Y. Ceylan et al. / Journal of Molecular Structure 1050 (2013) 69–72
71
Table 1
ments were performed in the temperature range of 120–450 K. It
was observed that the shapes and intensities of the lines in the
spectra changed along with temperature (Fig. 2). The obtained re-
sults may clarify that at lower temperatures free electrons are
localized on the chlorine atom, but as the temperature increases,
the free electron is delocalized between the chlorine and hydrogen
atoms.
The ESR parameters of free radicals produced by c
-irradiation on 4,40-bis(chloroace-
tyl)diphenylether. The error for all calculated g-values is estimated as 0.0005 and for
hyperfine splittings is 0.05 mT.
Radical
Hyperfine splittings Spin density g-Values
aCl ¼ 1:263 mT
k1
aHa ¼ 1:486 mT
aHb ¼ 0:637 mT
0.53
0.23
2.0115
From the analysis of the spectra, it was understood that the dis-
tance between the lines in the spectra were different. We inferred
from this result that two types of radicals were formed under gam-
ma-rays. After the conduct of an in-depth analysis on the molecu-
lar structure and the spectra recorded, it was understood that both
of these radical structures were identical, but the ESR parameters
of the radicals were different and unpaired electron was produced
by removing one of the paired electrons on chlorine atoms. Owing
to the chlorine atom, the spectrum was split to 1:1:1:1 intensity
ratios; then each line was split to 1:1 intensity ratio due to each
hydrogen atom labeled as a and b which are magnetically non-
equivalent. The interaction of the sample with gamma rays was
attributed as shown in Fig. 3 and the radicals were labeled RI
and RII (Fig. 3b and c).
aCl ¼ 0:905 mT
k2
aHx ¼ 0:615 mT
aHy ¼ 0:391 mT
0.22
0.14
2.0383
The hyperfine coupling values, g-constants and spin densities of
the radicals were obtained from experimental spectra as shown in
Table 1.
Electron spin density (
q) of the proton can be calculated by
means of Mc Connell equality (a = Q
q
). Here Q is the resonance
multiplier. For the hydrogen atom, QH is given 2.8 mT [9]. Table 1
indicates that unpaired electron spends a large portion of its time
on hydrogen atom. Calculated hyperfine couplings and g-values
were verified by computer simulation. There is a perfect match be-
tween the experimental spectra and computer simulation as
shown in Fig. 4.
The measurements were performed at regular intervals in three
days. From the obtained results, it was understood that produced
radical structures on 4,40-bis(chloroacetyl)diphenylether were
stable.
Fig. 4. The ESR spectrum of a c
-irradiated 4,40-bis(chloroacetyl)diphenylether (a)
and the simulation of the spectrum for RI + RII (b).
108–109.5]. The synthesis of the 4,40-bis(chloroacetyl)diphenylether
is shown in Fig. 1.
4. Conclusion
The investigation showed that non-radiated polycrystalline
sample did not have a radical structure. The ESR signals were re-
corded from the sample irradiated for 72 h. The ESR spectra analy-
sis indicated the formation of two identical radicals on irradiated
4,40-bis(chloroacetyl)diphenylether polycrystal sample. From the
analysis of recorded spectra, it was determined that the produced
radical structures on 4,40-bis(chloroacetyl)diphenylether were
stable.
2.2. Crystallization
4,40-Bis(chloroacetyl)diphenylether was prepared according to
the literature methods [14] from chloroacetylchloride and diphen-
ylether in the presence of AlCl3 as catalyst in a Friedel–Crafts
reaction.
2.3. ESR measurement
Acknowledgements
In the study, the sample used was polycrystal and in solid form
and the grain size of crystals was less than 0.05 mm. The polycrys-
tal sample was irradiated for 72 h by 60Co
c-ray source with dose
This study was partially supported by the Scientific Research
Projects Coordination centers of Selcuk and Akdeniz Universities.
Konya, Antalya/Turkey.
speed of 0.981 kGy/h. ESR spectra were recorded using Bruker
EMX 081 spectrometer (X-Band, Germany). The spectrometer
was set as follows: microwave power was 5 mW, modulation fre-
quency of magnetic field was 100 kHz, and modulation amplitude
was 0.2 mT (Tesla), and microwave–frequency was 9.390 GHz. The
high and low temperature measurements were performed be-
tween 120 K and 450 K using temperature control unit of the
spectrometer.
References
[4] World Health Organization (WHO), Environmental Health Criteria 162 (1994):
Brominated Diphenyl Ethers.
3. Results and discussion
ESR signals were not observed on non-irradiated 4,40-bis(chlo-
roacetyl)diphenylether. However, the ESR spectra were recorded
from the polycrystalline sample irradiated for 72 h. The measure-