A test set of -tetrasubstituted -phenylenediamines are experimentally explored using ESR (electron spin resonance) spectroscopy and analysed from a computational standpoint thereafter. This computational study aims to further aid structural characterisation by comparing experimental ESR hyperfine coupling constants (hfccs) with computed values calculated using ESR-optimised "J-style" basis sets (6-31G(d,p)-J, 6-31G(d,p)-J, 6-311++G(d,p)-J, pcJ-1, pcJ-2 and cc-pVTZ-J) and hybrid-DFT functionals (B3LYP, PBE0, TPSSh, ωB97XD) as well as MP2. PBE0/6-31g(d,p)-J with a polarised continuum solvation model (PCM) correlated best with the experiment, giving an 2 value of 0.8926. A total of 98% of couplings were deemed satisfactory, with five couplings observed as outlier results, thus degrading correlation values significantly. A higher-level electronic structure method, namely MP2, was sought to improve outlier couplings, but only a minority of couples showed improvement, whilst the remaining majority of couplings were negatively degraded.
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http://dx.doi.org/10.3390/ijms24043447 | DOI Listing |
Chemphyschem
December 2024
Oxford University, Department of Chemistry, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND.
With a view towards the development of molecular spintronics, non-linear optics, and qubits, a great amount of research effort aims to establish the factors which govern the spin classification of diradicals. Electron spin resonance (ESR) is an indispensable tool for such research. However, in some cases, the mere presence of an ESR spectrum is insufficient to ascertain that the presumed diradical is indeed a triplet state.
View Article and Find Full Text PDFChem Commun (Camb)
December 2024
MOE Key Laboratory of Cluster Science, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 102488, China.
Endohedral metallofullerenes (EMFs) are constructed by fullerene cages encapsulating various metal atoms or metal clusters, which usually exhibit some motion. However, due to the fact that the elusive endohedral dynamics are related to many factors, it remains a challenge to image the motion of internal species. Recently, the electron spin was found to be a sensitive probe to detect the motion of internal species in EMFs.
View Article and Find Full Text PDFFree Radic Biol Med
November 2024
State Key Laboratory of Environmental Chemistry and Eco-toxicology, Research Centre for Eco-environmental Sciences and University of the Chinese Academy of Sciences, The Chinese Academy of Sciences, Beijing, 100085, PR China; State Key Laboratory of Chemical Resource Engineering, Department of Environmental Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China. Electronic address:
Sci Rep
September 2024
Quantum Center of Excellence for Diamond and Emergent Materials, Indian Institute of Technology Madras, Chennai, 600036, India.
Electronic spins associated with the Nitrogen-Vacancy (NV) center in diamond offer an opportunity to study spin-related phenomena with extremely high sensitivity owing to their high degree of optical polarization. Here, we study both single- and double-quantum transitions (SQT and DQT) in NV centers between spin-mixed states, which arise from magnetic fields that are non-collinear to the NV axis. We demonstrate the amplification of the ESR signal from both these types of transition under laser illumination.
View Article and Find Full Text PDFNat Commun
September 2024
Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands.
The nuclear spin, being much more isolated from the environment than its electronic counterpart, presents opportunities for quantum experiments with prolonged coherence times. Electron spin resonance (ESR) combined with scanning tunnelling microscopy (STM) provides a bottom-up platform to study the fundamental properties of nuclear spins of single atoms on a surface. However, access to the time evolution of nuclear spins remained a challenge.
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