title: Determination of long-range scalar (1)H-(1)H coupling constants responsible for polarization transfer in SABRE.
abstract: SABRE (Signal Amplification By Reversible Exchange) nuclear spin hyperpolarization method can provide strongly enhanced NMR signals as a result of the reversible association of small molecules with para-hydrogen (p-H2) at an iridium metal complex. The conversion of p-H2 singlet order to enhanced substrate proton magnetization within such complex is driven by the scalar coupling interactions between the p-H2 derived hydrides and substrate nuclear spins. In the present study these long-range homonuclear couplings are experimentally determined for several SABRE substrates using an NMR pulse sequence for coherent hyperpolarization transfer at high magnetic field. Pyridine and pyrazine derivatives appear to have a similar ∼1.2 Hz (4)J coupling to p-H2 derived hydrides for their ortho protons, and a much lower (5)J coupling for their meta protons. Interestingly, the (4)J hydride-substrate coupling for five-membered N-heterocyclic substrates is well below 1 Hz.
authors: Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands. Electronic address: n.eshuis@science.ru.nl.
authors: Nan
authors: N
authors: Eshuis
authors: Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands. Electronic address: R.Aspers@nmr.ru.nl.
authors: Ruud L E G
authors: RL
authors: Aspers
authors: Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands. Electronic address: b.weerdenburg@gmail.com.
authors: Bram J A
authors: BJ
authors: van Weerdenburg
authors: Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands. Electronic address: M.Feiters@science.ru.nl.
authors: Martin C
authors: MC
authors: Feiters
authors: Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands. Electronic address: f.rutjes@science.ru.nl.
authors: Floris P J T
authors: FP
authors: Rutjes
authors: Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands. Electronic address: S.Wijmenga@nmr.ru.nl.
authors: Sybren S
authors: SS
authors: Wijmenga
authors: Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands. Electronic address: m.tessari@science.ru.nl.
authors: Marco
authors: M
authors: Tessari
keywords: Hyperpolarization; J-modulation; SABRE