A theoretical basis for spontaneous polarization transfer in non-hydrogenative parahydrogen-induced polarization

Abstract

When parahydrogen adds to a metal template containing a substrate of interest, the substrate and parahydrogen become coupled, and polarization is shared between the two without the incorporation of the parahydrogen into the substrate. A mechanism for this polarization transfer is presented in which the transfer is propagated through the scalar couplings. At zero field, polarization is transferred between two-, three-, and four-spin zero quantum states, but no single spin magnetization is created. The interplay between the chemical shift evolution and the evolution under scalar coupling at non-zero field generates additional longitudinal spin order and now includes single spin longitudinal z-magnetization. The additional chemical shift interaction introduces a field dependency to the nuclear spin states of the polarized substrate. The net effect of the polarization field strength on the resultant nuclear spin states is shown to be predictable but complex.

Delivering strong 1 H nuclear hyperpolarization levels and long magnetic lifetimes through signal amplification by reversible exchange

“…We proved this by measuring the bound and free protons' relaxation times at 263 K where ligand exchange is effectively quenched (SI Appendix, section 2.7). We hypothesized that the slow rate of productive polarization transfer (23) means that any increase in the bound protons' relaxation times would be seen in an improved final agent polarization level. Conceptually, this could also be achieved by introducing 2 H labeling into the N-heterocyclic carbene (NHC) ligand of the catalyst.…”

“…This route shows great potential for enhancing both analytical NMR and clinical diagnosis in the future (17)(18)(19)(20)(21)(22). SABRE does not change the chemical identity of the agent it hyperpolarizes but equilibrates polarization between p-H 2 and the selected agent through binding to an iridium center (23). This simple process takes just a few seconds and is illustrated in Fig.…”

Selective drug trace detection with low-field NMR

“…1(d)). Attempts have been made to explain such signals for three-and four-spin systems 16,17 but harmine is far more complex, and it is not clear why the antiphase signal arises. The frequency difference Dn ¼ 0.64 Hz between the two peaks in Fig.…”

Polarization transfer efficiency in PHIP experiments

“…Dynamic Nuclear Polarization (DNP) 1,2 and Parahydrogen Induced Polarization (PHIP), [3][4][5][6][7] which can be hydrogenative (ALTADENA, PASADENA) [5][6][7][8] …”