Tanner Christian P N, Lindale Jacob R, Eriksson Shannon L, Zhou Zijian, Colell Johannes F P, Theis Thomas, Warren Warren S
Department of Chemistry, Duke University, Durham, North Carolina 27708, USA.
Department of Chemistry, Duke School of Medicine, Duke University, Durham, North Carolina 27708, USA.
J Chem Phys. 2019 Jul 28;151(4):044201. doi: 10.1063/1.5108644.
Signal Amplification By Reversible Exchange (SABRE) and its heteronuclear variant SABRE in SHield Enables Alignment Transfer to Heteronuclei create large nuclear magnetization in target ligands, exploiting level crossings in an iridium catalyst that transiently binds both the ligands and parahydrogen. This requires a specific, small magnetic field to match Zeeman splittings to scalar couplings. Here, we explore a different strategy, direct creation of heteronuclear singlet states in the target ligands, which produces enhanced signals at other field strengths, including zero field. We also show that pulsed methods (including pulsed field nulling) coherently and selectively pump such singlets, affording a significant enhancement on the resulting hyperpolarization.
可逆交换信号放大（SABRE）及其在屏蔽环境中的异核变体SABRE能够将取向转移至异核，在目标配体中产生大的核磁化强度，这是通过利用铱催化剂中的能级交叉来实现的，该铱催化剂会瞬时结合配体和仲氢。这需要特定的小磁场，以使塞曼分裂与标量耦合相匹配。在此，我们探索了一种不同的策略，即在目标配体中直接创建异核单重态，这会在包括零场在内的其他场强下产生增强信号。我们还表明，脉冲方法（包括脉冲场归零）能够相干且选择性地泵浦此类单重态，从而在产生的超极化方面带来显著增强。
