Magnetic Resonance in Chemistry最新文献

{"title":"Navigating Guaiacyl and Syringyl Lignin Structural Complexity in Intact Plant Cell Walls Through ¹³C Chemical Shift Mapping by Two-Dimensional Solid-State NMR.","authors":"Peng Xiao, Priya Sahu, Debkumar Debnath, Dylan Archer Dingwell, Malitha C Dickwella Widanage, Charles H Cunningham, Yunqiao Pu, Tuo Wang","doi":"10.1002/mrc.70145","DOIUrl":"https://doi.org/10.1002/mrc.70145","url":null,"abstract":"<p><p>Lignin is a structurally complex and heterogeneous biopolymer whose in situ architecture remains difficult to resolve because of extensive spectral overlap and structural perturbations introduced during isolation and dissolution. These challenges have limited direct interrogation of native lignin within intact plant cell walls and underscore the need for analytical approaches capable of resolving lignin structure in its native context. Here, we present a framework that assists systematic ¹³C solid-state NMR identification of guaiacyl- and syringyl-based lignin motifs, including their associated monolignol units and interunit linkages with reduced level of ambiguity directly in native lignocellulosic materials. This approach is applicable to solid-state NMR analysis of ¹³C-enriched plant systems or dynamic nuclear polarization (DNP) analysis of unlabeled plant samples. By compiling and organizing diagnostic chemical shift patterns for syringyl and guaiacyl units across selected major linkage types, we delineate regions of uniqueness and overlap in 2D ¹³C correlation spectra. The scope is restricted to G/S-based lignin mapping, with applications to Arabidopsis, hardwoods, and softwoods. Application to Arabidopsis wild-type and lignin mutants, as well as to the hardwood species poplar and eucalyptus and the softwood spruce, reveals species-, genotype-, and developmental stage-dependent structural variations. The analysis further highlights the uncertainty arising from the structural complexity of the lignin network and demonstrates the need for higher dimensional correlation approaches for assignment of lignin structure. This work establishes a reference for the continued development of solid-state NMR-based G/S lignin analysis and advances the ability to interrogate native lignin architecture in intact plant cell walls.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149220456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interaction With Surface Spins as a Contribution to Nuclear Magnetic Relaxation of Liquids Adsorbed in Mesoporous Materials","authors":"Carlos Mattea,&nbsp;Hannah Leptin,&nbsp;Moritz Schmidt,&nbsp;Siegfried Stapf","doi":"10.1002/mrc.70130","DOIUrl":"10.1002/mrc.70130","url":null,"abstract":"<p>NMR relaxation of liquids in the presence of solid interfaces, such as silica gel or porous glass, is affected by slowed-down and anisotropic molecular reorientations compared to the bulk, but also by the presence of spins as potential relaxation partners on or close to the surface. The latter contribution is predominantly considered as unpaired electrons in metal centers or surface radicals, but dipolar interactions with spin-bearing nuclei such as ²⁹Si or ¹H may also contribute to relaxation of adsorbed species. In this study, an attempt is made at identifying the most relevant relaxation contributions by either adding or removing relaxation sinks: While immobilized stable radicals (TEMPO) on the surface shorten relaxation times of adsorbed liquids, the replacement of ¹H nuclei by ²H in hydroxyl groups is expected to remove the dominating part of nuclear dipolar spin–spin relaxation. In both cases, it is assumed that surface chemistry, which is the decisive parameter for spin relaxation mechanisms at interfaces, remains unchanged. Longitudinal and transverse relaxation, 2d T₁-T₂ maps, and frequency-dependent relaxation measurements of a number of homogeneous liquid phases as well as binary mixtures in the pore space of silica gel and porous glass are discussed in terms of the presence of radicals, whereas the replacement of OH by OD is observed to reduce relaxation rates in the systems under study.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 11","pages":"917-929"},"PeriodicalIF":2.1,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.70130","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148369018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"17O Quadrupole Coupling Constants in Water","authors":"Nabeeha Haque,&nbsp;Alexander G. de Dios,&nbsp;Angel C. de Dios","doi":"10.1002/mrc.70129","DOIUrl":"10.1002/mrc.70129","url":null,"abstract":"<p>An additive framework is developed to describe ¹⁷O quadrupole coupling constants (QCC's) in hydrogen-bonded water systems across isolated molecules, finite clusters, and ice-like environments. Density functional theory calculations using optimized geometries show that ¹⁷O QCC variations are primarily governed by hydrogen-bond interactions. A dimer model identifies hydrogen-bond distance as the dominant geometric factor, while angular and intramolecular distortions are minor. In ice and water clusters, first-nearest-neighbor interactions provide the largest contribution and are well captured by an additive donor–acceptor scheme, with improved accuracy upon inclusion of hydrogen bond distance dependence. Second nearest neighbor effects introduce smaller but systematic negative corrections arising from hydrogen-bond network asymmetry, restoring near-quantitative agreement with full calculations. The resulting model provides a computationally efficient and physically interpretable approach for predicting electric field gradients in aqueous environments and linking molecular simulations with ¹⁷O NMR observables.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 11","pages":"907-916"},"PeriodicalIF":2.1,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.70129","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148361266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probing the Enhancement of \u0000 \u0000 \u0000 \u0000 1\u0000 \u0000 H NMR Relaxation Rate in Hydrated Boehmite Systems","authors":"Alice Ducroix,&nbsp;Zlanseu Ruth Tan,&nbsp;Thierry Allard,&nbsp;Thibaud Chevalier,&nbsp;Guillaume Mériguet,&nbsp;Sandrine Leclerc,&nbsp;Serge Durand-Vidal,&nbsp;Flavien Guenneau,&nbsp;Natalie Malikova,&nbsp;Vincent Sarou-Kanian,&nbsp;Anne-Laure Rollet,&nbsp;Pierre Levitz","doi":"10.1002/mrc.70134","DOIUrl":"10.1002/mrc.70134","url":null,"abstract":"<div>\u0000 \u0000 <p>The \u0000<span></span><math>\u0000 <msup>\u0000 <mrow></mrow>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup></math>H NMR relaxation dispersion (NMRD) profile of water in boehmite systems has been studied in detail. The NMRD profiles, recorded for weakly hydrated particles up to diluted suspensions, exhibit the very same shape, and a mastercurve can be obtained. \u0000<span></span><math>\u0000 <msup>\u0000 <mrow></mrow>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup></math>H NMR relaxation rate \u0000<span></span><math>\u0000 <msub>\u0000 <mrow>\u0000 <mi>R</mi>\u0000 </mrow>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msub></math> strongly varies with the field indicating a slow dynamics at the surface of the boehmite particles. In addition, a bump around 0.7 MHz is observed. This characteristic feature may arise either from an interaction with a paramagnetic species or from an interaction with a quadrupolar nucleus. In the literature, this bump for aluminum hydroxide compounds has been independently attributed to one or the other interaction and a definitive answer must be provided. By decreasing the temperature, the bump increases, whereas the electron spin spectroscopy (ESR) detects a weak amount of paramagnetic species. \u0000<span></span><math>\u0000 <msup>\u0000 <mrow></mrow>\u0000 <mrow>\u0000 <mn>27</mn>\u0000 </mrow>\u0000 </msup></math>Al solid-state NMR spectrum is characterized a peak with a central transition at 9.7 ppm and quadrupolar constant equal to 2.7 MHz. The atomic force microscopy (AFM) image of individual boehmite particle evidences that the number of aluminum at the surface is high enough to be detected by solid-state NMR. Hence, the values of the \u0000<span></span><math>\u0000 <msup>\u0000 <mrow></mrow>\u0000 <mrow>\u0000 <mn>27</mn>\u0000 </mrow>\u0000 </msup></math>Al quadrupolar parameters obtained by solid-state NMR can be directly used for the calculation of the quadrupolar relaxation enhancement.</p>\u0000 </div>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 11","pages":"940-950"},"PeriodicalIF":2.1,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148437210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photochemical Pump, Benchtop NMR Probe Spectroscopy for Reaction Monitoring With paraHydrogen","authors":"Alastair D. Robinson,&nbsp;Fraser Hill-Casey,&nbsp;Simon B. Duckett,&nbsp;Meghan E. Halse","doi":"10.1002/mrc.70124","DOIUrl":"10.1002/mrc.70124","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 &lt;p&gt;The ability to observe transient intermediates and determine precise kinetic parameters is fundamental to understanding catalysis. This study demonstrates a methodology for the in situ investigation of photochemical ligand exchange and oxidative addition using a benchtop NMR spectrometer equipped with a through-bore UV irradiation system. To overcome the inherent sensitivity limitations of benchtop NMR, &lt;i&gt;para&lt;/i&gt;hydrogen-induced polarisation (PHIP) was employed, providing significant signal enhancements for hydride-containing products. Specifically, the addition of &lt;i&gt;p&lt;/i&gt;H\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;&lt;/math&gt; to &lt;i&gt;trans&lt;/i&gt;-[IrCl(CO)(PPh\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;&lt;/math&gt;)\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;&lt;/math&gt;], that proceeds over 10 min, was monitored yielding a second-order rate constant, 1.36 \u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;&lt;/math&gt; 0.02 M\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;&lt;/math&gt; s\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;&lt;/math&gt;. To resolve faster catalytic processes, pump-probe synchronisation between the UV pulse and NMR detection was implemented. A spin-lock pulse was also added to preserve the singlet state of the &lt;i&gt;p&lt;/i&gt;H\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;&lt;/math&gt;-derived hydride ligands in the reaction products, enabling the observation of coherent magnetic oscillations after reaction in the corresponding 2D pump-probe NMR spectra. Following optimisation on diagnostic zero-quantum correlations for &lt;i&gt;cis&lt;/i&gt;-[Ru(H)\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;&lt;/math&gt;(dppe)\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;&lt;/math&gt;], a set of iodo-derivatives of Vaska's complex were explored. For these systems two photochemical pathways were effectively mapped, enabling the identification of several ligand-exchange products. These results establish that the combination of hyperpolarisation and synchronised in situ irradiation makes benchtop NMR a powerful tool","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 11","pages":"896-906"},"PeriodicalIF":2.1,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148330700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Complexation Process of Pravastatin With Metal Ions (Gadolinium, Nickel, Zinc) by NMR Spectroscopy","authors":"A. A. Troshkina,&nbsp;I. Z. Rakhmatullin,&nbsp;A. S. Tarasov,&nbsp;A. R. Yulmetov,&nbsp;F. Kh. Karataeva,&nbsp;V. V. Klochkov","doi":"10.1002/mrc.70131","DOIUrl":"10.1002/mrc.70131","url":null,"abstract":"<div>\u0000 \u0000 <p>Understanding how drugs interact with metal ions is essential for predicting their stability, how well they are absorbed in the body, and possible side effects. Pravastatin is a commonly used statin to prevent cardiovascular heart disease and has several functional groups that can bind metal ions, but its interactions with transition metals and lanthanides are not well studied. This work examines the complexation process of pravastatin with transition metal ions zinc (Zn²⁺), nickel (Ni²⁺) and lanthanide gadolinium (Gd³⁺) using high-resolution NMR spectroscopy. It was found that the presence of ions (Ni²⁺, Gd³⁺) in an aqueous solution of pravastatin causes broadening of ¹H NMR signals, leading to a change in signal intensity in the HMQC spectra and disappearance of the correlation between the ¹H and ¹³C signals in the HMBC spectra. No significant changes were observed in the NMR spectra of similar experiments of pravastatin with zinc salt. The DOSY NMR spectrum of pravastatin in the presence of ions (Gd³⁺, Ni²⁺, and Zn²⁺) revealed a change in self-diffusion coefficients compared to the parent structure. An assumption about the possible centers of localization of Gd³⁺ and Ni²⁺ ions near the pravastatin molecule has been made.</p>\u0000 </div>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 11","pages":"930-939"},"PeriodicalIF":2.1,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148369025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Low-Field NMR Relaxometry for Elucidating the Effect of Temperature on the Rehydration Kinetics and pH and Ionic Strength on Rehydration Capacity of Texturized Soy Protein","authors":"Louise Margrethe Arildsen Jakobsen,&nbsp;Narges Fathali,&nbsp;Heidi Najbjerg,&nbsp;Hanne Christine Bertram","doi":"10.1002/mrc.70137","DOIUrl":"10.1002/mrc.70137","url":null,"abstract":"<p>Rehydration of texturized vegetable proteins (TVPs) is decisive for their functional properties, but little is known in relation to how rehydration conditions impact their ability to absorb and retain water. The present study aimed to investigate how rehydration dynamics and intrinsic water mobility of texturized soy protein are affected by temperature, pH, and ionic strength under dynamic or equilibrium conditions. Low-field NMR T₂ relaxation measurements were conducted dynamically on soy TVP during rehydration under different combinations of pH (5.4, 6.2, or 7.0), ionic strength (0.29, 0.46, or 0.71 M), and temperature (15, 25, or 35°C). Rehydration could be tracked from a decrease in the T₂ relaxation time constant, reflecting a reduced mobility of water protons when water molecules were immobilized in intrinsic structures. Kinetic modeling revealed a significant effect of temperature on the rate of rehydration, whereas pH and ionic strength did not affect the rate of rehydration. To evaluate equilibrium conditions, 24 h soaking experiments were conducted, which revealed significant effects of pH on the rehydration capacity and NMR T₂ relaxation. Increasing pH increased the rehydration capacity and T₂ relaxation time constants, indicating that water compartmentalization in TVPs can be modulated through pH effects on electrostatic repulsion. In conclusion, NMR relaxometry enables kinetic studies of soy TVP rehydration, and this study demonstrates that rehydration kinetics and equilibrium rehydration capacity can be decoupled. Temperature primarily governed the rate of water uptake, whereas pH influenced final rehydration capacity, while ionic strength in the range applied here did not affect rehydration capacity.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 11","pages":"951-958"},"PeriodicalIF":2.1,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.70137","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148549429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Theoretical Investigations of Structural Changes in Bimetallic MIL-53(Al/Cr)MOF Under Different States and Liquids.","authors":"Mei Ming, Hao Sui, Shao-Yi Wu, De-Chuan Sun, Chang-Chun Ding","doi":"10.1002/mrc.70144","DOIUrl":"https://doi.org/10.1002/mrc.70144","url":null,"abstract":"<p><p>MIL-53(Al/Cr) can exhibit pore expansion or contraction in response to different external stimuli and liquid environments. These macroscopic structural transitions are governed by the local rhombic distortion of the Cr³⁺ coordination octahedron. Based on the experimentally measured EPR spectra, the structural distortion characteristics of MIL-53(Al/Cr) are quantitatively studied in this work by using the perturbation formulas of the spin Hamiltonian parameters (SHPs) for 3d³ ions in rhombically distorted octahedra. The microstructure features under different states or liquids (specifically the bond-length distortion ΔR (0.0529-0.0671 Å) and bond-angle distortion δ (7.99°-10.14°) of the Cr³⁺ site, which exhibit a cooperative variation pattern characterized by an increase in ΔR accompanied by a decrease in δ during the narrow-pore to large-pore transition and the reverse trend upon the opposite transition) are studied. Based on this structural information, the relationship between the large-pore and narrow-pore breathing states and the microstructure is further clarified, thus elucidating the impact of the state and liquid on the macroscopic structure of the material.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149081301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gas-Phase Studies of ¹⁹F NMR Magnetic Shielding of Simple Isolated Molecules.","authors":"Włodzimierz Makulski","doi":"10.1002/mrc.70143","DOIUrl":"https://doi.org/10.1002/mrc.70143","url":null,"abstract":"<p><p>¹⁹F NMR spectra were recorded in gaseous CFCl₃/Xe mixtures on the NMR spectrometer, operated with a standard ²H(D) lock system. These results and shielding values obtained from the best relativistic quantum chemical calculations for single isolated CFCl₃ were used to establish the ¹⁹F nuclear magnetic moment: μ(¹⁹F) = 2.6283258(27) μ_N and a new absolute shielding scale based on liquid trichlorofluoromethane. The fluorine gas-to-liquid shift for trichlorofluoromethane was measured as Δσ_gl = -5.28(1) ppm. Next, the ¹H, ¹⁹F, and ³He NMR spectra were measured in CH₃F/³He and CF₄/³He gaseous mixtures as density functions. Extrapolating linear relationships to the zero-pressure limit yields frequency parameters for isolated CH₃F, CF₄, and helium atoms. These results have verified shielding constants for both fluorinated simple molecules. New exact results for the absolute ¹⁹F shielding of 16 chemical compounds measured in the gas phase were reported. Based on the new ¹⁹F shielding constant of the reference liquid CFCl₃, a large set of previously measured shielding constants for fluorine compounds in the gas phase was obtained.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148983118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing Ligand Epitope Mapping in Biomolecular Recognition by Variable Temperature Saturation Transfer Difference NMR (VT-STD NMR).","authors":"Gabriel Rocha, Svetla Daskalova, Juan C Muñoz-García, Jesús Angulo","doi":"10.1002/mrc.70141","DOIUrl":"https://doi.org/10.1002/mrc.70141","url":null,"abstract":"<p><p>Saturation transfer difference nuclear magnetic resonance (STD NMR) spectroscopy is a powerful and robust technique for the characterization of receptor-ligand interactions of medium to weak affinity in solution, providing binding epitope maps that reveal structural details of these interactions at atomic level. This knowledge is essential for understanding the structural basis of biomolecular recognition processes of biological relevance and plays a key role in drug discovery. Temperature is a critical factor influencing the sensitivity of STD NMR spectroscopy, as it directly affects the kinetics of complex formation, thereby modulating the observed STD effects. In this study, we systematically investigated the impact of temperature on STD NMR-derived binding epitope maps. Our findings highlight that, whenever protein stability permits, temperature should be considered an essential experimental parameter to be optimized for each system to obtain binding epitope maps with well-discriminated protein-ligand contact information. For the example cases studied herein, we demonstrate that temperature optimization allows to better assess the contribution of each individual contact to protein-ligand binding (enhanced ligand epitope mapping discrimination).</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148983167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}