The effect of ¹H-decoupling on hyperpolarized ¹³C signal decay – a study on choline chloride analogs and comparison to the effect of deuterium substitution of directly bonded protons

The spin-lattice relaxation time (T₁) of a DNP molecular probe is a key parameter in acquiring NMR signals in dissolution-DNP (d-DNP) experiments. Using molecular probes with long T₁, NMR spin signals can survive for a duration sufficient for the study of metabolism (1-3 min). Deuteration of directly bonded ¹³C protonated positions has been useful in prolonging the visibility of hyperpolarized labeled ¹³C sites that are otherwise protonated. Here, we sought to investigate whether proton irradiation could affect the T₁ of such ¹³C nuclei when such positions are in their naturally abundant form, i.e. directly bonded to protons.