Liquid-crystalline paramagnetic Cu(ll) complexes of enaminoketone ligands

Studies of complexes: [R-C6H4-CO(CH)2N-Alk]2Cu, (I), [Alk-CO(CH)2N-C6H4-R]2Cu, (II), and [R1-C6H4-CO(CH)2N-C6H4-R2]2Cu, (III), for various terminal substituents R, R1, R2, are presented. For alkyl substituents R, complexes are low-melting and low-clearing nematics (group (I)) and smectics A (group (II)). Mesophases are monotropic for pure compounds, enantiotropic for mixtures. Elongation of molecular core by introduction trans-cyclohexyl rings into R substituents leads to enantiotropic paramagnetic mesogens. Complexes of the group (III) are high-melting and high-clearing mesogens which usually undergo decomposition in the isotropic phase. Chiral highly twisted mesophases are observed for some optically active complexes.