Hadjiali, Sara, Roman Savka, Markus Plaumann, Ute Bommerich, Sarah Bothe, Torsten Gutmann, Tomasz Ratajczyk, et al. “Substituent Influences on the NMR Signal Amplification of Ir Complexes with Heterocyclic Carbene Ligands.” Applied Magnetic Resonance 50, no. 7 (July 2019): 895–902.
https://doi.org/10.1007/s00723-019-01115-x.
A number of Ir–N-heterocyclic carbene (Ir–NHC) complexes with asymmetric N-heterocyclic carbene (NHC) ligands have been prepared and examined for signal amplification by reversible exchange (SABRE). Pyridine was chosen as model compound for hyperpolarization experiments. This substrate was examined in a solvent mixture using several Ir–NHC complexes, which differ in their NHC ligands. The SABRE polarization was created at 6 mT and the 1H nuclear magnetic resonance signals were detected at 7 T. We show that asymmetric NHC ligands, because of their favorable chemistry, can adapt the SABRE active complexes to different chemical scenarios.