3D Covalent Organic Framework with "the" Topology.

Abstract

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, the first 3D COF, TUS-38, with the topology is constructed 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 twofold 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 that 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 6.3gg-1. Recyclability studies evidence that TUS-38 can be reused at least five times retaining 95% of its initial adsorption capacity; while density functional theory (DFT) calculations have heightened the understanding of the interactions between iodine molecules and the framework.