We produce hyperpolarized [1-13C]fumarate in the proton nuclear spin singlet state by pairwise trans-addition of parahydrogen to a molecular precursor using a ruthenium-based catalyst in water.

In dissolution-dynamic nuclear polarization, nuclear spins are hyperpolarized at cryogenic temperatures using radicals and microwave irradiation. The hyperpolarized solid is dissolved with hot solvent and the solution is transferred to a secondary magnet where strongly enhanced magnetic resonance signals are observed. Here we present a method for transferring the hyperpolarized solid. A bullet containing the frozen, hyperpolarized sample is ejected using pressurized helium gas, and shot into a receiving structure in the secondary magnet, where the bullet is retained and the polarized solid is dissolved rapidly. The transfer takes approximately 70 ms. A solenoid, wound along the entire transfer path ensures adiabatic transfer and limits radical-induced low-field relaxation. The method is fast and scalable towards small volumes suitable for high-resolution nuclear magnetic resonance spectroscopy while maintaining high concentrations of the target molecule. Polarization levels of approximately 30% have been observed for 1- 13 C-labelled pyruvic acid in solution.

We report chiral guest binding as a probe of prototropic tautomerism and macrocyclic inversion in a highly conjugated tetrapyrrole studied using (1)H NMR spectroscopy in conjunction with mandelic acid as the chiral guest. Both tautomerism and macrocycle inversion can be influenced in a non-trivial way depending on temperature and the respective concentrations of tetrapyrrole host, chiral guest or water. Chirality of the interacting guest is the key feature since it permits separation and detailed observation of macrocyclic inversion and tautomerism. Based on this, a methodology was developed to identify and characterize the dynamic processes. Our observations suggest that yields of products (e.g., of asymmetric reactions) can be affected by reactivity of functional groups (in molecules undergoing tautomerism or inversion) by varying solution properties including reagent concentrations and impurities such as water. This work establishes a connection between the important chemical concepts of chirality, tautomerism, and macrocyclic dynamics.

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Water exists in two forms, para and ortho, that have nuclear spin states with different symmetries. Here we report the conversion of fullerene-encapsulated para water to ortho water. The enrichment of para water at low temperatures is monitored via changes in the electrical polarizability of the material. Upon rapid dissolution of the material in toluene the excess para water converts to ortho water. In H_{2}^{16}O@C_{60} the conversion leads to a slow increase in the NMR signal. In H_{2}^{17}O@C_{60} the conversion gives rise to weak signal enhancements attributed to quantum-rotor-induced nuclear spin polarization. The time constants for the para-to-ortho conversion of fullerene-encapsulated water in ambient temperature solution are estimated as 30±4  s for the ^{16}O isotopolog of water, and 16±3  s for the ^{17}O isotopolog.