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DOI: 10.1055/s-0028-1087303
Anthracene-Fused Porphyrins
Contributor(s):Timothy M. Swager, Rebecca R. ParkhurstUniversity of Oxford, UK
Expanding the Porphyrin π-System by Fusion with Anthracene
Org. Lett. 2008, 10: 3945-3947
Publication History
Publication Date:
20 November 2008 (online)
Key words
π-extended porphyrins - near-IR absorption -
Significance
The authors synthesized the first examples of anthracene-fused porphyrins (2c, 4) via a Suzuki coupling followed by oxidative fusion. Attempts at oxidative fusion were only successful with electron-rich meso-(9-anthryl)porphyrin derivatives, which is consistent with results using pyrene. Regioselective synthesis of 10-bromo-1,8-dialkoxyanthracene also provided a challenge which the authors were able to circumvent through the use of 1,8-diacetoxyanthracene and subsequent deprotection.
Comment
The electronic properties of large π-conjugated chromophores are of great interest due to a small HOMO-LUMO gap allowing easy oxidation. Expansion of the π-system in porphyrins also creates a red-shift in absorption. This interest has led to the synthesis of many aromatic-fused porphyrins, however, anthracene has not been studied yet. The absorption spectra of 2c and 4 are both red-shifted as compared to the unfused precursors (1c and 3, respectively). The spectrum of 4 is very similar to that of previously studied naphthalene-fused porphyrins, whereas 1c is red-shifted an additional 130 nm with potential for applications in photovoltaics, photodynamic therapy, and nonlinear optics.