Supramolecular hydrogen bonding of [5,10,15,20-tetrakis(4-carboxyphenyl)- porphyrinato]palladium(II) in the presence of competing solvents

The title porphyrin compound forms hydrogen-bonded adducts with methanol (1:1), [Pd(C₄₈H₂₈N₄O₈)]-CH ₄O, (I), and with water and N,N-dimethylformamide (1:4:4), [Pd(C ₄₈H₂₈N₄O₈)]·4C ₃H₇NO·4H₂O, (II). In (I), the metalloporphyrin unit lies across a mirror plane in Cmca, while in (II), this unit lies across an inversion center in P1̄. Extended supramolecular hydrogen-bonded arrays are formed in (I) by intermolecular interactions between the carboxylic acid functions, either directly or through the methanol species. These layers have a wavy topology and large interporphyrin pores, which are filled in the crystal structure by double interpenetration as well as enclathration of additional noninteracting nitrobenzene solvent molecules. The supramolecular aggregation in (II) can be characterized by cascaded porphyrin layers, wherein adjacent porphyrin molecules are hydrogen bonded to one another through molecules of water that are incorporated into the hydrogen-bonding scheme. Molecules of dimethylformamide partly solvate the carboxylic acid groups and fill the interporphyrin space in the crystal structure.