Electrochemical and liquid crystal properties of ferrocene-based β-diketonato copper(II) and zinc(II) complexes

Heterometallic liquid crystals are of special interest because of the possibility to combine optical, magnetic and electric properties of different metal ions in one mesogenic molecule. In order to investigate new heteropolynuclear mesogenic systems, the long-chain alkyl bromophenyl ferrocenyl β-diketones and their copper(II) and zinc(II) complexes were synthesized and characterized. The X-ray crystal structure reveals that β-diketone ligands exist in the enol isomer form in the crystals. These compounds exhibited good absorption and electrochemical properties. The complexes showed high thermal stability. According to thermal polarizing microscopy and differential scanning calorimetry studies, all complexes display liquid crystal behaviours. The zinc(II) complexes display lower melting point and clear point as well as a wide mesophase range compared with the copper(II) complexes. The obtained metallomesogens are important footsteps toward the development of liquid crystal materials possessing heteropolynuclear, good redox activity and chemically stable ferrocene unit.