Time-Resolved EPR and Transient Absorption Studies on Phthalocyaninatosilicon Covalently Linked to Two PROXYL Radicals

Shoji Takeuchi, Kazuyuki Ishii, Nagao Kobayashi

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

By the combined use of electron paramagnetic resonance (EPR) and transient absorption measurements, photophysical properties of tetra-tert- butylphthalocyaninatosilicon (SiPc) covalently linked to two 2,2,5,5-tetramethyl-1-pyrrolidinyloxy (PROXYL) radicals (R2a) have been investigated in terms of the photocontrol of magnetic properties. The steady-state EPR spectrum of R2a indicates that two PROXYL radicals generate a spin-correlated radical pair, where the singlet ground state (S 0′) is close to the triplet ground state (T0′) . In time-resolved EPR (TREPR) spectra of R2a, A/E A/E A/E polarizations are initially seen, which then change into E/A E/A E/A polarizations. The initial and later polarizations are reproduced by spin-selective population of the S0′ and T0′ states, respectively. Quantitative analyses of TREPR and transient absorption signals show that the initial A/E A/E A/E polarizations are reproduced by spin-selective relaxation from the excited states, where the SiPc moiety is in the excited singlet state, and that the later E/A E/A E/A polarizations originate from the decay from excited multiplet states consisting of two doublet PROXYLs and SiPc in the excited triplet state.

Original languageEnglish
Pages (from-to)3276-3280
Number of pages5
JournalJournal of Physical Chemistry A
Volume108
Issue number16
DOIs
Publication statusPublished - 2004 Apr 22

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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