We designed a tetraaldehyde linker (4A2E, Figure center) based on a terphenyl core with 2 aldehydes attached to each outer phenyl ring. The aldehydes are attached in 3 and 5 positions to form a 60° and a 120° bite angle between them, which allows the formation of both kgm and sql networks. The linker core was functionalized in the 60° bay with methyl groups to increase the solubility and the 120° bay was functionalized with bulky methyl benzoate moieties. The linker 4A2E was synthesized in a threestep synthesis starting from 2-Bromoisopthalaldehyde (for details see supplementary method section). We employed the 4A2E linker for the synthesis of imine-based COFs using either phenylenediamine (PDA) or benzidine (Bz). The synthesis was performed as a solvothermal approach in a mixture of 1,4dioxane and mesitylene, with trifluoroacetic acid (TFA) serving as the catalyst. After the reaction, the precipitated COFs were filtered off and washed thoroughly with methanol, followed by Soxhlet extraction with methanol and activation by using supercritical CO2. After extensive screening of the solvent ratios and acid concentrations, we obtained two crystalline COFs 4A2E-PDA-COF and 4A2E-BZ-COF, using PDA and BZ as linear diamines, respectively. To verify the crystallinity of the 4A2E-PDA-COF, we performed PXRD. The diffractogram showed sharp reflexes with the most intense reflex at 5.22° 2θ, with additional less intense reflexes at 7.66°, 9.14°, 12.98°, 14.80°, and 21.40° (, B). As the linker geometry of 4A2E leads to two possible 2D nets, sql and kgm, we constructed structural models of both nets in AA eclipsed stacking in Materials Studio. Based on these models, we simulated PXRD patterns (Figure ). The simulated sql structure pattern clearly does not match the observed PXRD of 4A2E-PDA-COF, as it showed intense reflections at 6.73° and 7.34° which do not match with the experimentally observed reflections, while the reflection at 5.22° is missing in the simulated pattern. Surprisingly, the simulated PXRD based on the kgm structural model with a 𝑃3 ̅ symmetry and eclipsed stacking did not show a good fit either: while some of the reflections match, others are evidently missing. The most intense observed reflection at 5.16° matches well with the 110 reflection of the simulated structure, while the reflection at 10.77° can be explained by the 300 reflection. But crucially, the 100 reflection, predicted by the simulation at 2.98°, is completely absent in the experimentally observed pattern (Figure ) even when measured at small angles (Figure S 12), while the observed reflection at 7.66° is absent in the simulated kgm pattern. This led us to believe that the kgm structural model with eclipsed stacking does not describe the structure accurately.