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Removal of Paramagnetic Ions Prior to Analysis of Organic Reactions in Aqueous Solutions by NMR Spectroscopy

Febrian, Rio and Roddy, Joseph P. and Chang, Christine H. and Devall, Clinton T. and Bracher, Paul J. (2021) Removal of Paramagnetic Ions Prior to Analysis of Organic Reactions in Aqueous Solutions by NMR Spectroscopy. ACS Omega, 6 (23). pp. 14727-14733. ISSN 2470-1343. PMCID PMC8209789. doi:10.1021/acsomega.9b02610.

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This article describes a method for improving ¹H NMR spectra of aqueous samples containing paramagnetic metals by precipitation of metal cations with a variety of counteranions. The addition of hydroxide, phosphate, carbonate, and arsenate to solutions of transition metals such as Fe²⁺ and Mn²⁺ can reduce line broadening and improve the ability of a spectrometer to lock on the signal of deuterium. The method is most effective under strongly alkaline conditions, and care must be taken to observe whether the organic substrates undergo side reactions or are themselves removed from solution upon addition of the precipitating salts. As a demonstration of the practical value of the method, we show that NMR spectroscopy can be used to monitor the transition-metal-mediated hydrolysis of glycylglycine (Gly₂).

Item Type:Article
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URLURL TypeDescription CentralArticle
Bracher, Paul J.0000-0001-5769-8364
Additional Information:© 2021 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. Received: August 13, 2019; Accepted: October 14, 2019; Published: May 28, 2021. This work was supported by the NASA EPSCoR Missouri Research Infrastructure Development Program funded through NASA Grant Cooperative Agreement Number NNX15AK38A. R.F. was also supported by the NSF and the NASA Astrobiology Program, under the NSF Center for Chemical Evolution (CHE-1504217). C.H.C. and J.P.R. were supported by Caltech Summer Undergraduate Research Fellowships. The NSF and Saint Louis University jointly funded the spectrometer used to acquire ICP–OES data through the NSF Major Research Instrumentation Program (award CHE-1626501). We thank Prof. Harry B. Gray and Dr. Thomas D. Campbell for helpful discussions. Author Contributions. P.J.B. conceived the project. C.H.C. conducted the initial experiments at the California Institute of Technology. R.F., J.P.R., and C.T.D. conducted experiments at Saint Louis University. All authors interpreted data. R.F. and P.J.B. primarily wrote the paper with input from all authors. The authors declare no competing financial interest.
Funding AgencyGrant Number
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
Saint Louis UniversityUNSPECIFIED
Subject Keywords:Salts, Metals, Transition metals, Nuclear magnetic resonance spectroscopy, Precipitation
Issue or Number:23
PubMed Central ID:PMC8209789
Record Number:CaltechAUTHORS:20210604-140650414
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Official Citation:Removal of Paramagnetic Ions Prior to Analysis of Organic Reactions in Aqueous Solutions by NMR Spectroscopy. Rio Febrian, Joseph P. Roddy, Christine H. Chang, Clinton T. Devall, and Paul J. Bracher. ACS Omega 2021 6 (23), 14727-14733; DOI: 10.1021/acsomega.9b02610
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109391
Deposited By: George Porter
Deposited On:07 Jun 2021 20:23
Last Modified:23 Jun 2021 18:18

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