New heteropolynuclear metallomesogens: Copper(II), palladium(II), nickel(II) and oxovanadium(IV) chelates with [3]ferrocenophane-containing Schiff's base and β-aminovinylketone

New mesogenic heteropolynuclear complexes of Cu(II), Pd(II), Ni(II) and VO(IV) with the [3]ferrocenophane-containing Schiff's base, and Cu(II) and Pd(II) complexes with the [3]ferrocenophane-containing β-aminovinylketone have been synthesised. The obtained heterometallic mesogenes are identified by elemental analysis, proton nuclear magnetic resonance, infrared and ultraviolet-visible spectroscopies. Liquid crystalline properties are studied by thermal polarising optical microscopy and differential scanning calorimetry techniques. Both ligands and heteropolynuclear complexes exhibit thermotropic nematic and smectic C mesophases in various temperature ranges except for the Ni(II) complex. Mesomorphism of the prepared complexes is correlated with the geometry of their central chelate core. Considerably broader mesophases and lower transition temperatures are achieved in the synthesised metallomesogens by using the alkylidene-bridged ferrocene as a building unit.