Structural elucidation of a few electron-deficient porphyrin/fullerene cocrystallates: Effect of fullerene on the porphyrin ring conformation

A series of electron-deficient porphyrin/fullerene solvated cocrystallates, beta-tetracyano/tetrabromo-meso-tetraphenylporphyrin/C-n (n = 60 or 70) [(H2TPP(CN)(4))(3)center dot C-60, 1; (CuTPP(CN)(4))(3)center dot C-60, 2; (H2TPP(CN)(4))center dot C-70, 3; (H2TPPBr4)center dot(C-60)(2), 4] were examined by single crystal XRD analysis. Cocrystallates 1 and 2 showed hexagonal honeycomb layer-like structure while 3 and 4 revealed one-dimensional linear/zigzag chain structure. Porphyrin ring in the cocrystallates, 1-3 revealed enhanced distortion (r.m.s. > 0.245(6) angstrom) than that of a nearly planar parent H2TPP(CN)(4) (0.046(3) angstrom) structure. The supramolecular interactions in the cocrystallates, 1-4 revealed shortest (por)C center dot center dot center dot C(C-70) = 3.165 angstrom, (C-60)C center dot center dot center dot N-por = 3.034 angstrom and (C-60)C center dot center dot center dot C(C-60) = 2.992 angstrom close contact distances. The normal-coordinate structural decomposition analysis of the macrocycle in 1-3 revealed mainly saddling (similar to 71%) with minimal domed (10-15%) distortions. The nonplanar distortion in these cocrystallates has been ascribed to intermolecular interactions/crystal packing forces. (C) 2014 Elsevier B.V. All rights reserved.