Fig. 5

Topology diagrams for designing 2D and 3D COFs to create skeletons and pores different. a) Hexagonal COFs formed either by self-condensation of C2-symmetric units or combination of C3-symmetric vertices and C2-/C3-symmetric units. b) Tetragonal COFs formed based on the C4+C2 topology or C4+C4 topology. Four-armed C2 vertices and linear C2 linkers lead to the single-pore rhombic shape. c) Trigonal COFs built by C6-symmetric knots and C2-symmetric linkers; multi-pore rhombic COFs constructed by C3-symmetric vertices and C6-symmetric units; dual-pore kagome topology constructed by four-armed C2 vertices and linear C2 linkers. The dia network formed by d) [Td + C2] or g) [Td + Td] diagrams. The pts network formed by e) [Td + C2] or h) [Td + C4] diagrams. The bor, ctn or srs network formed by f) [Td + C3] and the helix network formed by i) [Td + C2] diagrams