Parahydrogen induced polarization of barbituric acid derivatives: 1H hyperpolarization studies.
Homogeneous hydrogenation of barbituric acid derivatives with parahydrogen yields a substantial increase of the (1)H NMR signals of the reaction products. These physiologically relevant compounds were hydrogenated at both ambient and elevated temperatures and pressures using a standard cationic rhodium catalyst. The resulting nonthermal nuclear spin polarization (hyperpolarization) is limited by the spin-lattice relaxation time T(1) of the corresponding nuclei in the products, being shorter than the time constant of the hydrogenation. The signal-to-noise ratio of the NMR spectra could be further increased upon signal averaging the antiphase PHIP signals of 25 successive scans following 30 degrees pulse experiments and a delay of 10 s.
Roth
Meike
M
Max-Planck-Institute for Polymer Research, NMR Division, Postfach 3148, D-55021 Mainz, Germany.
Bargon
Joachim
J
Spiess
Hans Wolfgang
HW
Koch
Achim
A