The presented results attempt to approximate the proper structure of the radical formed as a result of the oxidation of 1,2,3-propanetriol. To fulfil the aim unstable radical originated in 1,2,3-propanetriol was trapped by PBN. Resulted spin adduct was measured using EPR spectroscopy and the isotropic hyperfine coupling constants a ( N) and a ( H) were obtained by simulation of the EPR spectrum. The next step consisted of conducting a comparative analysis of EPR parameters, based on the calculations conducted at the DFT and MP2 methods level in open-shell formalism including solvent effects. For comparison, calculations were also carried out at the level of combined methods (UB3LYP/QCISD and UMP2/QCISD) in terms of the ONIOM formalism. Comparison of the experimental EPR data of the isotropic hyperfine coupling constants a ( N) and a ( H) with the calculated parameters indicate that oxidation of 1,2,3-propanetriol leads to a carbon centred radical where unpaired electron is situated on the second (middle) carbon of 1,2,3-propanetriol. What is important, this conclusion could be made regardless of the chosen calculation method. However, it could be stated that for calculation of the isotropic hyperfine coupling constants a ( N) and a ( H) of PBN/gly• adducts, UMP2 polarisable conductor calculation model with two ethanol molecules is explicitly defined.
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http://dx.doi.org/10.1002/mrc.4822 | DOI Listing |
Nat Commun
December 2024
Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
J Phys Chem A
December 2024
Department of Physics and Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, Ohio 44115, United States.
Single-crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopic experiments, complemented by quantum chemical DFT calculations, were carried out on the copper-doped metal-organic hybrid and Tutton salt analogue zinc creatininium sulfate to determine its crystal structure, to characterize the electronic structure of the doped Cu(II) binding site, and to propose a pathway for an excited-state, proton-coupled electron transfer (PCET) process in UV-exposed crystals. The crystal structure is isomorphous to that of cadmium creatininium sulfate, which has the transition ion, not in direct coordination with the creatinine, but forming a hexahydrate complex, which is bridged to a creatininium through an intervening sulfate ion. The EPR (2.
View Article and Find Full Text PDFMolecules
October 2024
Institute of Organic Chemistry, University of Regensburg, Universitaetstrasse 31, 93053 Regensburg, Germany.
This study examines experimental data on the influence of the surrounding medium and non-covalent interactions on the isotropic hyperfine coupling constant, A(N), of the stable nitroxide radical 2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO) in solution. The data were used to identify a density functional theory functional/basis set combination that accurately reproduces the experimental A(N) values. The variations in A(N) due to external factors are two orders of magnitude greater than the accuracy of its experimental measurements, making A(N) a highly sensitive experimental probe for quantifying these effects.
View Article and Find Full Text PDFJ Am Chem Soc
November 2024
Department of Chemistry, Yonsei University, Seoul 03722, Republic of Korea.
Synthesis and characterization of a thermally stable triarylphosphine radical cation, [P(8-Br-CH)][BArF] ([][BArF], BArF = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate), enabled by stabilization through -bromo-substituted naphthalenes, are described. Unlike previously reported phosphine radical cations that rely on sterically bulky substituents for stabilization, our approach leverages electronic stabilization via "through-space" radical delocalization. Single-crystal X-ray diffraction of [][BArF] reveals a tricapped tetrahedral geometry, resulting from the spatial proximity of the three bromine atoms to the phosphorus center, differentiated from the trigonal planar geometry observed in the previously reported triarylphosphine radical cations with sterically bulky substituents.
View Article and Find Full Text PDFJ Phys Chem A
September 2024
Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland.
In this article, we introduce a simple but reliable method to calculate the electric field dependence of the isotropic hyperfine coupling tensor for free radicals. This dependence, also referred to as the Bloembergen effect, can be of interest in analyzing EPR experiments for solid-state materials but is rarely studied for isolated radicals in the gaseous phase. The proposed method uses the numerical differentiation of the field-perturbed tensor and, consequently, as a purely numerical method, does not depend on a quantum chemical method used to determine the hyperfine tensor .
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