Regarding the above discussed degradation of the porous macroligand, we intended the improvement of the maintained porosity. In accordance with literature, the adjustment of the crosslinking degree plays a crucial role in the crafting of the porous structure, as it directly influences the rigidity of the formed frameworks. Thus, we varied the benzylic crosslinkers and applied differently substituted derivatives of bromomethyl-benzene in the AlCl3-catalyzed crosslinking of PPh3, namely di-(2B), tris-(3B), tetrakis-(4B) and hexakis-(6B) bromomethylbenzene. The comparison of the resulting polyphosphines in FTIR (Fig. ) reveals, that the enhanced amount of crosslinking abilities intensifies the vibrations of unreacted C-Br (538 cm -1 ) and causes the enlargement of C-O vibration bands (1046 cm -1 -1109 cm -1 ). From P-B2 to P-B4 one peak of the aliphatic C-H vibrations (2975 cm -1 ) and the CH2 deformation vibration (1380 cm -1 ) increases, while this trend is not observable for P-B6. The oxidation of the phosphine units seems to be favored by a higher crosslinking density, as the P=O vibration (1179 cm -1 ) enhances from P-B2 to P-B6. This augmented vibration mode matches with the finding that alkylation substituents in close proximity to the phosphorus atom promote the oxidation of phosphine species (Fig. ), which is more probable at high crosslinking densities. Nitrogen physisorption proves the formation of an extended porous structure from P-B2 (VPore = 0.21 mL g -1 ) to P-B4 (VPore = 0.57 mL g -1 ) (Fig. ). This increase results from an enhanced rigidity of the framework, which prevents its dense packing upon removal of the swelling solvent after the crosslinking reaction. At drastically high crosslinking degrees in P-B6, some pores are probably narrowed or blocked, leading to mainly microporous structures in P-B6 with a reduced overall pore volume of 0.34 mL g -1 . These results coincide with the outcome of Errahali et al., when they varied the amount of applied FDA in the crosslinking of tetraphenylmethane. 77 Considering the adsorbed amount of water, normalized by the available specific surface area from nitrogen physisorption (Fig. ), P-B2 shows a continuous uptake of water, which exceeds the polyphosphines with higher crosslinking degrees. P-B3 exhibits a comparable isotherm shape, whereas sigmoidal isotherms with an uptake at p/p0 = 0.35 are obtained for P-B4 and P-B6.