Electron paramagnetic resonance study of the physical gelation of a copper complex in cyclohexane

P. Terech , C. Chachaty , J. Gaillard , A.M. Giroud-Godquin

The dynamical behaviour and gelation kinetics of a copper complex substituted by eight paraffinic chains in cyclohexane has been investigated by X-band and Q-band Electron Paramagnetic Resonance spectroscopy. In the fluid-phase the complex exhibits a hyperfine structure, the anisotropy of which allows an estimate of the tumbling correlation time of the order of 4 x 10-10 s. In the gel-phase, the electron exchange between stacked complexes averages out the hyperfine structure, and the frequency dependence of the g tensor anisotropy is analysed in terms of a reduction of the tumbling rate to τ ≃ 8 × 10-9 s. The time dependence of the EPR signal provides a simple method to study the kinetics of segregation and gelation.

Mots clés: copper compounds; discotic liquid crystals; g factor; gels; hyperfine field interactions condensed matter; organic compounds; paramagnetic resonance of iron group ions and impurities; segregation

Domaines: Articles anciens

P. Terech, C. Chachaty, J. Gaillard, A.M. Giroud-Godquin. Electron paramagnetic resonance study of the physical gelation of a copper complex in cyclohexane. Journal de Physique, 1987, 48 (4), pp.663-671. ⟨10.1051/jphys:01987004804066300⟩. ⟨jpa-00210483⟩