Ionic liquid crystal precursors for inorganic particles: phase diagram and thermal properties of a CuCl nanoplatelet precursor.

We have recently reported (Angew. Chem. Int. Ed. 2004, 43 (40), 5380) the formation of CuCl nanoplatelets from an ionic liquid crystal precursor (ILCP) consisting of a 50/50 (wt/wt) mixture of bis(dodecylpyridinium) tetrachlorocuprate 1 and 6-O-palmitoyl ascorbic acid 2. Here we present the full ILCP phase diagram and the thermal behavior from a mixing ratio of 1/0 (i.e., pure 1) to 0/1 (i.e., pure 2). The ILCP exhibits a crystalline-smectic-isotropic phase transition at all mixing ratios, and the liquid crystal region is up to 90 degrees C wide. DSC shows a broad exothermic peak between ca. 70 and 170 degrees C, which is associated with the thermally induced CuCl formation. The reaction enthalpies reach -150 kJ/mol at around 50/50 (wt/wt) mixtures of the two components, and the activation energy for CuCl formation is ca. 190 kJ/mol. Thermogravimetric analysis shows that the samples degrade above ca. 200 degrees C.