Saturday, August 11, 2012

15N Magnetic Resonance Hyperpolarization via the Reaction of Parahydrogen with 15N-Propargylcholine

Reineri, F., et al., 15N Magnetic Resonance Hyperpolarization via the Reaction of Parahydrogen with 15N-Propargylcholine. J. Am. Chem. Soc., 2012. 134(27): p. 11146-11152.


15N-Propargylcholine has been synthesized and hydrogenated with para-H2. Through the application of a field cycling procedure, parahydrogen spin order is transferred to the 15N resonance. Among the different isomers formed upon hydrogenation of 15N-propargylcholine, only the nontransposed derivative contributes to the observed N-15 enhanced emission signal. The parahydrogen-induced polarization factor is about 3000. The precise identification of the isomer responsible for the observed 15N enhancement has been attained through a retro-INEPT (15N-1H) experiment. T1 of the hyperpolarized 15N resonance has been estimated to be ca. 150 s, i.e., similar to that reported for the parent propargylcholine (144 s). Experimental results are accompanied by theoretical calculations that stress the role of scalar coupling constants (JHN and JHH) and of the field dependence in the formation of the observed 15N polarized signal. Insights into the good cellular uptake of the compound have been gained.