The intrinsic flexibility of their alkyl-bridged diphosphines most probably allows the adaptable arrangement of the building blocks to obtain a close packing of the polymer chains upon removal of the solvent. In addition, the apparent crosslinking by flexible ethylene bridges derived from DCE reinforces this lack of rigidity. Ghafari et al. investigated the effect of different crosslinkers on the porosity and reported that less rigid alkyl units may cause the partial collapse of the framework upon drying, supporting the above hypothesis. However, this finding does not provide any evidence on the porous state under catalytic conditions, as the flexible pores possess swelling abilities in the solvated state, which probably improve the accessibility of the catalytically active species.