caa a22 4500 605546274 CHVBK 20210128100939.0 cr unu---uuuuu 210128e20151101xx s 000 0 eng 10.1007/s00723-015-0732-x doi (NATIONALLICENCE)springer-10.1007/s00723-015-0732-x Neutral Radicals in the Reaction of β-Carotene with NO2 and NO: Computational Study and Simulation of the EPR Spectra [Elektronische Daten] [Sara Mendiara, Luis Perissinotti] In our previous paper, the electron paramagnetic resonance (EPR) spectroscopy was applied to investigate the reaction of β-carotene with nitrogen dioxide and nitric oxide both in pure dioxane and dioxane/water solvent. In the present paper, the intermediates proposed in that reaction, the β-carotene neutral radicals and the cyclic nitroxide radicals, were studied. For that purpose, the density functional theory level was applied, using the unrestricted local spin density approximation (ULSDA) and unrestricted Becke-style 3-parameter with the Lee-Yang-Parr correlation functional (UB3LYP) and 6-31G and 6-31G(d) basis sets. The geometries, total energies and the isotropic hyperfine coupling constants (hfccs) of the intermediates with 1H and 14N nuclei were calculated. The EPR experimental peak-to-peak value of the triplet radical-type signal, measured in pure dioxane, was 12.0 Gauss (1.20mT). The method UB3LYP/6-31G(d), with d orbital functions, provided the most suitable value of 11.7 Gauss (1.17 mT) for the nitrogen hfcc of the intermediate cyclic nitroxide named: P 41(nitroxide). However, the method ULSDA/6-31G provided a value of 8.9 Gauss (0.89 mT) and UB3LYP/6-31G a value of 13.7 Gauss (1.37mT). Therefore, we confirmed that the method that used the d orbital functions was superior giving a result closer to the experimental one. The theoretical EPR spectrum of each intermediate was generated from the respective hfccs calculated. The EPR simulations were carried out with appropriate software. The peak-to-peak value of the theoretical simulation, taking into account two or three intermediates, was 12.1 Gauss (1.21mT). Then, the results achieved after the simulation validated our proposal. The study of these systems has particular importance because they increase the knowledge of both β-carotene and nitrogen oxide chemistry. Furthermore, it is very important the role of the β-carotene as a suitable protective agent in biological media. Springer-Verlag Wien, 2015 Mendiara Sara Departamento de Química, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, 7600, Mar del Plata, Argentina aut Perissinotti Luis Departamento de Química, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, 7600, Mar del Plata, Argentina aut Applied Magnetic Resonance Springer Vienna 46/11(2015-11-01), 1301-1322 0937-9347 46:11<1301 2015 46 723 https://doi.org/10.1007/s00723-015-0732-x text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00723-015-0732-x text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Mendiara Sara Departamento de Química, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, 7600, Mar del Plata, Argentina aut NATIONALLICENCE 700 1- Perissinotti Luis Departamento de Química, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, 7600, Mar del Plata, Argentina aut NATIONALLICENCE 773 0- Applied Magnetic Resonance Springer Vienna 46/11(2015-11-01), 1301-1322 0937-9347 46:11<1301 2015 46 723