Fig. 1: Strategy illustration and applications of functional COF-LZU1 films.

(i) the addition of modulators can slow down the formation of imine bonds by producing the modulator-stabilized carboxylic acid salt. (ii) a gentle drying process is introduced to balance the evaporation rate of solvent and the reorganization rate of metastable amorphous network to form COF films. (iii) COF films with the asymmetric structure have exhibited distinct reversible diffusion behavior of organic molecules, which can be used as sensitive actuators to diverse gases. (iv) versatile functional COF films can be easily synthesized by introducing functional molecules (such as fluorescence, chirality and catalyst) during the nucleation process.