Pillarurilarenes: Glycoluril-Expanded Pillararenes
Chao Ruan, Zhijin Li, Wenhao Lin, Ranran Wang, Wang Xie, Heng Li, Yunfeng Lu, Ruibing Wang, Shengke Li, Leyong Wang
Abstract
Glycoluril-expanded pillararenes composed of glycoluril and dialkoxybenzene units, namely, pillarurilarenes ( PURA ), were synthesized through a fragment coupling macrocyclization strategy. Partial replacement of dialkoxybenzene with glycoluril endows PURA with polarized equatorial methine protons for derivatization or CH–anion binding. Crystal structures of pillar[2]uril[4]arene and pillar[1]uril[4]arene containing two glycoluril units and one glycoluril unit, respectively, indicated the inward orientation of the glycoluril unit, as also suggested by 1 H nuclear magnetic resonance and density functional theory calculation. This work lays a good foundation for expanding pillararenes using non-aromatic rings.