Magnetic Resonance in Chemistry最新文献

{"title":"Optimal Experimental Design for Fast and Accurate Relaxation Time Measurements in Magnetic Resonance.","authors":"Natalie E Klein, Adam R Altenhof, Amber J Day, Michelle A Espy, Michael W Malone","doi":"10.1002/mrc.70140","DOIUrl":"https://doi.org/10.1002/mrc.70140","url":null,"abstract":"<p><p>Relaxation time constants in magnetic resonance are sensitive probes of molecular structure and dynamics and are critical for achieving spatial contrast in imaging, but measuring relaxation times is generally far more time-consuming than traditional 1D spectroscopic experiments. Furthermore, the accuracy of the measured constants depends on numerous experimental factors. Currently, there are several available methods for designing a relaxation measurement (e.g., linear or logarithmic time spacing), but it is often unclear which method is preferable, how to select the minimum and maximum time points, or how many increments should be used, with all choices affecting the experimental time and the accuracy. Here, we consider optimal experimental designs and show that they maximize information per measurement, leading to more precise estimates for a specified relaxation model while in favorable cases reducing the number of measurements, and potentially the experimental time, required to achieve comparable precision relative to conventional sampling designs. Theoretical results on optimal experimental designs are explored both via simulation studies (for both mono- and multiexponential models) and via experiments for monoexponential <math> <mrow> <msub><mrow><mi>T</mi></mrow> <mrow><mn>1</mn></mrow> </msub> </mrow> </math> measurements on nuclear magnetic resonance systems. We emphasize that the resulting designs are optimal for parameter estimation under an assumed model rather than for model discovery or relaxation-time distribution recovery. We conclude with practical guidelines for improved experimental design for relaxation-time measurements in magnetic resonance while clarifying the limitations of model-based optimal design.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148930612","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":"Theoretical Investigation on Local Structure Distortion of V4+-Doped DUT-5(Al) via EPR Parameter Calculation","authors":"Yun-chao Zhu,&nbsp;Chang-chun Ding,&nbsp;De-chuan Sun,&nbsp;Zhi-xiang Fan","doi":"10.1002/mrc.70122","DOIUrl":"10.1002/mrc.70122","url":null,"abstract":"<div>\u0000 \u0000 <p>To clarify the correlation between the V⁴⁺ doping and the structure of DUT-5(Al), this study establishes a theoretical calculation model for the electron paramagnetic resonance (EPR) parameters of V⁴⁺ with a 3d¹ electron configuration in orthorhombically compressed octahedrons. After verifying the rationality of the model by fitting with experimental data, the local structural distortion of [VO₆] clusters, the regulation mechanism of electronic states, and the essence of EPR components (<i>lp</i>, <i>np</i>, <i>BL</i>, and <i>Blp</i>) were systematically analyzed. The findings reveal that, due to the Jahn–Teller distortion, the [VO₆] units adopt an orthorhombically distorted octahedral structure, quantified by an axial compression parameter <i>ρ</i> ranging from 5.6% to 6.4%, and in-plane bond-length variation rate <i>τ</i> spanning 6.0% to 6.8%. The theoretical method adopted in this study can clarify the doping mechanism of transition metal ions in metal–organic frameworks (MOFs), provide theoretical support for interpreting the EPR phenomena of V⁴⁺-doped DUT-5(Al), and offer guidance for the rational design and performance optimization of transition metal-doped MOF materials.</p>\u0000 </div>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 10","pages":"824-832"},"PeriodicalIF":2.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148156937","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":"ShimNetV2-RM Neural Network for Post-Acquisition Correction of Spectral Lineshapes in NMR Reaction Monitoring","authors":"Sylwia Jopa,&nbsp;Marek Bukowicki,&nbsp;Krzysztof Kazimierczuk","doi":"10.1002/mrc.70128","DOIUrl":"10.1002/mrc.70128","url":null,"abstract":"<div>\u0000 \u0000 <p>NMR can be used to monitor reactions in situ, typically by acquiring a series of standard one-dimensional spectra at regular intervals. However, the experimental setup is more demanding than for stable, nonreacting samples. For example, the usual pre-acquisition correction of magnetic field homogeneity, known as shimming, can sometimes be too time-consuming to be repeated before each spectrum in a series. This results in a gradual increase in spectral lineshape distortions during the reaction. Fortunately, the spectra can be improved to some extent by applying post-acquisition corrections. We propose replacing the standard semi-manual reference deconvolution method with a neural network called ShimNetV2-RM. Our method, previously developed under the name ShimNet for standard nonreacting samples, can be tailored for reaction monitoring by constraining training parameters using well-shimmed pre- and post-monitoring spectra. To demonstrate the applicability of the proposed approach under realistic and demanding conditions, we applied ShimNetV2-RM to two representative copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions.</p>\u0000 </div>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 10","pages":"850-858"},"PeriodicalIF":2.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148272316","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":"Synthesis of 15N-Labeled Bevirimat Derivatives as Isotopic Chemical Probes of HIV-1 Maturation Inhibition","authors":"Kiara T. Reyes-Colón,&nbsp;Carla M. Díaz Corretjer,&nbsp;Branlee Sang-Laboy,&nbsp;Cornelis P. Vlaar,&nbsp;Marvin J. Bayro","doi":"10.1002/mrc.70121","DOIUrl":"10.1002/mrc.70121","url":null,"abstract":"<div>\u0000 \u0000 <p>Characterizing protein–drug interactions at the atomic level is challenging partly because small molecules can be difficult to detect within large biomolecular complexes. We have developed a strategy to introduce NMR-active isotopic ¹⁵N labels into derivatives of bevirimat (BVM), a triterpenoid inhibitor of HIV-1 maturation. Isotopically labeled compounds were synthesized through concise and efficient routes using commercially available, isotopically enriched building blocks. Three ¹⁵N-labeled BVM derivatives were prepared to be used as molecular probes to investigate HIV-1 protein interactions. These labeled compounds enable site-specific ¹⁵N detection of the inhibitor in both solution and solid-state NMR experiments, which will be useful to obtain molecular-level insight into the interactions between BVM derivatives and its target HIV-1 Gag protein. Synthetic incorporation of NMR-active isotopes produces chemical probes for atomic-level analysis of next-generation HIV-1 therapeutics derived from BVM and can be applied to other derivatives of betulinic acid with various medical applications.</p>\u0000 </div>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 10","pages":"833-839"},"PeriodicalIF":2.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148239635","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":"Pulse Programme Considerations for Quantitative NOE Analysis","authors":"Lianne H. E. Wieske,&nbsp;Gintarė Lygnugarytė,&nbsp;Máté Erdélyi","doi":"10.1002/mrc.70127","DOIUrl":"10.1002/mrc.70127","url":null,"abstract":"<p>Accurate NOE/ROE-based distance determination is a crucial tool in stereochemistry and conformational analysis of both protein and small molecule structure elucidation. Despite being widely used in countless fields of chemistry and biology, the factors determining the accuracy of the obtained distances are sometimes neglected. Herein, we present the systematic analysis of the performance of six commonly used NOESY and ROESY pulse programmes for quantitative NOE/ROE analysis, evaluating the quality of the data based on the number of quantifiable correlations and the accuracy of the corresponding NOE-derived interproton distances. The effect of two solvent suppression schemes on the NOE/ROE quantitativity is assessed. We found that the total number of quantifiable correlations and the errors of the derived distances depend on the pulse programme used, and the error increases drastically when two or more spectra are removed from the build-up curves for the generation of NOE/ROE build-up rates, using the initial-rate approximation. Solvent suppression using excitation sculpting results in the underestimation of the NOE-derived distances. EASY ROESY run without solvent suppression shows a bias towards overestimated NOE-derived distances. The obtained data suggest that the determination of quantitative interproton distances necessitates the careful selection of pulse programme.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 10","pages":"873-889"},"PeriodicalIF":2.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.70127","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148302189","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":"Qualitative and Quantitative Characterization of Isodon rubescens and Its Pharmaceutical Preparations Using NMR and UHPLC-QTOF-MS","authors":"Qiong Wu,&nbsp;Yan Li,&nbsp;Bin Yuan,&nbsp;Qing Xu,&nbsp;Yanfang Liu","doi":"10.1002/mrc.70123","DOIUrl":"10.1002/mrc.70123","url":null,"abstract":"<div>\u0000 \u0000 <p><i>Isodon rubescens</i> is a widely used traditional folk medicine in China. In this study, 13 natural products were isolated using a two-step ethanol extraction. Notably, flavonoid glycosides <b>2</b> and <b>4</b>, and polymeric caffeic acids <b>7</b> and <b>8</b>, were identified for the first time from the secondary extraction residues, highlighting the continued presence of bioactive compounds with potential for further development. Oridonin (<b>9</b>), the major active compound, was quantified in nine commercial preparations using quantitative NMR (qNMR). Its concentration in the drop pill (0.92 mg/g) was comparable to that in the raw extract (0.90 mg/g). The three tablet samples showed varying levels: Tablet 3 (2.66 mg/g) &gt; Tablet 1 (1.22 mg/g) &gt; Tablet 2 (1.09 mg/g). Capsule, tea bag, and syrup samples could not be quantified due to low concentrations.</p>\u0000 </div>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 10","pages":"840-849"},"PeriodicalIF":2.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148252192","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":"Assessment of Cryogen-Free NMR as Process Analytical Technology for Chemical Process Understanding Across Field Strengths","authors":"Maria Victoria Silva Elipe,&nbsp;Anh Le-McClain,&nbsp;Hector Robert,&nbsp;Ronald Soong,&nbsp;Stephen J. McBride","doi":"10.1002/mrc.70125","DOIUrl":"10.1002/mrc.70125","url":null,"abstract":"<div>\u0000 \u0000 <p>Understanding chemical reactions is central to pharmaceutical and chemical development, and nuclear magnetic resonance (NMR) spectroscopy is increasingly attractive for reaction analysis because it provides direct structural insight and quantitative information without dependence on response factors. However, conventional high-field NMR instruments are rarely located in chemistry laboratories due to demanding infrastructure requirements and reliance on liquid cryogens. Recent advances in cryogen-free magnet technologies address this limitation and enable practical deployment of NMR directly in laboratory and manufacturing environments.</p>\u0000 <p>This work evaluates cryogen-free NMR as a process analytical technology (PAT) by comparing a 400-MHz high-temperature superconducting (HTS) magnet NMR system with an 80-MHz benchtop NMR instrument. Two representative reactions were studied: a ring-closing metathesis reaction and the transesterification of a pinacol arylboronic ester to an aryl triolborate. The comparison focuses on data quality, the ability to extract kinetic and speciation information, and the strengths and limitations of each platform for complex reaction monitoring.</p>\u0000 <p>Results demonstrate that both cryogen-free systems can deliver meaningful reaction insights, including in cases with overlapping NMR signals, while offering distinct technical advantages. The higher-field HTS system provides improved resolution and analytical capability, whereas the benchtop instrument offers simplicity, accessibility, and ease of integration. Overall, cryogen-free NMR instruments lower barriers to adoption, eliminate liquid-cryogen's requirements, and expand the use of NMR for routine reaction monitoring. These technologies enable broader application of NMR-based PAT, and support more informed decision-making in chemistry laboratories and manufacturing settings across diverse reaction types and operational scales worldwide.</p>\u0000 </div>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 10","pages":"859-872"},"PeriodicalIF":2.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148276984","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":"Fast Field Cycling ¹⁹F NMR Relaxometry of Polytetrafluoroethylene.","authors":"Makoto Yamaguchi, Seiichi Kuroda, Kiyoshi Inokuma, Natsuki Fukuta","doi":"10.1002/mrc.70139","DOIUrl":"https://doi.org/10.1002/mrc.70139","url":null,"abstract":"<p><p>Polytetrafluoroethylene (PTFE) has been widely used in various forms, and its properties are affected by its fabrication processes. We applied fast field cycling (FFC) NMR relaxometry to commercially available PTFE and related compounds to investigate their chain dynamics in the solid state. Four different types of commercially available PTFE samples (powder, tape, and films) were subjected to XRD, Raman, and DSC measurements, and the crystallinity of the two film samples was found to be lower than that of the powder and the tape. Spin-lattice relaxation rates decreased with increasing relaxation magnetic field strength, following a power law, as explained by the defect diffusion model. In some cases, deviations from the power law dependence at the upper limit of the relaxation magnetic field indicated the contribution of Rouse dynamics. Based on DFT calculations on model compounds with different defect types, kinks were considered to be diffusing defects.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148828865","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":"CEEN: A Control Software for Coupled Electrochemistry, EPR, and NMR for Redox Flow Battery and Electrosynthesis Research","authors":"Vince Elter,&nbsp;Noël de Kler,&nbsp;Giu A. Silva Testa,&nbsp;Zhiyu Zhu,&nbsp;Federico Paruzzo,&nbsp;Simon Bruderer,&nbsp;Evan Wenbo Zhao","doi":"10.1002/mrc.70120","DOIUrl":"10.1002/mrc.70120","url":null,"abstract":"<p>We present CEEN (coupled electrochemistry, EPR, and NMR), a Python package designed for coupled and integrated control of Bruker benchtop NMR, benchtop EPR, and Gamry electrochemical workstations. The software enables synchronized acquisition and real-time visualization of electrochemical, NMR, and EPR data, simplifying operando measurements that traditionally require three independent control interfaces. We demonstrate CEEN through practical applications relevant to aqueous organic and inorganic redox flow battery (RFB) and electrochemical synthesis research. The same setup can be readily used to study any (electrochemical) flow process using magnetic resonance. CEEN streamlines the data acquisition workflow, enabling robust and information-rich operando NMR and EPR studies.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 9","pages":"793-800"},"PeriodicalIF":2.1,"publicationDate":"2026-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.70120","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147988189","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 Studies of the EPR Parameters and the Off-Center Displacement of Cu2+ Ion in Pb5Ge3O11 Crystal","authors":"Peipei Yan,&nbsp;Xiaojian Zhao,&nbsp;Yan Liang,&nbsp;Xiufeng Tao,&nbsp;Wenfeng Zheng,&nbsp;Jinglei Wang,&nbsp;Jinxuan Lv,&nbsp;Huaming Zhang,&nbsp;Yanwei Wang","doi":"10.1002/mrc.70108","DOIUrl":"10.1002/mrc.70108","url":null,"abstract":"<div>\u0000 \u0000 <p>The off-center displacement of the Cu²⁺ ion in Pb₅Ge₃O₁₁ (PGO) crystal is theoretically investigated by analyzing the electron paramagnetic resonance (EPR) parameters, <i>g</i>-factors <i>g</i>_<i>i</i> (<i>i</i> = <i>x</i>, <i>y</i>, <i>z</i>), and hyperfine structure constants <i>A</i>_<i>i</i> based on the high-order perturbation formulas of 3d⁹ ions in orthorhombically elongated octahedral crystal-fields. The doped Cu²⁺ was assumed to substitute the host Pb(8) site in the PGO lattice, with a different local environment from the original Pb²⁺ due to the Jahn–Teller (JT) effect. Based on the calculation, the off-center displacement <i>Δz</i> of impurity Cu²⁺ is about 0.19 Å, and the planar Cu²⁺-O²⁻ bonds are found to experience the relative bond length variation δ<i>R</i> (≈0.013 Å) along the <i>x</i> and <i>y</i> axes. The theoretical EPR parameters based on the above local structure parameters show good agreement with the experimental values.</p>\u0000 </div>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 9","pages":"785-792"},"PeriodicalIF":2.1,"publicationDate":"2026-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147988197","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}