Journal of Physical Chemistry B, Vol.111, No.32, 9492-9495, 2007
Magnetic orientation of 1,3,5-triphenyl-6-oxoverdazyl radical crystals
The magnetic orientation has been studied for paramagnetic organic radical crystals 1,3,5-triphenyl-6-oxoverdazyl and 1,5-di-p-tolyl-3-phenyl-6-oxoverdazyl in magnetic fields of 2-80 kOe at temperatures of 77-343 K. The X-ray diffraction measurement has revealed that the crystals are oriented with the crystallographic c axis perpendicular to the field. The anisotropic diamagnetic susceptibility arising from the benzene rings has been estimated for the crystals along the principal magnetic chi(1), chi(2), and chi(3) axes. (The chi(1) axis is at a small angle to the a axis in the monoclinic ac plane, and the chi(3) axis is along the b axis.) Since the paramagnetic susceptibility originating from the verdazyl ring is isotropic (though a large absolute value), it is shown that the magnetic orientation occurs by the anisotropy of the diamagnetic susceptibility in the crystals. The diamagnetic susceptibility is found to have a relation of chi(2) < chi(1) < chi(3) < 0.