Toward Optimized High-Relaxivity MRI Agents: The Effect of Ligand Basicity on the Thermodynamic Stability of Hexadentate Hydroxypyridonate/Catecholate Gadolinium(III) Complexes
Dan M. J. Doble, Marco Melchior, Brendon O'Sullivan, Carsten Siering, Jide Xu, Valérie C. Pierre, Kenneth N. Raymond
The thermodynamic stabilities of the Gd III complexes of five hexadentate ligands which incorporate catecholate and hydroxypyridonate subunits with a range of basicities have been determined. The most stable Gd III complex at a physiological pH of 7.4 was observed for a ligand of intermediate basicity. The stability of this complex is comparable to that of Gd III complexes that feature eight-coordinate ligands and are currently used as magnetic resonance imaging contrast agents in diagnostic medicine. The accompanying bar chart shows pGd (= −log [Gd III free ]; total concentrations: [Gd III ] = 10 - 6 M, [L] = 10 - 5 M) for five hexadentate ligands which incorporate catecholate and hydroxypyridonate subunits at a physiological pH of 7.4. The basicity of the ligands increases in going from 1 to 5.
This paper describes the synthesis of a new hydroxypyridinone applicable for MRI technology. The basicity was measured and related to the thermodynamic stability with Gd.
Reaction of interest:
Our interest was the formation of the ring 6- methyl...
Tweaks Necessary to Improve Yield
Summary:
This paper describes the synthesis of a new hydroxypyridinone applicable for MRI technology. The basicity was measured and related to the thermodynamic stability with Gd.
Reaction of interest:
Our interest was the formation of the ring 6- methyl...