Extensive research on the use of cyclodextrin for insulating pi-conjugated polymer chains has been carried out. However, the resulting polyrotaxanes do not exhibit high and constant covering ratios and are generally insoluble in organic solvents. Here we demonstrate a new method of synthesizing permethylated cyclodextrin-based polyrotaxanes involving the polymerization of linked rotaxane monomers. The insulated
Metal coordination to the polymer enabled easy and reversible tuning of the luminescent color without changes to the main chain skeleton. The permethylated α‐cyclodextrin (PM α‐CD)‐based insulation structure allowed the metalated polymers to demonstrate efficient emission even in the solid state, with identical spectral shapes to the dilute solutions. In addition, the coordination ability of the metal‐free
We describe a new concept for rotaxane synthesis through intramolecular slippage using π‐conjugated molecules as rigid axles linked with organic soluble and flexible permethylated α‐cyclodextrins (PM α‐CDs) as macrocycles. Through hydrophilic–hydrophobic interactions and flipping of PM α‐CDs, successful quantitative conversion into rotaxanes was achieved without covalent bond formation. The rotaxanes
我们描述了一种新的概念,即通过使用π共轭分子作为刚性轴与有机可溶性和柔性全甲基化α-环糊精(PMα-CDs)作为大环连接的分子内滑动来合成轮烷的新概念。通过亲水-疏水相互作用和PMα-CD的翻转,可以成功地定量转化为轮烷,而不会形成共价键。轮烷具有很高的脱线活化屏障,因此即使在不利于维持轮烷结构的条件下,它们也被动力学分离和衍生化。1个1 H NMR光谱实验清楚地表明,通过刚性轴连接的大环的受限运动使得可以通过调节前体结构中刚性轴的长度而不是塞子单元的空间体积来控制动力学稳定性。
A manganese porphyrin–α-cyclodextrin conjugate as an artificial enzyme for the catalytic epoxidation of polybutadiene
作者:Qi-Wei Zhang、Johannes A. A. W. Elemans、Paul B. White、Roeland J. M. Nolte
DOI:10.1039/c8cc02320d
日期:——
manganese porphyrin–α-cyclodextrin conjugate as a catalyst for the epoxidation of cis-polybutadiene with trans-epoxide preference, which is a reverse stereoselectivity as compared to normal porphyrin catalysts. A clamp-like mechanism is proposed based on a combination of circular dichroism analysis, molecular modeling, and a series of epoxidation experiments.
We synthesized symmetrically insulated oligo(para-phenylene) and oligothiophene with a pseudo-linked [3]rotaxane structure by full rotation of glucopyranose units via a flipping (tumbling) mechanism in the π-conjugated guest having two permethylated β-cyclodextrin units at both ends. We also succeeded in the synthesis of an organic-soluble fixed [3]rotaxane by a cross-coupling or complexation reaction of thus formed pseudo linked [3]rotaxane. Oligo(para-phenylene), oligothiophene, and porphyrin derivatives were used as π-conjugated guests with stopper groups.