Comparative photophysics of [26]- and [28]hexaphyrins(1.1.1.1.1.1): Large two-photon absorption cross section of aromatic [26]hexaphyrins(1.1.1.1.1.1)

Tae Kyu Ahn, Jung Ho Kwon, Deok Yun Kim, Dae Won Cho, Dae Hong Jeong, Seong Keun Kim, Masaaki Suzuki, Soji Shimizu, Atsuhiro Osuka, Dongho Kim

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Abstract

We have explored the electronic natures of representative expanded porphyrins, [26]- and [28]-hexaphyrins, to investigate the interplay between the aromaticity and antiaromaticity that is brought by two electron oxidation/reduction processes. The excited singlet and triplet states of [26]hexaphyrin in solution exhibit lifetimes of 125 ps and 1.8 μs, respectively, as revealed by various time-resolved spectroscopic measurements. On the other hand, [28]hexaphyrin shows faster singlet and triplet lifetimes than those of [26]hexaphyrin, which is largely in accordance with the perturbation of aromaticity due to the π electron formulation of [4n] in [28]hexaphyrins. The two-photon absorption cross-section values at 1200 nm for [26]hexaphyrins show ca. 9890 GM which is > 102 larger than those of porphyrins. The reduced TPA values of 2600 and 810 GM of [28]hexaphyrin and perfluorinated [28]hexaphyrin, respectively, match well with their relatively short excited-state lifetimes. Overall, the enhanced excited-state lifetimes for various hexaphyrins go in line with the increased TPA cross-section values and the ring planarity.

Original languageEnglish
Pages (from-to)12856-12861
Number of pages6
JournalJournal of the American Chemical Society
Volume127
Issue number37
DOIs
Publication statusPublished - Sep 21 2005
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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