1202.3620 (Dijana Zilic et al.)

Single crystals of DPPH grown from diethyl ether and carbon disulfide
solutions - Crystal structures, IR, EPR and magnetization studies    [PDF]

Dijana Zilic, Damir Pajic, Marijana Juric, Kresimir Molcanov, Boris Rakvin, Pavica Planinic, Kreso Zadro

Single crystals of the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH)
obtained from diethyl ether (ether) and carbon disulfide (CS2) were
characterized by the X-ray diffraction, IR, EPR and SQUID magnetization
techniques. The X-ray structural analysis and IR spectra showed that the DPPH
form crystallized from ether (DPPH1) is solvent free, whereas that one obtained
from CS2 (DPPH2) is a solvate of the composition 4DPPH.CS2. Principal values of
the g-tensor were estimated by the X-band EPR spectroscopy at room and low (10
K) temperatures. Magnetization studies revealed the presence of
antiferromagnetically coupled dimers in both types of crystals. However, the
way of dimerization as well as the strength of exchange couplings are different
in the two DPPH samples, which is in accord with their crystal structures. The
obtained results improved parameters accuracy and enabled better understanding
of properties of DPPH as a standard sample in the EPR spectrometry.

View original: http://arxiv.org/abs/1202.3620