Vogel Julian, Chen Yusheng, Fadler Rachel E, Flood Amar H, von Delius Max
Institute of Organic Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN, 47405, USA.
Chemistry. 2023 Jul 20;29(41):e202300899. doi: 10.1002/chem.202300899. Epub 2023 Jun 9.
The supramolecular recognition of anions is increasingly harnessed to achieve the self-assembly of supramolecular architectures, ranging from cages and polymers to (pseudo)rotaxanes. The cyanostar (CS) macrocycle has previously been shown to form 2 : 1 complexes with organophosphate anions that can be turned into [3]rotaxanes by stoppering. Here we achieved steric control over the assembly of pseudorotaxanes comprising the cyanostar macrocycle and a thread that is based, for the first time, on organo-pyrophosphonates. Subtle differences in steric bulk on the threads allowed formation of either [3]pseudorotaxanes or [2]pseudorotaxanes. We demonstrate that the threading kinetics are governed by the steric demand of the organo-pyrophosphonates and in one case, slows down to the timescale of minutes. Calculations show that the dianions are sterically offset inside the macrocycles. Our findings broaden the scope of cyanostar-anion assemblies and may have relevance for the design of molecular machines whose directionality is a result of relatively slow slipping.
阴离子的超分子识别越来越多地被用于实现超分子结构的自组装，其范围从笼状结构、聚合物到（准）轮烷。先前已证明，氰基星（CS）大环与有机磷酸根阴离子形成2:1配合物，通过封端可将其转化为[3]轮烷。在此，我们首次实现了对由氰基星大环和基于有机焦膦酸酯的线组成的准轮烷组装的空间控制。线上空间体积的细微差异使得能够形成[3]准轮烷或[2]准轮烷。我们证明，穿线动力学受有机焦膦酸酯的空间需求控制，在一种情况下，会减慢到分钟时间尺度。计算表明，二价阴离子在大环内部存在空间偏移。我们的研究结果拓宽了氰基星-阴离子组装的范围，可能与设计方向性源于相对缓慢滑动的分子机器相关。
