Planar Antiaromatic Core-Modified 24π Hexaphyrin(1.0.1.0.1.0) and 32π Octaphyrin(1.0.1.0.1.0.1.0) Bearing Alternate Hybrid Diheterole Units

Jayaprakash Ajay, Sriram Shirisha, Masatoshi Ishida, Kosuke Ito, Shigeki Mori, Hiroyuki Furuta, Sabapathi Gokulnath

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Abstract

The Lewis acid catalyzed self-condensation of hybrid diheterole (furan-pyrrole and thiophene-pyrrole) precursors has afforded novel Hückel antiaromatic 24π hexaphyrin(1.0.1.0.1.0) and 32π octaphyrin(1.0.1.0.1.0.1.0) structures without β-annulated bridges. Single-crystal X-ray diffraction analysis of the hybrid porphyrinoids (S 3 N 3 -ox and O 4 N 4 -ox) revealed a nearly planar conformation and the 1 H NMR spectra suggest the presence of paratropic ring currents. These antiaromatic macrocycles show characteristic optical features and underwent reversible two-electron reduction to Hückel aromatic 26π- and 34π-electron species, respectively, as is evident from the results of spectroscopic and theoretical studies (nucleus-independent chemical shift (NICS) and anisotropy of the current-induced density (ACID) calculations). The incorporation of hybrid diheteroles alternately into expanded porphyrin skeletons provides a novel approach to the fine-tuning of the electronic structures of planar antiaromatic macrocycles.

Original languageEnglish
Pages (from-to)2859-2867
Number of pages9
JournalChemistry - A European Journal
Volume25
Issue number11
DOIs
Publication statusPublished - Feb 21 2019

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All Science Journal Classification (ASJC) codes

  • Catalysis
  • Organic Chemistry

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