Magnetic Resonance in Chemistry最新文献_第8页

Distinguishing between COOH, COO−, and hydrogen disordered COOH sites in solids with 13C chemical shift anisotropy and T1 measurements 利用 13 C 化学位移各向异性和 T1 测量区分固体中的 COOH、COO- 和氢无序 COOH 位点。

IF 2 3区化学

Magnetic Resonance in Chemistry Pub Date : 2024-01-18 DOI: 10.1002/mrc.5425

Ryan Toomey, Jacob Powell, Jacob Cheever, James K. Harper

引用次数: 0

Brewing alcohol 101: An undergraduate experiment utilizing benchtop NMR for quantification and process monitoring 酿造酒精 101：利用台式 NMR 进行定量和过程监控的本科生实验。

IF 2 3区化学

Magnetic Resonance in Chemistry Pub Date : 2024-01-17 DOI: 10.1002/mrc.5428

Amy Jenne, Ronald Soong, Katelyn Downey, Rajshree Ghosh Biswas, Venita Decker, Falko Busse, Benjamin Goerling, Agnes Haber, Myrna J. Simpson, Andre J. Simpson

{"title":"Brewing alcohol 101: An undergraduate experiment utilizing benchtop NMR for quantification and process monitoring","authors":"Amy Jenne, Ronald Soong, Katelyn Downey, Rajshree Ghosh Biswas, Venita Decker, Falko Busse, Benjamin Goerling, Agnes Haber, Myrna J. Simpson, Andre J. Simpson","doi":"10.1002/mrc.5428","DOIUrl":"10.1002/mrc.5428","url":null,"abstract":"In recent years there has been a renewed interest in benchtop NMR. Given their lower cost of ownership, smaller footprint, and ease of use, they are especially suited as an educational tool. Here, a new experiment targeted at upper-year undergraduates and first-year graduate students follows the conversion of D-glucose into ethanol at low-field. First, high and low-field data on D-glucose are compared and students learn both the Hz and ppm scales and how J-coupling is field-independent. The students then acquire their own quantitative NMR datasets and perform the quantification using an Electronic Reference To Access In Vivo Concentration (ERETIC) technique. To our knowledge ERETIC is not currently taught at the undergraduate level, but has an advantage in that internal standards are not required; ideal for following processes or with future use in flow-based benchtop monitoring. Using this quantitative data, students can relate a simple chemical process (fermentation) back to more complex topics such as reaction kinetics, bridging the gaps between analytical and physical chemistry. When asked to reflect on the experiment, students had an overwhelmingly positive experience, citing agreement with learning objectives, ease of understanding the protocol, and enjoyment. Each of the respondents recommended this experiment as a learning tool for others. This experiment has been outlined for other instructors to utilize in their own courses across institutions, with the hope that a continued expansion of low-field NMR will increase accessibility and learning opportunities at the undergraduate level.","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 6","pages":"429-438"},"PeriodicalIF":2.0,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5428","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139478772","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}

引用次数: 0

Carbon-13 chemical shift tensor measurements for nitrogen-dense compounds 氮密集化合物的碳-13 化学位移张量测量。

IF 2 3区化学

Magnetic Resonance in Chemistry Pub Date : 2024-01-17 DOI: 10.1002/mrc.5422

Sean T. Holmes, Cameron M. Boley, Angelika Dewicki, Zachary T. Gardner, Cameron S. Vojvodin, Robbie J. Iuliucci, Robert W. Schurko

{"title":"Carbon-13 chemical shift tensor measurements for nitrogen-dense compounds","authors":"Sean T. Holmes, Cameron M. Boley, Angelika Dewicki, Zachary T. Gardner, Cameron S. Vojvodin, Robbie J. Iuliucci, Robert W. Schurko","doi":"10.1002/mrc.5422","DOIUrl":"10.1002/mrc.5422","url":null,"abstract":"This paper reports the principal values of the 13C chemical shift tensors for five nitrogen-dense compounds (i.e., cytosine, uracil, imidazole, guanidine hydrochloride, and aminoguanidine hydrochloride). Although these are all fundamentally important compounds, the majority do not have 13C chemical shift tensors reported in the literature. The chemical shift tensors are obtained from 1H→13C cross-polarization magic-angle spinning (CP/MAS) experiments that were conducted at a high field of 18.8 T to suppress the effects of 14N-13C residual dipolar coupling. Quantum chemical calculations using density functional theory are used to obtain the 13C magnetic shielding tensors for these compounds. The best agreement with experiment arises from calculations using the hybrid functional PBE0 or the double-hybrid functional PBE0-DH, along with the triple-zeta basis sets TZ2P or pc-3, respectively, and intermolecular effects modeled using large clusters of molecules with electrostatic embedding through the COSMO approach. These measurements are part of an ongoing effort to expand the catalog of accurate 13C chemical shift tensor measurements, with the aim of creating a database that may be useful for benchmarking the accuracy of quantum chemical calculations, developing nuclear magnetic resonance (NMR) crystallography protocols, or aiding in applications involving machine learning or data mining. This work was conducted at the National High Magnetic Field Laboratory as part of a 2-week school for introducing undergraduate students to practical laboratory experience that will prepare them for scientific careers or postgraduate studies.","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 3","pages":"179-189"},"PeriodicalIF":2.0,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139478773","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

Temperature lowering of liquid nitrogen via injection of helium gas bubbles improves the generation of parahydrogen-enriched gas 通过注入氦气泡降低液氮温度，可改善富含对氢的气体的生成。

IF 2 3区化学

Magnetic Resonance in Chemistry Pub Date : 2024-01-03 DOI: 10.1002/mrc.5423

James Daley, Joseph Siciliano, Vincent Ferraro, Elodie Sutter, Adam Lounsbery, Nicholas Whiting

{"title":"Temperature lowering of liquid nitrogen via injection of helium gas bubbles improves the generation of parahydrogen-enriched gas","authors":"James Daley, Joseph Siciliano, Vincent Ferraro, Elodie Sutter, Adam Lounsbery, Nicholas Whiting","doi":"10.1002/mrc.5423","DOIUrl":"10.1002/mrc.5423","url":null,"abstract":"The para spin isomer of hydrogen gas possesses high nuclear spin order that can enhance the NMR signals of a variety of molecular species. Hydrogen is routinely enriched in the para spin state by lowering the gas temperature while flowing through a catalyst. Although parahydrogen enrichments approaching 100% are achievable near the H2 liquefaction temperature of 20 K, many experimentalists operate at liquid nitrogen temperatures (77 K) due to the lower associated costs and overall simplicity of the parahydrogen generator. Parahydrogen that is generated at 77 K provides an enrichment value of ~51% of the para spin isomer; while useful, there are many applications that can benefit from low-cost access to higher parahydrogen enrichments. Here, we introduce a method of improving parahydrogen enrichment values using a liquid nitrogen-cooled generator that operates at temperatures less than 77 K. The boiling temperature of liquid nitrogen is lowered through internal evaporation into helium gas bubbles that are injected into the liquid. Changes to liquid nitrogen temperatures and parahydrogen enrichment values were monitored as a function of helium gas flow rate. The injected helium bubbles lowered the liquid nitrogen temperature to ~65.5 K, and parahydrogen enrichments of up to ~59% were achieved; this represents an ~16% improvement compared with the expected parahydrogen fraction at 77 K. This technique is simple to implement in standard liquid nitrogen-cooled parahydrogen generators and may be of interest to a wide range of scientists that require a cost-effective approach to improving parahydrogen enrichment values.","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 2","pages":"94-100"},"PeriodicalIF":2.0,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139087444","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

A reliable external calibration method for reaction monitoring with benchtop NMR 用于台式核磁共振反应监测的可靠外部校准方法。

IF 2 3区化学

Magnetic Resonance in Chemistry Pub Date : 2023-12-20 DOI: 10.1002/mrc.5421

Tristan Maschmeyer, Breanna Conklin, Thomas C. Malig, David J. Russell, Kenji L. Kurita, Jason E. Hein, José G. Napolitano

{"title":"A reliable external calibration method for reaction monitoring with benchtop NMR","authors":"Tristan Maschmeyer, Breanna Conklin, Thomas C. Malig, David J. Russell, Kenji L. Kurita, Jason E. Hein, José G. Napolitano","doi":"10.1002/mrc.5421","DOIUrl":"10.1002/mrc.5421","url":null,"abstract":"Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical technique with the ability to acquire both quantitative and structurally insightful data for multiple components in a test sample. This makes NMR spectroscopy a desirable tool to understand, monitor, and optimize chemical transformations. While quantitative NMR (qNMR) approaches relying on internal standards are well-established, using an absolute external calibration scheme is beneficial for reaction monitoring as resonance overlap complications from an added reference material to the sample can be avoided. Particularly, this type of qNMR technique is of interest with benchtop NMR spectrometers as the likelihood of resonance overlap is only enhanced with the lower magnetic field strengths of the used permanent magnets. The included study describes a simple yet robust methodology to determine concentration conversion factors for NMR systems using single- and multi-analyte linear regression models. This approach is leveraged to investigate a pharmaceutically relevant amide coupling batch reaction. An on-line stopped-flow (i.e., interrupted-flow or paused-flow) benchtop NMR system was used to monitor both the 1,1′-carbonyldiimidazole (CDI) promoted acid activation and the amide coupling. The results highlight how quantitative measurements in benchtop NMR systems can provide valuable information and enable analysts to make decisions in real time.","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 3","pages":"169-178"},"PeriodicalIF":2.0,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5421","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138799996","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}

引用次数: 0

Twenty years of nmrshiftdb2: A case study of an open database for analytical chemistry nmrshiftdb2二十年：分析化学开放数据库案例研究。

IF 2 3区化学

Magnetic Resonance in Chemistry Pub Date : 2023-12-19 DOI: 10.1002/mrc.5418

Stefan Kuhn, Heinz Kolshorn, Christoph Steinbeck, Nils Schlörer

引用次数: 0

Predicting 51V nuclear magnetic resonance observables in molecular crystals 预测分子晶体中的 51 V 核磁共振观测值。

IF 2 3区化学

Magnetic Resonance in Chemistry Pub Date : 2023-12-19 DOI: 10.1002/mrc.5420

Joshua D. Hartman, Daniel Capistran

{"title":"Predicting 51V nuclear magnetic resonance observables in molecular crystals","authors":"Joshua D. Hartman, Daniel Capistran","doi":"10.1002/mrc.5420","DOIUrl":"10.1002/mrc.5420","url":null,"abstract":"Solid-state nuclear magnetic resonance (NMR) spectroscopy and quantum chemical density functional theory (DFT) calculations are widely used to characterize vanadium centers in biological and pharmaceutically relevant compounds. Several techniques have been recently developed to improve the accuracy of predicted NMR parameters obtained from DFT. Fragment-based and planewave-corrected methods employing hybrid density functionals are particularly effective tools for solid-state applications. A recent benchmark study involving molecular crystal compounds found that fragment-based NMR calculations using hybrid density functionals improve the accuracy of predicted 51V chemical shieldings by 20% relative to traditional planewave methods. This work extends the previous study, including a careful analysis of 51V chemical shift anisotropy, electric field gradient calculations, and a more extensive test set. The accuracy of planewave-corrected techniques and recently developed fragment-based methods using electrostatic embedding based on the polarized continuum model (PCM) are found to be highly competitive with previous methods. Planewave-corrected methods achieve a 34% improvement in the errors of predicted 51V chemical shieldings relative to planewave. Additionally, planewave-corrected and fragment-based calculations were performed using PCM embedding, improving the accuracy of predicted 51V chemical shielding (CS) tensor principal values by 30% and \u0000<math>\u0000 <msub>\u0000 <mrow>\u0000 <mi>C</mi>\u0000 </mrow>\u0000 <mrow>\u0000 <mi>q</mi>\u0000 </mrow>\u0000 </msub></math> values by 15% relative to traditional planewave methods. The performance of these methods is further examined using a redox-active oxovandium complex and a common 51V NMR reference compound.","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 6","pages":"416-428"},"PeriodicalIF":2.0,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5420","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138799984","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}

引用次数: 0

Polarization transfer methods for quantitative analysis of flowing mixtures with benchtop 13C NMR spectroscopy 利用台式 13 C NMR 光谱定量分析流动混合物的极化转移方法。

IF 2 3区化学

Magnetic Resonance in Chemistry Pub Date : 2023-12-19 DOI: 10.1002/mrc.5417

Johnnie Phuong, Zeno Romero, Hans Hasse, Kerstin Münnemann

{"title":"Polarization transfer methods for quantitative analysis of flowing mixtures with benchtop 13C NMR spectroscopy","authors":"Johnnie Phuong, Zeno Romero, Hans Hasse, Kerstin Münnemann","doi":"10.1002/mrc.5417","DOIUrl":"10.1002/mrc.5417","url":null,"abstract":"Benchtop NMR spectroscopy is attractive for process monitoring; however, there are still drawbacks that often hamper its use, namely, the comparatively low spectral resolution in 1H NMR, as well as the low signal intensities and problems with the premagnetization of flowing samples in 13C NMR. We show here that all these problems can be overcome by using 1H-13C polarization transfer methods. Two ternary test mixtures (one with overlapping peaks in the 1H NMR spectrum and one with well-separated peaks, which was used as a reference) were studied with a 1 T benchtop NMR spectrometer using the polarization transfer sequence PENDANT (polarization enhancement that is nurtured during attached nucleus testing). The mixtures were analyzed quantitatively in stationary as well as in flow experiments by PENDANT enhanced 13C NMR experiments, and the results were compared with those from the gravimetric sample preparation and from standard 1H and 13C NMR spectroscopy. Furthermore, as a proxy for a process monitoring application, continuous dilution experiments were carried out, and the composition of the mixture was monitored in a flow setup by 13C NMR benchtop spectroscopy with PENDANT. The results demonstrate the high potential of polarization transfer methods for applications in quantitative process analysis with benchtop NMR instruments, in particular with flowing samples.","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 5","pages":"398-411"},"PeriodicalIF":2.0,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5417","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138799997","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}

引用次数: 0

Intracellular pyruvate–lactate–alanine cycling detected using real-time nuclear magnetic resonance spectroscopy of live cells and isolated mitochondria 利用活细胞和分离线粒体的实时核磁共振光谱检测细胞内丙酮酸-乳酸-丙氨酸循环

IF 2 3区化学

Magnetic Resonance in Chemistry Pub Date : 2023-12-14 DOI: 10.1002/mrc.5419

G. A. Nagana Gowda, John A. Lusk, Vadim Pascua

{"title":"Intracellular pyruvate–lactate–alanine cycling detected using real-time nuclear magnetic resonance spectroscopy of live cells and isolated mitochondria","authors":"G. A. Nagana Gowda, John A. Lusk, Vadim Pascua","doi":"10.1002/mrc.5419","DOIUrl":"10.1002/mrc.5419","url":null,"abstract":"Pyruvate, an end product of glycolysis, is a master fuel for cellular energy. A portion of cytosolic pyruvate is transported into mitochondria, while the remaining portion is converted reversibly into lactate and alanine. It is suggested that cytosolic lactate and alanine are transported and metabolized inside mitochondria. However, such a mechanism continues to be a topic of intense debate and investigation. As a part of gaining insight into the metabolic fate of the cytosolic lactate and alanine; in this study, the metabolism of mouse skeletal myoblast cells (C2C12) and their isolated mitochondria was probed utilizing stable isotope-labeled forms of the three glycolysis products, viz. [3-13C1]pyruvate, [3-13C1]lactate, and [3-13C1]alanine, as substrates. The uptake and metabolism of each substrate was monitored, separately, in real-time using 1H-13C 2D nuclear magnetic resonance (NMR) spectroscopy. The dynamic variation of the levels of the substrates and their metabolic products were quantitated as a function of time. The results demonstrate that all three substrates were transported into mitochondria, and each substrate was metabolized to form the other two metabolites, reversibly. These results provide direct evidence for intracellular pyruvate–lactate–alanine cycling, in which lactate and alanine produced by the cytosolic pyruvate are transported into mitochondria and converted back to pyruvate. Such a mechanism suggests a role for lactate and alanine to replenish mitochondrial pyruvate, the primary source for adenosine triphosphate (ATP) synthesis through oxidative phosphorylation and the electron transport chain. The results highlight the potential of real-time NMR spectroscopy for gaining new insights into cellular and subcellular functions.","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 2","pages":"84-93"},"PeriodicalIF":2.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138688904","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

PDSFit: PDS data analysis in the presence of orientation selectivity, g-anisotropy, and exchange coupling PDSFit：存在取向选择性、g-各向异性和交换耦合时的 PDS 数据分析

IF 2 3区化学

Magnetic Resonance in Chemistry Pub Date : 2023-12-12 DOI: 10.1002/mrc.5415

Dinar Abdullin, Pablo Rauh Corro, Tobias Hett, Olav Schiemann

{"title":"PDSFit: PDS data analysis in the presence of orientation selectivity, g-anisotropy, and exchange coupling","authors":"Dinar Abdullin, Pablo Rauh Corro, Tobias Hett, Olav Schiemann","doi":"10.1002/mrc.5415","DOIUrl":"10.1002/mrc.5415","url":null,"abstract":"Pulsed dipolar electron paramagnetic resonance spectroscopy (PDS), encompassing techniques such as pulsed electron–electron double resonance (PELDOR or DEER) and relaxation-induced dipolar modulation enhancement (RIDME), is a valuable method in structural biology and materials science for obtaining nanometer-scale distance distributions between electron spin centers. An important aspect of PDS is the extraction of distance distributions from the measured time traces. Most software used for this PDS data analysis relies on simplifying assumptions, such as assuming isotropic g-factors of ~2 and neglecting orientation selectivity and exchange coupling. Here, the program PDSFit is introduced, which enables the analysis of PELDOR and RIDME time traces with or without orientation selectivity. It can be applied to spin systems consisting of up to two spin centers with anisotropic g-factors and to spin systems with exchange coupling. It employs a model-based fitting of the time traces using parametrized distance and angular distributions, and parametrized PDS background functions. The fitting procedure is followed by an error analysis for the optimized parameters of the distributions and backgrounds. Using five different experimental data sets published previously, the performance of PDSFit is tested and found to provide reliable solutions.","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 1","pages":"37-60"},"PeriodicalIF":2.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5415","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138689011","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}

引用次数: 0