Articles written in Journal of Chemical Sciences

    • Synthesis of antipodal 𝛽-trisubstituted meso-tetraphenylporphyrins and the crystal structure of hexaphenylporphinatozinc(II) bispyridinate complex

      Bhyrappa Puttaiah Velkannan Veerapandian

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      series of antipodal 𝛽-trisubstituted meso-tetraphenylporphyrins, H2TPP(R)3 (R = CH3, Ph, PE, and 2′-thienyl) derivatives and their metal (Cu(II) and Zn(II)) complexes were synthesised and characterised by electronic absorption, 1H NMR spectroscopy and mass spectrometry. The magnitude of the red-shift in absorption bands in these free-base porphyrins depend on the nature of the substituent and follow the general trend: PE > 2′ > Ph > CH3. Synthesis, characterisation and crystal structure of 2,5,10,12,15,20-hexaphenylporphinato zinc(II) bispyridinate, ZnTPP(Ph)2(Py)2 complex is also reported. It shows planar geometry of the porphyrin ring with two 𝛽-phenyls located at the antipodal 2,12-pyrrole positions. The two axially coordinated pyridine ring planes are oriented almost parallel to each other and they are in staggered conformation relative to opposite pyrrolic nitrogens. The normal-coordinate structural decomposition analysis of the ZnTPP(Ph)2(Py)2 complex revealed slight wave distortion of the macrocycle.

    • Crystal structures of meso-tetrakis(2',6'/3',5'-difluorophenyl)porphyrins and their metal complexes: Influence of position of the fluoro groups on their structural properties


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      Two series of non-solvated structures of 5,10,15,20-tetrakis(2’,6’/3’,5’-difluorophenyl)porphyrins,H2T(2’,6’/3’,5’-DFP)P and their metal (Cu(II) and Zn(II)) complexes were determined by single crystal XRD.H2(2’,6’-DFP)P, 1 and its metal (Cu(II), 2 and Zn(II), 3) complexes showed near planar geometry of the porphyrinring with the maximum root-mean-square (r.m.s.) which is the average deviation of the 24 core atomsfrom their least-squares plane by 0.056(3) Å while MT(3’,5’-DFP)P (Cu(II), 4 and Zn(II), 5) structures featuresignificant distortion of the macrocycle (r.m.s. = 0.22(2) Å). Nearly planar structures 1-3 revealed morenumber of intermolecular short contacts than that observed in nonplanar structures 4 and 5. Normal coordinatestructure decomposition analysis of the structures 1-3 revealed negligible wave distortion of the macrocyclebut the corresponding nonplanar 4 and 5 structures feature mainly ruffled combined with minimal saddled distortions.The increased nonplanarity of the less sterically hindered derivatives 4 and 5 has been ascribed tointermolecular interactions and/or crystal packing forces.

    • Crystal structures of unsymmetrically mixed β-pyrrole substituted nickel(II)-meso-tetraphenylporphyrins


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      Crystal structures of solvated unsymmetrically substituted meso-tetraphenylporphyrins, 2,3,12,13, 17-pentachloro-5,7,8,10,15,18,20-hepta-phenylporphyrin, H₂TPP(Ph)₃(Cl)₅, 1 and its nickel(II), NiTPP(Ph)₃(Cl)₅, 2 were determined by single crystal XRD analysis. In addition, a new unsymmetricallysubstituted porphyrin, 2,3,12,13,17-pentacyano-5,7,8,10,15,18,20-heptaphenyl-porphinato nickel(II) complex, NiTPP(Ph)₃(CN)₅, 3 complex was synthesized and its solvated structure was examined by crystallography. These porphyrins exhibited dramatic nonplanar conformation of the macrocycle as evidenced from the averagedisplacement of the β-pyrrole carbon (±ΔCβ ) from the mean plane of the porphyrin ring and the trend in nonplanarity varies in the order: 2 (1.189(5) Å) > 1 (1.036(6) Å) > 3 (0.895(6) Å). The normal-coordinate structural decomposition analysis of these structures revealed mainly saddle distortion of the macrocycle combined with small degree of ruffled or domed distortions. The Hirshfeld surface analysis of structures 1-3 revealed solvate dependent intermolecular contacts with varying degree of H. . .H (43–49%), C. . .H (17–19%), H. . .Cl (25–30%) and N. . .H (~19%) contact contributions.

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