We will discuss, with the help of few selected examples, how the concept of through-space scalar spin-spin coupling between non covalently bonded nuclei has evolved in recent years. We will first present systems where 'no covalent bond' actually means that the two atoms are separated by a large number of bonds; then we will see cases where it is referred to true van der Waals dimers, but with the two atoms somehow constrained in their positions; we will finish with the most recent examples of liquids and even gaseous mixtures with full translational degrees of freedom in a regime of intermolecular/interatomic fast exchange.
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http://dx.doi.org/10.1002/cphc.202300963 | DOI Listing |
J Am Chem Soc
March 2024
State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, 2011-Collaborative Innovation Center of Chemistry for Energy Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian 116023, China.
Despite the extensive industrial and research interests in zeolites, their intrinsic catalytic nature is not fully understood due to the complexity of the hydroxyl-aluminum moieties. O NMR would provide irreplaceable opportunities for much-needed fine structural determination given the ubiquitous presence of oxygen atoms in nearly all species; however, the low sensitivity and quadrupolar nature of oxygen-17 make its NMR spectroscopic elucidation challenging. Here, we show that state-of-the-art double resonance solid-state NMR techniques have been combined with spectral editing methods based on scalar (through-bond) and dipolar (through-space) couplings, which allowed us to address the subtle protonic structures in zeolites.
View Article and Find Full Text PDFChemphyschem
March 2024
CNR Institute on Membrane Technology, Unit of Padova, Via Marzolo, 1, 35131, Padova, Italy.
We will discuss, with the help of few selected examples, how the concept of through-space scalar spin-spin coupling between non covalently bonded nuclei has evolved in recent years. We will first present systems where 'no covalent bond' actually means that the two atoms are separated by a large number of bonds; then we will see cases where it is referred to true van der Waals dimers, but with the two atoms somehow constrained in their positions; we will finish with the most recent examples of liquids and even gaseous mixtures with full translational degrees of freedom in a regime of intermolecular/interatomic fast exchange.
View Article and Find Full Text PDFJ Am Chem Soc
June 2022
Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava 84 536, Slovakia.
We present herein two complementary theoretical approaches for analyzing the transmission pathways of indirect nuclear spin-spin couplings in high-resolution nuclear magnetic resonance. This phenomenon is notably conceptually poorly understood in complex experimental situations in which both nonbonded ["through-space" (TS)] and more "classical" bonding ("through-bond") spin-spin coupling pathways are potentially involved. The computational approaches we propose allow the visualization and discussion of individual transmission pathways and estimation of their relative weight from numerical contributions to the spin-spin coupling constant -value.
View Article and Find Full Text PDFJ Am Chem Soc
November 2021
ARC Centre of Excellence for Innovations in Peptide & Protein Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia.
Fluorine atoms are known to display scalar F-F couplings in nuclear magnetic resonance (NMR) spectra when they are sufficiently close in space for nonbonding orbitals to overlap. We show that fluorinated noncanonical amino acids positioned in the hydrophobic core or on the surface of a protein can be linked by scalar through-space F-F () couplings even if the F spins are in the time average separated by more than the van der Waals distance. Using two different aromatic amino acids featuring CF groups, -trifluoromethyl-tyrosine and 4-trifluoromethyl-phenylalanine, we show that F-F TOCSY experiments are sufficiently sensitive to detect couplings between 2.
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