Self-Assembly and Exfoliation of a Molecular Solid Based on Cooperative B–N and Hydrogen Bonds

Herein we report that 4-pyridinylboronic acid (1) in the solid state self-assembles into tetrameric macrocycles via B–N bond formation. The tetramers are linked via O–H···O bonds resulting in a material that can be exfoliated via sonication to give thinner sheets as we demonstrate via Fourier transform infrared spectroscopy, transmission electron microscopy, selected area electron diffraction, and atomic force microscopy experiments. For comparison, the structure of the related compound 4-(pyridin-4-yl) phenylboronic acid (2) is also discussed.