Open AccessNMR SLIC Sensing of Hydrogenation Reactions Using Parahydrogen in Low Magnetic Fields
Author(s) -
Danila A. Barskiy,
Oleg G. Salnikov,
Roman V. Shchepin,
Matthew Feldman,
Aaron M. Coffey,
Kirill V. Kovtunov,
Igor V. Koptyug,
Eduard Y. Chekmenev
Publication year - 2016
Publication title -
journal of physical chemistry. c./journal of physical chemistry. c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.401
H-Index - 289
eISSN - 1932-7455
pISSN - 1932-7447
DOI - 10.1021/acs.jpcc.6b07555
Subject(s) - spin isomers of hydrogen , hyperpolarization (physics) , polarization (electrochemistry) , magnetic field , chemistry , imes , nuclear magnetic resonance spectroscopy , induced polarization , analytical chemistry (journal) , nuclear magnetic resonance , physics , catalysis , hydrogen , organic chemistry , carbene , quantum mechanics , electrical resistivity and conductivity
Parahydrogen-induced polarization (PHIP) is an NMR hyperpolarization technique that increases nuclear spin polarization by orders of magnitude, and it is particularly well-suited to study hydrogenation reactions. However, the use of high-field NMR spectroscopy is not always possible, especially in the context of potential industrial-scale reactor applications. On the other hand, the direct low-field NMR detection of reaction products with enhanced nuclear spin polarization is challenging due to near complete signal cancellation from nascent parahydrogen protons. We show that hydrogenation products prepared by PHIP can be irradiated with weak (on the order of spin-spin couplings of a few hertz) alternating magnetic field (called Spin-Lock Induced Crossing or SLIC) and consequently efficiently detected at low magnetic field (e.g., 0.05 T used here) using examples of several types of organic molecules containing a vinyl moiety. The detected hyperpolarized signals from several reaction products at tens of millimolar concentrations were enhanced by 10000-fold, producing NMR signals an order of magnitude greater than the background signal from protonated solvents.