Facile Synthesis of a Highly Crystalline, Covalently Linked Porous Boronate Network

A covalent organic framework (COF-18Å) based on poly(boronate ester)s has been successfully synthesized through a facile dehydration process in 85−95% isolated yield. Spectroscopic characterization confirms formation of the intended ester linkages as the key structural motif forming infinite 2D hexagonally porous sheets. Powder X-ray diffraction studies were used to determine the stacking orientation between the ester-linked sheets, such that atoms in adjacent layers lie directly over each other, resulting in a hexagonal array of 1D, 18 Å pores. COF-18Å exhibits rigid, thermally stable (to 500 °C) pores with high surface area (1260 m2/g) and a micropore volume of 0.29 cm3/g.