Investigation of aromaticity and photophysical properties in [18]/[20]π porphycene derivatives

Kil Suk Kim, Young Mo Sung, Takashi Matsuo, Takashi Hayashi, Dongho Kim

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


In this study, we have investigated the relationship between aromaticity and photophysical properties of trifluoromethyl-substituted [18]/[20]π porphycenes by using theoretical calculations and various spectroscopic methodologies. Interestingly, we have found that the HOMO-LUMO gap of [20]π porphycene is larger than that of [18]π porphycene, which is in a sharp contrast with those of typical [4n]/[4n+2]π porphyrinoids. Based on our observations, we demonstrate that the origin of this contrasting feature of [20]π porphycene arises from the uniquely large energy splitting between LUMO and LUMO+1 of [18]π porphycene compared with other aromatic [4n+2]π porphyrinoids with nearly degenerate LUMO/LUMO+1. Consequently, we can propose that the energy difference between LUMO and LUMO+1 levels of aromatic [4n+2]π porphyrinoids is an important factor in determining the electronic nature of their corresponding antiaromatic [4n]π porphyrinoids. Moreover, to the best of our knowledge, this is the first study to illustrate the photophysical properties of porphycenes with [4n]π electronic circuits. Mind the gap: Photophysical properties of trifluoromethyl-substituted [20]π porphycenes were investigated theoretically and spectroscopically. Compared with other [4n]π porphyrinoids, the [20]π porphycene molecule exhibits quite unique photophysical behaviors that originate from a large HOMO-LUMO gap (see image).

Original languageEnglish
Pages (from-to)7882-7889
Number of pages8
JournalChemistry - A European Journal
Issue number28
Publication statusPublished - 2011 Jul 4

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Organic Chemistry


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