Fig. 7

TEM analysis. TEM images of a Tri-COF-DAB and b Tetra-COF-DAB, and HR-TEM images of c Tri-COF-DAB and d Tetra-COF-DAB focusing on the regions marked by the red squares in a and b at a higher resolution. The images inserted in the upper right corners are their corresponding FFT patterns, and the structure projections in HR-TEM images are along the b-axis and the structural models are inserted in the middle