The Experts below are selected from a list of 27 Experts worldwide ranked by ideXlab platform
Martin M Thuo - One of the best experts on this subject based on the ideXlab platform.
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rapid acquisition of wideline mas solid state NMR spectra with fast mas proton detection and dipolar hmqc pulse sequences
Physical Chemistry Chemical Physics, 2016Co-Authors: Aaron J Rossini, Michael P Hanrahan, Martin M ThuoAbstract:The solid-state NMR spectra of many NMR active elements are often extremely broad due to the presence of chemical shift anisotropy (CSA) and/or the quadrupolar interaction (for Nuclei with spin I > 1/2). These NMR interactions often give rise to wideline solid-state NMR spectra which can span hundreds of kHz or several MHz. Here we demonstrate that by using fast MAS, proton detection and dipolar hetero-nuclear multiple-quantum (D-HMQC) pulse sequences, it is possible to rapidly acquire 2D spectra which correlate 1H chemical shifts to the indirectly detected wideline MAS powder patterns of dipolar coupled hetero-Nuclei. The D-HMQC pulse sequence enables broadband excitation of the wideline hetero-nuclear NMR spectrum and provides higher sensitivity by detecting the narrower and more sensitive 1H NMR signal. This approach is demonstrated for the rapid acquisition of 2D 1H detected 195Pt solid-state NMR spectra of cisplatin and transplatin and the 71Ga solid-state NMR spectrum of a self-assembled Ga coordination polymer of unconfirmed structure. This approach should be broadly applicable for the rapid acquisition of wideline MAS solid-state NMR spectra of moderately abundant NMR Nuclei.
Aaron J Rossini - One of the best experts on this subject based on the ideXlab platform.
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rapid acquisition of wideline mas solid state NMR spectra with fast mas proton detection and dipolar hmqc pulse sequences
Physical Chemistry Chemical Physics, 2016Co-Authors: Aaron J Rossini, Michael P Hanrahan, Martin M ThuoAbstract:The solid-state NMR spectra of many NMR active elements are often extremely broad due to the presence of chemical shift anisotropy (CSA) and/or the quadrupolar interaction (for Nuclei with spin I > 1/2). These NMR interactions often give rise to wideline solid-state NMR spectra which can span hundreds of kHz or several MHz. Here we demonstrate that by using fast MAS, proton detection and dipolar hetero-nuclear multiple-quantum (D-HMQC) pulse sequences, it is possible to rapidly acquire 2D spectra which correlate 1H chemical shifts to the indirectly detected wideline MAS powder patterns of dipolar coupled hetero-Nuclei. The D-HMQC pulse sequence enables broadband excitation of the wideline hetero-nuclear NMR spectrum and provides higher sensitivity by detecting the narrower and more sensitive 1H NMR signal. This approach is demonstrated for the rapid acquisition of 2D 1H detected 195Pt solid-state NMR spectra of cisplatin and transplatin and the 71Ga solid-state NMR spectrum of a self-assembled Ga coordination polymer of unconfirmed structure. This approach should be broadly applicable for the rapid acquisition of wideline MAS solid-state NMR spectra of moderately abundant NMR Nuclei.
Konstantin L Ivanov - One of the best experts on this subject based on the ideXlab platform.
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enhancing NMR of insensitive Nuclei by transfer of sabre spin hyperpolarization
Chemical Physics Letters, 2016Co-Authors: Andrey N Pravdivtsev, Alexandra V Yurkovskaya, Hansmartin Vieth, Herbert Zimmermann, Konstantin L IvanovAbstract:Abstract We describe the performance of methods for enhancing NMR (Nuclear Magnetic Resonance) signals of “insensitive”, but important NMR Nuclei, which are based on the SABRE (Signal Amplification By Reversible Exchange) technique, i.e., on spin order transfer from para hydrogen (H 2 molecule in its nuclear singlet spin state) to a substrate in a transient organometallic complex. Here such transfer is performed at high magnetic fields by INEPT-type NMR pulse sequences, modified for SABRE. Signal enhancements up to three orders of magnitude are obtained for 15 N Nuclei; the possibility of sensitive detection of 2D-NMR 1 H- 15 N spectra of SABRE complexes and substrates is demonstrated.
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transfer of sabre derived hyperpolarization to spin 1 2 heteroNuclei
RSC Advances, 2015Co-Authors: Andrey N Pravdivtsev, Alexandra V Yurkovskaya, Konstantin L Ivanov, Hansmartin Vieth, Herbert ZimmermannAbstract:In this paper, we describe a method of hyper-polarizing “insensitive” Nuclear Magnetic Resonance (NMR) Nuclei by exploiting the SABRE (Signal Amplification By Reversible Exchange) technique and transferring spin order from protons originating from parahydrogen. We demonstrate that hyperpolarization transfer is due to a coherent mechanism, which is operative at (i) very low magnetic field; (ii) geomagnetic field; (iii) high field in the presence of a suitable radiofrequency-excitation scheme. Experiments are performed using 15N-labelled pyridine as the SABRE substrate; NMR enhancements achieved for 15N Nuclei are more than 1000 for free pyridine in solution and more than 20 000 for pyridine bound to the SABRE complex. High-field SABRE experiments are particularly important for enhancing the sensitivity of NMR methods: they enable strong signal enhancements and avoid technically demanding field-cycling. Furthermore, such experiments use very low power for NMR excitation and make feasible continuous re-hyperpolarization of the substrate in high-field experiments: polarization can be quickly restored to the maximal level within only 15 seconds with the result that polarization levels stay constant over several hundred experiments. The techniques outlined are applicable to hyper-polarizing spin-1/2 hetero-Nuclei, such as 13C, 19F, 31P, etc. Development of such methods opens new avenues in NMR spectroscopy and imaging, which were out of reach for sensitivity reasons.
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highly efficient polarization of spin 1 2 insensitive NMR Nuclei by adiabatic passage through level anticrossings
Journal of Physical Chemistry Letters, 2014Co-Authors: Andrey N Pravdivtsev, Alexandra V Yurkovskaya, N N Lukzen, Konstantin L Ivanov, Hansmartin ViethAbstract:A method is proposed to transfer spin order from para-hydrogen, that is, the H2 molecule in its singlet state, to spin-1/2 heteroNuclei of a substrate molecule. The method is based on adiabatic passage through nuclear spin level anticrossings (LACs) in the doubly rotating frame of reference; the LAC conditions are fulfilled by applying resonant RF excitation at the NMR frequencies of protons and the heteroNuclei. Efficient conversion of the para-hydrogen-induced polarization into net polarization of the heteroNuclei is demonstrated; the achieved signal enhancements are about 6400 for 13C Nuclei at natural abundance. The theory behind the technique is described; advantages of the method are discussed in detail.
Michael P Hanrahan - One of the best experts on this subject based on the ideXlab platform.
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rapid acquisition of wideline mas solid state NMR spectra with fast mas proton detection and dipolar hmqc pulse sequences
Physical Chemistry Chemical Physics, 2016Co-Authors: Aaron J Rossini, Michael P Hanrahan, Martin M ThuoAbstract:The solid-state NMR spectra of many NMR active elements are often extremely broad due to the presence of chemical shift anisotropy (CSA) and/or the quadrupolar interaction (for Nuclei with spin I > 1/2). These NMR interactions often give rise to wideline solid-state NMR spectra which can span hundreds of kHz or several MHz. Here we demonstrate that by using fast MAS, proton detection and dipolar hetero-nuclear multiple-quantum (D-HMQC) pulse sequences, it is possible to rapidly acquire 2D spectra which correlate 1H chemical shifts to the indirectly detected wideline MAS powder patterns of dipolar coupled hetero-Nuclei. The D-HMQC pulse sequence enables broadband excitation of the wideline hetero-nuclear NMR spectrum and provides higher sensitivity by detecting the narrower and more sensitive 1H NMR signal. This approach is demonstrated for the rapid acquisition of 2D 1H detected 195Pt solid-state NMR spectra of cisplatin and transplatin and the 71Ga solid-state NMR spectrum of a self-assembled Ga coordination polymer of unconfirmed structure. This approach should be broadly applicable for the rapid acquisition of wideline MAS solid-state NMR spectra of moderately abundant NMR Nuclei.
Andrey N Pravdivtsev - One of the best experts on this subject based on the ideXlab platform.
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enhancing NMR of insensitive Nuclei by transfer of sabre spin hyperpolarization
Chemical Physics Letters, 2016Co-Authors: Andrey N Pravdivtsev, Alexandra V Yurkovskaya, Hansmartin Vieth, Herbert Zimmermann, Konstantin L IvanovAbstract:Abstract We describe the performance of methods for enhancing NMR (Nuclear Magnetic Resonance) signals of “insensitive”, but important NMR Nuclei, which are based on the SABRE (Signal Amplification By Reversible Exchange) technique, i.e., on spin order transfer from para hydrogen (H 2 molecule in its nuclear singlet spin state) to a substrate in a transient organometallic complex. Here such transfer is performed at high magnetic fields by INEPT-type NMR pulse sequences, modified for SABRE. Signal enhancements up to three orders of magnitude are obtained for 15 N Nuclei; the possibility of sensitive detection of 2D-NMR 1 H- 15 N spectra of SABRE complexes and substrates is demonstrated.
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transfer of sabre derived hyperpolarization to spin 1 2 heteroNuclei
RSC Advances, 2015Co-Authors: Andrey N Pravdivtsev, Alexandra V Yurkovskaya, Konstantin L Ivanov, Hansmartin Vieth, Herbert ZimmermannAbstract:In this paper, we describe a method of hyper-polarizing “insensitive” Nuclear Magnetic Resonance (NMR) Nuclei by exploiting the SABRE (Signal Amplification By Reversible Exchange) technique and transferring spin order from protons originating from parahydrogen. We demonstrate that hyperpolarization transfer is due to a coherent mechanism, which is operative at (i) very low magnetic field; (ii) geomagnetic field; (iii) high field in the presence of a suitable radiofrequency-excitation scheme. Experiments are performed using 15N-labelled pyridine as the SABRE substrate; NMR enhancements achieved for 15N Nuclei are more than 1000 for free pyridine in solution and more than 20 000 for pyridine bound to the SABRE complex. High-field SABRE experiments are particularly important for enhancing the sensitivity of NMR methods: they enable strong signal enhancements and avoid technically demanding field-cycling. Furthermore, such experiments use very low power for NMR excitation and make feasible continuous re-hyperpolarization of the substrate in high-field experiments: polarization can be quickly restored to the maximal level within only 15 seconds with the result that polarization levels stay constant over several hundred experiments. The techniques outlined are applicable to hyper-polarizing spin-1/2 hetero-Nuclei, such as 13C, 19F, 31P, etc. Development of such methods opens new avenues in NMR spectroscopy and imaging, which were out of reach for sensitivity reasons.
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highly efficient polarization of spin 1 2 insensitive NMR Nuclei by adiabatic passage through level anticrossings
Journal of Physical Chemistry Letters, 2014Co-Authors: Andrey N Pravdivtsev, Alexandra V Yurkovskaya, N N Lukzen, Konstantin L Ivanov, Hansmartin ViethAbstract:A method is proposed to transfer spin order from para-hydrogen, that is, the H2 molecule in its singlet state, to spin-1/2 heteroNuclei of a substrate molecule. The method is based on adiabatic passage through nuclear spin level anticrossings (LACs) in the doubly rotating frame of reference; the LAC conditions are fulfilled by applying resonant RF excitation at the NMR frequencies of protons and the heteroNuclei. Efficient conversion of the para-hydrogen-induced polarization into net polarization of the heteroNuclei is demonstrated; the achieved signal enhancements are about 6400 for 13C Nuclei at natural abundance. The theory behind the technique is described; advantages of the method are discussed in detail.