Thienylquinonoidal Porphyrins and Hexaphyrins with Singlet Diradical Ground States

Koji Naoda, Daiki Shimizu, Jun Oh Kim, Ko Furukawa, Dongho Kim, Atsuhiro Osuka

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

To explore stable organic diradicaloids, meso-thienylquinonoid-substituted porphyrins Pn and hexaphyrins Hn, where “n” denotes the number of thienyl units in the meso-substituents, were synthesized. P0 was identified as a closed-shell quinonoid, whereas P1 was shown to possess significant diradical character with diradical character index (y) of 0.99 and quite small singlet-triplet energy gap (ΔES-T) of −0.13 kcal mol−1. P1 was certainly stable, allowing its isolation, but decomposed gradually in solution. In the hexaphyrin series, it was shown that H0 and H1 were closed-shell quinonoids, but H2 was a highly stable diradicaloid with y=0.85 and ΔES-T of −3.72 kcal mol−1. The high stability of H2 was ascribed to effective spin delocalization over the entire conjugated network. Characteristically, H2 displays an intense absorption band in NIR region at λmax=1175 nm with molar absorption coefficient (ϵ) of 8.81×104 mol−1 L cm−1, a narrow HOMO–LUMO gap of 0.69 eV, and nine reversible redox potential waves.

Original languageEnglish
Pages (from-to)8969-8979
Number of pages11
JournalChemistry - A European Journal
Volume23
Issue number37
DOIs
Publication statusPublished - 2017 Jan 1

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Organic Chemistry

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