3D Covalent Organic Frameworks with Interpenetrated pcb Topology Based on 8-Connected Cubic Nodes

Abstract

The connectivity of building units for 3D covalent organic frameworks (COFs) has long been primarily 4 and 6, which have severely curtailed the structural diversity of 3D COFs. Here we demonstrate the successful design and synthesis of a porphyrin based, 8-connected building block with cubic configuration, which could be further reticulated into an unprecedented interpenetrated pcb topology by imine condensation with linear amine monomers. This study presents the first case of high-connectivity building units bearing 8-connected cubic nodes, thus greatly enriching the topological possibilities of 3D COFs.

Three-dimensional microporous and mesoporous covalent organic frameworks based on cubic building units

“…These results were in good agreement with those of the proposed models (1.5 nm for JUC-588 and 2.1 nm × 2.4 nm for JUC-589). Remarkably, JUC-589 represents the first example of mesoporous COFs based on an 8-connected node and shows a higher BET surface area and pore size compared to those of similar materials reported, such as BP-COF-1 (BET: 519 m 2 g −1 and pore size: 0.6 nm), 42 and NUST-5 (BET: 680 m 2 g −1 and pore size: 1.5 nm), 43 and NKCOF-23 (BET: 1900 m 2 g −1 and pore size: 1.7 nm). 44 …”

“…However, this avenue is still not quite explored. 43,44 In this work, we report two 3D microporous and mesoporous imine-linked COFs with bcu nets, termed JUC-588 and JUC-589, based on two novel cubic building blocks with different sizes. Both COFs show highly crystalline structures, large surface areas (2728 m 2 g À1 for JUC-588 and 2482 m 2 g À1 for JUC-589), and excellent thermal and chemical stabilities.…”

Metalated covalent organic frameworks: from synthetic strategies to diverse applications

“…Six-connected monomers with trigonal prism D 3h symmetry led to stp , 89 ceq , 90 acs , 91–93 and hea 94 topologies, while D 3d - and C 3 -symmetric six-connected monomers have been implemented in the synthesis of 3D COFs with pcu 95 and soc 96 topologies, respectively. Eight-connected building monomers produced 3D COFs with bcu 97 and pcb 98 topologies. Furthermore, by introducing specific geometric constraints into the monomers to control the spatial orientation of reactive groups in the monomers, the topological types of 3D COFs were further enriched, including ffc , 99 fjh , 100 and tbo 101 topologies formed by [4+3] condensation reactions and srs 102 topology formed by [3+3] condensation reactions.…”

Conjugated Three-Dimensional High-Connected Covalent Organic Frameworks for Lithium–Sulfur Batteries

“…3D COFs still remain relatively less explored in comparison with their 2D analogues due to the still limited building blocks and difficulty in solving their more complicated structure . Thus far, only building blocks with 3D tetrahedral ( T d ), − triangular prismatic ( D 3h ), − and cubic ( O h ) , symmetry have been used to fabricate 3D COFs, leading to corresponding materials with extended topologies of ctn , bor , dia , ion , pts , ljh , rra , nbo , tbo , fjh , ffc , acs , ceq , hea , stp , srs , pcb , and bcu , far from their analogous metal-organic frameworks (MOFs) . It is worth noting again that almost all of these 3D building blocks are of nonconjugated nature, resulting in the isolation of nonconjugated 3D COFs with relatively low conductivity.…”