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

Abstract

A series of electron-deficient porphyrin/fullerene solvated cocrystallates, β-tetracyano/tetrabromo-meso-tetraphenylporphyrin/Cn (n = 60 or 70) [(H2TPP(CN)4)3·C60, 1; (CuTPP(CN)4)3·C60, 2; (H2TPP(CN)4)·C70, 3; (H2TPPBr4)·(C60)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) Å) than that of a nearly planar parent H2TPP(CN)4 (0.046(3) Å) structure. The supramolecular interactions in the cocrystallates, 1–4 revealed shortest (por)C…C(C70) = 3.165 Å, (C60)C…Npor = 3.034 Å and (C60)C…C(C60) = 2.992 Å close contact distances. The normal-coordinate structural decomposition analysis of the macrocycle in 1–3 revealed mainly saddling (∼71%) with minimal domed (10–15%) distortions. The nonplanar distortion in these cocrystallates has been ascribed to intermolecular interactions/crystal packing forces.