Single-Crystalline Twelve-Connected Nanographene-Based Covalent Organic Frameworks

The expansion of reticular chemistry into increasingly complex architectures relies on the precise translation of molecular geometry into extended crystalline frameworks. Here, we report the design and synthesis of a dodeca-benzaldehyde-functionalized nanographene (hexakis[3,5-bis(p-formylphenyl)-4,6-dimethoxyphenyl]hexabenzocoronene, HBC-LA₁₂), a molecule that integrates hexagonal and triangular shapes into a dodecatopic hexagonal prismatic geometry. The reticulation of HBC-LA₁₂ with 6-connected triangular prismatic and 4-connected square-planar linkers yields two single-crystalline three-dimensional imine-linked covalent organic frameworks, termed COF-612 [(HBC-LA₁₂)(HAPT)₂]_imine and COF-412 [(HBC-LA₁₂)(PyTTA)₃]_imine. The structure of these frameworks realizes the previously inaccessible (3,6,6)- and (3,4,6)-connected networks in COFs, corresponding to the kez and cez topologies, respectively. These nets represent unprecedented edge-2-transitive architectures derived from the parent (6,12)-connected alb and (4,12)-connected shp nets. Gas-sorption analysis reveals that these frameworks possess permanent porosity with Brunauer-Emmett-Teller surface areas exceeding 5000 m² g^-1. This work demonstrates the incorporation of nanographenes into three-dimensional imine-linked COFs, yielding the highest-connectivity single-crystalline COFs with novel kez and cez underlying nets and the highest porosity reported for COFs to date.