A series of bidentate N-heterocyclic carbene (NHC) iridium catalysts, [Ir(κC,N-NHC)H₂L₂]BPh₄, are proposed for SABRE hyperpolarization. The steric and electronic properties of the NHCs are used to tune substrate affinity and thereby SABRE efficiency. The sterically hindered substrates 2,4-diaminopyrimidine and trimethoprim yielded maximum proton NMR signal enhancements of ∼300-fold and ∼150-fold, respectively.

中文翻译：

---

具有双齿N-杂环卡宾配体的可调谐铱催化剂设计，用于空间受阻基质的SABER超极化

提出了一系列双齿N-杂环卡宾（NHC）铱催化剂[Ir（κC，N-NHC）H ₂ L ₂ ] BPh ₄，用于SABER超极化。NHC的空间和电子性质用于调整底物亲和力，从而调整SABRE效率。位阻的底物2,4-二氨基嘧啶和甲氧苄啶产生的最大质子NMR信号增强分别为约300倍和约150倍。