Pub Date : 2024-12-01Epub Date: 2024-09-14DOI: 10.1016/j.jmro.2024.100163
Mark V. Höfler , Jonas Lins , David Seelinger , Lukas Pachernegg , Timmy Schäfer , Stefan Spirk , Markus Biesalski , Torsten Gutmann
This concept summarizes recent advances in development and application of DNP enhanced multinuclear solid-state NMR to study the molecular structure and surface functionalization of cellulose and paper-based materials. Moreover, a novel application is presented where DNP enhanced 13C and 15N solid-state NMR is used to identify structure moieties formed by cross-linking of hydroxypropyl cellulose. Given these two aspects of this concept-type of article, we thus combine both, a review on recent findings already published and unpublished recent data that complement the existing knowledge in the field of characterization of functional lignocellulosic materials by DNP enhanced solid-state NMR.
{"title":"DNP enhanced solid-state NMR – A powerful tool to address the surface functionalization of cellulose/paper derived materials","authors":"Mark V. Höfler , Jonas Lins , David Seelinger , Lukas Pachernegg , Timmy Schäfer , Stefan Spirk , Markus Biesalski , Torsten Gutmann","doi":"10.1016/j.jmro.2024.100163","DOIUrl":"10.1016/j.jmro.2024.100163","url":null,"abstract":"<div><div>This concept summarizes recent advances in development and application of DNP enhanced multinuclear solid-state NMR to study the molecular structure and surface functionalization of cellulose and paper-based materials. Moreover, a novel application is presented where DNP enhanced <sup>13</sup>C and <sup>15</sup>N solid-state NMR is used to identify structure moieties formed by cross-linking of hydroxypropyl cellulose. Given these two aspects of this concept-type of article, we thus combine both, a review on recent findings already published and unpublished recent data that complement the existing knowledge in the field of characterization of functional lignocellulosic materials by DNP enhanced solid-state NMR.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100163"},"PeriodicalIF":2.624,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142320068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01Epub Date: 2024-09-23DOI: 10.1016/j.jmro.2024.100166
Graham Norquay , Madhwesha R Rao , Jim M Wild
Background
The feasibility of imaging hyperpolarized 129Xe dissolved in brain tissue following inhalation of xenon gas in the lungs has recently been demonstrated in humans. The image contrast in 129Xe brain MRI represents a combination of factors, including regional perfusion, polarization decay and gas transfer rate across the blood-brain barrier.
Purpose
To investigate the repeatability of hyperpolarized 129Xe brain MRI in healthy normal individuals and to identify the dominant mechanisms of image contrast by assessing voxel-wise correlation between HP 129Xe brain MRI and models of 129Xe brain uptake derived from 1H arterial spin labeling (ASL) perfusion mapping.
Materials and Methods
To assess repeatability, 3 sets of hyperpolarized 129Xe brain images were acquired from 5 healthy volunteers. Quantitative maps of the human brain, including cerebral blood flow, volume and predicted xenon uptake, were derived from 1H arterial spin labeling and T2-weighted MRI. These maps were then spatially cross-correlated with hyperpolarized 129Xe brain MRI.
Results
Signal to noise ratios of 8.7–17.7 were observed across volunteers for a voxel size of 8 × 8 × 50 mm3 with intra-subject repeatability of between 6 and 29 %. Hyperpolarized 129Xe brain images showed voxel-wise correlations with cerebral blood flow (R = 0.32 to 0.62), volume (R = 0.33 to 0.63) and predicted xenon uptake (R = 0.34 to 0.63), but did not correlate with arterial transit time (R = 0.05 to 0.26).
Conclusion
Voxel-wise cross correlation between 129Xe and 1H ASL suggests that the regional quantity of dissolved xenon delivered by cerebral blood flow is the dominant mechanism of image contrast in HP 129Xe brain MRI, assuming normal blood-brain barrier function. Combining 1H and 129Xe brain MRI provides new opportunities to quantitatively investigate brain pathophysiology and function.
{"title":"Measurement and modeling of xenon gas transfer in the human brain with 1H and hyperpolarized 129Xe MRI","authors":"Graham Norquay , Madhwesha R Rao , Jim M Wild","doi":"10.1016/j.jmro.2024.100166","DOIUrl":"10.1016/j.jmro.2024.100166","url":null,"abstract":"<div><h3>Background</h3><div>The feasibility of imaging hyperpolarized <sup>129</sup>Xe dissolved in brain tissue following inhalation of xenon gas in the lungs has recently been demonstrated in humans. The image contrast in <sup>129</sup>Xe brain MRI represents a combination of factors, including regional perfusion, polarization decay and gas transfer rate across the blood-brain barrier.</div></div><div><h3>Purpose</h3><div>To investigate the repeatability of hyperpolarized <sup>129</sup>Xe brain MRI in healthy normal individuals and to identify the dominant mechanisms of image contrast by assessing voxel-wise correlation between HP <sup>129</sup>Xe brain MRI and models of <sup>129</sup>Xe brain uptake derived from <sup>1</sup>H arterial spin labeling (ASL) perfusion mapping.</div></div><div><h3>Materials and Methods</h3><div>To assess repeatability, 3 sets of hyperpolarized <sup>129</sup>Xe brain images were acquired from 5 healthy volunteers. Quantitative maps of the human brain, including cerebral blood flow, volume and predicted xenon uptake, were derived from <sup>1</sup>H arterial spin labeling and <em>T</em><sub>2</sub>-weighted MRI. These maps were then spatially cross-correlated with hyperpolarized <sup>129</sup>Xe brain MRI.</div></div><div><h3>Results</h3><div>Signal to noise ratios of 8.7–17.7 were observed across volunteers for a voxel size of 8 × 8 × 50 mm<sup>3</sup> with intra-subject repeatability of between 6 and 29 %. Hyperpolarized <sup>129</sup>Xe brain images showed voxel-wise correlations with cerebral blood flow (<em>R</em> = 0.32 to 0.62), volume (<em>R</em> = 0.33 to 0.63) and predicted xenon uptake (<em>R</em> = 0.34 to 0.63), but did not correlate with arterial transit time (<em>R</em> = 0.05 to 0.26).</div></div><div><h3>Conclusion</h3><div>Voxel-wise cross correlation between <sup>129</sup>Xe and <sup>1</sup>H ASL suggests that the regional quantity of dissolved xenon delivered by cerebral blood flow is the dominant mechanism of image contrast in HP <sup>129</sup>Xe brain MRI, assuming normal blood-brain barrier function. Combining <sup>1</sup>H and <sup>129</sup>Xe brain MRI provides new opportunities to quantitatively investigate brain pathophysiology and function.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100166"},"PeriodicalIF":2.624,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142327332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01Epub Date: 2024-10-10DOI: 10.1016/j.jmro.2024.100169
D. Panariti , B.J. Bayard , A. Barbon , Y.E. Kandrashkin , P.K. Poddutoori , A. van der Est , M. Di Valentin
Photoexcited triplet states of porphyrins are of great relevance in various applications due to their high yield, long lifetime, and strong electron spin polarization. This study delves into properties and spin dynamics of the triplet state of a series of hypervalent phosphorus(V) porphyrins. Transient Electron Paramagnetic Resonance (TrEPR) measurements, supported by quantum chemical calculations as well as by optical absorption/luminescence experiments, reveal that, unlike singlet states, the lowest triplet state does not exhibit charge-transfer (CT) character upon photoexcitation. However, the presence of excited CT singlet states alters the intersystem crossing in phosphorus(V) porphyrins, leading to a sign change in the initial multiplet polarization of the photoexcited triplet state. TrEPR results further demonstrate that significant net polarization develops in the triplet states of the phosphorus(V) porphyrins due to the dynamic Jahn-Teller effect. Yet, this effect remains largely unaffected by differences in their molecular structures.
{"title":"Electron spin polarization in the triplet state of methoxy-substituted phosphorus(V) tetraphenyl porphyrins","authors":"D. Panariti , B.J. Bayard , A. Barbon , Y.E. Kandrashkin , P.K. Poddutoori , A. van der Est , M. Di Valentin","doi":"10.1016/j.jmro.2024.100169","DOIUrl":"10.1016/j.jmro.2024.100169","url":null,"abstract":"<div><div>Photoexcited triplet states of porphyrins are of great relevance in various applications due to their high yield, long lifetime, and strong electron spin polarization. This study delves into properties and spin dynamics of the triplet state of a series of hypervalent phosphorus(V) porphyrins. Transient Electron Paramagnetic Resonance (TrEPR) measurements, supported by quantum chemical calculations as well as by optical absorption/luminescence experiments, reveal that, unlike singlet states, the lowest triplet state does not exhibit charge-transfer (CT) character upon photoexcitation. However, the presence of excited CT singlet states alters the intersystem crossing in phosphorus(V) porphyrins, leading to a sign change in the initial multiplet polarization of the photoexcited triplet state. TrEPR results further demonstrate that significant net polarization develops in the triplet states of the phosphorus(V) porphyrins due to the dynamic Jahn-Teller effect. Yet, this effect remains largely unaffected by differences in their molecular structures.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100169"},"PeriodicalIF":2.624,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142704450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01Epub Date: 2024-11-07DOI: 10.1016/j.jmro.2024.100173
Ilia B. Moroz, Neta Katzav, Asya Svirinovsky-Arbeli, Michal Leskes
In this protocol we outline the practical aspects and methodology for performing metal ions-based dynamic nuclear polarization (MI-DNP), focusing on materials science applications. In MI-DNP polarization is transferred from unpaired electrons of paramagnetic metal ions to nearby nuclear spins, thereby increasing the sensitivity of NMR spectroscopy. The protocol encompasses detailed steps for (i) selecting suitable metal ion dopant based on chemical, structural and electron paramagnetic resonance (EPR) considerations, (ii) characterizing the concentration, homogeneity and EPR properties of the dopant and (iii) performing the MI-DNP experiment itself, including optimization of the field position and reliable assessment of the DNP enhancement factors. By adhering to this protocol, the interested reader can implement the MI-DNP approach in an efficient way, facilitating spectroscopic studies of functional materials.
{"title":"A practical guide to metal ions dynamic nuclear polarization in materials science","authors":"Ilia B. Moroz, Neta Katzav, Asya Svirinovsky-Arbeli, Michal Leskes","doi":"10.1016/j.jmro.2024.100173","DOIUrl":"10.1016/j.jmro.2024.100173","url":null,"abstract":"<div><div>In this protocol we outline the practical aspects and methodology for performing metal ions-based dynamic nuclear polarization (MI-DNP), focusing on materials science applications. In MI-DNP polarization is transferred from unpaired electrons of paramagnetic metal ions to nearby nuclear spins, thereby increasing the sensitivity of NMR spectroscopy. The protocol encompasses detailed steps for (i) selecting suitable metal ion dopant based on chemical, structural and electron paramagnetic resonance (EPR) considerations, (ii) characterizing the concentration, homogeneity and EPR properties of the dopant and (iii) performing the MI-DNP experiment itself, including optimization of the field position and reliable assessment of the DNP enhancement factors. By adhering to this protocol, the interested reader can implement the MI-DNP approach in an efficient way, facilitating spectroscopic studies of functional materials.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100173"},"PeriodicalIF":2.624,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142653620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01Epub Date: 2024-11-26DOI: 10.1016/j.jmro.2024.100180
Shushu Gao , Jiamin Yuan , Fangxiu Ye , Zhiqiang Liu , Anming Zheng , Shutao Xu
Molecular sieves possess unique properties and have emerged as the predominant catalysts with shape selectivity in the petrochemical industry because of their well-defined pore architectures. However, the existence of a constrained pore surroundings of molecular sieves can limit intracrystalline diffusion, leading to underutilization of the active volume of the molecular sieve or rapid catalysts deactivation during catalytic processes. Moreover, the mechanism of adsorption and diffusion of molecules inside molecular sieves is crucial for the optimization and advancement of catalysts in heterogeneous catalysis. Due to the complexity of the diffusion process in molecular sieve materials, it is very necessary to develop characterization methods that are more sensitive and informative for studying the adsorption and diffusion of guests inside pores. Advancements in characterization techniques and theoretical calculations have led to a more profound comprehension of the adsorption and diffusion properties of molecular sieves at the microscopic scale. This article mainly summarizes the research progress of molecular adsorption and diffusion in molecular sieve materials using advanced 129Xe NMR, hyperpolarized (HP) 129Xe NMR, and pulsed-field gradient (PFG) NMR techniques in recent years and focuses on the principles of these techniques and applicability of the relationship of adsorption-diffusion using these techniques within several molecular sieve systems. Moreover, the effects of the topology and pore connectivity of molecular sieves on the adsorption and diffusion of guest molecules as well as the effects of intracrystalline diffusion on catalytic reactions are discussed.
{"title":"Applications of 129Xe and PFG NMR techniques on adsorption and diffusion of molecular sieve materials","authors":"Shushu Gao , Jiamin Yuan , Fangxiu Ye , Zhiqiang Liu , Anming Zheng , Shutao Xu","doi":"10.1016/j.jmro.2024.100180","DOIUrl":"10.1016/j.jmro.2024.100180","url":null,"abstract":"<div><div>Molecular sieves possess unique properties and have emerged as the predominant catalysts with shape selectivity in the petrochemical industry because of their well-defined pore architectures. However, the existence of a constrained pore surroundings of molecular sieves can limit intracrystalline diffusion, leading to underutilization of the active volume of the molecular sieve or rapid catalysts deactivation during catalytic processes. Moreover, the mechanism of adsorption and diffusion of molecules inside molecular sieves is crucial for the optimization and advancement of catalysts in heterogeneous catalysis. Due to the complexity of the diffusion process in molecular sieve materials, it is very necessary to develop characterization methods that are more sensitive and informative for studying the adsorption and diffusion of guests inside pores. Advancements in characterization techniques and theoretical calculations have led to a more profound comprehension of the adsorption and diffusion properties of molecular sieves at the microscopic scale. This article mainly summarizes the research progress of molecular adsorption and diffusion in molecular sieve materials using advanced <sup>129</sup>Xe NMR, hyperpolarized (HP) <sup>129</sup>Xe NMR, and pulsed-field gradient (PFG) NMR techniques in recent years and focuses on the principles of these techniques and applicability of the relationship of adsorption-diffusion using these techniques within several molecular sieve systems. Moreover, the effects of the topology and pore connectivity of molecular sieves on the adsorption and diffusion of guest molecules as well as the effects of intracrystalline diffusion on catalytic reactions are discussed.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100180"},"PeriodicalIF":2.624,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142745759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01Epub Date: 2024-11-09DOI: 10.1016/j.jmro.2024.100175
Max Filkins , Arthur Harrison , Guilhem J. Collier , Graham Norquay , Jim M. Wild , Sean P. Rigby , Galina E. Pavlovskaya , Thomas Meersmann
Pulmonary MRI of hyperpolarized xenon-129 (hp129Xe) dissolved in the lung parenchyma and vascular phase is gaining increasing attention for clinical assessment of gas exchange in multiple diseases. These conditions can involve thickening of barrier tissues due to fibrotic scarring or reduced capillary blood flow leading to diminished gas-blood exchange hence, the ratios between hp129Xe signals arising from the lung membrane (M), the red blood cells (RBC), and the gas phase hold significant diagnostic value. However, comparing hp129Xe signal ratios quantitatively across different studies may pose challenges due to varied experimental conditions and opted pulse sequence protocols.
A solution to this problem arises from materials science applications of hp129Xe where xenon dissolved in porous materials or polymers can display chemical shifts similar to the M and RBC shift in lungs. This work explored the generation of MR spectral profiles with respect to chemical shift and signal intensity ratios that closely resemble spectral profiles observed in human lungs in health and disease. At ambient temperatures, reticulated open cell polyurethane foam treated with olive oil as a fatty phase produced dissolved phase 129Xe chemical shifts of 215 ppm and 196 ppm, respectively, that emulate typical RBC and M signals. The uptake kinetics into the non-toxic materials was sufficiently similar to pulmonary signal uptake to enable hp129Xe MRI with dissolved phase ratios that closely resembled clinical data.
A phantom assembly was devised to allow for gas handling protocols that matched clinical protocols. The current iteration of the developed phantom enables rapid testing of basic experimental protocols and can be used for training purposes without regulatory approval and governance. Furthermore, the introduced concept shows a pathway for the development of a quantitative universal phantom standard for dissolved phase pulmonary hp129Xe MRI. A robust phantom standard will require materials with longer shelf lifetime than the oil-foam system used in this study and would benefit from a hierarchical porous network with more defined microstructure similar to that found in lungs.
{"title":"A standardized MRI phantom for dissolved phase 129Xe MRI","authors":"Max Filkins , Arthur Harrison , Guilhem J. Collier , Graham Norquay , Jim M. Wild , Sean P. Rigby , Galina E. Pavlovskaya , Thomas Meersmann","doi":"10.1016/j.jmro.2024.100175","DOIUrl":"10.1016/j.jmro.2024.100175","url":null,"abstract":"<div><div>Pulmonary MRI of hyperpolarized xenon-129 (hp<sup>129</sup>Xe) dissolved in the lung parenchyma and vascular phase is gaining increasing attention for clinical assessment of gas exchange in multiple diseases. These conditions can involve thickening of barrier tissues due to fibrotic scarring or reduced capillary blood flow leading to diminished gas-blood exchange hence, the ratios between hp<sup>129</sup>Xe signals arising from the lung membrane (M), the red blood cells (RBC), and the gas phase hold significant diagnostic value. However, comparing hp<sup>129</sup>Xe signal ratios quantitatively across different studies may pose challenges due to varied experimental conditions and opted pulse sequence protocols.</div><div>A solution to this problem arises from materials science applications of hp<sup>129</sup>Xe where xenon dissolved in porous materials or polymers can display chemical shifts similar to the M and RBC shift in lungs. This work explored the generation of MR spectral profiles with respect to chemical shift and signal intensity ratios that closely resemble spectral profiles observed in human lungs in health and disease. At ambient temperatures, reticulated open cell polyurethane foam treated with olive oil as a fatty phase produced dissolved phase <sup>129</sup>Xe chemical shifts of 215 ppm and 196 ppm, respectively, that emulate typical RBC and M signals. The uptake kinetics into the non-toxic materials was sufficiently similar to pulmonary signal uptake to enable hp<sup>129</sup>Xe MRI with dissolved phase ratios that closely resembled clinical data.</div><div>A phantom assembly was devised to allow for gas handling protocols that matched clinical protocols. The current iteration of the developed phantom enables rapid testing of basic experimental protocols and can be used for training purposes without regulatory approval and governance. Furthermore, the introduced concept shows a pathway for the development of a quantitative universal phantom standard for dissolved phase pulmonary hp<sup>129</sup>Xe MRI. A robust phantom standard will require materials with longer shelf lifetime than the oil-foam system used in this study and would benefit from a hierarchical porous network with more defined microstructure similar to that found in lungs.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100175"},"PeriodicalIF":2.624,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142704449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01Epub Date: 2024-11-23DOI: 10.1016/j.jmro.2024.100178
Shubham Kumar Debadatta, Sheetal Kumar Jain
Nitrogen vacancy centers in diamonds are promising spin-based quantum sensors and qubits. These optically addressable paramagnetic point defects have the potential to allow efficient dynamic nuclear polarization (DNP) under ambient conditions due to their large electron spin polarization and long spin coherence time. NV-based DNP studies have shown significant sensitivity enhancement of 13C nuclear magnetic resonance (NMR). In this work, we present an analytical theory using a density matrix and average Hamiltonian theory for NV-13C spin system under varying magnetic fields, internal interaction strengths, and microwave irradiation parameters. We use a reduced basis approach under selective excitation of a single quantum transition in NV-center electron spin levels to derive the expressions for the matching conditions, effective Hamiltonian and polarization transfer frequency. Our results provide insight into the optimal experimental conditions for efficient DNP and the impact of the internal interactions on the DNP performance. The theoretical predictions are verified using numerical simulations.
{"title":"Dynamic nuclear polarization mechanism in isolated NV-centers at high magnetic fields","authors":"Shubham Kumar Debadatta, Sheetal Kumar Jain","doi":"10.1016/j.jmro.2024.100178","DOIUrl":"10.1016/j.jmro.2024.100178","url":null,"abstract":"<div><div>Nitrogen vacancy centers in diamonds are promising spin-based quantum sensors and qubits. These optically addressable paramagnetic point defects have the potential to allow efficient dynamic nuclear polarization (DNP) under ambient conditions due to their large electron spin polarization and long spin coherence time. NV-based DNP studies have shown significant sensitivity enhancement of <sup>13</sup>C nuclear magnetic resonance (NMR). In this work, we present an analytical theory using a density matrix and average Hamiltonian theory for NV-<sup>13</sup>C spin system under varying magnetic fields, internal interaction strengths, and microwave irradiation parameters. We use a reduced basis approach under selective excitation of a single quantum transition in NV-center electron spin levels to derive the expressions for the matching conditions, effective Hamiltonian and polarization transfer frequency. Our results provide insight into the optimal experimental conditions for efficient DNP and the impact of the internal interactions on the DNP performance. The theoretical predictions are verified using numerical simulations.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100178"},"PeriodicalIF":2.624,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01Epub Date: 2024-11-17DOI: 10.1016/j.jmro.2024.100176
Dudari B. Burueva , Sergey V. Sviyazov , Nikita V. Chukanov , Nazim R. Mustafin , Oleg G. Salnikov , Eduard Y. Chekmenev , Kirill V. Kovtunov , Igor V. Koptyug
Sodium [13C]formate was successfully hyperpolarized using parahydrogen-induced polarization by means of side-arm hydrogenation (PHIP-SAH). Allyl [13C]formate was hyperpolarized using homogeneous hydrogenation of the corresponding unsaturated precursor (propargyl [13C]formate) in acetone-d6 with parahydrogen. The observed proton polarization was estimated as 16.6 ± 0.6 % while achieving 80 % chemical conversion. The 1H-to-13C polarization transfer was performed using magnetic field cycling. The highest observed polarization for 13C nuclei was estimated as 1.7 ± 0.2 % and was obtained at 250 nT polarization transfer magnetic field. We demonstrate that the 13C hyperpolarization is retained during the hydrolysis of allyl [13C]formate and hyperpolarized sodium [13C]formate was produced with P13C of 0.4 ± 0.1 %.
{"title":"Hyperpolarization of [13C]formate using parahydrogen","authors":"Dudari B. Burueva , Sergey V. Sviyazov , Nikita V. Chukanov , Nazim R. Mustafin , Oleg G. Salnikov , Eduard Y. Chekmenev , Kirill V. Kovtunov , Igor V. Koptyug","doi":"10.1016/j.jmro.2024.100176","DOIUrl":"10.1016/j.jmro.2024.100176","url":null,"abstract":"<div><div>Sodium [<sup>13</sup>C]formate was successfully hyperpolarized using parahydrogen-induced polarization by means of side-arm hydrogenation (PHIP-SAH). Allyl [<sup>13</sup>C]formate was hyperpolarized using homogeneous hydrogenation of the corresponding unsaturated precursor (propargyl [<sup>13</sup>C]formate) in acetone-d<sub>6</sub> with parahydrogen. The observed proton polarization was estimated as 16.6 ± 0.6 % while achieving 80 % chemical conversion. The <sup>1</sup>H-to-<sup>13</sup>C polarization transfer was performed using magnetic field cycling. The highest observed polarization for <sup>13</sup>C nuclei was estimated as 1.7 ± 0.2 % and was obtained at 250 nT polarization transfer magnetic field. We demonstrate that the <sup>13</sup>C hyperpolarization is retained during the hydrolysis of allyl [<sup>13</sup>C]formate and hyperpolarized sodium [<sup>13</sup>C]formate was produced with P<sub>13C</sub> of 0.4 ± 0.1 %.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100176"},"PeriodicalIF":2.624,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142704451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01Epub Date: 2024-11-16DOI: 10.1016/j.jmro.2024.100172
Karel Kouřil , Benno Meier
Hyperpolarization can boost the sensitivity of nuclear magnetic resonance. Other things being equal, a polarization increase by one order of magnitude leads to a time saving by two orders of magnitude. However, other things are rarely equal, and in this tutorial article we calculate how side effects of hyperpolarization, namely changes in duty cycle, dilution, and resolution, influence the net sensitivity and time savings of the (hyperpolarized) NMR experiment. The signal-to-noise ratio is calculated both in time- and frequency-domain for a sample at thermal equilibrium using the principle of reciprocity. The hyperpolarized time gain (HYTIGA) is calculated separately for concentration- and mass-limited samples. The article includes a detailed appendix on the measurement of the coil’s -factor.
{"title":"Hyperpolarization and sensitivity in nuclear magnetic resonance","authors":"Karel Kouřil , Benno Meier","doi":"10.1016/j.jmro.2024.100172","DOIUrl":"10.1016/j.jmro.2024.100172","url":null,"abstract":"<div><div>Hyperpolarization can boost the sensitivity of nuclear magnetic resonance. Other things being equal, a polarization increase by one order of magnitude leads to a time saving by two orders of magnitude. However, other things are rarely equal, and in this tutorial article we calculate how side effects of hyperpolarization, namely changes in duty cycle, dilution, and resolution, influence the net sensitivity and time savings of the (hyperpolarized) NMR experiment. The signal-to-noise ratio is calculated both in time- and frequency-domain for a sample at thermal equilibrium using the principle of reciprocity. The hyperpolarized time gain (HYTIGA) is calculated separately for concentration- and mass-limited samples. The article includes a detailed appendix on the measurement of the coil’s <span><math><mi>Q</mi></math></span>-factor.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"21 ","pages":"Article 100172"},"PeriodicalIF":2.624,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142704453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-01Epub Date: 2024-10-09DOI: 10.1016/j.jmro.2024.100167
Zhuoran Wang , Thomas C. Robinson , Domenico Gioffrè , Rochlitz Lukas , David Gajan , Aaron J. Rossini , Christophe Copéret , Anne Lesage
Surface organometallic chemistry has developed as an effective strategy for the rational design and synthesis of well-defined, single-site Pt-based heterogeneous catalysts. Given its high sensitivity to changes in electronic structure, 195Pt solid-state NMR spectroscopy offers a unique approach to investigate the chemical structure and local environment of Pt surface sites, providing invaluable insights for establishing structure-activity relationships. However, this approach is typically hindered by severe sensitivity issues, due to the low loading of Pt sites and the often-encountered large 195Pt chemical shift anisotropies. To overcome this limitation, 195Pt NMR signature of surface metal centers can be indirectly detected through protons. Indirect detection on 13C spins, has also been demonstrated to be feasible by combining isotopic labeling with dynamic nuclear polarization (DNP). Here, we extend this methodology to a supported Pt complex at natural abundance. The material was prepared by grafting (COD)PtMeOSi(OtBu)3 (COD = 1,5-cyclooctadiene, Me = methyl and tBu = tert‑butyl) onto partially dehydroxylated silica. DNP enhanced two-dimensional through-bond 13C{195Pt} heteronuclear correlation experiments were successfully implemented at fast magic angle spinning. They enabled the detection of the 0.37 % NMR-responsive surface species, thereby showcasing the remarkable sensitivity of this approach and its broad applicability. Key bonding information was obtained by measuring the correlated 13C and 195Pt isotopic chemical shifts as well as 1J(13C-195Pt) coupling constants, confirming directly the coordination structure of the surface Pt sites.
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