超分子催化指利用超分子化学的方法调控化学反应的速率和方向。超分子催化的研究最初来自于对天然酶催化行为的模拟，其中底物和催化剂的结合通过非共价相互作用。相比于天然酶，超分子催化剂往往结构相对简单，易于修饰和衍生化，具有更好的环境耐受性，同时还有可能被设计用于催化生物体系中原本不存在的反应。我们构建了一个基于葫芦脲[8]和Brooker部花青的高效超分子催化体系。通常而言，由于产物抑制效应，即因催化产物比反应物更容易与催化剂结合而导致催化剂失活，葫芦脲[8]作为超分子催化剂常常需要成化学计量比地添加到反应体系中，方能促使反应充分进行。但在我们此次构建的超分子催化体系中，1%当量的葫芦脲[8]即可在短时间内（10 min）促使体系中几乎所有Brooker部花青分子发生光致环加成反应，迅速抵达反应终点。我们探究了该体系中Brooker部花青光致异构化反应和光致环加成反应之间的竞争过程，验证了此体系中葫芦脲[8]是一个能够持续发挥催化功能的超分子催化剂，而非一个与底物成比例消耗的反应物，并分析了葫芦脲[8]在较高的催化活性和相对较大的转化数两方面的原因。超分子聚合物是单体之间通过具有高度选择性和方向性的非共价相互作用相连的聚集体。与传统聚合物一样，分子量是超分子聚合物的一项重要指标，决定了超分子聚合物及其相关材料的性能。由于超分子聚合物绝大多数处于热平衡状态，单体分子之间时刻发生着结合与解离过程，因此超分子聚合物的分子量常与单体分子的浓度直接关联。所以，在同一单体浓度下，超分子聚合物的分子量常常难以达到连续可调。我们将葫芦脲[8]/Brooker部花青超分子光催化体系，用于调控超分子聚合物的聚合过程。通过设计合成含Brooker部花青基团的双官能度单体，将其与葫芦脲[8]在水溶液中发生主客体复合，可以形成分子量较低的环状超分子寡聚物。通过施加紫外光辐照，可以使体系中的超分子寡聚物转化为高分子量的超分子聚合物。通过调节紫外光辐照时间，实现在同等单体初始浓度下获得不同分子量的超分子聚合物。此外，通过改变紫外光辐照波长以及引入竞争性客体分子，也可实现超分子聚合物的可控降解。
Supramolecular catalysis, which was originally inspired by natural enzymatic catalysis, refers to the modulation on the rate and the direction of chemical reactions based on the noncovalent interactions, such as hydrogen bonding, electrostatic interaction and host-guest interaction. In comparison to natural enzymes, supramolecular catalysts are always with simpler structure, easier to modify and more robust under various conditions. Meanwhile, supramolecular catalyst is able to be designed on the chemical reactions which do not have counterparts in biological systems.We have developed a supramolecular catalysis system based on cucurbit[8]uril and Brooker’s merocyanine. Because of the product inhibition effect, cucurbituril usually has to be added in a stoichiometrical extent. However, in this supramolecular catalysis system, 1% of cucurbit[8]uril was sufficient to catalyse the photodimerization of Brooker’s merocyane to the end within a short period (~ 10 min). We proved that in this system, cucurbit[8]uril acted as a catalyst but not a reactant, and we also investigated the reasons for the high catalytic activity of cucurbit[8]uril.Supramolecular polymers refer to the polymeric arrays of monomeric units that are linked by noncovalent interactions with reversibility and directionality. As most of the supramolecular polymers are under thermodynamic equilibrium once prepared, in which the monomers are frequently converging and splitting all the time, the molecular weight of supramolecular polymers is always dependent on the concentration of monomers. Therefore, when monomer concentration is constant, the molecular weight of supramolecular polymers is hard to be adjusted continuously. We have employed the supramolecular catalysis system of cucurbituril/Brooker’s merocyanine for the modulation on the molecular weight of supramolecular polymers. We synthesized a ditopic monomer with Brooker’s merocyanine moieties and mixed it with cucurbit[8]uril. By tuning UV irradiation time, we obtained the supramolecular polymers with different molecular weight under the same origianal concentration of monomer. By varying the wavelength of UV light source and adding competitive guest molecules, respectively, the controllable disassociation of the supramolecular polymers is realized.
