Cholesteric liquid crystal polymers containing coordinated copper(II) in the main chain

New main chain cholesteric liquid crystal copolymers having coordinated copper(II) atoms in the main chain have been prepared, together with some related model compounds. The (S)-(+)-1-amino-2-propylhexanoate group, directly bound to the metal ion, was used as the chiral centre. Phase behaviour and optical properties of polymers appear to be influenced by the molar amount of the chiral component and by the nature and molar proportion of the flexible segments of the backbone chain. Reflection spectra, including the visible frequency range, recorded for film samples in the planar texture clearly show a dependence of the cholesteric pitch on these structural parameters. Mixtures of structurally related chiral and non-chiral low molecular weight mesogens show cholesteric behaviour even with very low contents of the chiral component. For chiral-rich mixtures, liquid crystalline polymorphism involving a non-birefringent phase has been detected. (C) 2000 Elsevier Science Ltd. All rights reserved.