The Detection and Reactivity of Silanols and Silanes Using Hyperpolarized ²⁹Si Nuclear Magnetic Resonance

Abstract

Silanols and silanes are key precursors and intermediates for the synthesis of silicon‐based materials. While their characterization and quantification by 29Si NMR spectroscopy has received significant attention, it is a technique that is limited by the low natural abundance of 29Si and its low sensitivity. Here, we describe a method using p‐H2 to hyperpolarize 29Si. The observed signal enhancements, approaching 3000‐fold at 11.7 T, would take many days of measurement for comparable results under Boltzmann conditions. The resulting signals were exploited to monitor the rapid reaction of tris(tert‐butoxy)silanol with triflic anhydride in a T1‐corrected process that allows for rapid quantification. These results demonstrate a novel route to quantify dynamic processes and intermediates in the synthesis of silicon materials.

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.…”

Exploring the hyperpolarisation of EGTA-based ligands using SABRE

“…Relayed proton exchange effects are now expanding the scope to include nonligating molecules such as alcohols, 30 sugars 31 and silanols. 32 SABRE hyperpolarised molecules with MR signals responsive to factors such as pH 33,34 NO concentration 35 or H 2 O 2 36 have been reported.…”

Chloroquine and Lopinavir (COVID-19 Drug Candidates) Signal Amplification by Reversible Exchange

“…Of several methods to hyperpolarize drugs, the para-hydrogen based signal amplification by reversible exchange (SABRE) method is a promising tool for hyperpolarization of several key structures with nitrogen. Furthermore, its polarization could be transferred in real time from protons to other isotopes such as 13 Several great recent studies of producing hyperpolarized drugs or metabolites [16][17][18][19][20] , including pharmacokinetics using SABRE 21 , confirm that such a study would widen its application in this era, when scientific solutions are the only way to conquer this disaster. Therefore, a hyperpolarization study using SABRE may be a good and key start to applying MRI scanning by using hyperpolarized chloroquine/lopinavir in the future.…”