Representation of the structure of PNC [Co-vH2O], showing the void-defining cubic assembly of the six (dipPhO)8PcCo molecules. Note that the 2',6'-di-iso-propyphenoxy substituents are shown only for the central cubic stricture and omitted fully from the structures in (c) and (d). In each structure the square represents the unit cell of a ~37 Å). (c) The structure of PUNC[Co-cbipy-Co] stabilised using 4,4'-bipyridyl "wall-ties" (red) connecting the metal-centres across the cavity. (d) The fullerene-stabilised PUNC[cC60/Co]. Our approach to the preparation of functional porous molecular crystals uses the structure-directing octa (2',6'-di-iso-propyphenoxy)phthalocyanine and its metal complexes [(dipPhO) 8 PcM, Fig. ] to form crystals of cubic symmetry belonging to the Pn3 ! n space group. These Phthalocyanine Nanoporous Crystals (PNCs) possess a large unit cell (a ~37 Å) that contains two cage-like assemblies of six (dipPhO) 8 PcM molecules surrounding solvent filled voids (~24 Å diameter) that are interconnected at each corner through narrow channels of ~6 Å diameter (Fig. ). In addition, there are solvent-filled cavities of diameter ~12 Å between the (dipPhO) 8 PcM cage-like assemblies. The PNC structure is obtained from most metal complexes of (dipPhO) 8 PcM that have been assessed (e.g. M = Mg, Al, Ti, Mn, Fe, Co, Zn, Ru, In), even with large variations in size, shape, type and number of axial ligands attached to the metal cation. The PNC structure allows the transport of smallmolecules through both the void and the cavity, as demonstrated by the exchange of axial ligands on both side of the metal centre of the (dipPhO) 8 PcM complex. PNCs suffer structural collapse on removal of the included solvent, however, stability can be enhanced by the use of suitable bidentate ligands that bind two metal cations (e.g. Co 2+ or Fe 2+ ) across the cavity (e.g. 4,4'-bipyridyl, Fig. 1c). These molecular "wall-ties" ensure permanent porosity as confirmed by nitrogen adsorption. Highly stable Phthalocyanine Unsolvated Nanoporous Crystals (PUNCs) can also be prepared by the co-crystallisation of (dipPhO) 8 PcM (M = Co, Cu, Ag, H 2 ) with fullerenes C 60 or C 70 , which are efficiently incorporated within the cavity of the PNC (Fig ). For PUNC[cC 60 /Co], the use of fullerenes rather than ligands as "wall-ties" for stabilisation means that the axial site of the cobalt centre within the void is free for coordination chemistry. This allowed for the chemisorption of carbon monoxide onto the metal centred to be characterised directly by single crystal x-ray diffraction (scXRD). Following the successful incorporation of fullerenes, we were curious as to whether porphyrins could also be compatible with PNC formation. Initially, we focused on the crystallisation of the nitrido-linked heterodimer formed by reacting (dipPhO) 8 PcFe with TPPFeN 3 , as such bimetallic complexes display interesting catalytic properties. The scXRD data from the resulting (dipPhO) 8 PcFe-N-FeTPP suggests that the structure of the complex is very similar to that reported for unsubstituted PcFe-N-FeTPP, with both nitrido-linked complexes possessing fully eclipsed macrocycles and near-identical Fe-N-Fe bond lengths. Importantly, despite its low resolution (~1.5 Å), the scXRD data confirmed that (dipPhO) 8 PcFe-N-FeTPP successfully forms the PNC structure thereby further demonstrating the powerful ability of the (dipPhO) 8 Pc unit to direct crystallisation even when it is bound to a porphyrin (SI Fig. ).