Supersnowflakes: Stepwise Self-Assembly and Dynamic Exchange of Rhombus Star-Shaped Supramolecules

• Published in: Journal of the American Chemical Society 2017-06, Vol.139 (24), p.8174-8185
• Main Authors: Zhang, Zhe, Wang, Heng, Wang, Xu, Li, Yiming, Song, Bo, Bolarinwa, Olapeju, Reese, R. Alexander, Zhang, Tong, Wang, Xu-Qing, Cai, Jianfeng, Xu, Bingqian, Wang, Ming, Liu, Changlin, Yang, Hai-Bo, Li, Xiaopeng
• Format: Article
• Language: English
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.7b01326

With the goal of increasing the complexity of metallo-supramolecules, two rhombus star-shaped supramolecular architectures, namely, supersnowflakes, were designed and assembled using multiple 2,2′:6′,2″-terpyridine (tpy) ligands in a stepwise manner. In the design of multicomponent self-assembly, ditopic and tritopic ligands were bridged through Ru­(II) with strong coordination to form metal–organic ligands for the subsequent self-assembly with a hexatopic ligand and Zn­(II). The combination of Ru­(II)–organic ligands with high stability and Zn­(II) ions with weak coordination played a key role in the self-assembly of giant heteroleptic supersnowflakes, which encompassed three types of tpy-based organic ligands and two metal ions. With such a stepwise strategy, the self-sorting of individual building blocks was prevented from forming the undesired assemblies, e.g., small macrocycles and coordination polymers. Furthermore, the intra- and intermolecular dynamic exchange study of two supersnowflakes by NMR and mass spectrometry revealed the remarkable stability of these giant supramolecular complexes.