5 research outputs found
Die Anwendung von neuartigen Ir-Komplexen bei der parawasserstoffinduzierten Signalverstärkung in der NMR-Spektroskopie
The application of novel Ir-NHC polarization transfer complexes by SABRE
In recent years, the hyperpolarization method Signal Amplification By Reversible Exchange (SABRE) has developed into a powerful technique to enhance Nuclear Magnetic Resonance (NMR) signals of organic substrates in solution (mostly via binding to the nitrogen lone pair of N-heterocyclic compounds) by several orders of magnitude. In order to establish the application and development of SABRE as a hyperpolarization method for medical imaging, the separation of the Ir-N-Heterocyclic Carbene (Ir-NHC) complex, which facilitates the hyperpolarization of the substrates in solution, is indispensable. Here, we report for the first time the use of novel Ir-NHC complexes with a polymer unit substitution in the backbone of N-Heterocyclic Carbenes (NHC) for SABRE hyperpolarization, which permits the removal of the complexes from solution after the hyperpolarization of a target substrate has been generated
Indirect Detection of Short-lived Hydride Intermediates of Iridium N-Heterocyclic Carbene Complexes via Chemical Exchange Saturation Transfer (CEST) Spectroscopy
For the first time chemical-exchange saturation transfer (CEST) 1H NMR is utilized for the study of
short-lived hydride intermediates in the catalytic cycle of
the Iridium-based organometallic complex
[Ir(IMes)(Py)3(H)2]Cl, which are often not observable by
other NMR techniques, since they are low concentrated,
and undergo reversible ligand exchange with the main
complex. The intermediate complexes
[Ir(Cl)(IMes)(Py)2(H)2] and [Ir(CD3OD)(IMes)
(Py)2(H)2] are detected, assigned and characterized in situ
and at room temperature in solution. Understanding the
effects on the spin dynamics induced by these complexes
is necessary for enhancing the performance of the nuclear
spin hyperpolarization technique SABRE (Signal Amplification By Reversible Exchange). By eliminating
[Ir(Cl)(IMes)(Py)2(H)2] and manipulating the spin-system by RF-irradiation, we were able to increase the nuclear spin singlet lifetime of the two protons in the main
hydride complex by more than an order of magnitude,
from 2.2±0.1 s to 27.2±1.2 s. The presented CEST NMR
approach has a large application potential for studying
short-lived hydride intermediates in catalytic reactions