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Combined Electron Magnetic Resonance and Density Functional Theory Study of Thermally Induced Free Radical Reactions in Fructose and Trehalose Single Crystals

Mihaela Adeluta Tarpan UGent, Hendrik De Cooman UGent, Ewald Pauwels UGent, Michel Waroquier UGent, E. Sagstuen and Freddy Callens UGent (2009) Abstracts European conference on the spectroscopy of biological molecules.
abstract
Both as models for studying the effects of radiation on the DNA sugar unit and for applications in dosimetry, radiation-induced defects in sugars have in the past few decades been intensively studied with electron magnetic resonance (EMR) techniques, often with considerable success. However, irradiation generally gives rise to a large variety of free radicals, resulting in strongly composite Electron Paramagnetic Resonance (EPR) spectra. This complexity makes studying them quite a challenge. Despite considerable efforts, little is still known about the identity of the radicals and even less about the radical formation and transformation processes and mechanisms. At room temperature (RT) the primary radiation products, which may be stabilized upon low temperature (LT) irradiation, transform into stable radicals via multistep reaction mechanisms. While the species formed at LT are expected to be formed by simple processes, the molecular structure and geometry of the stable radicals may differ considerably from that of the intact molecule even in the solid state (crystals). Studying the intermediate radicals in the reactions occurring after LT irradiation helps elucidating the formation and identity of the stable radicals. The structural identification of these radicals is in most cases the result of a combination of EPR, Electron Nuclear Double Resonance (ENDOR) and ENDOR Induced EPR (EIE) experiments and advanced quantum chemistry calculations based on Density Functional Theory (DFT). In the present study a summary is given of the experimental EMR results obtained so far on radiation-induced radicals at different temperatures in fructose and trehalose single crystals and powders. “In situ” X-irradiation at LT (10 K) without annealing, leads to spectra strongly different from those observed after RT irradiation and offers the possibility to study and characterize the primary radiation products [1]. Performing EMR measurements on samples irradiated and/or annealed at various temperatures between LT (10 K or 77 K) and RT allows us to study the intermediate products, and such studies therefore have the potential to devise mechanistic links between the primary radicals and the stable radicals. In the present work, our own measurements are compared with results reported in the EMR literature. An outline at future experimental (EMR) and theoretical (DFT) research will also be given.
Please use this url to cite or link to this publication:
author
organization
year
type
conference
publication status
published
subject
in
Abstracts European conference on the spectroscopy of biological molecules
conference name
European conference on the spectroscopy of biological molecules
conference location
Palermo, Italy
conference start
2009-08-28
conference end
2009-09-02
project
HPC-UGent: the central High Performance Computing infrastructure of Ghent University
language
English
UGent publication?
yes
classification
C3
id
765763
handle
http://hdl.handle.net/1854/LU-765763
date created
2009-10-20 10:31:20
date last changed
2013-09-17 10:50:14
@inproceedings{765763,
  abstract     = {Both as models for studying the effects of radiation on the DNA sugar unit and for applications in dosimetry, radiation-induced defects in sugars have in the past few decades been intensively studied with electron magnetic resonance (EMR) techniques, often with considerable success. However, irradiation generally gives rise to a large variety of free radicals, resulting in strongly composite Electron Paramagnetic Resonance (EPR) spectra. This complexity makes studying them quite a challenge. Despite considerable efforts, little is still known about the identity of the radicals and even less about the radical formation and transformation processes and mechanisms. At room temperature (RT) the primary radiation products, which may be stabilized upon low temperature (LT) irradiation, transform into stable radicals via multistep reaction mechanisms. While the species formed at LT are expected to be formed by simple processes, the molecular structure and geometry of the stable radicals may differ considerably from that of the intact molecule even in the solid state (crystals). Studying the intermediate radicals in the reactions occurring after LT irradiation helps elucidating the formation and identity of the stable radicals. The structural identification of these radicals is in most cases the result of a combination of EPR, Electron Nuclear Double Resonance (ENDOR) and ENDOR Induced EPR (EIE) experiments and advanced quantum chemistry calculations based on Density Functional Theory (DFT). In the present study a summary is given of the experimental EMR results obtained so far on radiation-induced radicals at different temperatures in fructose and trehalose single crystals and powders. {\textquotedblleft}In situ{\textquotedblright} X-irradiation at LT (10 K) without annealing, leads to spectra strongly different from those observed after RT irradiation and offers the possibility to study and characterize the primary radiation products [1]. Performing EMR measurements on samples irradiated and/or annealed at various temperatures between LT (10 K or 77 K) and RT allows us to study the intermediate products, and such studies therefore have the potential to devise mechanistic links between the primary radicals and the stable radicals. In the present work, our own measurements are compared with results reported in the EMR literature. An outline at future experimental (EMR) and theoretical (DFT) research will also be given.},
  author       = {Tarpan, Mihaela Adeluta and De Cooman, Hendrik and Pauwels, Ewald and Waroquier, Michel and Sagstuen, E. and Callens, Freddy},
  booktitle    = {Abstracts European conference on the spectroscopy of biological molecules},
  language     = {eng},
  location     = {Palermo, Italy},
  title        = {Combined Electron Magnetic Resonance and Density Functional Theory Study of Thermally Induced Free Radical Reactions in Fructose and Trehalose Single Crystals},
  year         = {2009},
}

Chicago
Tarpan, Mihaela Adeluta, Hendrik De Cooman, Ewald Pauwels, Michel Waroquier, E. Sagstuen, and Freddy Callens. 2009. “Combined Electron Magnetic Resonance and Density Functional Theory Study of Thermally Induced Free Radical Reactions in Fructose and Trehalose Single Crystals.” In Abstracts European Conference on the Spectroscopy of Biological Molecules.
APA
Tarpan, M. A., De Cooman, H., Pauwels, E., Waroquier, M., Sagstuen, E., & Callens, F. (2009). Combined Electron Magnetic Resonance and Density Functional Theory Study of Thermally Induced Free Radical Reactions in Fructose and Trehalose Single Crystals. Abstracts European conference on the spectroscopy of biological molecules. Presented at the European conference on the spectroscopy of biological molecules.
Vancouver
1.
Tarpan MA, De Cooman H, Pauwels E, Waroquier M, Sagstuen E, Callens F. Combined Electron Magnetic Resonance and Density Functional Theory Study of Thermally Induced Free Radical Reactions in Fructose and Trehalose Single Crystals. Abstracts European conference on the spectroscopy of biological molecules. 2009.
MLA
Tarpan, Mihaela Adeluta, Hendrik De Cooman, Ewald Pauwels, et al. “Combined Electron Magnetic Resonance and Density Functional Theory Study of Thermally Induced Free Radical Reactions in Fructose and Trehalose Single Crystals.” Abstracts European Conference on the Spectroscopy of Biological Molecules. 2009. Print.