Direct Hyperpolarization of Nitrogen-15 in Aqueous Media with Parahydrogen in Reversible Exchange

• DOI: 10.1021/jacs.7b00569
• Publication Date: 2017-04-26T11:40:56Z
• Authors: Johannes F. P. Co...; Meike Emondts; Angus W. J. Logan; Kun Shen; Junu Bae; Roman V. Shchepin; Gerardo X. Ortiz; Peter Spannring; Qiu Wang; Steven J. Malcolmson; Eduard Y. Chekmenev; Martin C. Feiters; Floris P. J. T. R...; Bernhard Blümich; Thomas Theis; Warren S. Warren
• Keywords: Magnetic Resonance Spectroscopy; Molecular Structure; Nitrogen Isotopes; Water; Synthetic Organic Chemistry; 01 natural sciences; Hydrogen; 0104 chemical sciences

Signal amplification by reversible exchange (SABRE) is an inexpensive, fast, and even continuous hyperpolarization technique that uses para-hydrogen as hyperpolarization source. However, current SABRE faces a number of stumbling blocks for translation to biochemical and clinical settings. Difficulties include inefficient polarization in water, relatively short-lived 1H-polarization, and relatively limited substrate scope. Here we use a water-soluble polarization transfer catalyst to hyperpolarize nitrogen-15 in a variety of molecules with SABRE-SHEATH (SABRE in shield enables alignment transfer to heteronuclei). This strategy works in pure H2O or D2O solutions, on substrates that could not be hyperpolarized in traditional 1H-SABRE experiments, and we record 15N T1 relaxation times of up to 2 min.