Synthesis and properties of liquid‐crystalline side‐chain polymers containing β‐diketonato transition metal complexes

Abstract

Polymers (5-7) containing P-diketonato metal complexes of Cu2+, Ni2+ and Co3+ were synthesized from new thermotropic liquid-crystalline poly(acry1ate ester)s (4) with a mesogenic bidentate P-diketone in the side chain, and the liquid-crystalline properties were examined by differential scanning calorimetry (DSC), X-ray diffraction and polarizing microscopy. The mesophase of 4 is an enantiotropic smectic A phase showing a bathnet and focal conic fan texture in polarizing microscopy. Polymers 5 ac containing a bis(P-diketonato)copper(II) complex also exhibit an enantiotropic smectic A phase, and polymer 5d prepared from the vinyl monomer 8 shows a nematic phase. Concerning the complexes of polymers 6 and 7 with nickel(I1) and cobalt(III), only 6a and 7a containing a small amount of metal-chelating P-diketonate units exhibit liquid-crystalline behavior like the parent polymer 4. It was found that the fourcoordinated square planar bis(P-diketonate)copper(II) acts as the mesogen; both nickel(I1) and cobalt(II1) complexes do not work as mesogens and rather hinder the liquid crystallinity of 4. The electron spin resonance (ESR) spectra of 5a and 5 b change markedly along with the transition from the smectic A phase to the isotropic one. The broadening and simplification of the spectra for the isotropic phase indicates increased interaction between neighboring bis(P-diketonato)copper(II) complexes and substantial electron spin-spin interaction. The ESR spectra of 512 and 5d also imply this increased interaction between neighbouring complexes and spin-spin interaction regardless of the phase transition.

Calamitic metallomesogens: metal-containing liquid crystals with rodlike shapes

“…Increasing the percentage of copper units in the polymer 44 resulted in better monoaxial orientation in the nematic phase, 45 with the plane of the (square-planar) copper complex aligning parallel to the fiber axis. The polymer 45, based on dibenzoylmethane, where the phenyl rings are linked by O(CH2),0 spacers, was reported to exhibit smectic phases.…”

Anisotropic networks, elastomers and gels

“…Additionally high-energy- was produced by polymerization of hydrogen bonded 6.2. Metal co-ordinated reversible networks The co-ordination of mesogenic ligands with metals LC benzoic acids incorporating polymerizable groups, such anisotropic networks are normally cast from mix-as crosslinking units has also been used to prepare noncovalently bonded anisotropic networks [61 ]. The tures of low molar mass LCs with one or two ionic or ionizable terminal groups or their salts as crosslinkers 4-cyano-4¾ -biphenyl side groups of poly (acrylic esters) have been found to co-ordinate with platinum in ligand and preformed polymers like poly(acrylic acid ), poly (vinyl pyridine), etc.…”

Synthesis and characterization of well‐defined block and statistical copolymers based on lauryl methacrylate and 2‐(acetoacetoxy)ethyl methacrylate using RAFT‐controlled radical polymerization

“…So far, such polymers have been obtained by free radical polymerization of ethyl (meth)acryloylacetate10 and 2‐(acetoacetoxy)ethyl methacrylate (AEMA)11 or by the controlled oxidation of poly(vinyl alcohol) 12. Hanabusa et al13 have reported the synthesis and properties of liquid‐crystalline side‐chain homopolymers containing β‐dicarbonyl transition metal complexes of Cu 2+ , Ni 2+ , and Co 3+ . Moreover, Mastrorilli and coworkers have synthesized new supported metal complexes via thermal copolymerization of the metal complex precursors (cod)Rh(AEMA) and Pd(AEMA) 2 14.…”