Yuri G. Galyametdinov

Synthesis and characterization of a novel liquid crystalline side chain metallopolymer

The synthesis of a novel kind of form-retaining liquid crystalline crosslinked metallopolymer is reported. Copper(II) is complexed by Schiffs base units as part of a mesogenic side chain polymer. This leads to remarkable antiferromagnetic exchange interactions between the copper centers that are not present in related monomeric model compounds. IR spectroscopic investigations in the region 4000-200 cm -1 , X-ray diffractometry and temperature dependent magnetic susceptibility measurements were carried out to elucidate the structure of this new material. The observed considerably strong antiferromagnetic coupling is assumed to be due to the interactions between the copper centers through oxygen bridges in the polymeric matrix.

Side‐chain functionalized liquid crystalline polymers and blends, 6. Phase behavior, structure and magnetic properties of Cu(II) containing liquid crystalline ionomers

The new series of the LC ionomers containing copper ions has been obtained and their phase behavior has been studied. It was shown that at low metal ion concentrations in the LC ionomers (˜2 mol-%) the induction of the SmA phase is observed. An increase in the copper ion concentration is accompanied by a slight rise in clearing and glass transition temperatures. The magnetic properties of LC ionomers were studied at the first time. It was shown that LC ionomers are antiferromagneties with a strong exchange interaction J = 174–178 cm–1. Temperature dependencies of the magnetic moment and the magnetic anisotropy are adequately described in the framework of the 1-D-Heisenberg linear-chain model.

Dielectric, Electrooptical and Magnetic Properties of Metallomesogens

Abstract The dielectric behaviour of ferroelectric liquid crystals of copper (II) Schiff bases complexes were investigated by dielectric spectroscopy. The spontaneous polarization Ps and the switching time T were determined by means of the polarization reversal method. Temperature dependent magnetic susceptibility measurements were carried out in the temperature range of 4.2 - 450 K to examine the magnetic properties of the copper (II) complexes.

Cubic phase of 4′‐n‐Hexadecyloxy‐3′‐cyanobiphenyl‐4‐carboxylic acid (ACBC‐16)

The cubic phase structure of 4′‐n‐hexadecyloxy‐3′‐cyanobiphenyl‐4‐carboxylic acid (ACBC‐16) was examined by X‐ray diffraction. Unlike the octadecyloxy homologue showing an Im3m‐type cubic phase, the cubic phase of ACBC‐16 was of Ia3d type, both on heating and on cooling, similarly to the corresponding nitro‐substituted analogue (ANBC‐16). The lattice dimension a at 453 K was a = 11.0 nm, 2.5% larger than the value for ANBC‐16 and rather close to the value of ANBC‐17 or ‐18. It is expected that the appearance of the cubic phase type, as a function of the number of carbon atoms n in the alkoxy chain in the ACBC‐n series, is essentially the same as in the ANBC‐n series, but shifted towards shorter n by 1 or 2. In the latter ANBC‐n series, the cubic phase type is Ia3d for 15⩽n⩽18, while an Im3m type is formed for 19⩽n⩽21, both on heating and on cooling.

Magnetic investigations on liquid crystalline metallopolymers

Abstract In this contribution, magnetic investigations on materials, which essentially combine mesogenic and polymeric properties, were presented. In the glassy and the smectic phase of a copper(II) containing polymer we observed remarkable antiferromagnetic exchange interactions between the copper centers, whereas in the isotropic phase, the magnetism followed the Curie-Weiss law. The monomeric model compound showed Curie-Weiss behaviour. In addition, we describe the magnetic behaviour of mesogenic compounds, resulting from the incorporation of rare-earth ions in chelating units of the liquid-crystalline Schiff base polymer.

Calorimetric study of the cubic mesogen, ACBC(16)

The heat capacity of the cubic mesogen ACBC(16) was measured between 16 and 500 K by adiabatic calorimetry. As well as the known condensed phases, a new crystalline phase was found to undergo a glass transition at around 165 K. Phase transitions between crystal, SmC, cubic, and isotropic liquid phases took place at 399.16, 431.15, and 474.30 K, respectively. As in the case of ANBC, a broad hump was observed in the heat capacity of the isotropic liquid phase. The first order nature of the SmC–cubic phase transition was confirmed for the first time by the observation of supercooling of the cubic phase. The broad hump in the isotropic liquid phase was shown to extend to a low temperature side if the isotropic liquid was supercooled, suggesting that the event occurring at the hump is not directly related to the cubic–isotropic liquid phase transition.