Fluorinated Paramagnetic Probes for 19-F and 1-H MRS/ MRI

Abstract

Novel CF3-labelled lanthanide(III) complexes have been synthesised for use as probes for 19-F and 1-H magnetic resonance spectroscopy and imaging.
The syntheses and evaluation of two classes of fluorinated paramagnetic complexes are defined. Notably, the 19-F magnetic resonance relaxation processes for the complexes have been assessed, allowing for the analysis of the interplay between applied field, Ln(III) ion and rotational correlation time on relaxation properties.
Strategies employed to enhance signal intensity are discussed, examining a number of different of fluorinated mono- and di-amide cyclen ligands. Systems incorporating phosphinate pendant arms are of particular interest, resulting in complexes with favourable isomer distributions, faster longitudinal relaxation rates and narrower linewidths.
Finally, the synthesis of high molecular weight conjugates with paramagnetic fluorinated complexes is described. Three different classes of medium to high molecular adducts were considered, with the merits and limitations of each assessed. The desirable formation of one species in solution, ease of solubility and attractive 19F and 1H relaxometric properties render the chitosan conjugates promising candidates for future use as imaging probes.