Regulation mechanism of spin-orbit coupling in charge-transfer-induced luminescence of imidazopyrazinone derivatives

Hiroshi Isobe, Syusuke Yamanaka, Seiki Kuramitsu, Kizashi Yamaguchi

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)


The spin transition in the reactions of the derivatives of imidazo[1,2-a]pyrazin-3(7H)-one (1H) with a triplet molecular oxygen ( 3O2) has been investigated by the geometry optimization at the B3LYP/6-31+G(d) level and the evaluation of the electronic matrix elements for spin-orbit coupling (SOC) using the full Pauli-Breit SOC operator. The reductive activation for the 3O2 reaction is affected by the proton activity and solvent polarity of a surrounding reaction field. In a polar aprotic solvent, a base-prompted anionic substrate may react with 3O2 in a stepwise manner through complete electron transfer from the substrate anion to 3O2, while the irreversible concerted 3O2 addition via intersystem crossing may become complete in a less polar solvent. SOC in the thermal decomposition of a resulting peroxide adduct can be controlled by the protonation state of the substrate. There exists an optimal protonation state for the suppression of SOC in the charge-transfer-induced luminescence (CTIL) of the peroxide, which is closely related with the ability of a substituent to donate an electron. This will constitute a necessary condition for the high efficiency of chemi- and bioluminescence.

Original languageEnglish
Pages (from-to)132-149
Number of pages18
JournalJournal of the American Chemical Society
Issue number1
Publication statusPublished - Jan 9 2008
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry


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