Discrimination of PHIP Signals Through their Evolution in Multipulse Sequences

• Published in: Chemphyschem Vol. 22; no. 19; pp. 1939 - 1946
• Main Authors: Bussandri, S., Franzoni, M. B., Buljubasich, L., Acosta, R. H.
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 05.10.2021
• Subjects: echo trains; hyperpolarization; J-coupling; Line broadening; NMR; Reaction products; Resonance lines; spin dynamics
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.202100146

The antiphase character of the PHIP associated signals after a hydrogenation reaction is particularly sensitive to line broadening introduced by magnetic field inhomogeneities and interferences by the presence of resonance lines steaming from a large amount of thermally polarized spins. These obstacles impose a limitation in the detection of reaction products as well as in the experimental setups. A simple way to overcome these impediments consists of acquiring the signal with a train of refocusing pulses instead of a single r.f. pulse. We present here a number of examples where this multipulse acquisition, denominated PhD‐PHIP, displays its potentiality in improving the information related to hyperpolarized spins performed in a sample, where the former parahydrogen nuclei are part of a complex J‐coupling network. Refocusing pulses: Magnetic field inhomogeneities and the presence of thermally polarized spins perturb PHIP spectra. Multipulse acquisition appears as an excellent alternative to overcome this situation. A number of examples are presented, where the pulse sequence denominates PhD‐PHIP and shows its performance in avoiding line broadening due to inhomogeneities and separating thermal from hyperpolarized signals according to their evolution during acquisition.