1,721,121 research outputs found
Recent contributions of EPR to nitrone and nitroxide chemistry
No full textThe present contribution provides an overview of the latest research studies in which
Nitrones and Nitroxides are involved in the applications of Electron Paramagnetic
Resonance Spectroscopy (EPR) in different fields. Due to the free radical nature of
Nitroxides (Aminoxyls), their use in EPR investigations is rather straightforward, while for
Nitrones (N-oxides) it relies instead on their use as ‘‘radical scavengers’’, and/or by their
use in the EPR Spin Trapping technique. Since the chemistry of both Nitrones and
Nitroxides have been extensively described elsewhere, this contribution would only represent
an update on some of their most recent application involving EPR spectroscopy
Unusually Persistent Hydroxyl Spin Adducts
No full textComunicazione Scientifica al Regional Congress of the Italian Chemical Society “TUMA 2008”, L’Aquila (Italy
Features of some Aromatic Heterocyclic Nitrones and Nitroxides
No full textInvited keynote oral contributio
A Multi-Step procedure for evaluating the EPR parameters of Indolinonic Aromatic Aminoxyls: a combined DFT and spectroscopic study
No full textA DFT study on indolinonic aromatic aminoxyls has been carried out at different levels of theory. The comparison with previous
experimental data from ENDOR, X-rays and PND (polarized neutron diffraction) techniques confirms that such a computational
approach represents an important aid for understanding the properties of this class of aminoxyls such as hyperfine coupling constants
(hfcc), isotropic g-factors, spin density distributions and geometries. At first, a model compound was studied with different model chemistries;
B1LYP, B3LYP and PBE0 hybrid functionals were employed in conjunction with various medium to large size basis sets. The
study outlines that none of the model chemistries considered is able to correctly describe the EPR features of these radicals by itself.
For this reason, by taking into account a compromise between accuracy and computational cost, a multi-step procedure was checked
over a homogeneous series of indolinonic aminoxyls and then proposed
Combining DFT with Epr Spin Trapping
No full textComunicazione Scientifica al 2nd TheTIS Workshop - Theoretical Tools for In-silico Spectroscopy - Pisa (Italy
OH Radical Trapping with Benzoxazine nitrones: a combined computational and spectroscopic study.
Full text linkThe hydroxyl radical addition onto 3-aryl-2H-benzo[1,4]oxazin-4-oxides spin traps yielded very persistent nitroxides. Their EPR spectra showed unusually large splitting due to the trapped OH proton, whose assignment has been possible by means of the isotope exchange technique. A proper DFT study revealed isomeric molecular geometries with possible intramolecular hydrogen bonds (IHB) forming 5- and/or 6-membered rings, allowing to be envisioned relationships between EPR hyperfine coupling constants (h.f.c.c.) and IHB strengths
DFT calculations as a powerful tool for ESR spin trapping experiments
No full textA combined electron spin resonance (ESR) and density functional theory study has been carried out to obtain deeper insight in the
reaction mechanism of the photorearrangement of 3‐hydroxyindolic nitrones. Also, in this case, the combination of these
techniques constitutes a powerful tool when discriminating between different reaction pathways. In particular, density functional
theory calculations played an important role for unraveling the overlapping of signals coming from different species in the ESR
spin trapping experiments. In the present study, the computed energies and the corresponding ESR parameters of each possible
isomer hypothesized have been considered, taking also into account their different possibilities of intramolecular H‐bond
formation. However, the results obtained indicate that the possibility of intramolecular H‐bonding did not play a determinant role
in this case
Thermal stability of a new class of benzoxazine nitroxides
No full textComunicazione Scientifica al 7th Meeting of the European Federation of EPR Groups, Antwerp (Belgium
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