C3-symmetrical supramolecular architectures: fibers and organic gels from discotic trisamides and trisureas.
C3-symmetrical supramolecular architectures: fibers and organic gels from discotic trisamides and trisureas.
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DOI：
10.1021/ja020984n
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发表时间：
2002-11
影响因子：
15
通讯作者：
J. J. van Gorp-J.;J. Vekemans;E. Meijer
中科院分区：
文献类型：
--
作者：
J. J. van Gorp-J.;J. Vekemans;E. Meijer
描述了氢键C（3）-对称分子缔合成超分子堆叠。这些分子的结构突变已被执行，以阐明不同的二级相互作用（氢键，π-π堆叠）的磁盘到手性堆栈的自组装的贡献。已研究了12个C（3）对称分子，其中6个含有3个中心酰胺官能团（1a-f），6个含有3个中心脲基团（2a-f）。的磁盘的外围组是“小”，“中”，或“大”，其中一半是非手性的，另一半是手性的，使调查的超分子结构与CD光谱。在所有的情况下，细长的，螺旋堆叠形成在非极性溶液中，除了“中等”酰胺盘1c/d。C（3）对称盘的伸长堆叠形成凝胶，其通过AFM和SANS可视化，这证实了相互作用的方向性。对于“大”尿素盘2f，观察到长度高达2微米的纤维。温度依赖性和“军士和士兵”CD测量表明，尿素堆比相应的酰胺堆刚性大得多。在“中等”尿素盘2c/d的情况下，形成真正的刚性杆。当酰胺盘立即达到热力学平衡时，动力学因素似乎支配尿素聚集。在许多旨在可逆性与尿素堆叠的实验中，观察到滞后，这意味着这些尿素盘最初形成一个不明确的堆叠，随后慢慢转变成一个明确的，手性架构。
Hydrogen bonded C(3)-symmetrical molecules that associate into supramolecular stacks are described. Structural mutation on these molecules has been performed to elucidate the contribution of the different secondary interactions (hydrogen bonding, pi-pi stacking) to the self-assembly of the disks into chiral stacks. Twelve C(3)-symmetrical molecules have been investigated, six of which contain three central amide functionalities (1a-f) and six of which contain three central urea groups (2a-f). Peripheral groups of the disks are "small", "medium", or "large", half of them being achiral and the other half being chiral, to enable investigation of the supramolecular architectures with CD spectroscopy. In all of the cases, elongated, helical stacks are formed in apolar solution, except for the "medium" amide disks 1c/d. The elongated stacks of the C(3)-symmetrical disks form gels, which are visualized by AFM and SANS, and this confirms the directionality of the interactions. For the "large" urea disk, 2f, fibers with a length of up to 2 microm are observed. Temperature dependent and "sergeants-and-soldiers" CD measurements reveal that the urea stacks are much more rigid than the corresponding amide ones. In case of the "medium" urea disks, 2c/d, a true rigid rod, is formed. Where amide disks immediately reach their thermodynamic equilibrium, kinetic factors seem to govern urea aggregation. In a number of experiments aimed at reversibility with the urea stacks, hysteresis is observed, implying that these urea disks initially form a poorly defined stack, which subsequently transforms slowly into a well-defined, chiral architecture.