Wang Xue-Yuan, Zhu Jun, Wang Qi-Qiang, Ao Yu-Fei, Wang De-Xian
Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China.
University of Chinese Academy of Sciences , Beijing 100049 , China.
Inorg Chem. 2019 May 6;58(9):5980-5987. doi: 10.1021/acs.inorgchem.9b00295. Epub 2019 Apr 9.
Anion-π-directed self-assembly between a series of di- and trisulfonate anions and a rigid molecular cage 1 was presented. The self-assembly study was established on a combination of X-ray crystallography, NMR, mass spectrometry (MS), and scanning electron microscopy (SEM) techniques. As revealed in the crystal structures, the cage provided two V-shaped electron-deficient clefts to accommodate sulfonate groups through anion-π interactions. Depending on their structure, the series of anions showed different intermolecular interaction details with the cage and led to the formation of diverse self-assembly motifs. For 1,2-ethanedisulfonate (EDS), 1,3-propanedisulfonate (PDS), and 1,4-butanedisulfonate (BDS), very similar and uniform 2D ladder-like self-assemblies were formed. For 1,6-hexanedisulfonate (HDS) with a longer alkyl chain, a helical chain assembly was formed, while 1,3,5-tris(4-sulfophenyl)benzene (TSPB) led to a 3D frame structure. In solution, NMR titrations suggested that the cage can complex these anions, with association constants falling in range of 5-114 M. NMR spectra recorded at variable concentrations and temperatures and electrospray ionization MS further confirmed self-assembly formation. The morphologies of the diverse self-assemblies formed between the cage and sulfonates were revealed by SEM. This study, hence, provides evidence that anion-π interactions can play decisive roles in self-assembly.
本文介绍了一系列二磺酸根和三磺酸根阴离子与刚性分子笼1之间基于阴离子-π相互作用的自组装。该自组装研究是建立在X射线晶体学、核磁共振（NMR）、质谱（MS）和扫描电子显微镜（SEM）技术相结合的基础上的。晶体结构显示，该分子笼提供了两个V形缺电子裂缝，通过阴离子-π相互作用来容纳磺酸根。根据其结构，这一系列阴离子与分子笼表现出不同的分子间相互作用细节，从而导致形成不同的自组装图案。对于1,2-乙二磺酸根（EDS）、1,3-丙二磺酸根（PDS）和1,4-丁二磺酸根（BDS），形成了非常相似且均匀的二维梯状自组装结构。对于具有较长烷基链的1,6-己二磺酸根（HDS），形成了螺旋链组装结构，而1,3,5-三（4-磺酸苯基）苯（TSPB）则导致形成三维框架结构。在溶液中，核磁共振滴定表明该分子笼可以与这些阴离子络合，缔合常数在5 - 114 M范围内。在可变浓度和温度下记录的核磁共振光谱以及电喷雾电离质谱进一步证实了自组装的形成。扫描电子显微镜揭示了分子笼与磺酸盐之间形成的各种自组装的形态。因此，这项研究提供了证据，证明阴离子-π相互作用在自组装中可以发挥决定性作用。
