Structural, Photophysical, and Magnetic Circular Dichroism Studies of Three Rigidified meso-Pentafluorophenyl-Substituted Hexaphyrin Analogues

Masatoshi Ishida, Taniyuki Furuyama, Jong Min Lim, Sangsu Lee, Zhan Zhang, Sudip K. Ghosh, Vincent M. Lynch, Chang Hee Lee, Nagao Kobayashi, Dongho Kim, Jonathan L. Sessler

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Abstract

Detailed electronic, structural, photophysical, and redox studies of a series of meso-pentafluorophenyl-substituted hexaphyrins, namely amethyrin (1), rosarin (2), and rubyrin (3), are described. In prior work, it was found that the electronic states of the antiaromatic hexapyrrolic macrocycle, [24]rosarin 2, could be modified by exposure to several Brønsted acids (e.g., HCl, HBr and HI) to produce either one- and two-electron reduced species, or both. In an effort to gain further insights into the reactivity of hexaphyrins possessing different π-conjugation pathways, the β-dodecamethyl-substituted [24]amethyrin 1 was prepared and its electronic structure was analyzed along with that of the o-phenylene-bridged [26]rubyrin 3 and rosarin 2 The [4n] and [4n+2] π-conjugated formulations of 2 and 3, respectively, were inferred from steady-state, fs-transient absorption and two photon absorption measurements. Similar photophysical analyses lead to the conclusion that 1 is best considered as nonaromatic or weakly antiaromatic. Magnetic circular dichroism (MCD) spectroscopic analyses of hexaphyrins 1 and 3, as well as comparisons to 2, and theoretical perimeter MO diagram analyses provided support for the electronic assignments. In contrast to what was found for 2, simple protonation of 1 and 3 by halohydric acids did not induce an evident, redox-based change in the electronic structure of the macrocycle.

Original languageEnglish
Pages (from-to)6682-6692
Number of pages11
JournalChemistry - A European Journal
Volume23
Issue number27
DOIs
Publication statusPublished - 2017

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Organic Chemistry

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    Ishida, M., Furuyama, T., Lim, J. M., Lee, S., Zhang, Z., Ghosh, S. K., Lynch, V. M., Lee, C. H., Kobayashi, N., Kim, D., & Sessler, J. L. (2017). Structural, Photophysical, and Magnetic Circular Dichroism Studies of Three Rigidified meso-Pentafluorophenyl-Substituted Hexaphyrin Analogues. Chemistry - A European Journal, 23(27), 6682-6692. https://doi.org/10.1002/chem.201700759