RHEOLOGICAL AND NEUTRON-SCATTERING INVESTIGATIONS OF THE JELLY STATE OF BINUCLEAR COPPER-COMPLEXES IN CYCLOHEXANE

Binuclear copper(II) carboxylates are known to exhibit thermotropic mesophases. When dissolved into cyclohexane, viscoelastic jellies are obtained. Oscillatory shear experiments are Performed and the Maxwell model is used as a basic description of the rheological behaviour. At high frequency, a transient elastic three-dimensional network is evidenced. Small-angle neutron scattering experiments indicate that the network is constituted by aggregates with a rodlike local structure with a diameter of empty set = 17.5 angstrom (Cu2-S8) and only one molecule lying in the cross-section. The aggregates are formed with stacked molecules which are linked by axial copper-oxygen coordination bondings. The jelly state is found to be reminiscent with the related discotic thermotropism.