Pillar[6]arene-based water-soluble molecular boxes

Non-covalent molecular containers, cages and capsules have been studied persistently in the last two decades¹. This occurred due to their ability to reversibly isolate specific compounds from the bulk and to serve, inter alia, as nano-reactors where new phenomena, new chemistry and catalysis may occur. Pillar[n]arenes, first discovered by Ogoshi in 2008², are a new class of macrocycles that may be used as a building block for the preparation of such potentially valuable containers. To date, despite the 600 papers dealing with pillar[n]arenes no studies regarding water-or even organic soluble pillar[n]arene capsules or boxes are known. Here we present the first water-soluble pillar[6]arene-based molecular boxes prepared by capping per-amino-pillar[6]arenes with complementary lids, like mellitic acid, pyro mellitic acid and trimesic acid. The structures of these molecular boxes, which are based on multiple charge-assisted hydrogen bonds, will be described as well as their response to pH stimulus.

1. Ballester, P., Fujita, M., Rebek, J., Chem. Soc. Rev., 2015,44, 392-393
2. Ogoshi, T. et al., J. Am. Chem. Soc. 2008, 130, 5022-5023.