ИСТИНА

The nitroxide radicals are successfully used for investigation of the structure and dynamics of various matrixes. Recently these spine probes were applied for study of the room temperature ionic liquids (RTIL). The present work is devoted to investigation of the RTIL OmimBF4 at different temperatures; the common nitroxide radical TEMPOL was used as spine probe. It was found that in the some temperature range the EPR spectrum of the radical becomes a singlet. This phenomenon takes place on condition that concentration of the radicals is none less than 1•10 -3 mol/l. The shape and width of the singlet are not depending of both concentration and temperature. It is necessary to note that in low-molecular solvent toluene this phenomenon is not observed. We suppose that appearance of the singlet in EPR spectrum corresponds to formation of the “clusters” of radicals. This phenomenon may be connected with availability of some structure of ionic liquid. The local concentration of the probe in “clusters” and in the main solvent was estimated. On the basis of analysis of the spectra, recorded at different temperatures, the rotational diffusion of the paramagnetic molecules in OmimBF4 was investigated.