babra;James O. Taylor;Martin Pižl;R. Evans;A. Chippindale;F. H
中科院分区：
文献类型：
--
作者：
Longqi Chen;Kate J. C. Lim;T. S. Babra;James O. Taylor;Martin Pižl;R. Evans;A. Chippindale;F. H
设计并合成了一种由共轭三联苯基团连接的两个紫精类大环受体分子。单晶X-射线结构表明，两个紫精残基具有约1.5 μ m的跨环NN分离。7.4- 是的因此，内腔尺寸适合于包含富π电子物质。大环是氧化还原活性的，并且可以从包括三乙胺的合适的供体物质接受电子，由于形成顺磁性双（自由基阳离子）物质，导致从浅黄色到深绿色的显著颜色变化。循环伏安法表明，该大环化合物可以经历两个连续的可逆还原过程（E1/2 = -0.65和-0.97Vvs.Fc/Fc+）。DFT和TD-DFT研究准确地复制了四阳离子大环的结构和系统的三个主要氧化还原态的电子吸收光谱。这些计算还表明，在电化学还原过程中，自由基阳离子的未成对电子密度保持相对本地化的杂环内。大环形成超分子配合物的能力通过与含有富π电子的1，5-二羟基萘衍生物的客体分子形成准轮烷来证实。准轮烷的穿线和脱线在NMR时间尺度上是快速的，并且根据1H NMR滴定研究计算，该络合物表现出150 M-1（±30 M-1）的缔合常数。
A macrocyclic receptor molecule containing two viologen species connected by conjugated terphenyl groups has been designed and synthesised. The single-crystal X-ray structure shows that the two viologen residues have a transannular NN separation of ca. 7.4 Å. Thus, the internal cavity dimensions are suitable for the inclusion of π-electron-rich species. The macrocycle is redox active, and can accept electrons from suitable donor species including triethylamine, resulting in a dramatic colour change from pale yellow to dark green as a consequence of the formation of a paramagnetic bis(radical cationic) species. Cyclic voltammetry shows that the macrocycle can undergo two sequential and reversible reduction processes (E1/2 = -0.65 and -0.97 V vs. Fc/Fc+). DFT and TD-DFT studies accurately replicate the structure of the tetracationic macrocycle and the electronic absorption spectra of the three major redox states of the system. These calculations also showed that during electrochemical reduction, the unpaired electron density of the radical cations remained relatively localised within the heterocyclic rings. The ability of the macrocycle to form supramolecular complexes was confirmed by the formation of a pseudorotaxane with a guest molecule containing a π-electron-rich 1,5-dihydroxynaphthalene derivative. Threading and dethreading of the pseudorotaxane was fast on the NMR timescale, and the complex exhibited an association constant of 150 M-1 (±30 M-1) as calculated from 1H NMR titration studies.