Substoichiometric 3D Covalent Organic Frameworks Based on Hexagonal Linkers

Abstract

Covalent organic frameworks (COFs), a fast-growing field in crystalline porous materials, have achieved tremendous success in structure development and application exploration over the past decade. The vast majority of COFs reported to date are designed according to the basic concept of reticular chemistry, which is rooted in the idea that building blocks are fully connected within the frameworks. We demonstrate here that sub-stoichiometric construction of 2D/3D COFs can be accomplished by the condensation of a hexagonal linker with 4-connected building units. It is worth noting that the partially connected frameworks were successfully reticulated for 3D COFs for the first time, representing the highest BET surface area among imine-linked 3D COFs to data. The unreacted benzaldehydes in COF frameworks can enhance C 2 H 2 and CO 2 adsorption capacity and selectivities between C 2 H 2 /CH 4 and C 2 H 2 /CO 2 for sub-stoichiometric 2D COFs, while the reserved benzaldehydes control the interpenetrated architectures for the 3D case, achieving a rare non-interpenetrated pts topology for 3D COFs. This work not only paves a new avenue to build new COFs and endows residual function groups with further applications but also prompts redetermination of reticular frameworks in highly connected and symmetrical COFs.

Rational design of imine‐linked three‐dimensional mesoporous covalent organic frameworks with bor topology

“…Remarkably, 3D-bor-COF-3 is a non-interpenetrated structure, so its pore size achieved 3.8 nm, which is among the highest record of 3D COFs (Figure 1 and Table S2). [38][39][40][41] We also measured the pore sizes by high-resolution transmission electron microscopy (HRTEM), which is identical to the theoretical model (Figures 2(D), 2(H), and 2(I)).…”

“…Remarkably, 3D‐bor‐COF‐3 is a non‐interpenetrated structure, so its pore size achieved 3.8 nm, which is among the highest record of 3D COFs (Figure 1 and Table S2). 38–41 We also measured the pore sizes by high‐resolution transmission electron microscopy (HRTEM), which is identical to the theoretical model (Figures 2(D), 2(H), and 2(I)). To construct the bor COF, we selected the stereoscopic building unit 3,3′,5,5′‐tetrakis (4‐formylphenyl)bimesityl (TFBM) with a planar triangular building unit, 1,3,5‐tri(4‐aminophenyl)benzene (TAPB).…”

Synthesis and Visualization of Entangled 3D Covalent Organic Frameworks with High‐Valency Stereoscopic Molecular Nodes for Gas Separation

“…It is worth of noting that the C 2 H 2 /CH 4 selectivity of ZJUT‐3 is much higher than that of other reported materials, such as ZJNU‐69 (34.5), [34] ZJU‐199a (33.5), [35] and NOTT‐101 (26.7) [36] . The C 2 H 2 /CO 2 selectivity is comparable to some of best adsorbents, such as UPC‐112 (2.8), [37] FJU‐90 (4.3), [38] and 2D sql COFs (4.8) [39] …”

Metalated covalent organic frameworks: from synthetic strategies to diverse applications

“…75,76 However, 3D COFs have an abundant changeable topology. 77 3D COFs with ctn, 32,78 bor, 32 dia, 33,79 rra, 80 pts, [81][82][83][84][85] lon, 86 ljh, 87 and nbo 88 topologies have been formed based on fourconnected monomers with tetrahedral T d symmetry. Sixconnected monomers with trigonal prism D 3h symmetry led to stp, 89 ceq, 90 acs, [91][92][93] and hea 94 topologies, while D 3d -and C 3symmetric six-connected monomers have been implemented in the synthesis of 3D COFs with pcu 95 and soc 96 topologies, respectively.…”