Vadim A. Timoshenko

Thermal behavior of silver-containing mesogenic cyanobiphenyl films

Abstract Formation of nanostructures in metal-mesogenic co-condensate films have been studied during low temperature codeposition of metal and organic component vapors—long chain alkyl(alkoxy)cyanobiphenyls (CB): C n H 2 n +1 →C n H 2 n +1, where n =5 (5CB), 8 (8CB), and C n H 2 n +1 OC 6 H 5 C 6 H 5 CN, n =8 (8OCB). The existence of low temperature Ag–CB complexes was shown by IR, UV-visible and ESR techniques. Thermal degradation of the complexes by annealing of the samples up to 300 K led to the formation of nanosize (15–30 nm) silver particles incorporated in anisotropic CB-structure and their further aggregation in mesogenic matrices.

Spectroscopic Study of Silver-Containing Mesogenic Cyanobiphenyls in Solid Phase

Abstract Silver-containing mesogenic alkylcyanobiphenils (CB): CnH2n+1-C6H5-C6H5-CN, where n=5 (5 CB), 7 (7 CB), and 8 (8 CB) systems were obtained by low temperature co-condensation of metal and organic component vapours. The formation of low temperature Ag-CB complexes was shown by IR-, UV-visible and ESR techniques. Thermal degradation of the complexes led to the formation of nanosize (15–30) silver particles and their further aggregation in anisotropic matrices.

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.

The ESR-study of Chemical Interactions in triple solid ‘Ag-CCl4-5CB’ co-condensate mesogenic system

ABSTRACT The possibilities of new metal-mesogenic complex formation and their solid phase chemical reactions have been demonstrated using low temperature co-condensation techniques and ESR-spectroscopy for a solid triple system, containing silver, the mesogenic ligand 4-pentyl-4-cyanobiphenyl (5CB) and an alternative electron-acceptor ligand or the third reactive component carbon tetrachloride (CCl4). It was shown by ESR-spectroscopy that the existence of four paramagnetic products were stabilised in the system at low temperatures: silver atom π-complex with two cyanobiphenyl molecules, silver atom σ-complex with cyanobiphenyl molecule stabilised by CCl4 co-ligand, AgCl−CCl3• and silver nanoclusters, formed by silver atom aggregation in the mesogenic matrix. The relative thermal stability of these silver species and their thermal behavior are discussed.

The Esr Study of Complexation and Nanoclusters Growth in Silver-Liquid Crystal System

The ESR spectrum of Ag-5CB (C 5 H 11 -C 6 H 4 -C 6 H 4 -CN) and Ag-5Py (C 5 H 11 -C 5 H 3 N-C 6 H 4 -CN) co-condensate film at 90 K showed two doublet lines due to silver atoms included in ~ -complexes with cyanobiphenyls and wide anisotropic singlet line with g-factor equal to 2.0030, that could be referred to small silver clusters. It was found the integral intensity of doublet lines decreased during the annealing of samples in temperature range 80-200 K due to thermal decomposition of Ag-5CB complex followed by the aggregation of silver atoms.

Thermal- and light-induced nanocluster formation in silver–mesogenic cyanophenyl condensed films

Abstract Thermal- and light-induced formation of nanoclusters has been studied by ESR spectroscopy in silver–mesogenic cyanobiphenyl films obtained via low temperature co-deposition of metal and organic component vapors—long chain alkyl(alkoxy)cyanobiphenyls (CB): C n H 2 n +1 –C 6 H 5 –C 6 H 5 –CN, where n =5 (5CB), 8 (8CB) and C n H 2 n +1 O–C 6 H 5 –C 6 H 5 –CN, n =8 (8OCB). The combination of the results of IR, UV–Vis and ESR spectroscopy of silver–cyanobiphenyl co-condensate films shows the formation of metastable Ag(CB) 2 complexes at 90–200 K. Both thermal degradation of the complexes by annealing of the film samples up to 200–300 K and by light irradiation at lower temperatures lead to the formation of silver nanoclusters and their further aggregation in anisotropic matrix resulted in the production of anisotropic metal–mesogenic nanostructures.