New metallomesogens with enaminoketonato ligands

Several metallomesogens based on enaminoketonato ligands have been prepared. 1-Amino-1-(4'-butoxy-4-biphenyl)oct-1-en-3-one was synthesized by heterocycle hydrogenolysis in 3-(4'-butoxy-4-biphenyl)-5-amyl-isoxazole. Liquid crystalline complexes were obtained by reaction of this enaminoketone with nickel(II) or copper(II) acetates. Hydrogenolysis of the heterocycle in 3-(4-hydroxyphenyl)-5-amylisoxazole led to 1-amino-1-(4-hydroxyphenyl)oct-1-en-3-one. The corresponding copper(II) enaminoketonate was then obtained. The subsequent reaction of this compound with 4-alkoxy-benzoic acid chlorides gave liquid crystalline complexes with ester bridges in the core. A nematic phase was observed for all the synthesized metallomesogens. The bridging group influence on melting points, mesophase ranges and thermal stability of copper(II) complexes is discussed.