Hyperpolarized Magnetic Resonance of Exchangeable Protons Using Parahydrogen and Aminosilane

Abstract

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.

Parahydrogen‐Induced Polarization of Amino Acids

“…Theo bservation of direct SABRE polarization of amines [105] and carboxylates,s uch as acetate [106] and pyruvate, [107] via complexes such as [Ir(H) 2 (IMes)(NH 2 CH 2 Ph) 3 ]Cl and [Ir(H) 2 (IMes)(py) 2 (CO 2 CH 3 )] and [Ir(H) 2 (IMes)-(DMSO)(CO 2 COCH 3 )provides confidence that the SABRE hyperpolarization of amino acids is indeed viable through N, O-, or N,O-ligation modes. [108] Therefore,not surprisingly,an early study on SABRE by Appelt and co-workers [109] suggested that all of the proteinogenic amino acids could be hyperpolarized in this way.T hey used [Ir(COD)(PCy 3 )(py)]-[PF 6 ]a st he SABRE catalyst precursor in [D 4 ]MeOH. The measurements were carried out with ah ome-built NMR spectrometer at proton frequencies of 166 kHz and 10 kHz.…”

Reversible Hyperpolarization of Ketoisocaproate Using Sulfoxide‐containing Polarization Transfer Catalysts

“…Recently, these restrictions are being lifted through the use of relayed polarization transfer (SABRE‐Relay) [37–42] which allows polarization of molecules such as alcohols, [38] sugars, [39] silanols [40] and others [41] without their direct ligation to iridium. Similarly, the hyperpolarization of weakly donating O‐donor molecules such as pyruvate [43] and acetate [44] has been demonstrated.…”

Parawasserstoff‐induzierte Polarisation von Aminosäuren

“…Die direkte SABRE-Polarisation von Aminen [105] und Carboxylaten wie Acetat [106] und Pyruvat [107] [108] Es überrascht daher nicht, dass eine frühe SABRE-Arbeit von Appelt et al [109] [105] Solche Komplexe kçnnen die austauschbaren Protonen dieser Reagenzien hyperpolarisieren (Abbildung 10). Sobald sie sich mit einem zweiten Molekülv erbinden, kann die Hyperpolarisation auf dieses übertragen werden.…”