Abstract
While many drugs and metabolites contain nitrogen, harnessing their diagnostic 15N NMR signature for their characterization is underutilized because of inherent detection difficulties. Here, we demonstrate how precise ultralow field signal amplification by reversible exchange (±0.2 mG) in conjunction parahydrogen and an iridium precatalyst of the form IrCl(COD)(NHC) with the coligand d9-benzylamine allows the naturally abundant 15N NMR signatures of pyridine, pyrazine, metronidazole, and acetonitrile to be readily detected at 9.4 T in single NMR observations through >50% 15N polarization levels. These signals allow for rapid and precise reagent quantification via a response that varies linearly over the 2–70 mM concentration range.
Highlights
Hyperpolarization methods have been shown to dramatically improve the sensitivity of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI)[1,2] in a process that involves increasing the purity of the magnetic states they detect
We start by considering nonlabeled pyridine at 35 mM concentration because of its wide use in early Signal amplification by reversible exchange (SABRE) research[3,4,13] in conjunction with the precatalyst [IrCl(COD)(h22-1)]43 (5 mM) of Scheme 1
Our experimental measurements involved examining an NMR tube containing methanold[4] solutions of these reagents under 3 bar pressure of p-H2 at 99% purity. p-H2 gas is first dissolved by shaking the NMR tube while it is located in a preset magnetic field that lies between ±1 mG and ±70 G for ∼10 s
Summary
Hyperpolarization methods have been shown to dramatically improve the sensitivity of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI)[1,2] in a process that involves increasing the purity of the magnetic states they detect. The SABRE catalyst [Ir(H)2(h221)(py)3]Cl forms and a 1H NMR signal gain of 1452-fold can be seen for the ortho proton resonance of free pyridine that is present in the solution after being transferred from a 60 G field.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
