Spatial models of the current density field induced in the cyclopropane molecule by stationary, homogeneous magnetic fields, parallel to either the C3 or the C2 symmetry axis, have been constructed. A compact, abridged representation of the models is given via stagnation graphs that convey essential information. Maps of streamlines and moduli are also reported to complete current models that have proven useful to rationalize magnetic tensor properties, that is, magnetizability, 1H and 13C nuclear shieldings, and magnetic shielding along the C3 symmetry axis. Plots of Biot-Savart magnetic shielding density combined with current density visualization yield an accurate, detailed account of the shielding mechanisms. The magnetropicity of the system described by the current density model is fully consistent with the magnitude of magnetic tensors calculated at near Hartree-Fock level. In a field perpendicular to the molecular plane, cyclopropane sustains a diatropic sigma-ring current with the following peculiar features: (i) it follows the molecular periphery rather than the CC framework; (ii) it bifurcates in the proximity of the methylene moieties flowing along the CH bonds, both above and below the sigma(h) plane; (iii) it has an effect on the values of response properties, although it is not as large as expected from naive arguments (e.g., the center-of-mass value of the magnetic shielding constant is dominated by in-plane components rather than the out-of-plane component, which is in contrast to pi-aromatic systems such as benzene); (iv) it has a negligible effect on the strong anisotropy of carbon magnetic shielding, which is shown to arise from local currents. No evidence for strong diatropism, and therefore sigma-aromaticity of the cyclopropane molecule, was found on the magnetic criterion.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/jp0710638 | DOI Listing |
Molecules
January 2025
Department of Materials Science and Engineering, University of Utah, Salt Lake City, UT 84112, USA.
Conducting polymers represent a crucial class of functional materials with widespread applications in diverse fields. Among these, poly(3,4-ethylenedioxythiophene) (PEDOT) and its derivatives have garnered significant attention due to their distinctive optical, electronic, and magnetic properties, as well as their exceptional tunability. These properties often exhibit intricate interdependencies, manifesting as synergistic, concomitant, or antagonistic relationships.
View Article and Find Full Text PDFMolecules
December 2024
Institute of Earth Sciences, Faculty of Natural Sciences, University of Silesia in Katowice, 60, Będzińska, 41-200 Sosnowiec, Poland.
Cathinone and its synthetic derivatives belong to organic compounds with narcotic properties. Their structural diversity and massive illegal use create the need to develop new analytical methods for their identification in different matrices. NMR spectroscopy is one of the most versatile methods for identifying the structure of organic substances.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Department of Physics, University of Northeastern, IMIT-CONICET, Av. Libertad, 5500 Corrientes, Argentina.
In this study, we worked at the CCSD/aug-cc-pVTZ level to obtain the conformers of glycine in its neutral and zwitterionic forms in the gas and water phases. We then computed the NMR properties (spin-spin coupling constants and nuclear magnetic shieldings) at the SOPPA/aug-cc-pVTZ-J level. We attempt to elucidate the apparent discrepancy arising from two previous works by Valverde et al.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Physics, Faculty of Science, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran.
To protect against harmful electromagnetic interference (EMI), it is crucial to fabricate composite with high total electromagnetic shielding efficiency (SE); In this study, FeNi-NiFeO-SiO nanoparticles (NPs) were synthesized using one-pot method and decorated on carbon nanotube's (CNT) sidewall. The final product was magnetic-ceramic/conductive (FeNi-NiFeO-SiO/MWCNT) nanocomposite. The EMI shielding characteristic of FeNi-NiFeO-SiO NPs and FeNi-NiFeO-SiO/MWCNT nanocomposite was investigated in the range of X and Ku frequency band.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Research Unit of Structural Chemistry & Computational Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin 13125, Germany.
Density functional theory (DFT) calculations have emerged as a powerful theoretical toolbox for interpreting and analyzing the experimental nuclear magnetic resonance (NMR) spectra of chemical compounds. While DFT has been extensively used and benchmarked for isotropic NMR observables, the evaluation of the full chemical shielding tensor, which is necessary for interpreting residual chemical shift anisotropy (RCSA), has received much less attention, despite its recent applications in the structural elucidation of organic molecules. In this study, we present a comprehensive benchmark of carbon shielding anisotropies based on coupled cluster reference tensors taken from the NS372 benchmark data set.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!