Official websites use. Share sensitive information only on official, secure websites. Corresponding Author: Ronald A. Smaldone - ronald. Two dimensional covalent organic frameworks 2D-COFs are a class of crystalline porous organic polymers that consist of covalently linked, two dimensional sheets that can stack together through non-covalent interactions.
Here we report the synthesis of a novel COF, called PyCOFamide, which has an experimentally observed pore size that is greater than 6 nm in diameter. This is among the largest pore size reported to date for a 2D-COF. PyCOFamide exhibits permanent porosity and high crystallinity as evidenced by the nitrogen adsorption, powder X-ray diffraction, and high-resolution transmission electron microscopy. We show that the pore size of PyCOFamide is large enough to accommodate fluorescent proteins such as Superfolder green fluorescent protein and mNeonGreen.
This work demonstrates the utility of non-covalent structural reinforcement in 2D-COFs to produce larger, persistent pore sizes than previously possible. Two-dimensional covalent organic frameworks 2D-COFs are crystalline, porous, organic polymer networks built from organic monomers and linked together by dynamic covalent bonds.
One fundamental challenge in porous materials design involves the synthesis of structures with large, and persistent pores. There are several obstacles in this pursuit, including the solubility of large organic molecules needed to generate the large-pore sizes, 17 , 18 as well as the propensity for pore collapse or structural damage upon solvent removal. This strategy is beneficial as it can be used on any material and does not require any synthetic modification of the COF structure.
However, more recent work has shown that by designing non-covalent interactions that are directed specifically between the layers, COFs with significantly improved crystallinity and surface area can be attained, even without scCO 2 activation. In these situations, the only way to preserve these large-pores may be through a combination of structural reinforcement and improved activation methods. Here we present a supramolecular reinforcement strategy that strengthens the adhesion between the stacked 2D COF layers through the use of directed hydrogen bonding and stabilizes the large pores against collapse.
