| 16500142 |
Grampp G, Kattnig D, Mladenova B: ESR-spectroscopy in ionic liquids: Dynamic linebroadening effects caused by electron-self exchange reactions within the methylviologene redox couple. Spectrochim Acta A Mol Biomol Spectrosc. 2006 Mar 13;63(4):821-5. Epub 2006 Feb 24.
Well-resolved ESR-spectra of the methylviologene radical cation (MV*+) are recorded in room-temperature liquid ions as solvents. The temperature dependences of the ESR-coupling constants are similar to those measured in classical organic solvents. Electron-self exchange rates are reported for the methylviologene redox couple (MV++/MV*+) in 1-butyl-3-methylimidazolium hexafluorophosphate (bmim+ PF6-), 1-butlyl-3-methylimidazolium fluoroborate (bmim+ BF4-) and 1-ethyl-3-imidazolium ethylsulfate (emim+ O3SOEt-) within a temperature range of 350 K < or = T < or = 460 K. The diffusion controlled rate constants observed vary between 8.2 x 10 (7) M (-1) s (-1) and 1.2 x 10 (9) M (-1) s (-1). From temperature-dependent measurements the activation energies obtained range from 27.4 kJ/mol in emim+ O3SOEt- to 42.1 kJ/mol in bmim+ PF6-, respectively. |
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