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. &gt; 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. © 2014 Published by Elsevier B.V.

Puttaiah Bhyrappa

Department Of Chemistry

Karuppaiah Karunanithi

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Inorganica Chimica Acta

The modulation of physicochemical properties of the porphyrin macrocycle could find applications in nonlinear optics, dye-sensitized solar cells, photodynamic therapy etc. The synthesis of such porphyrins is challenging and gaining considerable importance. By appending appropriate substituents at the β-pyrrole or meso-carbon positions of the macrocycle could modulate the frontier orbitals of the porphyrin π-system. The present review discusses the reported synthetic routes employed for various mixed β-pyrrole substituted meso-tetraphenylporphyrins. Further, earlier work over the past 15 years on the influence of mixed β-substituent pattern in the electronic spectral, electrochemical redox and stereochemistry of the porphyrin macrocycle will be briefly discussed in this review article including their future prospects. © 2016 Elsevier Ltd

Tetrahedron Letters

Recent advances in mixed β-pyrrole substituted meso-tetraphenylporphyrins

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.

Inorganic Chemistry

Porphyrin-fullerene, C60, cocrystallates: Influence of C 60 on the porphyrin ring conformation

In the crystal structure of the title compound, C48H38N4, the molecule is positioned on a center of symmetry and the porphyrin ring shows a nearly planar geometry in spite of the presence of four bulky methyl groups at the anti-podal Β-pyrrole positions. © International Union of Crystallography 2007.

Acta Crystallographica Section E: Structure Reports Online

2,3,12,13-Tetra-methyl-5,10,15,20-tetra-phenyl-porphyrin

To examine the influence of mixed substituents on the structural, electrochemical redox behavior of porphyrins, two new classes of β-pyrrole mixed substituted free-base tetraphenylporphyrins H2(TPP(Ph) 4X4) (X = CH3, H, Br, Cl, CN) and H 2(TPP(CH3)4X4) (X = H, Ph, Br, CN) and their metal (M = Ni(II), Cu(II), and Zn(II)) complexes have been synthesized effectively using the modified Suzuki cross-coupling reactions. Optical absorption spectra of these porphyrins showed significant red-shift with the variation of X in H2(TPPR4X4), and they induce a 20-30 nm shift in the B band and a 25-100 nm shift in the longest wavelength band [Qx(0,0)] relative to the corresponding H2TPPR 4 (R = CH3, Ph) derivatives. Crystal structure of a highly sterically crowded Cu(TPP(Ph)4(CH3)4) ·2CHCl3 complex shows a combination of ruffling and saddling of the porphyrin core while the Zn(TPP(Ph)4Br4(CH 3OH))· CH3OH structure exhibits predominantly saddling of the macrocycle. Further, the six-coordinated Ni(TPP(Ph) 4(CN)4-(Py)2)·2(Py) structure shows nearly planar geometry of the porphyrin ring with the expansion of the core. Electrochemical redox behavior of the MTPPR4X4 compounds exhibit dramatic cathodic shift in first ring oxidation potentials (300-500 mV) while the reduction potentials are marginally cathodic in contrast to their corresponding MTPPX4 (X = Br, CN) derivatives. The redox potentials were analyzed using Hammett plots, and the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap decreases with an increase in the Hammett parameter of the substituents. Electronic absorption spectral bands of H2TPPR4X4 are unique that their energy lies intermediate to their corresponding data for the H 2(TPPX8) (X = CH3, Ph, Br, Cl) derivatives. The dramatic variation in redox potentials and large red-shift in the absorption bands in mixed substituted porphyrins have been explained on the basis of the nonplanarity of the macrocycle and substituent effects. © 2006 American Chemical Society.

Mixed substituted porphyrins: Structural and electrochemical redox properties

This work reports an improved protocol for the regioselective synthesis of 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin (H2TPPBr4) and the crystal structure of its Zn(II) complex which shows saddle shaped geometry. © 2003 Elsevier Science Ltd. All rights reserved.

Journal	Data powered by TypesetInorganica Chimica Acta
Publisher	Data powered by TypesetElsevier S.A.
ISSN	00201693
Open Access	No