The ligand nitrogen hyperfine structure in paramagnetic resonance spectra of Cu(II) ions in crystals of three deuterated amino acids has been resolved. In dimethylalanine and α-glycine crystals, the copper complex structure is symmetrical, and the two nitrogen nuclei interact equally with the central ion. In contrast, the structure in l-alanine was found to be deformed, with only one amino group participating in the ligand hyperfine interaction. The g tensor and hyperfine coupling tensors for 63Cu, 65Cu, and ligand 14N nuclei were determined for the Cu(II) complexes in these materials.
Crystals of disodium succinate have two distinct modifications, monoclinic and triclinic. These were recognized by electron spin resonance (e.s.r.) studies of. the free radicals produced by γ-irradiation. In the monoclinic crystals, e.s.r. spectra and radiation processes appear similar to those observed in γ- (or x-) irradiated succinic acid. The situation in triclinic crystals is more complex (see Part 2). In monoclinic crystals irradiated at 77 °K, two types of radical coexist. They were identified as − O 2 CCH 2 CH 2 ĊO 2 2− , 1, together with a distorted conformation of the radical − O 2 C(ĊHCH 2 )*CO 2 − , 2. On warming to room temperature the former species disappears while the latter changes irreversibly to a stable conformation − O 2 CĊHCH 2 CO 2 − , 3.
CH2CO2− radicals are stable in γ-irradiated sodium acetate crystals. The ESR spectra of CH2CO2− and carbon-13 labeled radicals, CH213CO2− and 13CH2CO2−, were studied in detail in the temperature range of 77°K to room temperature. It was found that the CH2 group executes an internal motion which is characterized by proton exchange in the oriented radicals. The motion is slowed on lowering the temperature, giving rise to an electron spin relaxation time of the order of microseconds at 77°K. The correlation time for the motion was found to be temperature dependent, varying as exp (V / kT) with an activation energy V of the order of 3 kcal mole−1.
