Control of chromophore symmetry by positional isomerism of peripheral substituents

Soji Shimizu, Yu Haseba, Mariko Yamazaki, Genji Kumazawa, Nagao Kobayashi

Research output: Contribution to journalArticle

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Abstract

The first example of the control of porphyrinoid chromophore symmetry based on the positional isomerism of peripheral substituents has been achieved by preparing tetraazaporphyrins (TAPs) with C4h, D2h, C 2v, and Cs symmetry due to the relative arrangement of peripheral tert-butylamino and cyano groups as push and pull substituents, respectively. The four structural isomers were successfully isolated and characterized by 1H NMR spectroscopy and X-ray crystallography. The band morphology in the Q-band region varies depending on the molecular symmetry due to the significant perturbation introduced into the chromophore by the push and pull substituents. The C4h and C2v isomers exhibit a single Q band, whereas the Q bands of the D2h and Cs isomers show a marked splitting. The magnetic circular dichroism spectra indicate that the push-pull TAPs retain the properties of the 16-membered 18π-electron perimeter generally observed for porphyrinoids. Theoretical calculations have demonstrated that the perturbation introduced by the substituents lowers the D4h symmetry of the parent TAP π-conjugated system, and this results in significant spectral changes. A novel approach to the fine-tuning of the spectral properties of porphyrinoids based on changes in the chromophore symmetry is described. Symmetry control: Control of porphyrinoid chromophore symmetry based on the positional isomerism of peripheral substituents has been achieved by preparing tetraazaporphyrins (TAPs) with C4h, D2h, C2v, and Cs symmetry as a result of the relative arrangement of peripheral substituents (see figure). A new approach to the fine-tuning of the spectral properties of porphyrinoids based on changes in the chromophore symmetry is described.

Original languageEnglish
Pages (from-to)4822-4828
Number of pages7
JournalChemistry - A European Journal
Volume20
Issue number16
DOIs
Publication statusPublished - Apr 14 2014

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Chromophores
Isomers
Tuning
X ray crystallography
Dichroism
Nuclear magnetic resonance spectroscopy
Electrons

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Organic Chemistry

Cite this

Control of chromophore symmetry by positional isomerism of peripheral substituents. / Shimizu, Soji; Haseba, Yu; Yamazaki, Mariko; Kumazawa, Genji; Kobayashi, Nagao.

In: Chemistry - A European Journal, Vol. 20, No. 16, 14.04.2014, p. 4822-4828.

Research output: Contribution to journalArticle

Shimizu, Soji ; Haseba, Yu ; Yamazaki, Mariko ; Kumazawa, Genji ; Kobayashi, Nagao. / Control of chromophore symmetry by positional isomerism of peripheral substituents. In: Chemistry - A European Journal. 2014 ; Vol. 20, No. 16. pp. 4822-4828.
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