A5065149855- Advanced NMR Techniques and Applications
- Electron Spin Resonance Studies
- Atomic and Subatomic Physics Research
- Solid-state spectroscopy and crystallography
- Spectroscopy and Quantum Chemical Studies
- NMR spectroscopy and applications
- Molecular spectroscopy and chirality
- Advanced MRI Techniques and Applications
- Nonlinear Dynamics and Pattern Formation
- Photosynthetic Processes and Mechanisms
Duke University
2019-2024
North Carolina State University
2019
Signal amplification by reversible exchange (SABRE) creates “hyperpolarization” (large spin magnetization) using a transition metal catalyst and parahydrogen, addressing the sensitivity limitations of magnetic resonance. SABRE its heteronuclear variant X-SABRE are simple, fast, general, but to date have not produced polarization levels as large more established methods. We show here that commonly used theoretical framework for these applications, which focuses on avoided crossings (also...
Herein, we demonstrate "direct" 13 C hyperpolarization of C-acetate via signal amplification by reversible exchange (SABRE). The standard SABRE homogeneous catalyst [Ir-IMes; [IrCl(COD)(IMes)], (IMes=1,3-bis(2,4,6-trimethylphenyl), imidazole-2-ylidene; COD=cyclooctadiene)] was first activated in the presence an auxiliary substrate (pyridine) alcohol. Following addition sodium 1-13 C-acetate, parahydrogen bubbling within a microtesla magnetic field (i.e. under conditions shield enables...
Abstract Signal amplification by reversible exchange (SABRE) is an efficient method to hyperpolarize spin-1/2 nuclei and affords signals that are orders of magnitude larger than those obtained thermal spin polarization. Direct polarization transfer heteronuclei such as 13 C or 15 N has been optimized at static microTesla fields using coherence high field, relies on steady state with the catalyst dictated chemical kinetics. Here we demonstrate pulsing excitation field induces complex coherent...
The inherently low signal-to-noise ratio of NMR and MRI is now being addressed by hyperpolarization methods. For example, iridium-based catalysts that reversibly bind both parahydrogen ligands in solution can hyperpolarize protons (SABRE) or heteronuclei (X-SABRE) on a wide variety ligands, using complex interplay spin dynamics chemical exchange processes, with common signal enhancements between 10 3 4 . This does not approach obvious theoretical limits, further enhancement would be valuable...
We report on an extension of the quasi-resonance (QUASR) pulse sequence used for signal amplification by reversible exchange (SABRE), showing that we may target distantly J-coupled 19F-spins. Polarization transfer from parahydrogen-derived hydrides to 19F nucleus is accomplished via weak five-bond J-couplings using a shaped QUASR radio frequency at 0.05 T magnetic field. The net result direct generation hyperpolarized z-magnetization, derived parahydrogen singlet order. An accumulation...
Hyperpolarized [1-13C]pyruvate is a revolutionary molecular probe enabling ultrafast metabolic MRI scans in 1 min. This technology now under evaluation over 30 clinical trials, which employ dissolution Dynamic Nuclear Polarization (d-DNP) to prepare batch of the contrast agent; however, d-DNP slow and expensive. The emerging SABRE-SHEATH hyperpolarization technique enables fast (under min) robust production hyperpolarized via simultaneous chemical exchange parahydrogen pyruvate on IrIMes...
Signal Amplification By Reversible Exchange (SABRE) and its heteronuclear variant SABRE in SHield Enables Alignment Transfer to Heteronuclei create large nuclear magnetization target ligands, exploiting level crossings an iridium catalyst that transiently binds both the ligands parahydrogen. This requires a specific, small magnetic field match Zeeman splittings scalar couplings. Here, we explore different strategy, direct creation of singlet states which produces enhanced signals at other...
Oscillating pulse SABRE (Signal Amplification by Reversible Exchange) that uses magnetic fields far away from the resonance condition of continuous excitation can triple polarization. The oscillating pulse, in effect, adjusts J-couplings between hydrides and target nuclei.
Abstract Herein, we demonstrate “direct” 13 C hyperpolarization of C‐acetate via signal amplification by reversible exchange (SABRE). The standard SABRE homogeneous catalyst [Ir‐IMes; [IrCl(COD)(IMes)], (IMes=1,3‐bis(2,4,6‐trimethylphenyl), imidazole‐2‐ylidene; COD=cyclooctadiene)] was first activated in the presence an auxiliary substrate (pyridine) alcohol. Following addition sodium 1‐ C‐acetate, parahydrogen bubbling within a microtesla magnetic field (i.e. under conditions shield enables...
Hyperpolarization methods in magnetic resonance overcome sensitivity limitations, especially for low-γ nuclei such as 13C and 15N. Signal Amplification By Reversible Exchange (SABRE) extended SABRE (X-SABRE) are efficient low-cost generating large polarizations on a variety of nuclei, but they most commonly use low fields (μT-mT). High field approaches, where hyperpolarization is generated directly the spectrometer, potentially much more convenient have been limited to selectively...
A new approach for quantum evolution in dynamic systems converged to all orders perturbation theory.
The theoretical description of the interplay between coherent evolution and chemical exchange, originally developed for magnetic resonance later applied to other spectroscopic regimes, was derived under incorrect statistical assumptions. Correcting these assumptions provides access exact form exchange interaction, which we derive within Lindblad master equation formalism generality. interaction is only different from traditional by a scalar correction factor higher-order interactions...
The inherently low signal-to-noise ratio of NMR and MRI is now being addressed by hyperpolarization methods. For example, iridium-based catalysts that reversibly bind both parahydrogen ligands in solution can hyperpolarize protons (SABRE) or heteronuclei (X-SABRE) on a wide variety ligands, using complex interplay spin dynamics chemical exchange processes, with common signal enhancements between $10^3-10^4$. This does not approach obvious theoretical limits, further enhancement would be...
Many important applications in biochemistry, materials science, and catalysis sit squarely at the interface between quantum statistical mechanics: coherent evolution is interrupted by discrete events, such as binding of a substrate or isomerization. Theoretical models for dynamics usually truncate incorporation these events to linear-response limit, thus requiring small step sizes. Here, we completely re-assess foundations chemical exchange redesign master equation treatment accurate all...
The theoretical description of the interplay between coherent evolution and chemical exchange, originally developed for magnetic resonance later applied to other spectroscopic regimes, was derived under incorrect statistical assumptions. Correcting these assumptions provides access exact form exchange interaction, which we derive within Lindblad master equation formalism generality. interaction is only different from traditional by a scalar correction factor higher-order interactions...
Signal Amplification By Reversible Exchange (SABRE) creates hyperpolarization (large spin magnetization) using a transition metal catalyst and parahydrogen, addressing the sensitivity limitations of magnetic resonance. SABRE its heteronuclear variant X-SABRE are simple, fast general, but to date have not produced polarization levels as large more established methods. We show here that inaccuracies in theoretical framework for these applications, which focuses on avoided crossings (also...