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Identification of radiation‐induced radical structure in azocalix[4]arene: an EPR study
Author(s) -
Usta Keziban,
Ozen Karakus Ozlem,
Usta Ayhan,
Deligoz Hasalettin
Publication year - 2013
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.3998
Subject(s) - chemistry , electron paramagnetic resonance , hyperfine structure , single crystal , radical , crystallography , spectral line , irradiation , analytical chemistry (journal) , nuclear magnetic resonance , organic chemistry , physics , astronomy , nuclear physics , quantum mechanics
A macrocyclic azocalix[4]arene (1) based ester derivative was synthesized. The single crystals of azocalix[4]arene were produced by slow evaporation of concentrated ethyl acetate solutions. These single crystals were exposed to 60 Co gamma rays with a dose rate of 0.980 kGy h ‐1 for 48 and 72 h to produce a stable free radical. Electron paramagnetic resonance (EPR) measurements were performed in three mutually perpendicular planes of the single crystal in the magnetic field, in addition, temperature dependence of the EPR signal was studied between 120 K and 450 K. The spectra were found to be temperature and angular dependent. Analysis based on the spectra recorded showed that a free radical was formed by fission of a C–H bond. This radical is described as • C a HC b H 3 The averages of the principal values of the hyperfine parameters and g ‐factor are: g = 2.0034 , A Ha = 1.28 mT , A H1=H2 = 1.00 mT , and A H3 = 0.49 m T . Copyright © 2013 John Wiley & Sons, Ltd.