Dinuclear Mesogens with Antiferromagnetic Properties



Herein, two new groups of isomeric bimetallic nickel(II) and copper(II) complexes containing pyrazine or pyrimidine rings are synthesized and examined. The complexes exhibit liquid-crystalline columnar phases in a broad temperature range. For the copper(II) complexes, super-exchange coupling between two CuII ions is observed. For the pyrimidine derivative in which the paramagnetic CuII ions are separated only by three atoms, an antiferromagnetic spin alignment is detected. When the distance between CuII ions increases to four atoms in the pyrazine derivative, the magnetic interaction becomes significantly weaker.