二元组装体集群时的高选择性杂化重组行为

多样性自组装体在混合时,通常表现出互不干扰的自分类性,能高度选择性地自分类堆积.但结构极为相似的组装子在相互混合时,会发生交互作用并表现出重组现象.文中合成和观测了具有芳香环边墙和不同酰胺侧链的C型甘脲分子夹为组装单元的混合组装行为.研究发现,此类分子在各自以单一态物质溶解于CDCl3时,能通过π-π相互作用和氢键形成二聚自组装体;若将两种具有不同酰胺侧链的C型甘脲分子夹两两混合,从理论上推测应有三种二聚自组装堆积态存在：A·A、B·B、A·B.但经1HNMR分析发现了一个有趣的现象,即当酰胺侧链上的取代基R′分别为具有C-H结构（如1和2）与PhF5基（5）的组装体两两混合时,二聚组装主要呈现出高度选择性杂化重组的A·B结构态.这种取代基控制的高选择性重组行为可能是基于π-π相互作用、N—H…O氢键,以及C—H…π等三重作用力的协同结果.

Highly selective hetero-reassembly of dimeric aggregate

We report the synthesis and characterization of eight C-shaped methylene-bridged glycoluril dimers （1-8） beating H-bonding groups on their aromatic rings. Compounds 1-8 form tightly associated homodimers in CDCl3, due to the combined driving force of π-π and H-bonding interactions. When the spatial distributions of the H-bonding groups of the molecular clips are similar （e.g., 1-7）, a mixture of homodimers （A.A and B.B） and heterodimers （A.B） is formed. The highly heterodimer-selective process is not easily rationalized given the steric similarity of 5 and 6, and the electronic similarity of 1 and 2, 1 and 3, which all show modest levels of selectivity when paired with 1 or 5, respectively. The effect of various structural modifications （e.g., side chain steric bulk and electronic effect） on the selectivity of reassembly is presented. On the basis of these results, the highly heterodimer-selective process may be driven by cooperative force of π-π interactions, H-bonding interactions and CH-π interactions. Furthermore, we also investigate self-sorting systems comprising heterodimer （1·5） and homodimer （8·8）.