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首页> 外文期刊>Chemistry: A European journal >Efficient synthesis and astonishing supramolecular architectures of several symmetric macrolactams
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Efficient synthesis and astonishing supramolecular architectures of several symmetric macrolactams

机译:几种对称大内酰胺的高效合成和惊人的超分子结构

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The synthesis of four C-n symmetric macrocyclic lactams cyclo-[NH-CH2-CH = CH-CH2-CO](n), (1, n=2; 2, n=3; 3, n=4) and cyclo-[NH-CH2-CH2-CH = CH-CO](3) (4) has been achieved by two approaches. A linear route leads to precursors that are subsequently macrocyclized in a separate step. The second, convergent approach relies on the symmetry of the targets: it includes suitably activated subunits, which are subjected to macrocyclization conditions. The subunits first oligomerize, then cyclize to form either pure macrolactams or mixtures. The macrolactam units 1, 2 and 4 stack on top each other through weak interactions (hydrogen bond and van der Waals), to form endless square, rectangular and triangular prisms, respectively. These stacks are further packed side by side in crystals grown from isotropic media. The overall dipoles in the crystals from lactams 1 and 4, which result mostly from the alignment of amide groups, are zero and large, respectively. Macrolactam 2 displays an astonishing isomorphism when allowed to cool down in anisotropic liquid crystal solutions. Large hollow hexagonal tubes are then obtained through a fractal process. Contrary to the three previous rings, 3 yields crystals where prisms of any shape are absent.
机译:四个Cn对称大环内酰胺的合成环[[NH-CH2-CH = CH-CH2-CO](n),(1,n = 2; 2,n = 3; 3,n = 4)和环-[ NH-CH2-CH2-CH = CH-CO](3)(4)已通过两种方法实现。线性途径导致前体,其随后在单独的步骤中被大环化。第二种收敛方法依赖于靶标的对称性:它包括适当活化的亚基,这些亚基会受到大环化条件的影响。亚基首先低聚,然后环化形成纯大内酰胺或混合物。大内酰胺单元1、2和4通过弱相互作用(氢键和范德华力)彼此堆叠在顶部,分别形成无穷的正方形,矩形和三角形棱柱。这些堆叠进一步并排填充在从各向同性介质中生长的晶体中。内酰胺1和4的晶体中的总偶极子分别为零和大,主要是由酰胺基团的排列引起的。当在各向异性液晶溶液中冷却时,Macrolactam 2表现出惊人的同构性。然后通过分形过程获得大型空心六角形管。与前面的三个环相反,3产生没有任何形状的棱镜的晶体。

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