ENDOR and HYSCORE analysis and DFT-assisted identification of the third major stable radical in sucrose single crystals X-irradiated at room temperature

wim — Mon, 03 Oct 2011 10:17:30 +0000

H. De Cooman, E. Pauwels, H. Vrielinck, E. Sagstuen, S. Van Doorslaer, F. Callens, M. Waroquier

Physical Chemistry Chemical Physics (PCCP)

11 (7), 1105-1114

2009

Abstract

Recently, the chemical structure of two of the three major stable radicals (T2 and T3) produced in sucrose single crystals by X-irradiation at room temperature was identified by comparing Density Functional Theory (DFT) calculations of Electron Magnetic Resonance parameters with experimental results [H. De Cooman, E. Pauwels, H. Vrielinck, E. Sagstuen, F. Callens and M. Waroquier, J. Phys. Chem. B, 2008, 112, 7298–7307]. Ambiguities concerning an unusual proton hyperfine coupling (HFC) tensor prevented the identification of the third major stable radical (T1). In the present work, experimental results of continuous wave Electron Nuclear Double Resonance experiments on sucrose single crystals and Hyperfine Sublevel Correlation Spectroscopy experiments on sucrose powder are presented that lift these remaining ambiguities. Using the final set of experimental HFC tensors and employing advanced DFT calculations, the chemical structure of the T1 radical is established: an allylic-type radical with approximately half of the spin density localised on the C2′ carbon of the fructose unit, involving glycosidic bond cleavage at the fructose side and a concerted formation of a carbonyl group at the C1′ carbon. The electronic structure of the T1 radical is discussed in more detail by means of additional DFT calculations, yielding a better understanding of the peculiar properties of the unusual proton HFC tensor mentioned above.

DOI

http://dx.doi.org/10.1039/B816641B

Private attachment

09 phys. chem. chem. phys 11(7)1105 de cooman.pdf

Schonland ambiguity in the determination of A tensors from angular dependence of ENDOR spectra: application to the stable T1 radical in sucrose single crystals

wim — Tue, 18 Oct 2011 07:31:32 +0000

H. De Cooman, H. Vrielinck, E. Pauwels, M. Waroquier, S. Van Doorslaer, F. Callens

Poster

Conference / event / venue

Benelux EPR 2008

Leuven (Heverlee), Belgium

Friday, 16 May, 2008

Center for Molecular Modeling - S. Van Doorslaer

ENDOR and HYSCORE analysis and DFT-assisted identification of the third major stable radical in sucrose single crystals X-irradiated at room temperature

Abstract

DOI

Private attachment

Schonland ambiguity in the determination of A tensors from angular dependence of ENDOR spectra: application to the stable T1 radical in sucrose single crystals

Conference / event / venue