Magnetic Resonance in Chemistry最新文献

Complete ¹H and ¹³C NMR Assignment of the ent-Labdane 2α-Hydroxyeperuic Acid Combining Conventional NMR Methods and HiFSA.

IF 1.9 3区化学

Magnetic Resonance in Chemistry Pub Date : 2025-03-11 DOI: 10.1002/mrc.5519

Francisco Juárez-Carrillo, Hugo A García-Gutiérrez, Mónica Luna-Vázquez, José Carlos Espinoza-Hicks, Judit A Aviña-Verduzco, Ramón Guzmán-Mejía, Concepción Armenta-Salinas, Carlos M Cerda-García-Rojas, Julio C Ontiveros-Rodríguez

引用次数: 0

Revisiting the Structure of Cacospongionolide E: An Approach Based on Empirical Rules and NMR Calculations.

IF 1.9 3区化学

Magnetic Resonance in Chemistry Pub Date : 2025-03-03 DOI: 10.1002/mrc.5518

Yuto Nishidono, Ken Tanaka

{"title":"Revisiting the Structure of Cacospongionolide E: An Approach Based on Empirical Rules and NMR Calculations.","authors":"Yuto Nishidono, Ken Tanaka","doi":"10.1002/mrc.5518","DOIUrl":"https://doi.org/10.1002/mrc.5518","url":null,"abstract":"In the field of natural product chemistry, the structures of several marine natural products have been erroneously determined. Here, we revisited the originally proposed structure of cacospongionolide E (1) using empirical rules in 13C NMR chemical shift analysis and density functional theory (DFT)-based NMR chemical shift calculations. Cacospongionolide E (1) is a marine natural product isolated from the Tyrrhenian sponge Fasciospongia cavernosa. Its originally proposed structure was established as sesterterpenoid of the trans-trans (TT) type, which adopts the trans-trans configuration of the 5-CH3/10-H-8-CH3/9-CH3 fragment. However, the present analysis based on empirical rules revealed that the reported 13C NMR chemical shifts of cacospongionolide E were more consistent with those of cis-trans (CT) type 2, which adopts the cis-trans configuration of the 5-CH3/10-H-8-CH3/9-CH3 fragment, than those of TT type 1. Furthermore, DFT-based 13C NMR chemical shift calculations, followed by the DP4 analysis, revealed that the reported 13C NMR chemical shifts of cacospongionolide E were more consistent with the calculated chemical shifts of CT type 2 than those of TT type 1. Thus, we propose the stereochemical revision of the structure of cacospongionolide E from the originally proposed structure 1 to our proposed structure 2. The study findings show that the proposed approach based on empirical rules and DFT-based NMR chemical shift calculations can identify the incorrect structures of marine natural products and provide the candidate for the correct structures.","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143542479","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}

引用次数: 0

Quantification of mRNA Using ³¹P NMR Spectroscopy and CRAFT.

IF 1.9 3区化学

Magnetic Resonance in Chemistry Pub Date : 2025-02-20 DOI: 10.1002/mrc.5516

Gennady Khirich, Vanessa A Noreika, Kaitlyn Doolittle Catlin, José G Napolitano, David J Russell, Oliver Birkholz, Jens Schumacher, Heinrich Haas, Ken Skidmore

{"title":"Quantification of mRNA Using 31P NMR Spectroscopy and CRAFT.","authors":"Gennady Khirich, Vanessa A Noreika, Kaitlyn Doolittle Catlin, José G Napolitano, David J Russell, Oliver Birkholz, Jens Schumacher, Heinrich Haas, Ken Skidmore","doi":"10.1002/mrc.5516","DOIUrl":"https://doi.org/10.1002/mrc.5516","url":null,"abstract":"Messenger RNA (mRNA) has emerged as a promising therapeutic modality in vaccine development due to its safety, efficacy, and rapid development potential. Reliable measurement and comparison of mRNA concentration in different chemical environments are crucial for research and manufacturing purposes. Conventionally, UV spectroscopy is used for quantification. However, variability in solution conditions, such as ionic strength, may influence the measurement of the UV absorbance at 260 nm, A260. This therefore necessitates accurate calibration of the extinction coefficient, ε, at a given set of solution conditions to the concentration of mRNA, as measured by an orthogonal and quantitative method. To that end, we utilized quantitative 31P NMR spectroscopy. We outline a general quantitative treatment of mRNA samples that may contain multiple polyadenylated mRNA sequences and show that the bias introduced by the method's assumptions into the measured mRNA concentrations is expected to be ≤ 4%. We also identified the limitations and subjectivities of accurate integration-based measurement of broad mRNA resonances in the frequency domain through a mini round-robin study. Quantification of broad mRNA signals using CRAFT in the time domain is shown to be superior to integration, as any subjectivity potentially introduced by the operator during spectral processing is obviated. This enables the use of 31P qNMR to accurately quantify total mRNA content and thus accurately calibrate mRNA extinction coefficients.","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143468482","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}

引用次数: 0

Solid-State NMR-Assisted Dynamic Characterization of two Isostructural Solvates of 5α-Bromo-6β,19-Epoxy-Androstan-3β,17β-Diol Diacetate.

IF 1.9 3区化学

Magnetic Resonance in Chemistry Pub Date : 2025-02-18 DOI: 10.1002/mrc.5517

Josué Vazquez-Chavez, Armando Navarro-Huerta, Marcos Flores-Álamo, Braulio Rodríguez-Molina, Martín A Iglesias-Arteaga

{"title":"Solid-State NMR-Assisted Dynamic Characterization of two Isostructural Solvates of 5α-Bromo-6β,19-Epoxy-Androstan-3β,17β-Diol Diacetate.","authors":"Josué Vazquez-Chavez, Armando Navarro-Huerta, Marcos Flores-Álamo, Braulio Rodríguez-Molina, Martín A Iglesias-Arteaga","doi":"10.1002/mrc.5517","DOIUrl":"https://doi.org/10.1002/mrc.5517","url":null,"abstract":"The study reports on the rotational dynamics of acetone-d6 (Form II) and DMSO-d6 (Form III) within the crystalline structures of two solvates of 5α-bromo-6β,19-epoxy-androstan-3β,17β-diol diacetate (Compound 1) by means of solid-state Nuclear Magnetic Resonance through the quadrupolar 2H spin-echo technique. The spectral data allowed the determination of the activation barriers (Ea) for rotation of the solvent molecules, with 6.24 kcal mol-1 for deuterated acetone in the Form II-d6 and 8.19 kcal mol-1 for the case of deuterated dimethylsulfoxide in Form III-d6. The use of calculations and the Transition State theory through the linear Eyring equation suggested that although the acetone molecules experience a low activation energy (Ea = 6.24 kcal mol-1), a highly ordered transition state during the molecular motion reduces its rotational rate. Conversely, the DMSO molecules, with a higher activation barrier (Ea = 8.19 kcal mol-1) attributed to a denser packing coefficient, have faster motional rates. Based on complementary X-ray and NMR spectroscopy techniques, this work provides detailed insights into the mechanistic phenomena involved in the mobility of small molecules inside crystalline arrangements.","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143449144","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}

引用次数: 0

The Optical Absorption and Electron Paramagnetic Resonance of Cu²⁺ Incorporated Dicalcium Lead Propionate.

IF 1.9 3区化学

Magnetic Resonance in Chemistry Pub Date : 2025-02-18 DOI: 10.1002/mrc.5515

Awadhesh Kumar Yadav, Ram Kripal

{"title":"The Optical Absorption and Electron Paramagnetic Resonance of Cu2+ Incorporated Dicalcium Lead Propionate.","authors":"Awadhesh Kumar Yadav, Ram Kripal","doi":"10.1002/mrc.5515","DOIUrl":"https://doi.org/10.1002/mrc.5515","url":null,"abstract":"Following γ-ray exposure, a room-temperature study of electron paramagnetic resonance (EPR) is conducted on Cu2+-doped dicalcium lead propionate (DCLP), Ca2Pb(C2H5COO)6. Cu2+ is found at four magnetically equivalent sites replacing Ca2+. EPR spectra are fitted to a rhombic symmetry Hamiltonian in order to determine the spin Hamiltonian parameters. The determined parameters are gx = 2.0245 ± 0.0002, gy = 2.1024 ± 0.0002, gz = 2.3476 ± 0.0002, Ax = (56 ± 2) × 10-4 cm-1, Ay = (78 ± 2) × 10-4 cm-1, and Az = (98 ± 2) × 10-4 cm-1. The experimental value of g-anisotropy is compared with the evaluated one. The wavefunction for the ground state is determined to be 0.999|x2 - y2> - 0.004|3z2 - r2>. The complex's bonding nature is determined with the aid of an optical study. The optical transitions dx2-y2 → dxy(2B1g → 2B2g), dx2-y2 → dxz,yz(2B1g → 2Eg), and dx2-y2 → d3 z2-r2(2B1g → 2A1g) are observed at 12,121, 18,691, and 25,316 cm-1, respectively. The molecular orbital coefficients α0 2, β1 2, β0 2, and β'2 and Fermi contact term K for Cu2+-doped DCLP are found as 0.63, 1.00, 1.00, 0.40, and 0.44, respectively.","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143449146","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}

引用次数: 0

RPA(D) and HRPA(D): Calculating NMR Spin–Spin Coupling Constants in Free Amino Acid Residues

IF 1.9 3区化学

Magnetic Resonance in Chemistry Pub Date : 2025-02-14 DOI: 10.1002/mrc.5514

Christoffer H. S. Møller, Stephan P. A. Sauer

引用次数: 0

EPR Spectra Hyperfine Structure of Fluorine-Containing Nitroxide Radicals in Liquid Solutions: Prediction by DFT

IF 1.9 3区化学

Magnetic Resonance in Chemistry Pub Date : 2025-02-03 DOI: 10.1002/mrc.5513

Mikhail V. Matveev, Sergei S. Lunkov, Natalia A. Chumakova

引用次数: 0

Theoretical Studies on the EPR Parameters and Local Structures for the Orthorhombic and Tetragonal Cu2+ Centers in Cu1−xHxZr2(PO4)3

IF 1.9 3区化学

Magnetic Resonance in Chemistry Pub Date : 2025-01-30 DOI: 10.1002/mrc.5509

Xiaojian Zhao, Yan Liang, Ruizhen Tian, Guijin Li, Xilin Zhou, Zifa Zhou, Xiaolan Zhang

{"title":"Theoretical Studies on the EPR Parameters and Local Structures for the Orthorhombic and Tetragonal Cu2+ Centers in Cu1−xHxZr2(PO4)3","authors":"Xiaojian Zhao, Yan Liang, Ruizhen Tian, Guijin Li, Xilin Zhou, Zifa Zhou, Xiaolan Zhang","doi":"10.1002/mrc.5509","DOIUrl":"10.1002/mrc.5509","url":null,"abstract":"<div>\u0000 \u0000 The defect structures of the orthorhombical and tetragonal Cu2+ centers in Cu1−xHxZr2(PO4)3 are theoretically studied by analyzing their experimental electron paramagnetic resonance (EPR) parameters, based on the perturbation formulas of these parameters for a 3d9 ion in orthorhombically and tetragonally elongated octahedra, respectively. The above centers are attributed to the Cu2+ ions locating at M(1) site, and the crystal field parameters (CFPs) are quantitatively determined from the superposition model and the local structures of the Cu2+ sites. Based on the calculation, the parallel Cu-O bonds may undergo the relative elongations ΔZO (≈ 0.113 Å) and ΔZT (≈ 0.102 Å) for the orthorhombical and tetragonal Cu2+ centers in Cu1−xHxZr2(PO4)3 along z-axis, respectively. Meanwhile, the planar Cu-O bonds are found to experience the relative variation δr (≈ 0.056 Å) along the x- and y-axes for the orthorhombical Cu2+ center because of the Jahn–Teller (JT) effect. The theoretical EPR parameters based on the above local structures agree well with the observed values.\u0000 </div>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"63 4","pages":"314-321"},"PeriodicalIF":1.9,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143066608","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}

引用次数: 0

Quantum Chemical NMR Spectroscopic Structural Analysis in Solution: The Investigation of 3-Indoleacetic Acid Dimer Formation in Chloroform and DMSO Solution

IF 1.9 3区化学

Magnetic Resonance in Chemistry Pub Date : 2025-01-26 DOI: 10.1002/mrc.5511

Haroldo C. Da Silva, Isabel S. Hernandes, Wagner B. De Almeida

{"title":"Quantum Chemical NMR Spectroscopic Structural Analysis in Solution: The Investigation of 3-Indoleacetic Acid Dimer Formation in Chloroform and DMSO Solution","authors":"Haroldo C. Da Silva, Isabel S. Hernandes, Wagner B. De Almeida","doi":"10.1002/mrc.5511","DOIUrl":"10.1002/mrc.5511","url":null,"abstract":"<div>\u0000 \u0000 We present a DFT-PCM NMR study of 3-indoleacetic acid (3-IAA), used as a working example, including explicit solvent molecules, named PCM-nCHCl3, PCM-nDMSO (n = 0, 2, 4, 8, 14, 20, and 25), to investigate the dimer formation in solution. Apart from well-known cyclic (I) and open (II) acetic acid (AA) dimers, two new structures were located on DFT-PCM potential energy surface (PES) for 3-IAA named quasicyclic A (III) and quasicyclic B (IV), the last one having N–H…O hydrogen bond (instead of O–H…O). In addition, four other structures having π–π type interactions named V, VI, VII, and VIII were also obtained completing the sample on the PES. Our theoretical results and experimental 1H NMR data (CDCl3) strongly indicate that 3-IAA should exist in a quasicyclic form (III) in a chloroform solution different from AA. Solute–solvent interactions play a key role in O–H and N–H chemical shifts. The strong H-bond formation between the S=O and O–H and N–H groups produces large chemical shift value THAT masquerades the identification of dimer formation in DMSO solution based on 1H NMR chemical shift changes. However, analysis of 13C NMR and relative energy DFT-PCM-nDMSO results strongly indicate the presence of parallel ring interacting dimer having OH…benzene ring bond (VI). There can be a competition between solute–solute and solute–solvent interactions, and polar DMSO solvent can break the quasicyclic dimers (III and IV) intermolecular O–H…O and N–H…O bonds yielding two solvated monomeric species hydrogen bonded to O=S(CH3)2 groups, what may take place for other organic molecules in solution. However, it did not happen for the π–π interacting dimers and structure VI survived in DMSO solution.\u0000 </div>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"63 4","pages":"292-313"},"PeriodicalIF":1.9,"publicationDate":"2025-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143046566","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}

引用次数: 0

Increasing the Orthogonality of 4-Pyridiniophenols: An NMR Study of Their Solvatomagnetism

IF 1.9 3区化学

Magnetic Resonance in Chemistry Pub Date : 2025-01-23 DOI: 10.1002/mrc.5512

Fabián Martínez-Gómez, Marcos Caroli Rezende, Valentina Rodríguez-Huenchún, Rodrigo Ormazábal-Toledo

引用次数: 0