Vinylene-Linked Covalent Organic Frameworks with Subtly Tuned Stacking for Near-Infrared Light-Driven Photocatalysis of Organic Transformations.

Interlayer alignment holds a pivotal role for layered materials in tailoring their physical properties and chemical activities. Herein, we designed and synthesized a D2h-symmetric pyrene-derived monomer with four methyl substituents adjacent to the two nitrogen atoms embedded at the 2,7-positions of its molecular periphery. It smoothly underwent Knoevenagel condensation with linear diformylarenes to form a series of novel two-dimensional (2D) covalent organic frameworks (COFs), whose individual layers are reticulated by vinylene linking of diazapyrene vertices with arene nodes, then vertically aligned in an eclipsed or inclined stacking mode through the synergistic impacts of the twisted conformation interlocking, dipole-dipole, and π-π interactions of the building blocks. Their highly crystalline structures with large domain sizes of up to around 0.4 μm were considerably confirmed by high-resolution low-dose transmission electron microscopy imaging, powder X-ray diffraction patterns, and theoretical simulations. Correspondingly, such kinds of COFs exhibit exceptional properties, including high specific surface areas close to theoretical values, strong light-harvesting extended to the near-infrared-II, and outstanding photogenerated charge dynamics, allowing for high-performance photothermal conversion and catalysis of multiple organic transformations upon near-infrared light stimulation. These findings demonstrate that the crystal growth and properties of 2D COFs can be promoted by subtly tuning interlayer stacking via building-block design.