Supramolecular Networks of Octahydroxy Porphyrins

Abstract

Multifunctionalized octahydroxy porphyrins, 5,10,15,20-tetrakis-(2′,6′-dihydroxyphenyl)-porphyrin, H₂T(2′,6′-DHP)P, and 5,10,15,20-tetrakis-(3′,5′-dihydroxyphenyl)porphyrin, H₂T(3′,5′-DHP)P, have been developed as solid state building blocks for the self-assembly of hydrogen bonded supramolecular networks. A series of solid state X-ray structures of these porphyrins with various solvates show strong inter-porphyrin interactions through their peripheral hydroxyl substituents by means of directional hydrogen bonding. The position of the hydroxyl groups and the nature of the lattice guest (i.e., solvate) have dramatic influences on the molecular packing and the porosity of the structures. In particular, with ethyl acetate as solvate, the crystal structure of H₂T(3′,5′-DHP)P exhibits a one dimensional columnar network, whereas H₂T(2′,6′-DHP)P shows essentially a two dimensional, hydrogen-bonded, layered structure. With benzonitrile as solvate, the structure of H₂T(3′,5′-DHP)P changes substantially to a two dimensional corrugated structure in order to accommodate a larger pore size. The pore volumes filled by solvate in these structures are exceptionally large: 56%, 61%, and 67% of the unit cell volume, respectively. Crystal structure data for H₂T(3′,5′-DHP)P • 5 EtOAc: C₆₄H₇₀N₄O₁₈, M = 1183.24, triclinic, P1, a = 7.245 (2) Å, b = 14.727 (3) Å, c = 14.835 (4) Å, α = 90.18 (2)°, β = 92.90 (2)° and γ = 90.02 (2)°, V = 1580.8(7) A³, Z = 1; R1 = 0.113, wR2 = 0.280 (on 2588, I > 2σ(I) observed data). For H₂T(2′,6′-DHP)P • EtOAc: C₆₀H₆₂N₄O₁₆, M = 1095.14, triclinic, P1, a = 13.736 (3) Å, b = 14.032 (3) Å, c = 17.029 (3) Å, α = 93.77 (3)°, β = 110.92 (3)° and γ = 111.81 (3)°, V = 2770.9 (10) A³, Z = 2; R1 = 0.045, wR2 = 0.112 (on 6260, I > 2σ(I) observed data). For H₂T(3′,5′-DHP)P • 7 C₇H₅N: C₉₃H₆₅N₁₁O₈, M = 1464.56, monoclinic, P2₁/m, a = 11.105 (4) Å, b = 25.744 (7) Å, c = 14.022 (3) Å, β = 108.09 (2)°, V = 3811(2) A³, Z = 2; R1 = 0.062, wR2 = 0.130 (on 2588, I > 2σ(I) observed data).