Photo-induced valence tautomerism in a Co compound

Osamu Sato, Shinya Hayami, Zhong Ze Gu, Kazuyuki Takahashi, Rie Nakajima, Kanako Seki, Akira Fujishima

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39 Citations (Scopus)


Photo-illumination effects have been measured for where LS, tmeda, 3,5-DBSQ and 3,5-DBCat denote low-spin, N,N,N′,N′-tetramethylethylenediamine, 3,5-di-tert-butyl-1,2-semiquinonate and 3,5-di-tert-butyl-1,2-catecholate, respectively. When the title compound was illuminated at 5 K, the magnetization value increased from μeff = 1.7 to 2.3 μB. The absorption spectra after illumination show that the absorption band at around 800 nm, characteristic of the [CoII-HS(tmeda)(3,5-DBSQ)2] state (HS denotes high-spin), increased and the charge transfer band from 3,5-DBCat to 3,5-DBSQ at 2500 nm was reduced. IR spectra show that the C-O stretching peak at 1280 cm-1 is significantly decreased. These results confirm that a photo-induced intra-molecular electron transfer, [CoIII-LS(tmeda)(3,5-DBSQ)(3,5-DBCat)] → [CoII-HS(tmeda)(3,5-DBSQ)2], was induced. The lifetime of the metastable state at 5 K was 175 min.

Original languageEnglish
Pages (from-to)111-114
Number of pages4
JournalJournal of Photochemistry and Photobiology A: Chemistry
Issue number1-3
Publication statusPublished - Jun 28 2002
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Physics and Astronomy(all)


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