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Molecular Crystals and Liquid Crystals, Vol.524, 3-16, 2010
Liquid-Crystalline Properties of 2,5-Bis(4-n-Alkoxybenzoyloxy)-3,6-Dichloro-1,4-Benzoquinones and Their Copper (II) ComplexesSynthesis and Characterization
A new series of 2,5-bis(4-n-alkoxybenzoyloxy)-3,6-dichloro-1,4-benzoquinones, C6Cl2O2(OOCC6H4OR)2 and their copper (II) compounds, C6Cl2O2(OOCC6H4OR)2 Cu(CH3COO)2 center dot H2O where R=CmH2m+1 and m=6,7,8,9,10, 11,12,14, and 16 have been synthesized. The compounds have been characterized by elemental analyses, fourier transform infrared (FTIR) far IR, 1H, and 13C NMR spectra. The UV-Visible, electron spin resonance (ESR), and magnetic susceptibility studies of the copper compounds have also been made. Mesomorphic properties of these compounds were studied by differential scanning calorimetry and polarizing microscopy. The mesomorphic nature of these compounds depends on the alkoxy chain length. The compounds (m=6, 7, 8, 14) exhibit the nematic mesophase. Compound (m=9)shows a nematic mesophase in heating cycle and both a nematic and a smectic A mesophase in the cooling cycle, whereas compound (m=10) shows enantiotropic nematic and smectic A mesophases. Compound (m=11) shows a monotropic smectic A mesophase and compound (m=12) shows an enantiotropic smectic A mesophase, whereas m=16 nonmesomorphic. The copper (II) complexes of these compounds were found to be nonmesogenic.
Keywords:Chloranil based mesogens;copper (II) compounds;monotropic mesogens;nematic mesophase;smectic mesophase