Optimisation of pyruvate hyperpolarisation using SABRE by tuning the active magnetisation transfer catalyst
Hyperpolarisation techniques such as signal amplification by reversible exchange (SABRE) can deliver NMR signals several orders of magnitude larger than those derived under Boltzmann conditions. SABRE is able to catalytically transfer latent magnetisation from para-hydrogen to a substrate in reversible exchange via temporary associations with an iridium complex. SABRE has recently been applied to the hyperpolarisation of pyruvate, a substrate often used in many in vivo MRI studies. In this work, we seek to optimise the pyruvate-13C2 signal gains delivered through SABRE by fine tuning the properties of the active polarisation transfer catalyst. We present a detailed study of the effects of varying the carbene and sulfoxide ligands on the formation and behaviour of the active [Ir(H)2(η2-pyruvate)(sulfoxide)(NHC)] catalyst to produce a rationale for achieving high pyruvate signal gains in a cheap and refreshable manner. This optimisation approach allows us to achieve signal enhancements of 2140 and 2125-fold for the 1-13C and 2-13C sites respectively of sodium pyruvate-1,2-[13C2].
Duckett, Simon B.,Iali, Wissam,Rayner, Peter J.,Semenova, Olga,Tickner, Ben. J.,Whitwood, Adrian C.
p. 1343 - 1355
(2020/03/26)
Hydrogen transfer from CpRe(CO)2H2 to trans-Ir(CO)(Cl)(PPh3)2 via a Heterobimetallic Re-Ir Intermediate
The reaction of CpRe(CO)2H2 (3) with trans-Ir(CO)(Cl)(PPh3)2 (4) led to the formation of CpRe(CO)3 (14) and of equimolar amounts of H2Ir(PPh3)2(CO)(Cl) (15) and mer-H2Ir(PPh3)3(Cl) (16). When the reaction was carried out in the presence of added PPh3, only 14 and 16 were formed. When the reaction was carried out under a CO atmosphere, only 14 and 15 were formed. Reaction of 3 with (PPh3)3(CO)IrH led to the formation of 14 and fac- and mer-IrH3(PPh3)3 (20). These reactions are proposed to proceed by oxidative addition of a rhenium-hydrogen bond to an iridium center. The resulting heterobimetallic dihydride intermediate then rapidly decomposes by simultaneous transfer of H from Re to Ir and transfer of CO from Ir to Re.
Casey, Charles P.,Rutter Jr., Edward W.
p. 2333 - 2335
(2008/10/08)
HOMO- AND HETERO-DINUCLEAR HYDRIDE-BRIDGED COMPLEXES CONTAINING CYCLOOCTADIENE: THE CRYSTAL AND MOLECULAR STRUCTURE OF 4-C8H12)Ir(μ-H)(μ-Cl)-IrH2(PPh3)2>
The reaction of with 2> (M = Rh or Ir, cod = cyclo-octa-1,5-diene) gives the dinuclear complexes 4-C8H12)M(μ-H)(μ-Cl)IrH2(PPh3)2>.The di-iridium compound has been subjected to an X-ray analysis which establishes that the iridium(I) atom adpots a square-planar coordination geometry while the iridium (III) atom is in a pseudo-octahedral environment if the direct Ir-Ir interaction is ignored.The two Ir atoms are bridged by a hydride and a chloride ligand.The Ir-Cl bridge is highly asymmetric , and this asymmetry is discussed in terms of the relative transeffect of the ligands present.
Hlatky, Gregory G.,Johnson, Brian F. G.,Lewis, Jack,Raithby, Paul R.
p. 1277 - 1280
(2007/10/02)
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