Determining Covalent\nOrganic Framework Structures\nUsing Electron Crystallography and Computational Intelligence

The\nstructural characterization of new materials often\nposes immense\nchallenges, especially when obtaining single-crystal structures is\ndifficult, which is a common difficulty with covalent organic frameworks\n(COFs). Despite this, understanding the atomic structure is crucial\nas it provides insights into the arrangement and connectivity of organic\nbuilding blocks, offering the opportunity to establish the correlation\nof structure–function relationships and unravel material properties.\nIn this study, we present an approach for determining the structures\nof COFs, an integration of electron crystallography and computational\nintelligence (COF+). By applying established chemistry knowledge and\nemploying particle swarm optimization (PSO) for trial structure generation,\nwe overcome existing limitations, thus paving the way for advancements\nin COF structural determination. We have successfully implemented\nthis technique on four representative COFs, each with unique characteristics.\nThese examples underline the accuracy and efficacy of our approach\nin addressing the challenges tied to COF structural determination.\nFurthermore, our approach has revealed new structure candidates with\ndifferent topologies or interpenetrations that are chemically feasible.\nThis discovery demonstrates the capability of our algorithm in constructing\ntrial COF structures without being influenced by topological factors.\nOur new approach to COF structure determination represents a significant\nadvancement in the field and opens new avenues for exploring the properties\nand applications of COF materials.