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Diazirine moieties are chemically stable and have been incorporated into biomolecules without impediment of biological activity. The 15 N 2 labeled diazirines are appealing motifs for hyperpolarization supporting relaxation protected states with long-lived lifetimes. The (-CH 15 N 2 ) diazirine groups investigated here are analogues to methyl groups, which provides the opportunity to transfer polarization stored on a relaxation protected (-CH 15 N 2 ) moiety to 1 H, thus combining the advantages of long lifetimes of 15 N polarization with superior sensitivity of 1 H detection. Despite the proximity of 1 H to 15 N nuclei in the diazirine moiety, 15 N T 1 times of up to (4.6±0.4) min and singlet lifetimes T s of up to (17.5±3.8) min are observed. Furthermore, we found terminal diazirines to support hyperpolarized 1 H 2 singlet states in CH 2 groups of chiral molecules. The singlet lifetime of 1 H singlets is up to (9.2±1.8) min, thus exceeding 1 H T 1 relaxation time (at 8.45 T) by a factor of ≈100., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are supremely important techniques with numerous applications in almost all branches of science. However, until recently, NMR methodology was limited by the time constant T1 for the decay of nuclear spin magnetization through contact with the thermal molecular environment. Long-lived states, which are correlated quantum states of multiple nuclei, have decay time constants that may exceed T1 by large factors. Here we demonstrate a nuclear long-lived state comprising two (13)C nuclei with a lifetime exceeding one hour in room-temperature solution, which is around 50 times longer than T1. This behavior is well-predicted by a combination of quantum theory, molecular dynamics, and quantum chemistry. Such ultra-long-lived states are expected to be useful for the transport and application of nuclear hyperpolarization, which leads to NMR and MRI signals enhanced by up to five orders of magnitude., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)