New mononuclear cyclopalladated liquid-crystalline materials whose molecular structure consists of two different thermotropic ligands, namely, 4,4'-bis(hexyloxy)azoxybenzene and N-(4-(dodecyloxy)-salicylidene)-4'-n-CnH2n+1-aniline (n = 0, 1-4, 6, 8), connected by a palladium atom, have been prepared. These lateral-lateral fused mesogens, obtained as mixtures of N,N-cis and N,N-trans isomers (about 1:5 ratio), display good thermal stability and mesomorphic properties which depend on the length of the n-CnH2n+1 chain: monotropic nematic and/or smectic A (n = 0, 2, 4) and enantiotropic nematic (n = 1), nematic and smectic (n = 3), and smectic A (n = 6, 8). Contrarily, the clearing points for n = 1-4, 6, and 8 belong in a very narrow range: 143 +/- 3-degrees-C. Preliminary X-ray investigations in the solid and smectic phases show two different periodicities (nearly 45 and 28 angstrom for n = 0, 1-4; 25 and 29 angstrom for n = 6, 8) thus suggesting a peculiar molecular packing.

TRANSITION-METALS COMPLEXED TO ORDERED MESOPHASES - SYNTHESIS AND MESOMORPHIC PROPERTIES OF CYCLOPALLADATED 4,4'-BIS(HEXYLOXY)AZOXYBENZENE COMPLEXED TO NORMAL-(4-(DODECYLOXY)SALICYLIDENE)-4'-ALKYLANILINES

BARTOLINO, Roberto
1992

Abstract

New mononuclear cyclopalladated liquid-crystalline materials whose molecular structure consists of two different thermotropic ligands, namely, 4,4'-bis(hexyloxy)azoxybenzene and N-(4-(dodecyloxy)-salicylidene)-4'-n-CnH2n+1-aniline (n = 0, 1-4, 6, 8), connected by a palladium atom, have been prepared. These lateral-lateral fused mesogens, obtained as mixtures of N,N-cis and N,N-trans isomers (about 1:5 ratio), display good thermal stability and mesomorphic properties which depend on the length of the n-CnH2n+1 chain: monotropic nematic and/or smectic A (n = 0, 2, 4) and enantiotropic nematic (n = 1), nematic and smectic (n = 3), and smectic A (n = 6, 8). Contrarily, the clearing points for n = 1-4, 6, and 8 belong in a very narrow range: 143 +/- 3-degrees-C. Preliminary X-ray investigations in the solid and smectic phases show two different periodicities (nearly 45 and 28 angstrom for n = 0, 1-4; 25 and 29 angstrom for n = 6, 8) thus suggesting a peculiar molecular packing.
LIQUID-CRYSTALS; COPPER(II), DERIVATIVES; HOMOLOGOUS SERIES
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11770/134113
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