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

• A new family of cocrystallates, MTPPX4/Cn was examined by single crystal XRD.
• Cocrystallates of MTPP(CN)4/C60 showed honeycomb-layer like structure.
• H2TPP(Br or CN)4/C60/70) cocrystallates form 1-D chain structures.
• Porphyrin ring in the cocrystallates revealed significant nonplanar distortion.
• Macrocyclic nonplanarity is ascribed to intermolecular/crystal packing forces.

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.

A new class of electron-deficient porphyrin/fullerene solvated cocrystallates, (MTPP(CN)4)3·C60 (M = 2H and Cu(II)), H2TPPBr4·(C60)2 and H2TPP(CN)4·C70 were examined by single crystal XRD analysis. They feature interesting supramolecular interactions leading to nonplanar conformation of the porphyrin macrocycle in contrast to the parent planar H2TPP(X)4 (X = Br and CN) structures.Figure optionsDownload as PowerPoint slide