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Efficient Dynamic Nuclear Polarization at 800 MHz/527 GHz with Trityl‐Nitroxide Biradicals 下载免费PDF全文
Dr. Guinevere Mathies Dr. Marc A. Caporini Dr. Vladimir K. Michaelis Prof. Yangping Liu Dr. Kan‐Nian Hu Deni Mance Prof. Jay L. Zweier Dr. Melanie Rosay Prof. Marc Baldus Prof. Robert G. Griffin 《Angewandte Chemie (International ed. in English)》2015,54(40):11770-11774
Cross‐effect (CE) dynamic nuclear polarization (DNP) is a rapidly developing technique that enhances the signal intensities in magic‐angle spinning (MAS) NMR spectra. We report CE DNP experiments at 211, 600, and 800 MHz using a new series of biradical polarizing agents referred to as TEMTriPols, in which a nitroxide (TEMPO) and a trityl radical are chemically tethered. The TEMTriPol molecule with the optimal performance yields a record 1H NMR signal enhancement of 65 at 800 MHz at a concentration of 10 mM in a glycerol/water solvent matrix. The CE DNP enhancement for the TEMTriPol biradicals does not decrease as the magnetic field is increased in the manner usually observed for bis‐nitroxides. Instead, the relatively strong exchange interaction between the trityl and nitroxide moieties determines the magnetic field at which the optimum enhancement is observed. 相似文献
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Yoh Matsuki Dr. Thorsten Maly Dr. Olivier Ouari Dr. Hakim Karoui Dr. François Le Moigne Dr. Egon Rizzato Dr. Sevdalina Lyubenova Dr. Judith Herzfeld Prof. Thomas Prisner Prof. Paul Tordo Prof. Robert G. Griffin Prof. 《Angewandte Chemie (International ed. in English)》2009,48(27):4996-5000
A new polarizing agent with superior performance in dynamic nuclear polarization experiments is introduced, and utilizes two TEMPO (2,2,6,6‐tetramethylpiperidine‐1‐oxyl) moieties connected through a rigid spiro tether (see structure). The observed NMR signal intensities were enhanced by a factor of 1.4 compared to those of TOTAPOL, a previously described TEMPO‐based biradical with a flexible tether.
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Xinyi. Cai Dr. Alessandra Lucini Paioni Agnes Adler Ru Yao Wenxiao Zhang David Beriashvili Adil Safeer Andrei Gurinov Prof. Antal Rockenbauer Prof. Dr. Yuguang Song Prof. Dr. Marc Baldus Prof. Dr. Yangping Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(50):12758-12762
Dynamic nuclear polarization (DNP) is a powerful method to enhance the sensitivity of solid-state magnetic nuclear resonance (ssNMR) spectroscopy. However, its biomolecular applications at high magnetic fields (preferably>14 T) have so far been limited by the intrinsically low efficiency of polarizing agents and sample preparation aspects. Herein, we report a new class of trityl-nitroxide biradicals, dubbed SNAPols that combine high DNP efficiency with greatly enhanced hydrophilicity. SNAPol-1, the best compound in the series, shows DNP enhancement factors at 18.8 T of more than 100 in small molecules and globular proteins and also exhibits strong DNP enhancements in membrane proteins and cellular preparations. By integrating optimal sensitivity and high resolution, we expect widespread applications of this new polarizing agent in high-field DNP/ssNMR spectroscopy, especially for complex biomolecules. 相似文献
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Björn C. Dollmann Dr. Andrei L. Kleschyov Dr. Vasily Sen Dr. Valery Golubev Prof. Dr. Laura M. Schreiber Prof. Dr. Hans W. Spiess Dr. Kerstin Münnemann Dr. Dariush Hinderberger 《Chemphyschem》2010,11(17):3656-3663
A potentially biocompatible class of spin‐labeled macromolecules, spin‐labeled (SL) heparins, and their use as nuclear magnetic resonance (NMR) signal enhancers are introduced. The signal enhancement is achieved through Overhauser‐type dynamic nuclear polarization (DNP). All presented SL‐heparins show high 1H DNP enhancement factors up to E=?110, which validates that effectively more than one hyperfine line can be saturated even for spin‐labeled polarizing agents. The parameters for the Overhauser‐type DNP are determined and discussed. A striking result is that for spin‐labeled heparins, the off‐resonant electron paramagnetic resonance (EPR) hyperfine lines contribute a non‐negligible part to the total saturation, even in the absence of Heisenberg spin exchange (HSE) and electron spin‐nuclear spin relaxation (T1ne). As a result, we conclude that one can optimize the use of, for example, biomacromolecules for DNP, for which only small sample amounts are available, by using heterogeneously distributed radicals attached to the molecule. 相似文献
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Adam N. Smith Dr. Marc A. Caporini Prof. Gail E. Fanucci Prof. Joanna R. Long 《Angewandte Chemie (International ed. in English)》2015,54(5):1542-1546
Dynamic nuclear polarization (DNP) magic‐angle spinning (MAS) solid‐state NMR (ssNMR) spectroscopy has the potential to enhance NMR signals by orders of magnitude and to enable NMR characterization of proteins which are inherently dilute, such as membrane proteins. In this work spin‐labeled lipid molecules (SL‐lipids), when used as polarizing agents, lead to large and relatively homogeneous DNP enhancements throughout the lipid bilayer and to an embedded lung surfactant mimetic peptide, KL4. Specifically, DNP MAS ssNMR experiments at 600 MHz/395 GHz on KL4 reconstituted in liposomes containing SL‐lipids reveal DNP enhancement values over two times larger for KL4 compared to liposome suspensions containing the biradical TOTAPOL. These findings suggest an alternative sample preparation strategy for DNP MAS ssNMR studies of lipid membranes and integral membrane proteins. 相似文献
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Tailoring of Polarizing Agents in the bTurea Series for Cross‐Effect Dynamic Nuclear Polarization in Aqueous Media 下载免费PDF全文
Claire Sauvée Dr. Gilles Casano Dr. Sébastien Abel Prof. Antal Rockenbauer Dr. Dimitry Akhmetzyanov Dr. Hakim Karoui Prof. Didier Siri Dr. Fabien Aussenac Dr. Werner Maas Dr. Ralph T. Weber Prof. Thomas Prisner Dr. Mélanie Rosay Prof. Paul Tordo Dr. Olivier Ouari 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(16):5598-5606
A series of 18 nitroxide biradicals derived from bTurea has been prepared, and their enhancement factors ? (1H) in cross‐effect dynamic nuclear polarization (CE DNP) NMR experiments at 9.4 and 14.1 T and 100 K in a DNP‐optimized glycerol/water matrix (“DNP juice”) have been studied. We observe that ? (1H) is strongly correlated with the substituents on the polarizing agents, and its trend is discussed in terms of different molecular parameters: solubility, average e–e distance, relative orientation of the nitroxide moieties, and electron spin relaxation times. We show that too short an e–e distance or too long a T1e can dramatically limit ? (1H). Our study also shows that the molecular structure of AMUPol is not optimal and its ? (1H) could be further improved through stronger interaction with the glassy matrix and a better orientation of the TEMPO moieties. A new AMUPol derivative introduced here provides a better ? (1H) than AMUPol itself (by a factor of ca. 1.2). 相似文献
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Dao Le Fabio Ziarelli Trang N. T. Phan Giulia Mollica Pierre Thureau Fabien Aussenac Olivier Ouari Didier Gigmes Paul Tordo Stphane Viel 《Macromolecular rapid communications》2015,36(15):1416-1421
High‐field dynamic nuclear polarization (DNP) has emerged as a powerful technique for improving the sensitivity of solid‐state NMR (SSNMR), yielding significant sensitivity enhancements for a variety of samples, including polymers. Overall, depending upon the type of polymer, the molecular weight, and the DNP sample preparation method, sensitivity enhancements between 5 and 40 have been reported. These promising enhancements remain, however, far from the theoretical maximum (>1000). Crucial to the success of DNP SSNMR is the DNP signal enhancement (εDNP), which is the ratio of the NMR signal intensities with and without DNP. It is shown here that, for polymers exhibiting high affinity toward molecular oxygen (e.g., polystyrene), removing part of the absorbed (paramagnetic) oxygen from the solid‐state samples available as powders (instead of dissolved or dispersed in a solvent) increases proton nuclear relaxation times and εDNP, hereby providing up to a two‐fold sensitivity increase (i.e., a four‐fold reduction in experimental time).
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Alexandre Zagdoun Dr. Aaron J. Rossini Dr. Matthew P. Conley Wolfram R. Grüning Martin Schwarzwälder Dr. Moreno Lelli Dr. W. Trent Franks Prof. Dr. Hartmut Oschkinat Prof. Dr. Christophe Copéret Prof. Dr. Lyndon Emsley Dr. Anne Lesage 《Angewandte Chemie (International ed. in English)》2013,52(4):1222-1225
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Highly Stable Water‐Soluble Platinum Nanoparticles Stabilized by Hydrophilic N‐Heterocyclic Carbenes 下载免费PDF全文
Edwin A. Baquero Dr. Simon Tricard Dr. Juan Carlos Flores Prof. Dr. Ernesto de Jesús Prof. Dr. Bruno Chaudret 《Angewandte Chemie (International ed. in English)》2014,53(48):13220-13224
Controlling the synthesis of stable metal nanoparticles in water is a current challenge in nanochemistry. The strategy presented herein uses sulfonated N‐heterocyclic carbene (NHC) ligands to stabilize platinum nanoparticles (PtNPs) in water, under air, for an indefinite time period. The particles were prepared by thermal decomposition of a preformed molecular Pt complex containing the NHC ligand and were then purified by dialysis and characterized by TEM, high‐resolution TEM, and spectroscopic techniques. Solid‐state NMR studies showed coordination of the carbene ligands to the nanoparticle surface and allowed the determination of a 13C–195Pt coupling constant for the first time in a nanosystem (940 Hz). Additionally, in one case a novel structure was formed in which platinum(II) NHC complexes form a second coordination sphere around the nanoparticle. 相似文献
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Dr. Maria Concistré Dr. Subhradip Paul Marina Carravetta Ilya Kuprov Dr. Philip T. F. Williamson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(68):15852-15854
Combining dynamic nuclear polarization with proton detection significantly enhances the sensitivity of magic-angle spinning NMR spectroscopy. Herein, the feasibility of proton-detected experiments with slow (10 kHz) magic angle spinning was demonstrated. The improvement in sensitivity permits the acquisition of indirectly detected 14N NMR spectra allowing biomolecular structures to be characterized without recourse to isotope labelling. This provides a new tool for the structural characterization of environmental and medical samples, in which isotope labelling is frequently intractable. 相似文献
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Dr. Carlos Fernández‐de‐Alba Dr. Hiroki Takahashi Alexandre Richard Yves Chenavier Dr. Lionel Dubois Vincent Maurel Dr. Daniel Lee Dr. Sabine Hediger Dr. Gaël De Paëpe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(12):4512-4517
Magic‐angle spinning dynamic nuclear polarization (MAS‐DNP) has been proven to be a powerful technique to enhance the sensitivity of solid‐state NMR (SSNMR) in a wide range of systems. Here, we show that DNP can be used to polarize lipids using a lipid‐anchored polarizing agent. More specifically, we introduce a C16‐functionalized biradical, which allows localization of the polarizing agents in the lipid bilayer and DNP experiments to be performed in the absence of excess cryo‐protectant molecules (glycerol, dimethyl sulfoxide, etc.). This constitutes another original example of the matrix‐free DNP approach that we recently introduced. 相似文献
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Selective Host–Guest Interaction between Metal Ions and Metal–Organic Frameworks Using Dynamic Nuclear Polarization Enhanced Solid‐State NMR Spectroscopy 下载免费PDF全文
Dr. Zhiyong Guo Dr. Takeshi Kobayashi Dr. Lin‐Lin Wang Tian Wei Goh Dr. Chaoxian Xiao Dr. Marc A. Caporini Dr. Melanie Rosay Prof. Dr. Duane D. Johnson Prof. Dr. Marek Pruski Prof. Dr. Wenyu Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16308-16313
The host–guest interaction between metal ions (Pt2+ and Cu2+) and a zirconium metal–organic framework (UiO‐66‐NH2) was explored using dynamic nuclear polarization‐enhanced 15N{1H} CPMAS NMR spectroscopy supported by X‐ray absorption spectroscopy and density functional calculations. The combined experimental results conclude that each Pt2+ coordinates with two NH2 groups from the MOF and two Cl? from the metal precursor, whereas Cu2+ do not form chemical bonds with the NH2 groups of the MOF framework. Density functional calculations reveal that Pt2+ prefers a square‐planar structure with the four ligands and resides in the octahedral cage of the MOF in either cis or trans configurations. 相似文献
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On The Potential of Dynamic Nuclear Polarization Enhanced Diamonds in Solid‐State and Dissolution 13C NMR Spectroscopy 下载免费PDF全文
Dr. Christian O. Bretschneider Prof. Dr. Ümit Akbey Dr. Fabien Aussenac Dr. Greg L. Olsen Dr. Akiva Feintuch Prof. Dr. Hartmut Oschkinat Prof. Dr. Lucio Frydman 《Chemphyschem》2016,17(17):2691-2701
Dynamic nuclear polarization (DNP) is a versatile option to improve the sensitivity of NMR and MRI. This versatility has elicited interest for overcoming potential limitations of these techniques, including the achievement of solid‐state polarization enhancement at ambient conditions, and the maximization of 13C signal lifetimes for performing in vivo MRI scans. This study explores whether diamond's 13C behavior in nano‐ and micro‐particles could be used to achieve these ends. The characteristics of diamond's DNP enhancement were analyzed for different magnetic fields, grain sizes, and sample environments ranging from cryogenic to ambient temperatures, in both solution and solid‐state experiments. It was found that 13C NMR signals could be boosted by orders of magnitude in either low‐ or room‐temperature solid‐state DNP experiments by utilizing naturally occurring paramagnetic P1 substitutional nitrogen defects. We attribute this behavior to the unusually long electronic/nuclear spin‐lattice relaxation times characteristic of diamond, coupled with a time‐independent cross‐effect‐like polarization transfer mechanism facilitated by a matching of the nitrogen‐related hyperfine coupling and the 13C Zeeman splitting. The efficiency of this solid‐state polarization process, however, is harder to exploit in dissolution DNP‐enhanced MRI contexts. The prospects for utilizing polarized diamond approaching nanoscale dimensions for both solid and solution applications are briefly discussed. 相似文献