Liquid Crystalline Complexes of Cu(II) and Pd(II) with Ferrocene-Containing Ligands

The new liquid crystalline heteronuclear complexes Cu(II) 1a and Pd(II) 1b with a non-mesogenic ferrocene-containing β-enaminoketone L1 of the formula C5H5FeC5H4-C6H 4-NH-C2H2-(CO)-C6H 4OC12H25, showing monotropic nematic and smectic A phases, are studied. The ortho-palladated Cl-bridged dimeric complex 3 with a non-mesogenic ferrocene-containing Schiffs base L2 of the formula C5H5FeC5H4-C6H 4-N=CH-C6H4OC10H21, forming a stable smectic A phase, has been synthesized. The novel mixed-ligand heteronuclear complexes 4-7 have been obtained by treatment of the ortho-palladated complex 3 with appropriate ligands. Some of the resulting products exhibit the rather low-melting (below 100deg;C) smectic A phases. Structures of the compounds are studied by elemental analysis, 1H and 13C NMR, and ESR spectroscopies

Stripping-voltammetric determination of transition metals using electrodes modified by azacrown compounds

Voltammetric properties of macrocyclic complexes of transition metals are studied by using a carbon-paste electrode modified by diaza-18-crown-6, Cyclam, and their derivatives. A selective stripping-voltammetric procedure is proposed for determining Ni(II) and Co(II) with a carbon-paste electrode modified by Cyclam and its derivatives. To improve the sensitivity and selectivity of analysis, it is suggested that metal ions be preconcentrated at the surface of the modified electrode by using a 0.1 M NaCl solution as a supporting electrolyte with the following recording of voltammograms in the range from -0.3 to 0.8 V in a 0.1 M KOH solution. The detection limits for Ni(II) and Co(II) are 4 × 10-8 and 1.2 × 10-7 M, respectively. © 1996 MAEe Cyrillic signK Hayκa/Interperiodica Publishing

Liquid-crystalline CuII and PdII complexes with nonmesogenic ferrocene-containing β-aminovinyl ketone

New liquid-crystalline heteropolynuclear complexes L2M (M = Cu2+ (2a), Pd2+ (2b)) were synthesized by the reactions of C5H5FeC5H4-C6H4NH-C2H2-(CO)-C6H4OC12H25 (1, LH) with copper(II) and palladium(II) acetates. Compound 2b was found to possess monotropic nematic and smectic phases; 2a exhibits the monotropic nematic phase and a phenomenon of "double melting." The compositions and structures of compounds 1 and 2a,b were established by elemental analysis, 1H and 13C NMR, ESR, and IR spectroscopy

Stripping-voltammetric determination of transition metals using electrodes modified by azacrown compounds

Voltammetric properties of macrocyclic complexes of transition metals are studied by using a carbon-paste electrode modified by diaza-18-crown-6, Cyclam, and their derivatives. A selective stripping-voltammetric procedure is proposed for determining Ni(II) and Co(II) with a carbon-paste electrode modified by Cyclam and its derivatives. To improve the sensitivity and selectivity of analysis, it is suggested that metal ions be preconcentrated at the surface of the modified electrode by using a 0.1 M NaCl solution as a supporting electrolyte with the following recording of voltammograms in the range from -0.3 to 0.8 V in a 0.1 M KOH solution. The detection limits for Ni(II) and Co(II) are 4 × 10-8 and 1.2 × 10-7 M, respectively. © 1996 MAEe Cyrillic signK Hayκa/Interperiodica Publishing

Novel membrane mimetic systems based on amphiphilic oxyethylated calix[4]arene: Aggregative and liquid crystalline behavior

Self-organization of amphiphilic calixarenes oxyethylated at a lower rim has been investigated in water and water-organic solutions. In the range of isotropic solutions three types of structural transitions were indicated by a complex of methods. The first critical point indicated by surface tension, dynamic light scattering and atomic force microscopy methods is probably connected with the formation of " infinite" organized structures (of hundreds nanometers in size) through the open association model. This aggregative phenomenon covers the concentration range below 10-3M. In the case of aqueous calixarene solutions these large aggregates co-exist with small micelle-like particles and undergo a rearrangement with an increase in the concentration. The second structural transition occurs beyond 10-3M. It is revealed in aqueous calixarene solutions by surface tension, spine probe, viscosimetry and dynamic light scattering methods. Small aggregates (~10nm in diameter) are formed in this range through a closed model typical for conventional surfactants. The third transition indicated by viscosimetry and in single case by tensiometry can be connected with an elongation of aggregates. The polarization microscopy and X-ray diffraction studies reveal the anisotropic behavior with the concentration of solutions. Parameters of the existence of liquid crystalline mesophases are found to be influenced by the structure of substituents at both the upper and lower rims, as well as by the nature of solvent. © 2010 Elsevier B.V

Rare-earth-containing magnetic liquid crystals

Rare-earth-containing metallomesogens with 4-alkoxy-N-alkyl-2- hydroxybenzaldimine ligands are reported. The stoichiometry of the complexes is [Ln(LH)3(NO3)3], where Ln is the trivalent rare-earth ion (Y, La, and Pr to Lu, except Pm) and LH is the Schiff base. The Schiff base ligands are in the zwitterionic form and coordinate through the phenolic oxygen only. The three nitrate groups coordinate in a bidentate fashion. The X-ray single- crystal structures of the nonmesogenic homologous complexes [Ln(LH)3(NO3)3], where Ln = Nd(III), Tb(III), and Dy(III) and LH = CH3OC6H3(2-OH)CH=NC4H9, are described. Although the Schiff base ligands do not exhibit a mesophase, the metal complexes do (SmA phase). The mesogenic rare-earth complexes were studied by NMR, IR, EPR, magnetic susceptibility measurements, X-ray diffraction, and molecular modeling. The metal complexes in the mesophase have a very large magnetic anisotropy, so that these magnetic liquid crystals can easily be aligned by an external magnetic field

Monitoring the orientation of rare-earth-doped nanorods for flow shear tomography

Rare-earth phosphors exhibit unique luminescence polarization features originating from the anisotropic symmetry of the emitter ion's chemical environment. However, to take advantage of this peculiar property, it is necessary to control and measure the ensemble orientation of the host particles with a high degree of precision. Here, we show a methodology to obtain the photoluminescence polarization of Eu-doped LaPO4 nano rods assembled in an electrically modulated liquid-crystalline phase. We measure Eu3+ emission spectra for the three main optimal configurations ({\sigma}, {\pi} and {\alpha}, depending on the direction of observation and the polarization axes) and use them as a reference for the nano rod orientation analysis. Based on the fact that flowing nano rods tend to orient along the shear strain profile, we use this orientation analysis to measure the local shear rate in a flowing liquid. The potential of this approach is then demonstrated through tomographic imaging of the shear rate distribution in a microfluidic system.Comment: 8 pages, 3 figures + supplementary files for experimental and numerical method

Liquid Crystalline Complexes of Cu(II) and Pd(II) with Ferrocene-Containing Ligands

The new liquid crystalline heteronuclear complexes Cu(II) 1a and Pd(II) 1b with a non-mesogenic ferrocene-containing β-enaminoketone L1 of the formula C5H5FeC5H4-C6H 4-NH-C2H2-(CO)-C6H 4OC12H25, showing monotropic nematic and smectic A phases, are studied. The ortho-palladated Cl-bridged dimeric complex 3 with a non-mesogenic ferrocene-containing Schiffs base L2 of the formula C5H5FeC5H4-C6H 4-N=CH-C6H4OC10H21, forming a stable smectic A phase, has been synthesized. The novel mixed-ligand heteronuclear complexes 4-7 have been obtained by treatment of the ortho-palladated complex 3 with appropriate ligands. Some of the resulting products exhibit the rather low-melting (below 100deg;C) smectic A phases. Structures of the compounds are studied by elemental analysis, 1H and 13C NMR, and ESR spectroscopies

Liquid Crystalline Complexes of Cu(II) and Pd(II) with Ferrocene-Containing Ligands

The new liquid crystalline heteronuclear complexes Cu(II) 1a and Pd(II) 1b with a non-mesogenic ferrocene-containing β-enaminoketone L1 of the formula C5H5FeC5H4-C6H 4-NH-C2H2-(CO)-C6H 4OC12H25, showing monotropic nematic and smectic A phases, are studied. The ortho-palladated Cl-bridged dimeric complex 3 with a non-mesogenic ferrocene-containing Schiffs base L2 of the formula C5H5FeC5H4-C6H 4-N=CH-C6H4OC10H21, forming a stable smectic A phase, has been synthesized. The novel mixed-ligand heteronuclear complexes 4-7 have been obtained by treatment of the ortho-palladated complex 3 with appropriate ligands. Some of the resulting products exhibit the rather low-melting (below 100deg;C) smectic A phases. Structures of the compounds are studied by elemental analysis, 1H and 13C NMR, and ESR spectroscopies

Stripping-voltammetric determination of transition metals using electrodes modified by azacrown compounds

Voltammetric properties of macrocyclic complexes of transition metals are studied by using a carbon-paste electrode modified by diaza-18-crown-6, Cyclam, and their derivatives. A selective stripping-voltammetric procedure is proposed for determining Ni(II) and Co(II) with a carbon-paste electrode modified by Cyclam and its derivatives. To improve the sensitivity and selectivity of analysis, it is suggested that metal ions be preconcentrated at the surface of the modified electrode by using a 0.1 M NaCl solution as a supporting electrolyte with the following recording of voltammograms in the range from -0.3 to 0.8 V in a 0.1 M KOH solution. The detection limits for Ni(II) and Co(II) are 4 × 10-8 and 1.2 × 10-7 M, respectively. © 1996 MAEe Cyrillic signK Hayκa/Interperiodica Publishing