TY - JOUR
T1 - Long-Lived 13C2 Nuclear Spin States Hyperpolarized by Parahydrogen in Reversible Exchange at Microtesla Fields
AU - Zhou, Zijian
AU - Yu, Jin
AU - Colell, Johannes F.P.
AU - Laasner, Raul
AU - Logan, Angus
AU - Barskiy, Danila A.
AU - Shchepin, Roman V.
AU - Chekmenev, Eduard Y.
AU - Blum, Volker
AU - Warren, Warren S.
AU - Theis, Thomas
N1 - Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/7/6
Y1 - 2017/7/6
N2 - Parahydrogen is an inexpensive and readily available source of hyperpolarization used to enhance magnetic resonance signals by up to four orders of magnitude above thermal signals obtained at ∼10 T. A significant challenge for applications is fast signal decay after hyperpolarization. Here we use parahydrogen-based polarization transfer catalysis at microtesla fields (first introduced as SABRE-SHEATH) to hyperpolarize 13C2 spin pairs and find decay time constants of 12 s for magnetization at 0.3 mT, which are extended to 2 min at that same field, when long-lived singlet states are hyperpolarized instead. Enhancements over thermal at 8.5 T are between 30 and 170 fold (0.02 to 0.12% polarization). We control the spin dynamics of polarization transfer by choice of microtesla field, allowing for deliberate hyperpolarization of either magnetization or long-lived singlet states. Density functional theory calculations and experimental evidence identify two energetically close mechanisms for polarization transfer: First, a model that involves direct binding of the 13C2 pair to the polarization transfer catalyst and, second, a model transferring polarization through auxiliary protons in substrates.
AB - Parahydrogen is an inexpensive and readily available source of hyperpolarization used to enhance magnetic resonance signals by up to four orders of magnitude above thermal signals obtained at ∼10 T. A significant challenge for applications is fast signal decay after hyperpolarization. Here we use parahydrogen-based polarization transfer catalysis at microtesla fields (first introduced as SABRE-SHEATH) to hyperpolarize 13C2 spin pairs and find decay time constants of 12 s for magnetization at 0.3 mT, which are extended to 2 min at that same field, when long-lived singlet states are hyperpolarized instead. Enhancements over thermal at 8.5 T are between 30 and 170 fold (0.02 to 0.12% polarization). We control the spin dynamics of polarization transfer by choice of microtesla field, allowing for deliberate hyperpolarization of either magnetization or long-lived singlet states. Density functional theory calculations and experimental evidence identify two energetically close mechanisms for polarization transfer: First, a model that involves direct binding of the 13C2 pair to the polarization transfer catalyst and, second, a model transferring polarization through auxiliary protons in substrates.
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U2 - 10.1021/acs.jpclett.7b00987
DO - 10.1021/acs.jpclett.7b00987
M3 - Article
C2 - 28594557
AN - SCOPUS:85021980105
SN - 1948-7185
VL - 8
SP - 3008
EP - 3014
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 13
ER -