Anomalous temperature effects of the ESR spectra were found in copper doped zinc (II)-bis-(histidine) powders. In the L-histidine complex, reversible transitions between solid-like and liquid-like spectra were observed at 8 °C by increasing, and at 0 ́C by decreasing temperature. In the mixed L-histidine-D-histidine complex, the magnetic parameters of solid-like spectra change strongly around -20°C. The anomalies were explained by Jahn-Teller effect stabilized square planar geometry around the doping copper centers in the lattice of zinc complex with tetrahedral geometry. The phase transitions can be induced by rearrangements of the water molecules coordinated to the copper ions into their regular positions in the zinc lattice. This molecular displacement can facilitate either uniaxial rotation or torsional oscillation of the histidine molecules in the respective lattices.
|Number of pages||4|
|Journal||The Journal of Chemical Physics|
|Publication status||Published - Dec 1 1986|
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry