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Heslington, United Kingdom

Olaru A.M.,University of York | Roy S.S.,University of York | Lloyd L.S.,University of York | Coombes S.,Astrazeneca | And 2 more authors.
Chemical Communications

The creation of magnetic states that have long lifetimes has been the subject of intense investigation, in part because of their potential to survive the time taken to travel from the point of injection in a patient to the point where a clinically diagnostic MRI trace is collected. We show here that it is possible to harness the signal amplification by reversible exchange (SABRE) process to create such states in a hyperpolarised form that improves their detectability in seconds without the need for any chemical change by reference to the model substrate 2-aminothiazole. We achieve this by transferring Zeeman derived polarisation that is 1500 times larger than that normally available at 400 MHz with greater than 90% efficiency into the new state, which in this case has a 27 second lifetime. © 2016 The Royal Society of Chemistry. Source

Lloyd L.S.,University of York | Adams R.W.,University of York | Bernstein M.,Astrazeneca | Coombes S.,Astrazeneca | And 5 more authors.
Journal of the American Chemical Society

The characterization of materials by the inherently insensitive method of NMR spectroscopy plays a vital role in chemistry. Increasingly, hyperpolarization is being used to address the sensitivity limitation. Here, by reference to quinoline, we illustrate that the SABRE hyperpolarization technique, which uses para-hydrogen as the source of polarization, enables the rapid completion of a range of NMR measurements. These include the collection of 13C, 13C{1H}, and NOE data in addition to more complex 2D COSY, ultrafast 2D COSY and 2D HMBC spectra. The observations are made possible by the use of a flow probe and external sample preparation cell to re-hyperpolarize the substrate between transients, allowing repeat measurements to be made within seconds. The potential benefit of the combination of SABRE and 2D NMR methods for rapid characterization of low-concentration analytes is therefore established. © 2012 American Chemical Society. Source

Ruddlesden A.J.,University of York | Mewis R.E.,University of York | Mewis R.E.,Manchester Metropolitan University | Green G.G.R.,York Neuroimaging Center | And 2 more authors.

A novel neutral iridium carbene complex Ir(κC,O-L1)(COD) (1) [where COD = cyclooctadiene and L1 = 3-(2-methylene-4-nitrophenolate)-1-(2,4,6-trimethylphenyl)imidazolylidene] with a pendant alkoxide ligand has been prepared and characterized. It contains a strong Ir-O bond, and X-ray analysis reveals a distorted square planar structure. NMR spectroscopy reveals dynamic solution-state behavior commensurate with rapid seven-membered ring flipping. In CD2Cl2 solution, under hydrogen at low temperature, this complex dominates, although it exists in equilibrium with a reactive iridium dihydride cyclooctadiene complex. 1 reacts with pyridine and H2 to form neutral Ir(H)2(κC,O-L1)(py)2, which also exists in two conformers that differ according to the orientation of the seven-membered metallocycle, and while its Ir-O bond remains intact, the complex undergoes both pyridine and H2 exchange. As a consequence, when placed under para-hydrogen, efficient polarization transfer catalysis (PTC) is observed via the signal amplification by reversible exchange (SABRE) approach. Due to the neutral character of this catalyst, good hyperpolarization activity is shown in a wide range of solvents for a number of substrates. These observations reflect a dramatic improvement in solvent tolerance of SABRE over that reported for the best PTC precursor IrCl(IMes)(COD). For THF, the associated 1H NMR signal enhancement for the ortho proton signal of pyridine shows an increase of 600-fold at 298 K. The level of signal enhancement can be increased further through warming or varying the magnetic field experienced by the sample at the point of catalytic magnetization transfer. (Chemical Equation Presented). © 2015 American Chemical Society. Source

Johnston P.,York Neuroimaging Center | Johnston P.,Queensland University of Technology | Kaufman J.,Swinburne University of Technology

The Thatcher Illusion is generally discussed as a phenomenon related to face perception. Nonetheless, we show that compellingly strong Thatcher Effects can be elicited with nonface stimuli, provided that the stimulus set has a familiar standard configuration and a canonical view. Apparently, the Thatcher Illusion is not about faces, and nor is it about Thatcher. It just might, however, be about Britain. © 2014, Pion Limited. All rights reserved. Source

Aguilar J.A.,University of York | Aguilar J.A.,University of Manchester | Adams R.W.,University of York | Duckett S.B.,University of York | And 3 more authors.
Journal of Magnetic Resonance

A new family of NMR pulse sequences is reported for the recording of para-hydrogen enhanced NMR spectra. This Only Para-hydrogen SpectroscopY (OPSY) approach uses coherence selection to separate hyperpolarized signals from those of fully relaxed and thermally equilibrated protons. Sequence design, performance, practical aspects and applicability to other hyperpolarization techniques are discussed. © 2010 Elsevier Inc. All rights reserved. Source

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