Magnetic Resonance in Chemistry最新文献

{"title":"How to Disentangle Cation and Anion Dynamics of Fully Protonated Ionic Liquids: A Fast Field Cycling NMR Case Study","authors":"Lennart Kruse,&nbsp;Angel Mary Chiramel Tony,&nbsp;Daniel Rauber,&nbsp;Ralf Ludwig,&nbsp;Dietmar Paschek,&nbsp;Anne Strate","doi":"10.1002/mrc.70072","DOIUrl":"10.1002/mrc.70072","url":null,"abstract":"<p>The molecular dynamics of ionic liquids (ILs) can be probed using fast field cycling (FFC) NMR relaxometry. Conventionally, such studies focus on ILs where only one ionic species carries NMR-active nuclei or on systems combining \u0000<span></span><math>\u0000 <msup>\u0000 <mrow></mrow>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup></math>H nuclei on the cations with \u0000<span></span><math>\u0000 <msup>\u0000 <mrow></mrow>\u0000 <mrow>\u0000 <mn>19</mn>\u0000 </mrow>\u0000 </msup></math>F nuclei on the anions. This way, the dynamics of cations and anions can be resolved individually. However, the situation becomes considerably more complex in fully protonated systems where both ions contain protons, because the various relaxation pathways can no longer be disentangled. Here we report the first FFC NMR investigation of such a case, using the IL triethylammonium methanesulfonate ([TEA][OMs]). Our strategy exploits selective partial deuteration of the ionic species, which enables the separate evaluation of cation and anion dynamics. We demonstrate for the first time that, from the known partial relaxation rates together with the determined interionic distances and self-diffusion coefficients, the relaxation contribution arising from cation–anion interactions can be quantified. Remarkably, this approach even allows reconstruction of the total relaxation rate observed experimentally for the fully protonated IL. This methodology provides a fundamentally new route to overcoming the limited spectral resolution of FFC NMR relaxometry at low fields. More broadly, it establishes a framework for disentangling relaxation processes in complex multicomponent systems, thereby extending the applicability of FFC NMR to more challenging classes of ILs and related materials.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 3","pages":"265-272"},"PeriodicalIF":1.4,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12867595/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145677862","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":"Residual Chemical Shift Anisotropies in the Structure Determination of Small Molecules","authors":"Nilamoni Nath,&nbsp;Juan Carlos Fuentes Monteverde,&nbsp;Swaraj Pathak,&nbsp;Christian Griesinger","doi":"10.1002/mrc.70064","DOIUrl":"10.1002/mrc.70064","url":null,"abstract":"<p>The determination of the relative and absolute configuration of natural compounds is a very challenging task. Among other anisotropic NMR parameters, residual chemical shift anisotropy (RCSA) induced by anisotropic media is an invaluable tool to determine relative configurations of natural and synthetic organic molecules in solution. This review introduces various RCSA-based methodologies for the structural elucidation of natural products. The current availability of alignment media in organic solvents for RCSA measurements is also discussed as are applications of RCSAs for structural analysis of various natural products.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 3","pages":"286-311"},"PeriodicalIF":1.4,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12867594/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145723347","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":"NMR-Based Structural Analysis of Highly Substituted Pyridines From Kondrat'eva Aza-Diels–Alder Cycloadditions","authors":"Galdina V. Suárez-Moreno,&nbsp;Francisco Méndez,&nbsp;Atilano Gutierrez-Carrillo,&nbsp;Mónica A. Rincón-Guevara,&nbsp;Yoarhy A. Amador-Sánchez,&nbsp;Alejandro Islas-Jácome,&nbsp;Eduardo González-Zamora","doi":"10.1002/mrc.70075","DOIUrl":"10.1002/mrc.70075","url":null,"abstract":"<p>Pyridines are a crucial class of heterocycles with widespread applications in natural products, pharmaceuticals, and fluorescent organic materials. In this manuscript, we report the results from a kinetic and mechanistic investigation of an inverse-electron-demand Diels–Alder (IEDDA) cycloaddition involving an oxazole-type diene synthesized via an Ugi–Zhu multicomponent reaction (UZ-3CR). This heterodiene reacts efficiently with various dienophiles such as <i>E</i>-4-oxopentenoic acid, fumaric acid, and monoethyl maleate, yielding highly substituted pyridines in good to excellent yields. Reaction conditions were optimized, and the influence of solvent polarity on regioselectivity was evaluated. The necessity of protonation for successful cycloadditions was probed using structurally diverse dienophiles, revealing the essential role of the carboxylic acid group in triggering the reactions. Mechanistic insights were supported by a comprehensive NMR study (¹H, ¹³C, and ¹⁵N), which provided indirect evidence of in situ protonation of the oxazole ring. Notably, ¹⁵N NMR revealed significant downfield shifts of the oxazole nitrogen, consistent with its protonation, and the emergence of new nitrogen signals corresponding to pyridine products. This study demonstrates the synthetic utility of Ugi–Zhu-derived 5-aminooxazoles in IEDDA cycloadditions and highlights the critical role of acid-promoted activation in enabling efficient pyridine synthesis. We report the results from a kinetic and mechanistic investigation of an IEDDA cycloaddition involving an oxazole-type diene synthesized via an UZ-3CR.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 3","pages":"324-332"},"PeriodicalIF":1.4,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12867586/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145775041","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":"Electron Paramagnetic Resonance Research in India: A Honed-In Overview of the Last Three Decades","authors":"S. V. Bhat","doi":"10.1002/mrc.70063","DOIUrl":"10.1002/mrc.70063","url":null,"abstract":"<div>\u0000 \u0000 <p>The article reviews the electron paramagnetic resonance research carried out in India over the last three decades. After providing a broad picture of the number and type of publications pertaining to the period, studies on condensed matter physics topics such as manganites, high-Tc superconductors and water are spotlighted.</p>\u0000 </div>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 3","pages":"273-285"},"PeriodicalIF":1.4,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145708570","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":"","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 4","pages":"438-450"},"PeriodicalIF":1.4,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148096389","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":"","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 4","pages":"427-437"},"PeriodicalIF":1.4,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148090661","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":"","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 4","pages":"416-426"},"PeriodicalIF":1.4,"publicationDate":"2026-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148083506","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":"","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 4","pages":"400-415"},"PeriodicalIF":1.4,"publicationDate":"2026-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148072593","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":"","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 2","pages":"161-164"},"PeriodicalIF":1.4,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148134363","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":"","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"64 2","pages":"161-164"},"PeriodicalIF":1.4,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148069113","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}