Disc-like chiral palladium and platinum complexes: Synthesis and mesomorphic properties

Abstract

ortho-Palladated and -platinated benzalimines are a widely studied novel type of liquid-crystals. These sheet-shaped materials contain two or even four metal atoms and carry eight and twelve flexible side-chains, respectively, Here we present the preparation and mesomorphic properties of dinuclear chiral homologues of such sheet-like compounds. On their own, the chiral members of the dinuclear cyclopalladated series exhibit no liquid-crystalline properties, but show mesophase inductions (Col(h)-phase) in mixtures with an electron-acceptor, e.g., 2,4,7-trinitrofluorenone (TNF). A diplatinated chiral analogue, however, monotropically exhibits the cholesteric nematic discotic (ND) type of mesophase, Mixtures of this platinum nematogen with TNF also show the induction of a columnar mesophase (Col(h)) due to charge-transfer interactions.