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Gadolinium(III)-Based Dual 1H/19F Magnetic Resonance Imaging Probes
{We present two novel octadentate cyclen-based ligands containing one (L1) or two (L2) phenylacetamide pendants that feature 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 the luminescence lifetime measurements recorded on the Eu(III) and Tb(III) analogues. A detailed 1H and 17O relaxometric characterisation revealed the parameters that govern the relaxivities of these complexes. The water exchange rate of the mono-amide derivative GdL1 (kex298 \textequals 1.52$\times$106 s-1) is faster than that determined for the bis-amide complex GdL2 (kex298 \textequals 0.73$\times$106 s-1). 1H and 19F NMR studies indicate that the complexes are present in solution almost exclusively as the square antiprismatic (SAP) isomers. 19F NMR relaxation studies provided Gd\mbox{$\cdot$}\mbox{$\cdot$}\mbox{$\cdot$}F distances of 7.4 + 0.1 and 9.1 + 0.1 \AA for GdL1 and GdL2, respectively. Phantom MRI studies revealed the favourable properties of GdL2 as a dual 1H/19F MRI probe, while the shorter Gd\mbox{$\cdot$}\mbox{$\cdot$}\mbox{$\cdot$}F distance of GdL1 reduces the signal to noise ratio due to the very short transverse relaxation time of the 19F NMR signal.}
@article{item_3023969, title = {{Gadolinium(III)-Based Dual 1H/19F Magnetic Resonance Imaging Probes}}, journal = {{Chemistry \textendash A European Journal}}, abstract = {{We present two novel octadentate cyclen-based ligands containing one (L1) or two (L2) phenylacetamide pendants that feature two CF3 groups either at positions 3 and 5 (L1) or 4 (L2). The corresponding Gd3+ complexes possess one coordinated water molecule, as confirmed by the luminescence lifetime measurements recorded on the Eu(III) and Tb(III) analogues. A detailed 1H and 17O relaxometric characterisation revealed the parameters that govern the relaxivities of these complexes. The water exchange rate of the mono-amide derivative GdL1 (kex298 \textequals 1.52$\times$106 s-1) is faster than that determined for the bis-amide complex GdL2 (kex298 \textequals 0.73$\times$106 s-1). 1H and 19F NMR studies indicate that the complexes are present in solution almost exclusively as the square antiprismatic (SAP) isomers. 19F NMR relaxation studies provided Gd\mbox{$\cdot$}\mbox{$\cdot$}\mbox{$\cdot$}F distances of 7.4 + 0.1 and 9.1 + 0.1 \AA for GdL1 and GdL2, respectively. Phantom MRI studies revealed the favourable properties of GdL2 as a dual 1H/19F MRI probe, while the shorter Gd\mbox{$\cdot$}\mbox{$\cdot$}\mbox{$\cdot$}F distance of GdL1 reduces the signal to noise ratio due to the very short transverse relaxation time of the 19F NMR signal.}}, volume = {25}, number = {18}, pages = {4782--4792}, publisher = {Wiley-VCH}, address = {Weinheim}, year = {2019}, slug = {item_3023969}, author = {Pujales-Paradela, R and Savi\'c, T and Esteban-Gomez, D and Angelovski, G and Carniato, F and Botta, M and Platas-Iglesias, C} }