Preparation, characterization and mesomorphic properties of nickel and copper complexes derived from N,N′-bis[3-(3′,4′-dialkoxyphenyl)-3-oxopropenyl]ethylenediamine

Abstract

The preparation, characterization and mesomorphic properties of copper and nickel complexes derived from N,N′-bis[3-(3′,4′-dialkoxyphenyl)-3-oxopropenyl]ethylenediamine are reported. Liquid crystalline behavior for these structurally similar complexes was found to be strongly dependent both on the number of sidechains and metal centers incorporated. Nickel complexes with four or six alkoxy sidechains exhibited columnar phases. However, nickel complexes with two alkoxy sidechains and all copper complexes regardless the numbers of the sidechains were not liquid crystalline. The structure of the mesophases was confirmed as columnar hexagonal (Col _h ) by powder XRD diffraction. The data that the copper complexes have slightly lower isotropic temperatures than the analogous nickel complexes suggested that the lack of liquid crystallinity for the copper complexes may be attributed to weaker molecular interactions. The results also indicated that nickel complexes with four sidechains showed a wider range of mesophase temperature than complexes with six sidechains.