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Koppe J, Frerichs JE, Hansen MR. Pushing the Detection Limit of Static Wideline NMR Spectroscopy Using Ultrafast Frequency-Swept Pulses. J Phys Chem Lett 2023; 14:10748-10753. [PMID: 38010530 DOI: 10.1021/acs.jpclett.3c02758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
We report a simple design strategy for wideband uniform-rate smooth truncation (WURST) pulses that enables ultrafast frequency sweeps to maximize the sensitivity of Carr-Purcell-Meiboom-Gill (CPMG) acquisition in static wideline nuclear magnetic resonance (NMR). Three compelling examples showcase the advantage of ultrafast frequency sweeps over currently employed WURST-CPMG protocols, demonstrating the potential of investigating materials that are typically inaccessible to static wideline NMR techniques, e.g., paramagnetic solids with short homogeneous transverse relaxation times.
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Affiliation(s)
- Jonas Koppe
- Institute for Physical Chemistry, University of Münster, Corrensstrasse 28/30, DE-48149 Münster, Germany
- Centre de RMN Très Hauts Champs de Lyon (UMR5082 - CNRS, ENS Lyon, UCB Lyon 1), Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Joop Enno Frerichs
- Institute for Physical Chemistry, University of Münster, Corrensstrasse 28/30, DE-48149 Münster, Germany
| | - Michael Ryan Hansen
- Institute for Physical Chemistry, University of Münster, Corrensstrasse 28/30, DE-48149 Münster, Germany
- Center for Multiscale Theory and Computation (CMTC), University of Münster, Corrensstrasse 40, DE-48149 Münster, Germany
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Kimball JJ, Altenhof AR, Jaroszewicz MJ, Schurko RW. Broadband Cross-Polarization to Half-Integer Quadrupolar Nuclei: Wideline Static NMR Spectroscopy. J Phys Chem A 2023; 127:9621-9634. [PMID: 37922436 DOI: 10.1021/acs.jpca.3c05447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2023]
Abstract
Cross-polarization (CP) is a technique commonly used for the signal enhancement of NMR spectra; however, applications to quadrupolar nuclei have heretofore been limited due to a number of problems, including poor spin-locking efficiency, inconvenient relaxation times, and reduced CP efficiencies over broad spectral bandwidths─this is unfortunate, since they constitute 73% of NMR-active nuclei in the periodic table. The Broadband Adiabatic Inversion CP (BRAIN-CP) pulse sequence has proven useful for the signal enhancement of wideline and ultra-wideline (i.e., 250 kHz to several MHz in breadth) powder patterns arising from stationary samples; however, a comprehensive investigation of its application to half-integer quadrupolar nuclei (HIQN) is currently lacking. Herein, we present theoretical and experimental considerations for applying BRAIN-CP to acquire central-transition (CT, +1/2 ↔ -1/2) powder patterns of HIQN. Consideration is given to parameters crucial to the success of the experiment, such as the Hartmann-Hahn (HH) matching conditions and the phase modulation of the contact pulse. Modifications to the BRAIN-CP sequence such as flip-back (FB) pulses and ramped contact pulses applied to the 1H spins are used for the reduction of experimental times and increased CP bandwidth capabilities, respectively. Spectra for a series of quadrupolar nuclei with broad CT powder patterns, including 35Cl (S = 3/2), 55Mn (S = 5/2), 59Co (S = 7/2), and 93Nb (S = 9/2), are acquired via direct excitation (CPMG and WCPMG) and indirect excitation (CP/CPMG and BRAIN-CP) methods. We demonstrate that proper implementation of the sequence can enable 1H-S broadband CP over a bandwidth of 1 MHz, which to the best of our knowledge is the largest CP bandwidth reported to date. Finally, we establish the basic principles necessary for simplified optimization and execution of the BRAIN-CP pulse sequence for a wide range of HIQNs.
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Affiliation(s)
- James J Kimball
- Department of Chemistry & Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
| | - Adam R Altenhof
- Department of Chemistry & Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
| | - Michael J Jaroszewicz
- Department of Chemical & Biological Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Robert W Schurko
- Department of Chemistry & Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
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Jaroszewicz MJ, Altenhof AR, Schurko RW, Frydman L. An automated multi-order phase correction routine for processing ultra-wideline NMR spectra. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 354:107528. [PMID: 37632988 DOI: 10.1016/j.jmr.2023.107528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 07/25/2023] [Accepted: 07/26/2023] [Indexed: 08/28/2023]
Abstract
Efficient acquisition of wideline solid-state nuclear magnetic resonance (NMR) spectra with patterns affected by large inhomogeneous broadening is accomplished with the use of broadband pulse sequences. These specialized pulse sequences often use frequency-swept pulses, which feature time-dependent phase and amplitude modulations that in turn deliver broad and uniform excitation across large spectral bandwidths. However, the resulting NMR spectra are often affected by complex frequency-dependent phase dispersions, owing to the interplay between the frequency-swept excitations and anisotropic resonance frequencies. Such phase distortions necessitate the use of multi-order non-linear corrections in order to obtain absorptive, distortion-free patterns with uniform phasing. Performing such corrections is often challenging due to the complex interdependence of the linear and non-linear phase contributions, and how these may affect the NMR signal. Hence, processing of these data usually involves calculating the spectra in magnitude mode wherein the phase information is discarded. Herein, we present a fully automated phasing routine that is capable of processing and phase correcting such wideline NMR spectra. Its performance is corroborated via processing of NMR data acquired using both the WURST-CPMG (Wideband, Uniform-Rate, Smooth Truncation with Carr-Purcell Meiboom-Gill acquisition) and BRAIN-CP (BRoadband Adiabatic Inversion Cross Polarization) pulse sequences for a variety of nuclei (i.e., 119Sn, 195Pt, 35Cl, 87Rb, and 14N). Based on both simulated and experimental NMR datasets, it is demonstrated that automatic phase corrections up to and including second order can be readily achieved without a priori information regarding the nature of the phase-distorted NMR datasets, and independently of the exact manner in which time-domain NMR data are collected and subsequently processed. In addition, it is shown that NMR spectra acquired at both single and multiple transmitter frequencies that are processed with this automated phasing routine have improved signal-to-noise properties than those processed with conventional magnitude calculations, along with powder patterns that better match those of ideal NMR spectra, even for datasets possessing low signal-to-noise ratios and/or affected by spectral artifacts.
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Affiliation(s)
- Michael J Jaroszewicz
- Department of Chemical and Biological Physics, Weizmann Institute, Rehovot 7610001, Israel.
| | - Adam R Altenhof
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA; National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA
| | - Robert W Schurko
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA; National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA.
| | - Lucio Frydman
- Department of Chemical and Biological Physics, Weizmann Institute, Rehovot 7610001, Israel; National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA.
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Holmes ST, Hook JM, Schurko RW. Nutraceuticals in Bulk and Dosage Forms: Analysis by 35Cl and 14N Solid-State NMR and DFT Calculations. Mol Pharm 2021; 19:440-455. [PMID: 34792373 DOI: 10.1021/acs.molpharmaceut.1c00708] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This study uses 35Cl and 14N solid-state NMR (SSNMR) spectroscopy and dispersion-corrected plane-wave density functional theory (DFT) calculations for the structural characterization of chloride salts of nutraceuticals in their bulk and dosage forms. For eight nutraceuticals, we measure the 35Cl EFG tensor parameters of the chloride ions and use plane-wave DFT calculations to elucidate relationships between NMR parameters and molecular-level structure, which provide rapid NMR crystallographic assessments of structural features. We employ both 35Cl direct excitation and 1H→35Cl cross-polarization methods to characterize a dosage form containing α-d-glucosamine HCl, observe possible impurity and/or adulterant phases, and quantify the weight percent of the active ingredient. To complement this, we also investigate 14N SSNMR spectroscopy and DFT calculations to characterize nitrogen atoms in the nutraceuticals. This includes a discussion of targeted acquisition experimental protocols (i.e., acquiring a select region of the overall pattern that features key discontinuities) that allow ultrawideline spectra to be acquired rapidly, even for unreceptive samples (i.e., those with long values of T1(14N), short values of T2eff(14N), or very broad patterns). It is hoped that these experimental and computational protocols will be useful for the characterization of various solid forms of nutraceuticals (i.e., salts, polymorphs, hydrates, solvates, cocrystals, amorphous solid dispersions, etc.), help detect impurity and counterfeit solid phases in dosage forms, and serve as a foundation for future NMR crystallographic studies of nutraceutical solid forms, including studies using ab initio crystal structure prediction algorithms.
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Affiliation(s)
- Sean T Holmes
- Department of Chemistry & Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.,National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
| | - James M Hook
- NMR Facility, Mark Wainwright Analytical Centre, The University of New South Wales, Sydney, New South Wales 2052, Australia.,School of Chemistry, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Robert W Schurko
- Department of Chemistry & Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.,National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
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Koppe J, Bußkamp M, Hansen MR. Frequency-Swept Ultra-Wideline Magic-Angle Spinning NMR Spectroscopy. J Phys Chem A 2021; 125:5643-5649. [PMID: 34138561 DOI: 10.1021/acs.jpca.1c02958] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent years have witnessed the development of solid-state NMR techniques that allow the direct investigation of extremely wide inhomogeneously broadened resonance lines. To date, this typically involves the application of frequency sweeps as offered by wideband uniform rate smooth truncation (WURST) pulses. While the effects of such advanced irradiation schemes on static samples are well understood, the interference between the varying carrier frequency and the time-dependent evolution of the spin system under magic-angle spinning (MAS) conditions is more complex. Herein, we introduce the well-known WURST-Carr-Purcell-Meiboom-Gill (WCPMG) pulse sequence for spinning samples. Using numerical spin-density matrix analysis, an ideal design based on fast frequency sweeps and high truncation of the incorporated WURST pulses is presented that enables uniform excitation/refocusing under MAS conditions with low-to-moderate radio-frequency power requirements. This permits the acquisition of ultra-wideline MAS NMR lines exceeding 500 kHz with chemical shift resolution in a single transmitter step.
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Affiliation(s)
- Jonas Koppe
- Institute for Physical Chemistry, Westfälische Wilhelms-Universität, Corrensstr. 28/30, DE-48149 Münster, Germany
| | - Max Bußkamp
- Institute for Physical Chemistry, Westfälische Wilhelms-Universität, Corrensstr. 28/30, DE-48149 Münster, Germany
| | - Michael Ryan Hansen
- Center for Multiscale Theory and Computation (CMTC), Westfälische Wilhelms-Universität, Corrensstrasse 40, DE-48149 Münster, Germany
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Altenhof AR, Jaroszewicz MJ, Harris KJ, Schurko RW. Broadband adiabatic inversion experiments for the measurement of longitudinal relaxation time constants. J Chem Phys 2021; 154:034202. [PMID: 33499635 DOI: 10.1063/5.0039017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Accurate measurements of longitudinal relaxation time constants (T1) in solid-state nuclear magnetic resonance (SSNMR) experiments are important for the study of molecular-level structure and dynamics. Such measurements are often made under magic-angle spinning conditions; however, there are numerous instances where they must be made on stationary samples, which often give rise to broad powder patterns arising from large anisotropic NMR interactions. In this work, we explore the use of wideband uniform-rate smooth-truncation pulses for the measurement of T1 constants. Two experiments are introduced: (i) BRAIN-CPT1, a modification of the BRAIN-CP (BRoadband Adiabatic-INversion-Cross Polarization) sequence, for broadband CP-based T1 measurements and (ii) WCPMG-IR, a modification of the WURST-CPMG sequence, for direct-excitation (DE) inversion-recovery experiments. A series of T1 constants are measured for spin-1/2 and quadrupolar nuclei with broad powder patterns, such as 119Sn (I = 1/2), 35Cl (I = 3/2), 2H (I = 1), and 195Pt (I = 1/2). High signal-to-noise spectra with uniform patterns can be obtained due to signal enhancements from T2 eff-weighted echo trains, and in favorable cases, BRAIN-CPT1 allows for the rapid measurement of T1 in comparison to DE experiments. Protocols for spectral acquisition, processing, and analysis of relaxation data are discussed. In most cases, relaxation behavior can be modeled with either monoexponential or biexponential functions based upon measurements of integrated powder pattern intensity; however, it is also demonstrated that one must interpret such T1 values with caution, as demonstrated by measurements of T1 anisotropy in 119Sn, 2H, and 195Pt NMR spectra.
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Affiliation(s)
- Adam R Altenhof
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, USA
| | - Michael J Jaroszewicz
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada
| | - Kristopher J Harris
- Department of Chemistry, Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - Robert W Schurko
- National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, USA
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Koppe J, Hansen MR. Minimizing Lineshape Distortions in Static Ultra-wideline Nuclear Magnetic Resonance of Half-Integer Spin Quadrupolar Nuclei. J Phys Chem A 2020; 124:4314-4321. [DOI: 10.1021/acs.jpca.0c03658] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jonas Koppe
- Institute for Physical Chemistry, Westfälische Wilhelms-Universität, Corrensstr. 28/30, DE-48149 Münster, Germany
| | - Michael Ryan Hansen
- Institute for Physical Chemistry, Westfälische Wilhelms-Universität, Corrensstr. 28/30, DE-48149 Münster, Germany
- Center for Multiscale Theory and Computation (CMTC), Westfälische Wilhelms-Universität, Corrensstrasse 40, D-48149 Münster, Germany
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