PERSISTENCE OF SHORT-RANGE ORDER IN THE FLUID PHASES OF A MESOGEN COPPER COMPLEX STUDIED BY EPR

The synthesis and thermal characterization of a new copper complex, (4 -n-pentoxyphenyl)-4-n-decyloxysalicylaldiminate] Cu(II), having mesomo rphic properties is given. The EPR spectrum of this material has been measured for its different phases as a function of temperature. The re sults are compared with those for two other Cu(II) compounds, bis[4-n- decyloxysalicylate] Cu[II) and bis[N-(n-pentyl)-4-n-decyloxysalicylald iminate] Cu(II) which have a related molecular structure, but are not mesomorphic. The influence on the spectra of exchange interactions in all the phases, as well as the molecular motion in the fluid phases is discussed, and it is concluded that the exchange interactions are not destroyed by the molecular motion. These facts suggest that molecular motion in the high temperature phases takes places whilst keeping a s hort range order, resulting in a locally correlated motion.