By V. Padmini Tamilenthi
Series of metal (Cu) complexes with bidentate Schiff-bases viz. N-(4-n-alkyloxy salicylidene)-4-n-alkoxyanilines, obtained by the 1:1 condensation of 4-n-alkoxy salicylaldehyde and 4-n-dodecyloxyaniline, 4-n-hexyloxyaniline, 4-n-octyloxyaniline, 4-n-decyloxyaniline, 4-n-dodecyloxyaniline, 4-n-tetradecyloxyaniline and 4-n-hexadecyloxy aniline, have been prepared and characterized. The synthesis of the ligands N- (4-n-hexyloxysalicylidene)-4-n-alkyloxyanilines as well as the complexes and characterization by thermal microscopy for mesomorphism are presented. The ligands are found to exhibit interesting smectic phases (mostly tilted phases in addition to nematic phases and polymorphism, while the complexes showed-orthogonal smectic A, and tilted smectic phases. The mesomporphic range as well as the polymorphism decreases with an increase in chain length. The complexation of these ligands with Cu(II) salt leads to thermally stable metallomesogens possessing larger mesomorphic range and reduced number of mesomorphic phases.
Key Words : Copper complexes, Schiff bases, liquid crystals, metallomesogens, mesomorphism.
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