Liquid-Crystalline Properties of 2,5-Bis(4-n-Alkoxybenzoyloxy)-3,6-Dichloro-1,4-Benzoquinones and Their Copper (II) Complexes—Synthesis and Characterization

摘要

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·H₂O where RË­C_mH_2m+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.