title: Effects of Magnetic Field Cycle on the Polarization Transfer from Parahydrogen to Heteronuclei through Long-Range J-Couplings.
abstract: Hyperpolarization of (13)C carboxylate signals of metabolically relevant molecules, such as acetate and pyruvate, was recently obtained by means of ParaHydrogen Induced Polarization by Side Arm Hydrogenation (PHIP-SAH). This method relies on functionalization of the carboxylic acid with an unsaturated alcohol (side arm), hydrogenation of the unsaturated alcohol using parahydrogen, and polarization transfer to the target (13)C signal. In this case, parahydrogen protons are added three to four bonds away from the target (13)C nucleus, while biologically relevant molecules had been hyperpolarized, using parahydrogen, through hydrogenation of an unsaturated bond adjacent to the target (13)C signal. The herein reported results show that the same polarization level can be obtained on the (13)C carboxylate signal of an ester by means of addition of parahydrogen to the acidic or to the alcoholic moiety and successive application of magnetic field cycle (MFC). Experimental results are supported by calculations that allow one to predict that, upon accurate control of magnetic field strength and speed of the passages, more than 20% polarization can be achieved on the (13)C-carboxylate resonance of the esters by means of side arm hydrogenation and MFC.
authors.affiliation: Department Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, Torino 10125, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Cavallari
authors.affiliation: Department Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, Torino 10125, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Carrera
authors.affiliation: Department Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, Torino 10125, Italy.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Boi
authors.affiliation: Department Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, Torino 10125, Italy.
authors.forename: Silvio
authors.initials: S
authors.lastname: Aime
authors.affiliation: Department Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, Torino 10125, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Reineri
mesh_terms: D000438:Alcohols / Q000737:chemistry; D002247:Carbon Isotopes; D002264:Carboxylic Acids / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D060526:Magnetic Fields; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D015394:Molecular Structure; D011522:Protons; D012015:Reference Standards
chemical_list: D000438:Alcohols; D002247:Carbon Isotopes; D002264:Carboxylic Acids; D011522:Protons; D006859:Hydrogen