Synthesis, spectroscopy, electrochemistry, and mesomorphism of triple- decker porphyrins consisting of two cerium ions and three 5,15- diarylporphyrins

Hideya Miwa, Nagao Kobayashi, Kazue Ban, Kazuchika Ohta

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32 Citations (Scopus)

Abstract

Triple-decker sandwich complexes, which consist of two cerium ions and three strip-like diarylporphyrins, have been synthesized and their spectroscopic and electrochemical properties and mesomorphism are reported and compared with those of the corresponding double deckers and the parent monomers. The Soret band of the triple-deckers lies at longer and shorter wavelengths than those of the double-deckers and monomers, respectively, while a sequence of small absorptions is observed in the Q band region: These are interpreted on the basis of knowledge of triple-deckers made from tetraphenylporphyrin and octaethylporphyrin. Magnetic circular dichroism (MCD) spectroscopy suggests that the Soret bands of the triple-deckers are a: superimposition of at least two transitions to orbitally degenerate states. In the MCD spectra, Faraday A-terms are observed corresponding to each absorption band, suggesting that these triple-deckers take D(4h) or more plausibly D(4d) structures. Triple-deckers containing dialkoxyphenyl groups at the 5,15-positions of their parent porphyrin show a mesophase possessing both lamellar and columnar structures at lower temperatures and a columnar mesophase at higher temperatures, which differ in stacking distances. On the other hand, those containing tetraalkoxylated terphenyl groups at the 5,15- positions of their parent porphyrin show only a columnar mesophase with a single stacking distance. These differences in the mesomorphism are explained by differences of the magnitude of the steric hindrance of the side chains for rotation along the axis connecting the center of the three porphyrins.

Original languageEnglish
Pages (from-to)2719-2728
Number of pages10
JournalBulletin of the Chemical Society of Japan
Volume72
Issue number12
DOIs
Publication statusPublished - 1999 Dec

ASJC Scopus subject areas

  • Chemistry(all)

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