Unraveling the Structural Features and Host-Guest Chemistry of Amide Functionalized COFs with MicroED

Project Description

Two-dimensional covalent organic frameworks (COF) are class of crystalline polymers comprised of covalently linked two-dimensional sheets which assemble through noncovalent interactions into 3D structures. Our group recently reported a series of imine-linked COFs called COFamides, that rely on hydrogen bonding interactions that reinforce the framework structure enabling the synthesis of materials with pores as large as 6 nm in diameter.

COFs are commonly synthesized as polycrystalline solids with domain lengths smaller than 100 nm. One of the main obstacles to solving the single-crystal structures of 2D COFs is that producing high-quality crystals for conventional X-ray techniques is a significant challenge. One goal of this project is to obtain atomic scale information about how the hydrogen bonding interactions act to stabilize the extended structure of the framework. Another goal is to investigate the potential for COFamides to act as “crystalline sponges” that can place guest molecules in an ordered arrangement where their X-ray structures can be more easily obtained. The complexity of these materials and the incorporation of proteins in the pores make advanced techniques such as microED uniquely suited to analyze crystals are too small for other methods of structural determination. The tunable, large pore size of COFamide offers the potential to study a wide variety of guest molecules, aggregates of small molecules, or selective extraction of guests from complex mixtures.

Instruments