Accessing long lived 1H states via 2H couplings

In this paper we demonstrate long-lived states involving a pair of chemically equivalent protons, with lifetimes similar to 30 times T-1 up to a total lifetime of similar to 117 s at high field (8.45 T). This is demonstrated on trans-ethylene-d(2) in solution, where magnetic inequivalence gives access to the long-lived states. It is shown that the remaining J-coupling between the two quadrupolar deuterium spins, J(QQ), splits the conditions for optimally generating proton singlet states. Detailed simulations of the spin evolution are performed, shedding light on the coherent evolution during singlet-triplet conversion as well as on the incoherent evolution that causes relaxation. Subsequently, the simulations are compared with experimental results validating the theoretical insights. Possible applications include storage of hyperpolarization in the proton long-lived state. Of particular interest may be utilization of parahydrogen induced polarization to directly induce the examined long-lived states. (C) 2016 Elsevier Inc. All rights reserved.