The 6-8° peak intensity decreases together with the AAs probability. This peak also becomes asymmetric towards higher 2θ angles when ABCe/s content exceeds 25%. This asymmetry is also seen in the experimental PXRD pattern, with best agreement in 3: The most probable stacking mode of COF-5 is AAs (Table ). The corresponding AA stat pattern directly matches the experimental pattern (Figure ). The wide peak around 2θ=27° observed in experiment suggests there is some structural disorder. This can originate from a small proportion (<10%) of AB(C) stat (Figure SI-16).