Molecular conformation and magnetic behavior of macrocyclic columnar liquid crystals

We report the results of deuterium NMR experiments performed on macrocyclic columnar mesogens. The columnar hexagonal mesophase, aligned in a static magnetic field, exhibits an unusual positive anisotropy of the diamagnetic tensor so that the column axes tend to orient themselves parallel to the direction of the applied field. A different kind of alignment can be detected when, by rotating the sample, the average columnar axes direction is made perpendicular to the field: the molecular cores tend to orient their long axis perpendicular to the field direction. This is the first case, to our knowledge, where a field-induced transversal alignment is observed in columnar mesophases. This peculiar alignment allowed the assignment of the flattened cone conformation to the macrocyclic core in the mesophase. © 1994 American Chemical Society.