The incorporation of metal free TPP into the readily accessible voids of PNCs prompted insitu attempts to introduce metal cations into the porphyrin macrocycle to replicate similar post-synthetic modifications of porphyrin-based MOFs. Full incorporation of Cu 2+ into the porphyrin macrocycle of PNC[cH 2 O-Co/vTPP] to give PNC[cH 2 O-Co/vTPPCu] was achieved by the simple addition of CuCl 2 to the methanol solvent in contact with crystals. Similarly, starting with crystals of the metal free PNC[H 2 /vTPP], Co 2+ could be fully incorporated to provide PNC[cMeOH-Co/vTPPCo-OH 2 ], thus demonstrating the reactivity of both macrocycles within the PNC towards in-situ postcrystallisation metal incorporation.