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Porphyrin-fullerene, C60, cocrystallates: Influence of C 60 on the porphyrin ring conformation
, Karuppaiah Karunanithi
Published in
Volume: 49
Issue: 18
Pages: 8389 - 8400
To examine the influence of fullerene on the macrocyclic ring conformation, crystal structures of a series of cocrystals of 2,3,5,10,12,13,15,20- octaphenylporphyrin, M(TPP)(Ph)4 (M = 2H, Co(II), Cu(II)), and 2,312,13-tetramethyl-5,7,8,10,15,17,18,20-octaphenyl-porphinato copper(II), CuTPP(Ph)4(CH3)4, derivatives with fullerene, C60, were elucidated. Furthermore, crystal structures of the parent porphyrins, M(TPP)(Ph)4 (M = Co(II), Cu(II)) complexes, were also determined. All the cocrystals revealed one-to-one stoichiometry between the porphyrin and C60 and were free of lattice solvates. Porphyrin rings in M(TPP)(Ph)4·C60 cocrystals revealed significant distortion with the root-mean-square (rms) value as high as 0.265(2) Å which is the average deviation of the 24 atoms core from the least-squares plane. Crystal structures of the parent M(TPP)(Ph)4 (M = Co(II), Cu(II)) complexes indicated near planarity of the 24-atom core with the root-mean-square deviation value of 0.016(2) Å. Molecular packing in the M(TPP)(Ph)4·C60 cocrystals showed essentially one-dimensional chains interconnected by weak interporphyrin and porphyrin-fullerene close contacts. The Nporphyrin⋯C(C 60) shortest distances between the H2(TPP)(Ph)4 (M = 2H, Co(II), Cu(II)) and fullerene in the cocrystals are 3.031(5) Å, 3.062(4) Å, and 3.059(3) Å, respectively. Similarly, close contact M⋯C distances in the M(TPP)(Ph)4·C60 (M = Co(II), Cu(II)) are 2.761(6) Å and 2.886(3) Å, respectively. In the Cu(TPP)(Ph)4(CH3)4·C60 cocrystal, the shift of macrocyclic ring toward planarity was evidenced from the rms value of 0.236(2) Å relative to that observed in CuTPP(Ph) 4(CH3)4·CHCl3 (0.391(2) Å). The distortion of the macrocyclic ring in M(TPP)(Ph) 4·C60 complexes was examined by normal-coordinate-structure decomposition (NSD) analyses. Their out-of-plane displacement of the core atoms revealed predominant contribution being saddle (∼95-96%) and gentle domed distortions (3-4%). In the case of M(TPP)(Ph)4(CH3)4·C60 cocrystal, it showed mainly saddled (∼83%), minimal ruffled (8%) and domed (8%) distortions of the macrocyclic ring. In-plane displacement on the 24-atom core of the porphyrin in these cocrystallates features generally a varying degree of N-str (B1g) and bre (A1g) distortions. © 2010 American Chemical Society.
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JournalInorganic Chemistry
Open AccessNo