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. Author manuscript; available in PMC: 2015 Jul 14.
Published in final edited form as: J Phys Chem C Nanomater Interfaces. 2015 Mar 11;119(13):7525–7533. doi: 10.1021/acs.jpcc.5b02036

Figure 4.

Figure 4

(a) 1H NMR spectrum from a mixture containing d6-ethanol solvent, the PVP polymer comb catalyst particles (PVPCs), and the (fully protonated) pyridine substrate thermally polarized at 9.4 T following activation with pH2 bubbling. (b) 1H NMR spectrum of the sample in (a) obtained after PVPC activation but with pH2 bubbling occurring at high field, acquired immediately after cessation of pH2 gas bubbling; for the most part, no high-field (in situ) SABRE effect was observed. (c) 1H (ex situ) HET-SABRE NMR spectrum obtained from the same sample, acquired immediately after 30 s of pH2 bubbling at low field (~100 G) and rapid transfer of the sample into the NMR magnet. All spectra shown were acquired with a single scan (90° pulse). Peaks at about δ≈1.1, ≈3.6, and ≈5.2 ppm are from residual protons from the deuterated ethanol solvent. The peak at ≈4.5 ppm is from (ortho-)hydrogen (oH2) gas. The inset shows the expected hexacoordinate structure of the activated catalytic moiety, exchanging with pH2 and the substrate pyridine (Py).