Magnetic Resonance in Chemistry最新文献

{"title":"Quantitative analysis of selected alkaloids of Mitragyna speciosa using ¹H quantitative nuclear magnetic resonance spectroscopy.","authors":"Suleiman Abubakar Garba, Khozirah Shaari, Mohd Rashidi Abdul Manap, Soo Yee Lee, Isah Abdulazeez, Siti Munirah Mohd Faudzi","doi":"10.1002/mrc.5477","DOIUrl":"https://doi.org/10.1002/mrc.5477","url":null,"abstract":"<p><p>Mitragyna speciosa is a perennial plant native to Asia, well known for its psychoactive properties. Its major alkaloid mitragynine is known to have sedative and euphoric effects. Hence, the plant has been a subject of abuse, leading to addiction, necessitating efficient analytical methods to detect its psychoactive constituents. However, current chromatography-based methods for detecting the alkaloids are time consuming and costly. Quantitative nuclear magnetic resonance (qNMR) spectroscopy emerges as a promising alternative due to its nondestructive nature, structural insights, and short analysis time. Hence, a rapid and precise qNMR method was developed to quantify selected major psychoactive alkaloids in various parts of M. speciosa. Mitragynine, specioliatine, and speciogynine were quantified in relation to the integral value of the -OCH₃ groups of the alkaloids and the internal standard 1,4-dinitrobenzene. The precision and reproducibility of the method gave a relative standard deviation (RSD) of 2%, demonstrating the reliability of the method. In addition, the method showed excellent specificity, sensitivity, high linearity range (R² = 0.999), and limits of detection (LOD) and quantification (LOQ) values. The analysis revealed that the red-veined M. speciosa leaves contained higher levels of mitragynine (32.34 mg/g), specioliatine (16.84 mg/g) and speciogynine (7.69 mg/g) compared to the green-veined leaves, stem bark, or fruits.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142073234","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":"The Solvatomagnetism of E_T(33) Betaine and of Its Phenolic Precursor.","authors":"Fabián Martínez-Gómez, Marcos Caroli Rezende, Valentina Rodríguez-Huenchún","doi":"10.1002/mrc.5478","DOIUrl":"https://doi.org/10.1002/mrc.5478","url":null,"abstract":"<p><p>The ¹H and ¹³C NMR spectra of the N-(3,5-dichloro-4-hydroxyphenyl)- 2,4,6-triphenylpyridinium perchlorate and of its deprotonated betaine 4-(2,4,6-triphenylpyridinio)-2,6-dichlorophenolate (Wolfbeis's E_T(33) dye) were recorded in various solvents and analyzed in search of solvent-dependent shifts that characterize their solvatomagnetism, which was compared with the well-known UV-vis spectral behavior of this important solvatochromic dye. Although the NMR spectra of E_T(33) and its phenolic precursor in different solvents correlated only poorly with their UV-vis spectral responses, they provided valuable information on specific structural features and solute-solvent interactions that are not available from their UV-vis spectra.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142080800","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":"Recent advances in liquid-phase NMR of the coal-derived products.","authors":"Leonid B Krivdin","doi":"10.1002/mrc.5476","DOIUrl":"https://doi.org/10.1002/mrc.5476","url":null,"abstract":"<p><p>Present review focuses on the most recent advances in a liquid-phase nuclear magnetic resonance (NMR) of the coal-derived products-coal tar pitches, asphaltenes, and humic and fulvic acids, covering exclusively the results in the liquid-phase NMR studies leaving apart an overwhelming amount of publications dealing with the solid-state NMR investigations in this field (which are comprehensively reviewed elsewhere). Owing to the complexity of the coal-derived products, their ¹H and ¹³C NMR spectra consist of a number of overlapping signals belonging to different hydrocarbon types. Comprehensive studies of coal tar pitches, asphaltenes, and humic and fulvic acids by means of NMR over the past several decades revealed characteristic functional groups of those fractions together with spectral regions in which they resonate. Quantitative ¹H and ¹³C NMR spectra characterize aromatic and saturated carbons spread over many structural moieties, which provides a solid guideline into molecular structure of the coal-derived products. Nowadays, quantitative ¹³C NMR measurements yield information about a variety of structural parameters such as functional group distribution, aromaticity, degree of condensation of aromatic rings, and medium chain lengths together with many other more specific parameters. The structural NMR studies of coal and coal-derived products are developing on a backdrop of a marked progress in computational NMR. At present, we are witnessing an unprecedentedly fast development of theoretical and computational methods in the field of NMR spectroscopy. Discussed in the present review are the most recent advances in the NMR studies of the processing products of peat, lignite or brown coal, anthracite or hard coal, and graphite in solution, like coal tar pitches, asphaltenes, and humic and fulvic acids.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141855913","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":"Differentiation of regioisomeric N-alkylation of some indazoles and pyrazolopyridines by advanced NMR techniques.","authors":"Fatima Doganc, Hakan Göker","doi":"10.1002/mrc.5471","DOIUrl":"https://doi.org/10.1002/mrc.5471","url":null,"abstract":"<p><p>Indazole scaffold have two interconvertible tautomeric forms. Regioselectivities were determined for N-benzylations and alkylation of some non-substituted and substituted indazoles, under basic conditions (K₂CO₃) in DMF. The ratio of regioisomers occurrence between N¹:N² is almost equal. Their structures were established through a combination of NOESY and ¹H-¹³C/¹⁵N HMBC NMR methods. Additionally, pyrazolo[3,4-b]pyridines have also three possible tautomeric forms; primarily 1H and 2H, with 7H isomers being rare. Pyrazolo[4,3-b]pyridines have only known two possible tautomeric forms so far; 1H and 2H.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141616757","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":"Revealing elusive conformations of sucrose from hydrogen bond J-coupling in H2O: A combined NMR and quantum mechanics study","authors":"Jeahoo Kwon,&nbsp;Hannah L. Reeves,&nbsp;Lee-Ping Wang,&nbsp;Darón I. Freedberg","doi":"10.1002/mrc.5473","DOIUrl":"10.1002/mrc.5473","url":null,"abstract":"<p>Hydrogen bonding is a crucial feature of biomolecules, but its characterization in glycans dissolved in aqueous solutions is challenging due to rapid hydrogen exchange between hydroxyl groups and H₂O. In principle, the scalar (<i>J</i>) coupling constant can reveal the relative orientation of the atoms in the molecule. In contrast to <i>J</i>-coupling through H-bonds reported in proteins and nucleic acids, research on <i>J</i>-coupling through H-bonds in glycans dissolved in water is lacking. Here, we use sucrose as a model system for H-bonding studies; its structure, which consists of glucose (Glc) and fructose (Frc), is well-studied, and it is readily available. We apply the in-phase, antiphase-HSQC-TOCSY and quantify previously unreported through H-bond <i>J</i>-values for Frc–OH1–Glc–OH2 in H₂O. While earlier reports of Brown and Levy indicate this H-bond as having only a single direction, our reported findings indicate the potential presence of two involving these same atoms, namely, G2OH ➔ F1O and F1OH ➔ G2O (where F and G stand for Frc and Glc, respectively). The calculated density functional theory <i>J</i>-values for the G2OH ➔ F1O agree with the experimental values. Additionally, we detected four other possible H-bonds in sucrose, which require different phi, psi (ϕ, ψ) torsion angles. The ϕ, ψ values are consistent with previous predictions of du Penhoat et al. and Venable et al. Our results will provide new insights into the molecular structure of sucrose and its interactions with proteins.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5473","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141563680","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":"Acetonyl C^N^N platinum(II) complexes of arylbipyridines.","authors":"Vladislav M Abramov, Maria D Tokhtueva, Vsevolod V Melekhin, Oleg S Eltsov","doi":"10.1002/mrc.5475","DOIUrl":"https://doi.org/10.1002/mrc.5475","url":null,"abstract":"<p><p>This paper presents the first example of the formation of acetonyl tridentate CˆNˆN complexes of arylbipyridines in the reaction of chloroplatinum complexes with acetone in the presence of alkali. The chemical structure of obtained substances was established by means of ¹H,¹³C NMR, COSY, HSQC, and HMBC techniques. The attribution of all proton and carbon signals in NMR spectra was performed using 1D and 2D NMR experiments for the synthesized acetonyl cycloplatinated complexes. A comparative analysis of the values of the C-Pt spin-spin coupling constants of the same order was carried out, which showed a significant difference in bond lengths and valence angles inthe cyclic fragments of the arylbipyridine ligand.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141563679","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":"Editorial: A new era for Magnetic Resonance in Chemistry","authors":"Patrick Giraudeau,&nbsp;Roberto R. Gil","doi":"10.1002/mrc.5474","DOIUrl":"10.1002/mrc.5474","url":null,"abstract":"<p>As the newly appointed editorial leadership of <i>Magnetic Resonance in Chemistry</i> (MRC), we are honored to introduce our revamped and highly dedicated editorial team. I, Roberto R. Gil, am now the sole Editor-in-Chief, joined by Patrick Giraudeau, who has been promoted from Associate Editor to Deputy Editor. We are also supported by our exceptional Associate Editors: Bozhana Mikhova, Teodor Parella, and Leonard Mueller. Together, we form a smaller but highly focused and committed team, dedicated to maintaining the high standards and innovative spirit that <i>MRC</i> is known for.</p><p>We would like to extend our heartfelt gratitude to the former Co-Editor-in-Chief, Gary E. Martin, for his 8 years of dedicated service to the journal. Additionally, we wish to thank Jean-Nicolas Dumez and Leonid Krivdin for their dedication and contributions as Associate Editors.</p><p>In alignment with our vision for continuous improvement and modernization, we are thrilled to announce a significant change in how we handle special issues. Starting in 2024, special issues will be transformed into special collections. This strategic shift offers numerous advantages, most notably the flexibility of populating these collections as manuscripts are accepted and added to the Early View section of the journal. This means that high-quality research can be disseminated more swiftly, ensuring that our readers have timely access to the latest developments in the field.</p><p>Our commitment to excellence remains unwavering, and we believe these changes will enhance the journal's impact and accessibility. Detailed information about the new article types can be found in the Guidelines to Authors section on our website.</p><p>We are excited about these developments and confident that they will enrich the MRC community. On behalf of the entire editorial team, I extend our gratitude for your continued support and contributions. We look forward to a year of groundbreaking research and inspiring discoveries in 2024 and beyond.</p><p>Sincerely,</p><p><i>Roberto R. Gil</i></p><p>Editor-in-Chief</p><p><i>Patrick Giraudeau</i></p><p>Deputy Editor</p><p>Magnetic Resonance in Chemistry</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5474","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141492480","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":"Investigations on the EPR g factors and local structures for the orthorhombic and tetragonal Cu2+ centers in Pb[Zr0.54Ti0.46]O3","authors":"Xiaohua Huang,&nbsp;Meiyun Zhang,&nbsp;Fangfang Guo,&nbsp;Houdao Cai,&nbsp;Xilin Zhou,&nbsp;Cuidi Feng","doi":"10.1002/mrc.5472","DOIUrl":"10.1002/mrc.5472","url":null,"abstract":"<p>The defect models of the orthorhombical and tetragonal Cu²⁺ centers in Pb[Zr_0.54Ti_0.46]O₃ are attributed to Cu²⁺ ions occupying the sixfold coordinated octahedral Ti⁴⁺ site with and without charge compensation, respectively. The electron paramagnetic resonance (EPR) <i>g</i> factors <i>g</i>_<i>i</i> (<i>i</i> = <i>x</i>, <i>y</i>, <i>z</i>) of the Cu²⁺ centers in Pb[Zr_0.54Ti_0.46]O₃ are theoretically studied by using the perturbation formulas of a 3d⁹ ion under orthorhombically and tetragonally elongated octahedra. Based on the calculation, the impurity off-center displacements are about 0.253 and 0.162 Å for the orthorhombical and tetragonal Cu²⁺ centers, respectively. Meanwhile, the planar Cu²⁺–O²⁻ bonds are found to experience the relative variation Δ<i>R</i> (≈0.102 Å) along the <i>a</i>- and <i>b</i>-axes for the orthorhombical Cu²⁺ center due to the Jahn–Teller (JT) effect. The theoretical EPR <i>g</i> factors based on the above local structures agree well with the observed values.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141469246","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":"A theoretical study of the electron paramagnetic resonance spectra and local environment in copper(II) complexes with different imidazole and chlorido ligands","authors":"Jun-Shan Hu,&nbsp;Xin-Xin Wang,&nbsp;Si-Qi Li,&nbsp;Jia-Man Li,&nbsp;Chang-Chun Ding","doi":"10.1002/mrc.5470","DOIUrl":"10.1002/mrc.5470","url":null,"abstract":"<p>Copper(II) chloride anionic coordination complexes with different imidazole-derived ligands due to the potential cytotoxic activity play the important role in protein. By investigating the experimental electron paramagnetic resonance (EPR) and ultraviolet–visible (UV–vis) spectra of [CuCl(C₆H₁₀N₂)₄]Cl, [CuCl(C₆H₁₀N₂)₄]Cl, [CuCl₂(C₄H₆N₂)₄], and [Cu₂Cl₂(C₅H₈N₂)₆]Cl₂·2H₂O, the local structure of the corresponding Cu²⁺ centers and the role of different ligands are obtained. Based on the well-agreed EPR parameters and the d-d transitions (10<i>D</i>_<i>q</i>), the four Cu²⁺ centers show tetragonal and orthorhombic distortion, corresponding to the different anisotropies of EPR signals. In addition, the general rules of governing the impact of methanol in imidazolylalkyl derivatives are also discussed, especially the influence on the local environment (symmetry, distortion, covalency, and crystal field) of above four copper(II) chloride anionic coordination complexes. Therefore, the obtained results in this study will be beneficial to provide a theoretical basis for the experimental design of desired copper-containing imidazolyl alkyl derivatives.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141311041","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":"Simple MATLAB and Python scripts for multi-exponential analysis","authors":"Armin Afrough,&nbsp;Rasoul Mokhtari,&nbsp;Karen L. Feilberg","doi":"10.1002/mrc.5453","DOIUrl":"10.1002/mrc.5453","url":null,"abstract":"<p>Multi-exponential decay is prevalent in magnetic resonance spectroscopy, relaxation, and imaging. This paper describes simple MATLAB and Python functions and scripts for regularized multi-exponential analysis methods for 1D and 2D data and example test problems and experiments. Regularized least-squares solutions provide production-quality outputs with robust stopping rules in ~5 and ~20 lines of code for 1D and 2D inversions, respectively. The software provides an open-architecture simple solution for transforming exponential decay data to the distribution of their decay lifetimes. Examples from magnetic resonance relaxation of a complex fluid, a Danish North Sea crude oil, and fluid mixtures in porous materials—brine/crude oil mixture in North Sea reservoir chalk—are presented. Developed codes may be incorporated in other software or directly used by other researchers, in magnetic resonance relaxation, diffusion, and imaging or other physical phenomena that require multi-exponential analysis.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5453","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141175472","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}