title: Parahydrogen induced polarization of barbituric acid derivatives: 1H hyperpolarization studies.
abstract: 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.
authors.affiliation: Max-Planck-Institute for Polymer Research, NMR Division, Postfach 3148, D-55021 Mainz, Germany.
authors.forename: Meike
authors.initials: M
authors.lastname: Roth
authors.forename: Joachim
authors.initials: J
authors.lastname: Bargon
authors.forename: Hans Wolfgang
authors.initials: HW
authors.lastname: Spiess
authors.forename: Achim
authors.initials: A
authors.lastname: Koch