MOLECULAR-CONFORMATION AND MAGNETIC-BEHAVIOR OF MACROCYCLIC COLUMNAR LIQUID-CRYSTALS

We report the results of deuterium NMR experiments performed on macroc yclic columnar mesogens. The columnar hexagonal mesophase, aligned in a static magnetic field, exhibits an unusual positive anisotropy of th e diamagnetic tenser so that the column axes tend to orient themselves parallel to the direction of the applied field. A different kind of a lignment can be detected when, by rotating the sample, the average col umnar axes direction is made perpendicular to the field: the molecular cores tend to orient their long axis perpendicular to the field direc tion. This is the first case, to our knowledge, where a field-induced transversal alignment is observed in columnar mesophases. This peculia r alignment allowed the assignment of the flattened cone conformation to the macrocyclic core in the mesophase.