LIQUID-CRYSTALLINE NETWORKS FROM CROSS-LINKABLE ORGANOMETALLIC MESOGENS

The synthesis and the phase properties of some crosslinkable mesogens containing tetracoordinated Pd(II) or Cu(II) chemical species are repo rted. The metal complexes, which belong to the class of salicylaldimin ates, exhibit enantiotropic liquid crystalline behaviour of the nemati c type, as found by the combined use of calorimetry, polarizing micros copy, and X-ray diffraction. Crosslinking in the liquid crystalline ph ase was brought about thermally or by UV-initiated radical polymerizat ion. This led to glassy materials preserving the original structural a nisotropy up to temperatures considerably higher than the isotropizati on temperature of the monomer. Preliminary investigation of the behavi our of binary organometallic systems containing one cross-linkable and one non-crosslinkable mesogenic component shows that phase separation occurs in the crosslinked material, notwithstanding the monophasic na ture of the original liquid crystal mixture.