DFT calculations as a powerful tool for ESR spin trapping experiments.

A 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. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]