High H₂ Solubility of Perfluorocarbon Solvents and Their Use in Reversible Polarization Transfer from para-Hydrogen

This research uses perfluorocarbons (PFCs) as effective alternatives to traditional toxic solvents in reversible para-hydrogen-induced polarization (PHIP) for NMR signal enhancement. Hydrogen solubility in PFCs is shown here to be an order of magnitude higher than in typical organic solvents by determination of Henry's constants. We demonstrate how this high H₂ solubility enables the PFCs to deliver substantial polarization transfer from para-hydrogen, achieving up to 2400-fold signal gains for ¹H NMR detection and 67,000-fold (22% polarization) for ¹⁵N NMR detection at 9.4 T in substrates such as pyridine and nicotine. Notably, methylperfluorobutylether outperforms catalytic efficiency in methanol-d₄ and dichloromethane-d₂ for pyridine at low catalyst loadings. This makes PFCs particularly advantageous for applications demanding high NMR sensitivity. With high polarization efficiency and reduced toxicity, PFCs hold strong potential for expanding hyperpolarized NMR applications across the biomedical and analytical fields.