Orienting effect of magnetic field on some copper metallomesogen powders: single crystal-like alignment

EPR spectra of some powdered metallomesogens cooled in magnetic fields of 0.3/1.2 T showed at 77 K, a distinctive change in line shape from that at room temperature (RT), indicating appearance of field-induced alignment. However, conformation and length of the chains have to match the packing requirement. Thus, the closed packed C7Cu shows 100% alignment, whereas C11OCu/C9OCu show only partial alignment. These have a tendency to self-assemble into random domains in the polycrystalline solid at RT, which tend to orient themselves along the magnetic field at 77 K. This is the first report of a dry paramagnetic powder, showing a single crystal-like alignment along H at the high temperature of 77 K. (C) 2000 Elsevier Science B.V. All rights reserved.