London Dispersion Interactions inside Macrocycles

本文研究了伦敦分散作用（LDI）对大环化合物分子识别过程的贡献，主要是葫芦[n|脲（CBN）和控制其内腔内的化学反应。CBN是分子容器类型的水溶性大环主体分子，也就是说，它们能够将许多有机客体包封在它们的疏水空腔内。CBN内腔内结合的驱动力主要追溯到疏水效应，但LDI是一个重要的调节剂。在最初的六个实验研究路线中，有五个将在第二项目阶段进一步进行：1）建立在我们对惰性气体（He，Ne，Ar，Kr和H2O）与最小的CBN同系物CB 5结合中的LDI的量化基础上，我们计划研究不同对接阳离子在所得CB 5·惰性气体·阳离子络合物中调节LDI的潜力。2)我们将扩大我们的调查上的强极化硼酸盐集群的类型（B12 X12）2-取代碳硼烷，这与双阴离子硼酸盐集群具有中性核心的高亲和力结合。为了剖析LDI的溶剂效应，我们还将研究这类配合物的溶剂同位素效应。3)作为超分子催化的一个例子，我们已经研究了CB 7内的环戊二烯的二聚反应，我们已经发现了百万倍的速率增强;这项研究将扩展到甲基环戊二烯引入催化反应的化学选择性。4)我们建议评估的相对丰度的包合物与排阻配合物在气相中作为一个有趣的方法来研究LDI。通过合作，我们已经开始研究一系列有机铵离子与CB 6在气相中的反应。为了直接比较，我们已经在优先计划的第一阶段确定了铵离子与水中CB 6的结合常数。5)CBN大环在气相中的反转过程也将被检查，这被认为是由分子内LDI驱动的。在整个项目中，将使用核磁共振光谱、等温滴定量热法、染料置换滴定、有机合成和量子化学计算来确定结合亲和力以及热力学参数，从而评估LDI的重要性。

We propose to investigate the contribution of London dispersion interactions (LDI) to the molecular recognition process of macrocycles, prominently cucurbit[n|urils (CBn) and to the control of chemical reactions inside their inner cavity. CBn are water-soluble macrocyclic host molecules of the molecular container type, that is, they are able to encapsulate numerous organic guests inside their hydrophobic cavity. The driving force for binding inside the inner cavity of CBn is primarily traced back to a hydrophobic effect, but LDI present an important modulator. Out of the original six experimental lines of investigation, five will be further pursued in the second project phase: 1) Building up on our quantification of LDI in the binding of noble gases (He, Ne, Ar, Kr, and Xe) to the smallest CBn homologue, CB5, we plan to study the potential of different docking cations to modulate LDI in the resulting CB5•noble gas•cation complexes. 2) We will extend our investigation on the high-affinity binding of strongly polarizable borate clusters of the type (B12X12)2– to substituted carboranes, which in contrast to the dianionic borate clusters possess a neutral core. In order to dissect solvent effects from LDI, we will also study the solvent isotope effect for this type of complexes. 3) As an example of supramolecular catalysis, we have investigated the dimerization of cyclopentadiene inside CB7, for which we have found a million-fold rate enhancement; this study will be extended to methylcyclopentadiene to introduce chemoselectivity into the catalytic reaction. 4) We propose to assess the relative abundance of inclusion versus exclusion complexes in the gas phase as an interesting approach to study LDI. Through collaborations, we have started to investigate a series of organic ammonium ions with CB6 in the gas phase. For direct comparison, we already determined the binding constants of the ammonium ions to CB6 in water during the first phase of the priority programme. 5) The inversion process of CBn macrocycles in the gas phase will also be examined, which is thought to be driven by intramolecular LDI. Throughout the project, NMR spectroscopy, isothermal titration calorimetry, dye displacement titrations, organic synthesis and quantum-chemical calculations will be used to determine the binding affinities as well as thermodynamic parameters and, thus, to evaluate the importance of LDI.