Determination of the <b>g</b> Tensors for the Dominant Stable Radicals in X-Irradiated β-<scp>d</scp>-Fructose Single Crystals

Tarpan, Mihaela Adeluta; Vrielinck, Henk; Cooman, Hendrik De; Callens, Freddy

doi:10.1021/jp9017019

Cited by 8 publications

(16 citation statements)

References 28 publications

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“…For most of the radicals discussed here, the HF tensors were analyzed before the g tensors, which were extracted from EIE measurements and relied on the knowledge of the HF tensors [13,57,63]. It is more instructive, however, to start the discussion with the problem of extracting a g tensor from angular dependent resonance field positions.…”

Section: Example Of Schonland Ambiguity In Data Analysismentioning

confidence: 99%

“…crystals 100% enriched in 13 C for angular dependent EPR and ENDOR studies, but for systems in which the radicals have been thoroughly characterized on crystals with natural C isotopic distribution, powder EPR (if possible complemented with powder ENDOR) measurements may provide unambiguous information [13,81].…”

Section: Semi-empirical Theory: Information Obtained From Hf Interactmentioning

confidence: 99%

“…Two dominant radicals, labeled F1/F2, were found to exhibit quite comparable HF interactions and, based on single molecule DFT calculations, a C2-centered model was proposed for both of them [89,122] (an alternative labeling of the fructose atoms was used in that work). Although Tarpan et al in later work also determined the g tensors of F1/F2 and applied selective 13 C enrichment in fructose powders [13,14,81], the identity of these main stable radicals remains uncertain. Using the most advanced DFT methods presently available, a C3(-H) model, featuring a neighboring carbonyl group and possibly also ring opening, seems the most plausible.…”

Section: Fructosementioning

confidence: 99%

“…This resulted primarily from a detailed comparison of proton hyperfine (HF) interactions, determined from single crystal electron nuclear double resonance (ENDOR) experiments, with the results of highlevel density functional theory (DFT) calculations. The situation for other sugars and related carbohydrates is similar: although stable radical production has been reported for several decades, reliable identifications of their structures are in gen-eral much more recent [10][11][12] or has to date not yet been achieved [13,14]. A first important reason for this is that stable radical structures in organic solids very often differ substantially from the pristine molecule (crystal) structures and are the result of a complex reaction chain after the initial ionization or electron capture process [15].…”

Section: Introduction and Motivation Of The Studymentioning

confidence: 99%

“…These were used as purchased, without further refinement. In the case of fructose, selectively 13 C and 2 H labeled carbohydrate powders (Sigma Aldrich, Omicron Chemicals) were included in the study.…”

Section: Introduction and Motivation Of The Studymentioning

confidence: 99%

See 4 more Smart Citations

Radiation Chemistry of Solid-State Carbohydrates Using EMR

Vrielinck

Cooman

Callens

et al. 2014

Applications of EPR in Radiation Research

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We review our research of the past decade towards identification of radiation-induced radicals in solid state sugars and sugar phosphates. Detailed models of the radical structures are obtained by combining EPR and ENDOR experiments with DFT calculations of g and proton HF tensors, with agreement in their anisotropy serving as most important criterion. Symmetry-related and Schonland ambiguities, which may hamper such identification, are reviewed. Thermally induced transformations of initial radiation damage into more stable radicals can also be monitored in the EPR (and ENDOR) experiments and in principle provide information on stable radical formation mechanisms. Thermal annealing experiments reveal, however, that radical recombination and/or diamagnetic radiation damage is also quite important. Analysis strategies are illustrated with research on sucrose. Results on dipotassium glucose-1-phosphate and trehalose dihydrate, fructose and sorbose are also briefly discussed. Our study demonstrates that radiation damage is strongly regio-selective and that certain general principles govern the stable radical formation.

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Section: Example Of Schonland Ambiguity In Data Analysismentioning

confidence: 99%

Section: Semi-empirical Theory: Information Obtained From Hf Interactmentioning

confidence: 99%

Section: Fructosementioning

confidence: 99%

Section: Introduction and Motivation Of The Studymentioning

confidence: 99%

Section: Introduction and Motivation Of The Studymentioning

confidence: 99%

See 3 more Smart Citations

Radiation Chemistry of Solid-State Carbohydrates Using EMR

Vrielinck

Cooman

Callens

et al. 2014

Applications of EPR in Radiation Research

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On the identity of the last known stable radical in X-irradiated sucrose

Kusakovskij

Cooman

Sagstuen

et al. 2017

Chemical Physics Letters

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Identification of radiation-induced radicals in relatively simple molecules is a prerequisite for the understanding of reaction pathways of the radiation chemistry of complex systems. Sucrose presents an additional practical interest as a versatile radiation dosimetric system. In this work, we present a periodic density functional theory study aimed to identify the fourth stable radical species in this carbohydrate. The proposed model is a fragment suspended in the lattice by hydrogen bonds with an unpaired electron at the original C5' carbon of the fructose unit. It requires a double scission of the ring accompanied by substantial chemical and geometric reorganization.

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Electron Magnetic Resonance and Density Functional Theory Study of Room Temperature X-Irradiated β-d-Fructose Single Crystals

et al. 2010

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Stable free radical formation in fructose single crystals X-irradiated at room temperature was investigated using Q-band electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR), and ENDOR induced EPR (EIE) techniques. ENDOR angular variations in the three main crystallographic planes allowed an unambiguous determination of 12 proton HFC tensors. From the EIE studies, these hyperfine interactions were assigned to six different radical species, labeled F1-F6. Two of the radicals (F1 and F2) were studied previously by Vanhaelewyn et al. [Vanhaelewyn, G. C. A. M.; Pauwels, E.; Callens, F. J.; Waroquier, M.; Sagstuen, E.; Matthys, P. J. Phys. Chem. A 2006, 110, 2147.] and Tarpan et al. [Tarpan, M. A.; Vrielinck, H.; De Cooman, H.; Callens, F. J. J. Phys. Chem. A 2009, 113, 7994.]. The other four radicals are reported here for the first time and periodic density functional theory (DFT) calculations were used to aid their structural identification. For the radical F3 a C3 carbon centered radical with a carbonyl group at the C4 position is proposed. The close similarity in HFC tensors suggests that F4 and F5 originate from the same type of radical stabilized in two slightly different conformations. For these radicals a C2 carbon centered radical model with a carbonyl group situated at the C3 position is proposed. A rather exotic C2 centered radical model is proposed for F6.

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Determination of the g Tensors for the Dominant Stable Radicals in X-Irradiated β-d-Fructose Single Crystals

Cited by 8 publications

References 28 publications

Radiation Chemistry of Solid-State Carbohydrates Using EMR

Radiation Chemistry of Solid-State Carbohydrates Using EMR

On the identity of the last known stable radical in X-irradiated sucrose

Electron Magnetic Resonance and Density Functional Theory Study of Room Temperature X-Irradiated β-d-Fructose Single Crystals

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