Since NPh3 has a more planar geometry (119.6 ° between C-N bonds), it interacts only weakly with the catalyst, whereas the more trigonal pyramidal structure of PPh3 (102.8 ° between C-P bonds) enables unhindered coordination to the Lewis acid. This strong interaction diminishes the nucleophilicity of the aromatic rings, resulting in a deactivation of PPh3 under the applied crosslinking conditions. Additionally, a large orbital overlap between nitrogen and the aromatic carbon atom facilitates the mesomeric stabilization of the arene σ-complex in the reaction mechanism of the electrophilic aromatic substitution, which is less favored for the differently sized orbitals of phosphorus and carbon. A corresponding reactivity trend was observed by Rozyyev et al., who screened several monomers for their applicability in the solvent knitting method. Generally, these findings question the crosslinking manner, which intends the FeCl3-catalyzed interconnection of PPh3 via the external crosslinker FDA and the supplementation of an aromatic co-monomer like benzene. Regarding the differences in the monomer reactivity, it is questionable, whether the phosphine forms covalent bonds between the aromatic units or whether its incorporation is based on physical interactions or entrapment effects inside the framework of the crosslinked co-monomer. In order to ensure the integration of PPh3 in the crosslinking process, we eliminated co-monomers and used the more reactive AlCl3 instead of FeCl3. 64 The shift to an AlCl3-catalyzed Friedel-Crafts alkylation enables the crosslinking of the monomeric PPh3 (IV). The yield of P-FDA (265 %) highly exceeds the theoretical value for an ideal, complete interconnection of PPh3 by the external crosslinker FDA, indicating the involvement of further reagents (Table ). As described in literature, the used dichlorinated solvent not only functions as porogen, but also acts as additional crosslinker source. According to previous works, we thus used DCM as solvent and sole agent for the crosslinking of PPh3 (V)