Coordination and hydrogen-bonding assemblies in hybrid reaction products between 5,10,15,20-tetra-4-pyridylporphyrin and dysprosium trinitrate hexahydrate

Abstract

Reactions of the title free-base porphyrin compound (TPyP) with dysprosium trinitrate hexahydrate in different crystallization environments yielded two solid products, viz. [mu-5,15-bis(pyridin-1-ium-4-yl)-10,20-di-4-pyridylporphyrin]bis[aquatetranitratodysprosium(III)] benzene solvate, [Dy(2)(NO(3))(8)(C(40)H(28)N(8))(H(2)O)(2)] x C(6)H(6), (I), and 5,10,15,20-tetrakis(pyridin-1-ium-4-yl)porphyrin pentaaquadinitratodysprosate(III) pentanitrate diethanol solvate dihydrate, (C(40)H(30)N(8))[Dy(NO(3))(2)(H(2)O)(5)](NO(3))(5) x 2 C(2)H(6)O x 2 H(2)O, (II). Compound (I) represents a 2:1 metal-porphyrin coordinated complex, which lies across a centre of inversion. Two trans-related pyridyl groups are involved in Dy coordination. The two other pyridyl substituents are protonated and involved in intermolecular hydrogen bonding along with the metal-coordinated water and nitrate ligands. Compound (II) represents an extended hydrogen-bonded assembly between the tetrakis(pyridin-1-ium-4-yl)porphyrin tetracation, the [Dy(NO(3))(2)(H(2)O)(5)](+) cation and the free nitrate ions, as well as the ethanol and water solvent molecules. This report provides the first structural characterization of the exocyclic dysprosium complex with tetrapyridylporphyrin. It also demonstrates that charge balance can be readily achieved by protonation of the peripheral pyridyl functions, which then enhances their capacity in hydrogen bonding as H-atom donors rather than H-atom acceptors.