Adiabatic Single Scan Two-Dimensional NMR Spectrocopy

Pelupessy, Philippe

doi:10.1021/ja034958g

Cited by 188 publications

(185 citation statements)

References 16 publications

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“…These sequences differed from published ultrafast HSQC correlations by relying on a direct excitation of the X heteronuclei; following their spatial encoding these coherences were converted via X-1 H antiphase states onto 1 H signals, purged of background contamination with a short gradient pulse (P), and observed while applying a train of oscillating gradients with synchronized X-spin decoupling. A constant-time version on the basis of a pair of adiabatic π sweeps was used for the sake of preserving both quadrature components of the antiphase coherences 27 , which could be subsequently transformed into observable signal with a sensitivity enhancement advantage 28 . An initial 1 H π/2 pulse was also included that exploited the encoding gradients for the sake of better suppressing all of the non-relevant proton background signals.…”

Section: Instrumental Methodsmentioning

confidence: 99%

Ultrafast two-dimensional nuclear magnetic resonance spectroscopy of hyperpolarized solutions

2007

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Two-dimensional (2D) NMR is an important tool for elucidating molecular structure and dynamics 1 . However, the method is limited by the low sensitivity inherent to NMR techniques, resulting in typical acquisition times for 2D NMR spectra ranging from minutes to hours. A number of hyperpolarization techniques have been explored to boost NMR's sensitivity, including an ex situ dynamic nuclear polarization method capable of yielding-for an array of molecules and under conventional observation conditions for liquid samplessignals that exceed those currently afforded by the highestfield spectrometers by several orders of magnitude 2 . Whereas this methodology is able to provide the sensitivity equivalent of ∼10 6 scans, it is constrained to extract its 'super-spectrum' within a single transient, making it a poor starting point for conventional 2D NMR acquisitions. Here, we show that if the ex situ dynamic nuclear polarization approach is suitably merged with spatially encoded ultrafast NMR spectroscopy 3 , 2D NMR spectra of liquid samples at submicromolar concentrations can be acquired within ∼0.1 s.The future of NMR hinges on the efforts devoted to increase the resolution and sensitivity of this branch of spectroscopy. Key among the physical concepts that define NMR's resolving power are multidimensional (nD) acquisitions, which spread and correlate the resonances arising from individual sites onto multiple frequency axes 1,4,5 . Although these experiments are intrinsically lengthier than their conventional one-dimensional (1D) counterparts, nD NMR's success is best portrayed by its nearly ubiquitous contemporary practice in chemistry and biology, as well as by its various NMR imaging (MRI) clinical derivations. Comparable improvements regarding NMR's sensitivity, a particularly pressing issue given the weak signals associated with magnetic resonance observations in bulk, have been slower in coming. Moreover, the moderate dependence that sensitivity exhibits on the magnetic field, B NMR , has led to diminishing returns despite investments on ever-larger NMR magnets. Driven by this reality, recently there has been an increased interest in devising alternatives that prepare nuclei in 'hyperpolarized' states, whose spin population differences depart from the usual ≈10 −5 Boltzmann distributions and approach unity values. Methods proposed and demonstrated for achieving such metastable spin states include chemical synthesis and parahydrogen 6,7 , optical pumping 8,9 and microwave-driven transfers of magnetization from electrons to nearby nuclei via dynamic nuclear polarization 10-13 (DNP). DNP is arguably the most generally applicable of these methods, providing relatively high enhancements reaching up to the γ electron /γ nucleus ratio between the spins' magnetogyric constants, while having the relatively modest requirement that the targeted system be mixed with a free radical to be irradiated at its Larmor frequency.A logical approach to exploit the benefits of DNP within a high-resolution liquid-state NMR setting wou...

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Section: Instrumental Methodsmentioning

confidence: 99%

Ultrafast two-dimensional nuclear magnetic resonance spectroscopy of hyperpolarized solutions

2007

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“…The latter solution is only possible if the sweep width of the adiabatic encoding pulses adequately covers the frequency range imposed on the S spins by the gradients. If losses due to transverse relaxation, scalar couplings or diffusion during the encoding interval are significant, it is important to reduce the frequency range of the adiabatic pulse as much as possible [7,15,24] and only a prolongation of the encoding gradients is feasible. Note that in our experiments the total length of the encoding period was only 12 ms so that the frequency range of the adiabatic pulse could safely be chosen large enough to absorb increases in the amplitude of the encoding gradient.…”

Section: Theorymentioning

confidence: 99%

“…This advantage can be achieved by replacing the usual incrementation of the t 1 -evolution interval by a spatial encoding of the phases across the sample, while decoding is performed with the help of alternating gradients applied during the detection period. The spatial encoding can be greatly improved by using adiabatic frequency-modulated pulses [7][8][9]. This new technique has been successfully combined with liquid chromatography [10] and with methods to increase the polarization of nuclear spins [11].…”

Section: Introductionmentioning

confidence: 99%

Improving resolution in single-scan 2D spectroscopy

Pelupessy

Duma

Bodenhausen

2008

Journal of Magnetic Resonance

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“…A complete mathematical description of this model is given in the next section. This model is a resembling and a mathematical abstraction of an application of the Radon transform in NMR spectroscopy [1][2][3][4][5][6][7][8][9]. A survey on the subject is presented in [12].…”

Section: Introductionmentioning

confidence: 99%

“…Perhaps the realizations that the traditional reconstruction method is not the most efficient way has led many authors to introduce alternative methods that are generally related to Radon transform: Kupce and Freeman [1], [2], [3], Kim and Szyperski [4], Kozminski and Zhukov [5], and many others including [7][8][9]. In [11], three methods were reviewed and a forth method is proposed.…”

Section: Introductionmentioning

confidence: 99%