Figure 2.

SABRE studies with the PEGylated Ir catalyst (7/14) in 100% deuterated ethanol. (a) Thermally polarized reference ¹H NMR scan from the solution following activation with pH₂ in the presence of excess substrate (py); the spectrum is vertically scaled 5-fold compared to panel b, which shows the successful observation of SABRE enhancement after 1 min of bubbling with ∼5.1 atm of pH₂ at ∼11 mT, then transfer to 9.39 T for high-field acquisition; enhancements up to ∼40–60-fold were observed with 3.5 mM catalyst and the given conditions. Panels c and d show spectra from a separate experiment, where no high-field SABRE effect was observed, i.e., where pH₂ bubbling/SABRE mixing was performed entirely at 9.39 T (d), compared to a corresponding thermally polarized spectrum (c). (Vertical scale for panels c and d is different from that of panels a and b.) Insets show amplified hydride regions from spectra in panels b and d, respectively.