DYNAMICS AND MOLECULAR ORDER OF THE LIQUID-CRYSTALLINE COMPLEXES OF 5-OCTADECYLOXYISOPHTHALIC ACID AND CYCLIC OLIGO-AMINES, INVESTIGATED BYH-2 NMR-SPECTROSCOPY

Complexes of 5-octadecyloxyisophthalic acid with piperazine, 1,4,7-tri azacyclononane and 1,4,7,10-hexaazacyclooctadecane were selectively de uterated in various positions, and investigated with variable-temperat ure solid-state H-2 n.m.r. spectroscopy All systems form stable, enant iotropic liquid-crystalline phases at high temperature , and the dynam ics in these phases can be described by a single motional model. This model involves fast rotation around the director coupled with a rapid phenyl flip. Macroscopically oriented liquid-crystalline phases with t he director parallel to the magnetic field are found on cooling in a m agnetic field of 7 I for the piperazine complexes, but only partial ma croscopic order was achieved for the complexes with 1,4,7,10-hexaazacy clooctadecane and 1,4,7-triazacyclononane under these conditions, and also for the former in a magnetic field of 11 T. In contrast to the pu re acid C(18)ISA, the stability of the phases is determined by the hyd rogen/ionic bonds between the acid and the bases, and not by the alkyl -alkyl interactions.