The presence of 14N nucleus in the scalar coupling network results in a 3-fold decrease of 15N T1 and polarization values for all 15N sites in 15N2-metronidazole versus15N3-metronidazole in SABRE hyperpolarization in microtesla fields.

The NMR hyperpolarization of uniformly 15 N-labeled [ 15 N 3 ]metronidazole is demonstrated by using SABRE-SHEATH. In this antibiotic, the 15 NO 2 group is hyperpolarized throughs pin relays createdb y 15 Ns pins in [ 15 N 3 ]metronidazole, and the polarization is transferred from parahydrogen-derivedh ydrides over six chemical bonds. In less than am inute of parahydrogen bubbling at approximately 0.4 mT, ah igh level of nuclear spin polarization( P 15N ) of around 16 %i sa chieved on all three 15 Ns ites. This prod-uct of 15 Np olarization andc oncentration of 15 Ns pins is arounds ix-fold bettert han any previous value determined for 15 NS ABRE-derived hyperpolarization. At 1.4 T, the hyperpolarized state persists fort ens of minutes (relaxation time, T 1 %10 min). An ovel synthesis of uniformly 15 N-enriched metronidazole is reported with ay ield of 15 %. This approachc an potentially be used for synthesis of aw ide variety of in vivom etabolic probesw ith potentialu ses ranging from hypoxiasensing to theranostic imaging.[a] Prof.