We present here a systematic study about the influence of the size and type of nuclear charge-distribution models (Gaussian and point-like) on the NMR spectroscopic parameters, the nuclear magnetic shielding σ and the indirect nuclear spin J-coupling. We found that relativistic effects largely enhance the nuclear charge-distribution effects (NChDE) on those parameters being them quite sensitive to the nuclear model adopted for calculations. Results for two rare gas atoms (Kr, Rn) and few molecular systems like HX, (X = Br, I, At), CH(4), SnH(4), SnIH(3), SnI(2)H(2), and PbIH(3) are presented. J-couplings are more sensitive than shieldings in both, relativistic and non-relativistic (NR) regimes. The highest effect (close to 11% of variation in relativistic calculations with that two different nuclear models) is observed for J(Pb-I) in PbIH(3). A similar effect is found for J(Pb-H) in the same molecule, close to 9%. The NChDE for σ(Sn) in SnI(4-n)H(n) with n = 1, 2 is as large as few ppm (between 3 and 8.56 ppm). For J(Sn-H) in this set of molecules, it goes from 37 Hz for SnH(4) to 54 Hz for SnI(2)H(2). Furthermore, we found that the vicinal NChDE is very small though not zero. For (1)J(Sn-H) in SnIH(3), the NChDE of iodine is close to 2 Hz (0.1%). We also studied the NChDE on the ground state electronic energies of atoms and molecules. We found that these effects are only important within the relativistic regime but not within the NR one. They are in good agreement with previous works.
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http://dx.doi.org/10.1063/1.4729253 | DOI Listing |
Chem Commun (Camb)
January 2025
Department of Chemistry, Quantum Chemistry, TU Darmstadt, Peter-Grünberg-Str. 4, 64287 Darmstadt, Germany.
The two key parameters extracted from Mössbauer spectroscopy, isomer shift and quadrupole splitting, have well-known temperature dependencies. While the behavior of the values following a temperature change has long been known, its microscopic origins are less clear. For quantum chemical calculations - formally representing the situation at 0 K - significant discrepancies with the experiment can arise, especially at elevated temperatures.
View Article and Find Full Text PDFChem Sci
January 2025
Radioisotope Science and Technology Division, Oak Ridge National Laboratory Oak Ridge TN 37830 USA
Lanthanides (Ln) are typically found in the +3 oxidation state. However, in recent decades, their chemistry has been expanded to include the less stable +2 oxidation state across the entire series except promethium (Pm), facilitated by the coordination of ligands such as trimethylsilylcyclopentadienyl, CHSiMe (Cp'). The complexes have been the workhorse for the synthesis and theoretical study of the fundamental aspects of divalent lanthanide chemistry, where experimental and computational evidence have suggested the existence of different ground state (GS) configurations, 4f or 4f 5d, depending on the specific metal.
View Article and Find Full Text PDFJ Phys Chem B
December 2024
Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008, India.
Understanding RNA-protein interactions is crucial for uncovering the mechanisms of cellular processes and can provide insights into the basis of various diseases, paving the way for the development of targeted therapeutic interventions. Exposure to stress conditions, such as hypoxia, leads to a drop in intracellular pH, which, in turn, alters the ionization states of amino acid residues and RNA bases, affecting the charge distribution and electrostatic interactions between RNA and proteins. In addition, pH also perturbs the structure and dynamics of proteins via the disruption of H-bonds and ionic interactions.
View Article and Find Full Text PDFAppl Radiat Isot
March 2025
School of Nuclear Science and Technology, Lanzhou University, 730000, Lanzhou, China; Engineering Research Center for Neutron Application Technology, Ministry of Education, Lanzhou University, 730000, Lanzhou, China; MOE Frontiers Science Center for Rare Isotopes, Lanzhou University, Lanzhou, 730000, China. Electronic address:
In this work, the phenomenological potential-driving model based on the random neck rupture model is used to calculate and evaluate the independent yields and cumulative yields of fission products for the mass/charge distribution in the U(n, f) reaction with an incident neutron energy of 0.5 MeV and 14 MeV. In particular, the energy dependence of independent yields, including Kr, Sr, Zr, Mo, Ru, Xe, Cs, Ba and Ce, is evaluated for an incident neutron energy below 20 MeV and compared with GEFY6.
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, Frontiers Science Center for Rare Isotopes, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China.
Optimizing the electronic structure with increasing intrinsic stability is a usual method to enhance the catalysts' performance. Herein, a series of cerium dioxide (CeO) based solid solution materials is synthesized via substituting Ce atoms with transition metal (Co, Cu, Ni, etc.), in which CoCeO shows optimized band structure because of electron transition in the reaction, namely Co (3d4s) + Ce (4f5d 6s) → Co (3d4s) + Ce (4f5d6s), with more stable electronic configuration.
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