Liquid Crystal Derivatives of Transition Metals (I): Tetracoordinated Copper (II) Complexes Derived From Schiffs Bases

Abstract

The synthesis, characterization and thermal behavior of several new series of Copper (II) complexes derived from Schiffs bases are reported. The complexes are of the type: [Cu{C₆H₃O(OR)‒C(Z)=N‒R′}₂] (R=n‒C _n H_2n+1+, R′=p-n-alkoxy-(C₆H₄)‒, p-n-alkyl‒(C₆H₄)‒, n-alkyl; Z˭H, CH₃).

Sehiffs base complexes of Copper (II) derived from an aldehyde show thermotropic mesophases (smectic discotic polymorphism), whereas complexes derived from a ketone do not. When the amine forming the imine ligand is an aromatic amine the complexes form liquid crystals, whereas if the amine is aliphatic the complexes do not give liquid crystals.

Key Words:

• The relationship between the molecular structure and the mesomorphic behavior is discussed.
• transition metal complexes
• copper
• Schiffs bases
• liquid crystals
• smectic–discotic polymorphism