Showing papers by "Bachcha Singh published in 2004"

Dielectric relaxation studies in n-(4-octyloxy-2-hydroxybenzylidene)-4-carbethoxyaniline

Abstract: Temperature dependent dielectric spectroscopy of a newly synthesized compound N-(4-octyloxy-2-hydroxybenzylidene)-4-carbethoxyaniline, having a wide temperature range (˜70°C) Smectic A (SmA) phase has been carried out in the frequency range 100 Hz–10 MHz. Dielectric permittivity and loss in the homeotropic ( and ) and planar ( and ) alignments of the molecules have been determined. Relaxation frequencies corresponding to the rotation of the molecules about their short axes have been found to lie below 1 MHz and exhibit Arrhenius behaviour. Relaxation frequencies corresponding to the rotation of the molecules about their long axes are expected to lie above 10 MHz. Dielectric anisotropy (Δe′ = − ) has been found to be negative throughout the range of the SmA phase.

Synthesis, Characterization and Mesomorphic Properties of n-(4-n-Alkoxy-2-Hydroxybenzylidene)-4-Carbethoxyaniline and their Copper Complexes

Abstract: New homologous series of N-(4-n-alkoxy-2-hydroxybenzylidene)-4-carbethoxyaniline, H2n + 1CnOC6H3(OH)C(H) = NC6H4COOC2H5 (n = 6, 8, 10, 12, 16) have been synthesized. These compounds were reacted with copper acetate to get the metal complexes. All these compounds have been characterized by elemental analysis, FT-IR and NMR spectroscopy. Mesomorphic properties of these compounds were studied by differential scanning calorimeter and polarizing microscope. These compounds exhibit wide range enantiotropic SmA phase as confirmed by their typical optical texture under polarizing microscope. In the heating cycle, all the members of the series (hexyl to hexadecyl) show SmA phase in the range of 70 to 115°C and this range is almost independent of the alkoxy chain (except in decyl). All the members show supercooling effect and the range of SmA phase is increased in the cooling cycle in comparison to the corresponding heating cycle. The copper (II) complexes of the series also show enantiotropic SmA phase but at high...