Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, 3663 North Zhongshan Road, Shanghai, China, 200062.
J Org Chem. 2010 Nov 5;75(21):7373-80. doi: 10.1021/jo101648p.
The construction of a new series of dendritic tris(crown ether) hexagons via coordination-driven self-assembly is described. Combining 120° crown ether-containing diplatinum(II) acceptors with 120° dendritic dipyridyl donors in a 1:1 ratio allows for the formation of a new family of dendritic triple crown ether derivatives with a hexagonal cavity in quantitative yields. The number and the position of these pendant groups can be precisely controlled on the hexagonal metallacycle. The structures of all dendritic multiple crown ether hexgaons are confirmed by multinuclear NMR ((1)H and (31)P), ESI-MS and ESI-TOF-MS, and elemental analysis. The complexation of these dendritic trivalent receptors with dibenzylammonium cations was investigated by (1)H NMR titration experiments. The thermodynamic binding constants between the receptors and guests were established by using the nonlinear least-squares fit method based on (1)H NMR titration experiments. It was found that the association constants of each assembly decrease correspondingly upon the increase of the generation of the dendrons from [G0] to [G3], which might be caused by the steric effect of the dendrons on host-guest complexation.
通过配位驱动的自组装方法构建了一系列新型支化三（冠醚）六元环。在 1:1 的比例下，将含有 120°冠醚的双铂（II）受体与 120°支化二吡啶供体结合，定量生成了一种新型支化三冠醚衍生物的家族，其空腔呈六边形。这些悬垂基团的数量和位置可以在六边形金属环上精确控制。通过多核 NMR((1)H 和 (31)P)、ESI-MS 和 ESI-TOF-MS 以及元素分析，确定了所有支化多冠醚六元环的结构。通过 (1)H NMR 滴定实验研究了这些支化三价受体与二苄基铵阳离子的络合作用。通过基于 (1)H NMR 滴定实验的非线性最小二乘法拟合方法，确定了受体与客体之间的热力学结合常数。结果发现，随着树枝状分子代数从 [G0] 增加到 [G3]，每个组装体的缔合常数相应降低，这可能是由于树枝状分子对主客体络合的空间位阻效应所致。
