hfs–Zero-Field Paramagnetic Resonance of ·CH Radicals

Abstract

An introduction to the method of hfs–zero-field paramagnetic resonance is given in this article and spectra of the radicals of barbituric acid, malonic acid, cyclohexane-1, 1-diacetic acid, fumaric acid, and α-alanine are shown. From these spectra the hfs-coupling-tensor values were determined.

Electron paramagnetic resonance spectroscopy at zero magnetic field

“…Birkle and Schoffa analyzed the ZFR spectra of the -CHradicals produced on irradiating malonic acid, barbituric acid, and cyclohexane-1,1-diacetic acid. 98 The only discrepancy with previous EPR work was in the Az value for the barbituric acid radical (ZFR: -25.4 MHz; EPR: -31.4 MHz99).…”

“…The interpretation by EPR of the spectrum of irradiated fumaric acid in terms of radicals HOOC-RCH-CH-COOH and HOOC-CH2-CH-COOH (the latter being the succinic acid radical) by Cook et al104 was confirmed by combination of the two predicted ZFR spectra. 98 Geiger et al used Gaussian line shapes to simulate the ZFR spectra of the radical HOOC-CH2-O-CH-COOH in irradiated diglycolic acid. 105 In this species the main interaction is with the a proton but there are very small interactions with the methylene protons.…”