Transformation Strategy for Highly Crystalline Covalent Triazine Frameworks: From Staggered AB to Eclipsed AA Stacking.

Fabrication of crystalline covalent triazine frameworks (CTFs) under mild conditions without introduction of carbonization is a long-term challenging subject. Herein, a tandem transformation strategy was demonstrated for the preparation of highly crystalline CTFs with high surface areas under mild and metal- and solvent-free conditions. CTF-1 with a staggered AB stacking order (orange powder) obtained in the presence of a catalytic amount of superacid at 250 °C was transformed to highly crystalline CTF-1 with an eclipsed AA stacking order (greenish powder) and surface area of 646 m2 g-1 through annealing at 350 °C under nitrogen. The strategy can be extended to the production of crystalline fluorinated CTFs with controllable fluorine content. This finding unlocks opportunities to design crystalline CTFs with tunable photoelectric properties.