Highly pure synthesis, spectral assignments, and two-photon properties of cruciform porphyrin pentamers fused with benzene units

Hiroki Uoyama, Kil Suk Kim, Kenji Kuroki, Jae Yoon Shin, Toshi Nagata, Tetsuo Okujima, Hiroko Yamada, Noboru Ono, Dongho Kim, Hidemitsu Uno

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Tetrameric porphyrin formation of 2-hydroxymethylpyrrole fused with porphyrins through a bicyclo[2.2.2]octadiene unit gave bicyclo[2.2.2]octadiene- fused porphyrin pentamers. Thermal conversion of the pentamers gave fully π-conjugated cruciform porphyrin pentamers fused with benzene units in quantitative yields. UV/Vis spectra of fully π-conjugated porphyrin pentamers showed one very strong Q absorption and were quite different from those of usual porphyr-ins. From TD-DFT calculations, the HOMO level is 0.49 eV higher than the HOMO-1 level. The LUMO and LUMO+ 1 levels are very close and are lower by more than 0.27 eV than those of other unoccupied MOs. The strong Q absorption was interpreted as two mutually orthogonal single-electron transitions (683 nm: 86%, HOMO LUMO; 680 nm: 86%, HOMO->LUMO + 1). The two-photon absorption (TPA) cross section value (σ(2)) of the benzene-fused porphyrin pentamer was estimated to be 3900 GM at 1500 nm, which is strongly correlated with a cruciform molecular structure with multidirectional π-conjugation pathways.

Original languageEnglish
Pages (from-to)4063-4074
Number of pages12
JournalChemistry - A European Journal
Issue number13
Publication statusPublished - 2010 Apr 6


All Science Journal Classification (ASJC) codes

  • Catalysis
  • Organic Chemistry

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