Pillar[5]arene host-guest chemistry in water: From trapped rotaxanes to pH and temperature responsive supramolecular boxes

The pillar[n]arene family, a new family of macrocycles, has proven itself in the last decade as an important component of modern supramolecular chemistry.¹ One of the main advantages of pillar[n]arenes is their relatively easy synthesis and functionalization which enables, among other things, the formation of water-soluble pillar[n]arenes that may have important biological implications and applications.² Here we present the first cases of trapped water-soluble rotaxanes based on host-guest interactions between per-amino-pillar[5]arene and aliphatic bis-sulfonate guests. In addition, further to our previous work,³ we also present the formation of the first pillar[5]arene-based water-soluble supramolecular boxes. The effect of both temperature and pH on these systems will be described.

1. (a) Ogoshi, T. et al., J. Am. Chem. Soc. 2008, 130, 5022-5023. (b) Ogoshi, T.; Yamagishi, T. A.; Nakamoto, Y. Chem. Rev. 2016, 116, 7937–8002.
2. (a) Feng, W.; Jin, M.; Yang, K.; Pei, Y.; Pei, Z. Chem. Commun. 2018, 54, 13626–13640. (b) Xiao, T.; Qi, L.; Zhong, W.; Lin, C.; Wang, R.; Wang, L. Mater. Chem. Front., 2019, 3, 1973-1993
3. Kaizerman-Kané, D.; Hadar, M.; Tal, N.; Dobrovetsky, R.; Zafrani, Y.; Cohen, Y. Angew. Chem. Int. Ed. 2019, 58, 5302–5306.