Paramagnetic probes for chemical shift imaging are described, in which a reporting tert-butyl resonance is integrated and placed about 6 to 6.5 � from a lanthanide ion. At this distance, the resonance is shifted to a region of the 1H NMR spectral window far away from the usual range, permitting selective observation. Furthermore, judicious selection of the lanthanide ion, according to the applied magnetic field strength, leads to relaxation rate enhancements of the order of 100�200, permitting more rapid data acquisition per unit time in both spectroscopy and imaging experiments. 1 The enhanced sensitivity allows the detection of these complexes in mice within a few minutes using shift imaging, following tail vein injection of doses of the order of 0.1 mmol kg-1. Similar strategies have been developed for various 19F paramgnetic probes using complexes labelled with trifluoromethyl groups.In complexes with large ligand fields (>>kT), the breakdown of Bleaney's theory of magnetic anisotropy becomes more apparent and the validity of literature values of magnetic susceptibility for the later lanthanide ions (Tb to Yb) has been brought into question.1. P. Harvey, A. M. Blamire, J. I. Wilson, K-L, N. A. Finney, A. M. Funk, P. K. Senanayake and D. Parker, Chem. Sci. 2013, 4  , 4251.

Moving the goal posts: PARASHIFT contrast agents for magnetic resonance

247th National Meeting (2014)

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