Three-Dimensional Covalent Organic Framework with “the” Topology

Discovery of new topology covalent organic frameworks (COFs) is a mainstay in reticular chemistry and materials research because it not only serves as a stepwise guide to the designed construction of covalent-organic architectures but also helps to comprehend function from structural design point-of-view. Proceeding on this track, we have constructed the first three-dimensional (3D) COF, TUS-38, with the topology by reticulating a planar triangular 3-c node of D3h symmetry with a tetragonal prism 8-c node of D2h symmetry via [3+8] reversible imine condensation reaction. TUS-38 represents a 2-fold interpenetrated multidirectional pore network with a high degree of crystallinity and structural integrity. Interestingly, stemming from the nitrogen-rich s-triazine rings with electron-deficient character and -C=N- linkages composing the TUS-38 framework which benefit to the charge transfer and hence dipole-dipole electrostatic interactions between the framework and iodine in addition to exclusive topological characteristics of the exotic the net, TUS-38 achieves an exemplary capacity for iodine vapor uptake reaching 6.3 g g-1, thereby qualifying as top-level adsorbent for radioactive iodine capture. Recyclability studies evidence that TUS-38 could be reused at least five times retaining 95% of its initial adsorption capacity; while density functional theory (DFT) calculations have heightened our understanding of the interactions between iodine molecules and the framework. This study, therefore, stretches the topological boundaries of COFs with the brand new the net and we envision the widespread adoption of such unique topological configurations in combatting the environmental, climate and energy crises.