Shiro Konishi

Esr studies of crown complexed semiquinone ion pairs in solution

Abstract ESR spectra of alkyl-substituted p -benzosemiquinone anion radicals produced by sodium reduction in the presence of 18-crown-6 in tetrahy drofuran show, remarkable temperature and concentration dependences, not observed in the absence of the crown. The observed spectral changes are interpreted in terms of equilibria between structurally different ion pairs.

Absorption spectroscopic and ESR studies on one-electron reduction products of copper(II) and oxovanadium(IV) tetraphenylporphyrins produced by γ-radiolysis in 2-methyltetrahydrofuran solutions at 77 K

Abstract Optical absorption spectra of one-electron reduced species of copper(II) and oxovanadium(IV) tetraphenylporphyrins. Cu(II)TPP and V(IV)OTPP, in 2-methyltetrahydrofuran at 77 K reveal that not the central metal but the porphyrin ligand is reduced by an excess electron. The triplet ESR spectrum resulting from the spin-spin interaction between two odd electrons located on the porphyrin ligand and the central metal is observed for the one-electron reduced species of V(IV)OTPP while not for that of Cu(II)TPP.

Optical absorption and triplet ESR spectra of oxovanadium(IV)tetraphenylporphyrin cation radical

Abstract One-electron oxidized species of oxovanadium(IV)tetraphenylporphyrin in 1,1′,2,2′-tetrachloroethane solution produced by γ-ray irradiation at 77 K exhibits the optical-absorption and triplet-ESR spectra which are interpreted in terms of the porphyrin-ring oxidation and the spin—spin interaction between the two unpaired electrons; one on the ring and the other on the metal.

Optical absorption and quartet ESR spectra of one-electron reduced nitric oxide adduct of manganese(II) tetraphenylporphyrins in rigid solution at 77 K

Abstract The S = 3 2 ESR spectrum is observed for the one-electron reduced species of the nitric oxide adduct of manganese(II) tetraphenylporphyrin in 2-methyltetrahydrofuran solution produced by γ-irradiation at 77 K. The optical absorption and ESR spectra indicate that an excess electron is captured by the central manganese atom.