• A theoretical study of porphyrin isomers and their core-modified analogues:cis-trans isomerism, tautomerism and relative stabilities

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    • Keywords

       

      Porphyrin isomers; core-modified analogues; theoretical studies; tautomerism; oxa-porphyrin; thiaporphyrin

    • Abstract

       

      Semiempirical (AM1 and PM3) and density functional theory (DFT) calculations were performed on about 50 porphyrin isomers with 25 each of 1,2 (syn) and 1,3 (anti) tautomeric forms. The corresponding oxa-and thia-core-modified analogues were also computed. The variations of relative energies and stabilities of the core-modified analogues were compared with parent porphyrin1 and the corresponding oxa-and thia-analogues. The trends in relative energies are not significantly changed while going from parent system to oxa-and thia-core-modified porphyrins in case of bothsyn andanti tautomers. Isomers of types [2·2·0·0], [3·0·1·0], [3·1·0·0], and [4·0·0·0] are destabilized due to the absence of methine bridge, which results in angle strain for tetrapyrroles. Isomers having [2·1·1·0], [2·1·0·1], [2·0·2·0] and [2·2·0·0] connectivity, the Z isomers, are more stable compared to the correspondingE isomers in bothsyn andanti forms of parent and core-modified analogues.

    • Author Affiliations

       

      M Punnagai1 Saju Joseph1 G Narahari Sastry1

      1. Molecular Modelling Group, Organic Chemical Sciences, Indian Institute of Chemical Technology, Hyderabad - 500 007, India
    • Dates

       
  • Journal of Chemical Sciences | News

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