FORMATION OF DISORDERED HEXAGONAL ARRANGEMENTS IN BIS(BETA,DELTA-TRIKETONATO)COPPER(II) COMPLEXES

Two homologous series of henyl)-3-(3,4,5-trialkoxyphenyl)propane-1,3-d iones and 1-(2-hydroxyphenyl)-3-(3,3, 5-trialkoxyphenyl)propane-1,3-di ones were prepared by base-catalysed rearrangement of 4-alkoxy-2-(3,4, 5-trialkoxybenzoyloxy)ac and 2-(3,4,5-trialkoxybenzoyloxy)acetophenone s respectively. The reaction of these beta,delta-triketones with coppe r(Ir) acetate gave liquid-crystalline dicopper complexes, bis[1-(4-alk oxy-2-hydroxyphenyl)-3-(3,4, 5-trialkoxyphenyl)propane-1,3-dionato]- a nd bis[1-(2-hydroxyphenyl)-3-(3,4,5-trialkoxyphenyl) 1,3-dionato]-copp er(II). These copper complexes exhibit disordered hexagonal columnar ( D-bd,,) mesophases which were identified by DSC analysis and polarized optical microscopy, and were also confirmed by X-ray powder diffracti on. The variable-temperature EPR spectra were also studied.