title: Unsolvated 5,10,15,20-tetra-4-pyridylporphyrin, its sesquihydrate and its 2-chlorophenol disolvate: conformational versatility of the ligand.
abstract: Unsolvated 5,10,15,20-tetra-4-pyridylporphyrin, C(40)H(26)N(8), (I), its sesquihydrate, C(40)H(26)N(8).1.514H(2)O, (II), and its 2-chlorophenol disolvate, C(40)H(26)N(8).2C(6)H(5)ClO, (III), reveal different conformational features of the porphyrin core. In (I), the latter is severely deformed from planarity, apparently in order to optimize the intermolecular interactions and efficient crystal packing of the molecular entities. The molecular framework has a C(1) symmetry. In (II), the porphyrin molecules are located on 4 symmetry axes, preserving the marked deformation from planarity of the porphyrin core. The molecular units are interlinked into a single-framework supramolecular architecture by hydrogen bonding to one another via molecules of water, which lie on twofold rotation axes. In (III), the porphyrin molecules are located across centres of inversion and are characterized by a planar conformation of the 24-membered macrocyclic porphyrin ring. Two trans-related pyridyl substituents are hydrogen bonded to the 2-chlorophenol solvent molecules. The interporphyrin organization in (III) is similar to that observed for many other tetraarylporphyrin compounds. However, the organization observed in (I) and (II) is different and of a type rarely observed before. This study reports for the first time the crystal structure of the unsolvated tetrapyridylporphyrin.
authors.affiliation: School of Chemistry, Sackler Faculty of Exact Sciences, Tel-Aviv University, Ramat-Aviv, 69978 Tel-Aviv, Israel.
authors.forename: Sophia
authors.initials: S
authors.lastname: Lipstman
authors.forename: Israel
authors.initials: I
authors.lastname: Goldberg