Abstract

The 2 mm band spectra have been obtained for imidazoline nitroxides, nitronyl and imino nitroxides, containing various substituents in different positions of a radical cycle in frozen toluene solutions. The spectra allowed the determination of all g tensor principal values and the A, , component of the hyperfine interaction tensor with the nitrogen nucleus of ,N-0.1989), pp. 15-57.

The anion and cation radicals of vitamin K 1 and its analog menadione were characterized using the magnetic resonance techniques of Electron Nuclear Double Resonance (ENDOR), Electron Spin Echo Envelope Modulation (ESEEM), and Electron Paramagnetic Resonance (EPR) at X-band and 2 mm-band. The g-factor anisotropy of the radicals at 2 mmband allow them to be distinguished from each other in the solid state. The g-factor matrix of the radical anion of vitamin K~ is virtually identicat with that reported for the reduced A~ acceptor in green plant photosystem I thus demonstrating that reduced A~ is the anion radical of vitamin K 1.

2-mm band EPR spectroscopy was used to compare the spectra of paramagnetic particles produced under adsorption of p-quinones (p-benzoquinone, chloranil, fluoranil) on ah activated surface of HY zeolites, p-quinone cation and anion radicals, and the complexes of p-quinones with A1C13 in a frozen nonpolar solvent. The adsorption is observed to give rise to the paramagnetic complexes of quinones and zeolite surface Lewis sites.

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