T. I. Shabatina

Solid phase transformations of labile samarium-cyanobiphenyl complexes

Abstract Samarium containing cyanobiphenyl(CB) solid phase samples were obtained by low temperature co-deposition of the reagent vapors under the molecular beam conditions using special vacuumed cryostats. Film samples were studied by IR-and UV-visible spectroscopy in the temperature range 80–300 K. The formation of two Sm-CB complexes of different compositions. The kinetics of solid phase transformations in the system was discussed.

Copper Atom Interaction with Mesogenic Cyanobiphenyls in Solid Co-Condensates

ABSTRACT New metal-mesogenic systems based on copper and mesogenic cyanobiphenyls 5CB and 8CB have been produced by low temperature co-condensation of their component vapors. The formation of low temperature complexes of copper atoms with the cyanobiphenyl π-system in the solid state at 80–150 K was shown by ESR- and UV-Vis spectroscopic data. The thermal stability of the complexes and their thermal behavior on warming of the co-condensate samples up to room temperature are discussed.

Cage effect in reactions of free radicals formation and recombination in nematic and cholesteric liquid crystals

Abstract The kinetics of free radical formation during thermal decomposition of AIBN and free radical recombination in nematic 5CB-50CB mixtures and cholesteric ChOl-ChPel mixtures has been studied. The effect of orientational order of the systems on probabilities of radical escape and their recombination has been found.

Phenomenological Approach to the Description of the Dimerization Kinetics in Nematic Mesophase

Abstract The expression has been obtained, which determines the observed reaction rate constant in the nematic mesophase as a function of scalar liquid crystal order parameter. The expression includes the experimentally obtained parameters. It has been used for the estimation of the rate constants for 2-methyl-2-nitrosopropane at selected temperatures in nematic liquid crystal MBBA.

Dimerization of Some Liquid Crystalline 4′4′-Alkyl-Cyanophenyl Derivatives in Solid Phase and Inert Matrices

Abstract Molecular association of liquid crystalline 4,4′-pentylcyanobiphenyl 5CB), 1-p-cyanophenyl-4-parameters of dimerization process have been obtained for nematic pentyl-cyclohexane (5CH) 2-p-cyanophenyl-5-pentylpyridine(5Py) was studied in bulk, solutions and inert matrices at 77–330K by low temperature reflection IR-spectroscopy and isothermal Calve calorimetric methods. The thermodynamic and kinetic mesophase. The factors effected the dimer stability were considered.

New chiral metal-mesogenic nanosystems “silver - thiocholesterol” and their adsorption properties

ABSTRACT New chiral matrices for thin film chromatography were obtained using hybrid metal-mesogenic nanosystems «silver – thiocholesterol» with different metal to ligand ratio, immobilized on silica gel particles. It was shown, that heteroatomic derivative of cholesterol – thiocholesterol and its composition with small silver nanoparticles formed in the system by the chemical reduction of silver ions possess liquid crystalline cholesteric mesophase. Molar ratio between thiocholesterol ligand molecules (L) and silver (Ag) insignificantly influenced on the size of silver nanoparticles formed in the system: for molar ratio Ag : L = 1:5 the main diameter of nanoparticles was equal to (2,7 ± 0,4) nm, for molar ratio Ag : L = 1:2 – (2, 2 ± 0,4) nm, for molar ratio Ag : L = 1:0,5 – (2,1 ± 0,6) nm. The new chiral matrices for thin film chromatography possess enantioselectivity related to optical isomers of 2,2′-diamino-1,1′-binaphtol (DABN) and trifluoroantranylethanol (TFAE). We have succeeded to select optical isomers of TFAE with selecting factor equal to 1,56.

The Phase-Structural Transitions in Liquid Crystalline Alkoxycyanobiphenyls and The Kinetics of Nitroxides Formation

Abstract The kinetics of photoinduced nitroxides formation has been studied by ESR in mesogenic alkoxycyanobiphenyls 60CB, 70CB, 80CB and their mixtures in temperature range 173-383 K. The nitroxide formation effectively takes place in isotropic, nematic, smectic and solid states of the systems. The reaction kinetics is sensitive to the phase structure on the molecular level.

Formation of Di-Tert-Buthylnitroxide Radicals in Liquid Crystals Studied by ESR

The photolysis of 2-nitroso-2-methylpropane in the nematic liquid crystals (in MBBA and in 4-methoxy-4-hexyloxyphenylbenzoate (MHOPhB) has been studied in isotropic phase, in liquid crystalline phase and in frozen state. MBBA was found to have negative temperature coefficient (E = −3.5 kcal/mole) in liquid crystalline phase. In all the three phases of MHOPhB low temperature dependence of photolysis rate (E = 1.9 kcal/mol) was observed.