Gadolinium(III)‐Based Dual 1H/19F Magnetic Resonance Imaging Probes

We present two novel octadentate cyclen‐based ligands bearing one (L1) or two (L2) phenylacetamide pendants with two CF3 groups either at positions 3 and 5 (L1) or 4 (L2). The corresponding Gd3+ complexes possess one coordinated water molecule, as confirmed by luminescence lifetime measurements on t...

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Bibliographic Details
Published in:Chemistry : a European journal 2019-03, Vol.25 (18), p.4782-4792
Main Authors: Pujales‐Paradela, Rosa, Savić, Tanja, Esteban‐Gómez, David, Angelovski, Goran, Carniato, Fabio, Botta, Mauro, Platas‐Iglesias, Carlos
Format: Article
Language:English
Subjects:
Acetanilide
Chemistry
fluorine
Gadolinium
Isomers
macrocycles
Magnetic properties
Magnetic resonance imaging
magnetic resonance imaging (MRI)
Medical imaging
NMR
NMR spectroscopy
Noise reduction
Nuclear magnetic resonance
Relaxation time
Resonance
Water chemistry
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Summary:We present two novel octadentate cyclen‐based ligands bearing one (L1) or two (L2) phenylacetamide pendants with two CF3 groups either at positions 3 and 5 (L1) or 4 (L2). The corresponding Gd3+ complexes possess one coordinated water molecule, as confirmed by luminescence lifetime measurements on the EuIII and TbIII analogues. A detailed 1H and 17O relaxometric characterization has revealed the parameters that govern the relaxivities of these complexes. The water‐exchange rate of the mono‐amide derivative GdL1 (kex298=1.52×106 s−1) is faster than that determined for the bis‐amide complex GdL2 (kex298=0.73×106 s−1). 1H and 19F NMR studies have indicated that the complexes are present in solution almost exclusively as the square‐antiprismatic (SAP) isomers. 19F NMR relaxation studies indicated Gd⋅⋅⋅F distances of 7.4±0.1 and 9.1±0.1 Å for GdL1 and GdL2, respectively. Phantom MRI studies revealed the favorable properties of GdL2 as a dual 1H/19F magnetic resonance imaging (MRI) probe, whereas the shorter Gd⋅⋅⋅F distance of GdL1 reduces the signal‐to‐noise ratio due to the very short transverse relaxation time of the 19F NMR signal. Proton versus fluorine: Gadolinium(III) complexes based on cyclen units functionalized with pendant arms bearing CF3 substituents have been designed and synthesized. These agents provide responses in magnetic resonance imaging at both the 1H and 19F frequencies.
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.201806192