Square-grid coordination networks of (5,10,15,20-tetra-4-pyridylporphyrin- ato)zinc(II) in its clathrate with two guest molecules of 1,2-dichloro-benzene: Supramolecular isomerism of the porphyrin self-assembly

The title compound, (5,10,15,20-tetra-4-pyridylporphyrinato)zinc(II) 1,2-dichloro-benzene disolvate, [Zn(C₄₀H₂₄N ₈)]̇2C₆H_H4H_Cl2 _H, contains a clathrate-type structure. It is composed of two-dimensional square-grid coordination networks of the self-assembled porphyrin moiety, which are stacked one on top of the other in a parallel manner. The inter-porphyrin cavities of the overlapping networks combine into channel voids accommodated by the dichloro-benzene solvent. Mol-ecules of the porphyrin complex are located on crystallographic inversion centres. The observed two-dimensional assembly mode of the porphyrin units represents a supra-molecular isomer of the unique three-dimensional coordination frameworks of the same porphyrin building block observed earlier. The significance of this study lies in the discovery of an additional supra-molecular isomer of the rarely observed structures of metalloporphyrins self-assembled directly into extended coordination polymers without the use of external ligand or metal ion auxiliaries.