Internal and ExternalPockets in Pillar[<i>n</i>]arene Sheets and Their Host–GuestBinding Beyond Cavity VolumeLimitations

Constructing binding pockets by hierarchically assembling tailored building blocks and understanding structure–property relationships are challenging goals. Herein, amphiphilic pillar[5]arene and pillar[6]arene were prepared and used to construct 2D sheets, which consisted of well-defined hydrophobic and hydrophilic interlayers. In the hydrophobic interlayers, internal hydrophobic pockets were created by packing pairs of pillar[<i>n</i>]arenes, and external hydrophobic pockets were simultaneously generated from gaps between pillar[<i>n</i>]arenes due to electrostatic attractions. Aromatic hydrocarbons were accommodated in these hydrophobic pockets by ball milling. Due to the external pockets, bulky guests larger than the pillar[<i>n</i>]arene cavity sizes were also captured in the sheets.