Hyperpolarized Magnetic Resonance of Exchangeable Protons Using Parahydrogen and Aminosilane

Efficient, room temperature hyperpolarization of exchangeable solvent protons combining parahydrogen (p-H-2), aminopropyldiethoxymethylsilane (APDMS), and IrCl(COD)-(IMes) to generate an active aminosilane-iridium complex broadens the capabilities of signal amplification by reversible exchange (SABRE)-type hyperpolarization of protons. A primary pool of hyperpolarized exchangeable protons transfers its hyperpolarization to cosolutes with labile protons, partly overcoming the catalytic specificity of SABRE-type spin-transfer catalysis. The silane functionality of APDMS appears to be crucial to its improvement. Its role is unprecedented in p-H-2-based hyperpolarization of nuclear spins and promises to broaden its applicability of ultrasensitive solution-state NMR spectroscopy for the detection and elucidation of molecular behavior, at concentrations undetectable by conventional NMR spectroscopy.