Time-resolved electron paramagnetic resonance of the lowest excited triplet state of phenazinium cation.
Time-resolved and steady-state electron paramagnetic resonance (EPR) spectra have been observed for the lowest excited triplet (T(1)) states of phenazine (Phz) and its singly protonated cation (phenazinium) in sulfuric acid-ethanol mixtures at 77K. The single protonation appears to have little effect on the anisotropic sublevel populating rates of the T(1) state of phenazine. However, the zero-field splitting (ZFS) parameter D decreases on the protonation, reflecting the increase of delocalization of the two unpaired electrons. The sublevel preferentially populated by intersystem crossing (ISC) is T(y) in both phenazine and phenazinium (the y-axis is parallel to the in-plane long axis). From the analysis of the observed anisotropy in the ISC rates and the semi empirical molecular orbital calculations of the ZFS parameters, we concluded that the T(1) state of phenazinium is the (3)A(1)(pipi*) state.
Deguchi
Makoto
M
Department of Applied Chemistry, Graduate School of Engineering, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
Suzuki
Daisuke
D
Ito
Ryo
R
Matsumoto
Michiko
M
Yagi
Mikio
M
D002412:Cations / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D000431:Ethanol / Q000737:chemistry; D010619:Phenazines / Q000737:chemistry*; D011522:Protons; D013464:Sulfuric Acids / Q000737:chemistry; D013997:Time Factors
D002412:Cations; D010619:Phenazines; D011522:Protons; D013464:Sulfuric Acids; D000431:Ethanol; C033158:sulfuric acid