• Isomers of β-substituted di and tri-nitrotetraphenylporphyrins and their copper(II) derivatives: Structure, optical and electrochemical redox properties

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    • Keywords

       

      Isomers; di and trinitrotetraphenylporphyrins; ring-redox potentials; crystal structure; trinitrotetraphenylporphyrinatocopper(II)

    • Abstract

       

      Controlled nitration ofmeso-tetraphenylporphyrinatocopper(II) using fuming nitric acid leads to the formation of different β-substituted nitro derivatives. Five isomers of dinitro and three isomers of trinitrotetraphenylporphyrins have been isolated and characterised using FAB/MS,1H NMR, UV-VIS and IR spectroscopies. The single crystal X-ray data on the copper(II) derivative of one of the isomers of trinitrotetraphenylporphyrin revealed ‘saddle’ conformation of the porphyrin core resulting from the nitro group substitution at theβ-pyrrole carbons. The electrochemical redox behaviour of the free-base porphyrins and their copper(II) derivatives revealed that successive substitution of nitro groups at the pyrrole carbons shifts the one-electron ring oxidations anodically while the ring reduction occurs at a less cathodic potential relative to the unsubstituted porphyrin. The isomer specific shifts in the redox potentials bear a direct relationship with the relative energy levels of HOMO/LUMO obtained from AM1 calculations.

    • Author Affiliations

       

      S Dahal1 2 V Krishnan1 2 M Nethaji1 2

      1. Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore - 560 012, India
      2. Jawaharlal Nehru Centre for Advanced Scientific Research, Indian Institute of Science Campus, Bangalore - 560 012, India
    • Dates

       
  • Journal of Chemical Sciences | News

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