Orthometallated palladium(II) imine complexes as candidate materials for the biaxial nematic phase. Crystal and molecular structure of three palladium imine complexes

The synthesis, characterisation and liquid crystal properties of some forty palladium imine complexes are reported, along with the single crystal X-ray structures of three derivatives. The complexes contain an imine ligand, bound to palladium in an ortho-metallated fashion, and a beta-diketonate; the liquid crystal behaviour is studied as a function of the structure of both ligands. The design of these complexes sought to address methods for promoting specific lateral interactions as a means to induce correlations perpendicular to the main liquid crystal director. Such interactions could stabilise lower-symmetry nematic phases such as N-B, a proposition supported by calculations.