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Published on: October 31, 2019
Radical Dimerization in a Plastic Organic Crystal Leads to Structural and Magnetic Bistability with Wide Thermal
Alina Dragulescu-Andrasi1, Alexander S Filatov2, Richard T Oakley3
1Department of Chemistry and Biochemistry , Florida State University , Tallahassee , Florida 32306 , United States.
Abstract:
The nitroxyl radical 1-methyl-2-azaadamantane N-oxyl (Me-AZADO) exhibits magnetic bistability arising from a radical/dimer interconversion. The transition from the rotationally disordered paramagnetic plastic crystal, Me-AZADO, to the ordered diamagnetic crystalline phase, (Me-AZADO)2, has been conclusively demonstrated by crystal structure determination from high-resolution powder diffraction data and by solid-state NMR spectroscopy. The phase change is characterized by a wide thermal hysteresis with high sensitivity to even small applied pressures. The molecular dynamics of the phase transition from the plastic crystal to the conventional crystalline phase has been tracked by solid-state (1H and 13C) NMR and EPR spectroscopies.
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