Prediction of GD(III) Complex Thermodynamic Stability

Abstract

[Abstract] Gadolinium(III) complexes are widely employed as contrast agents in diagnostic magnetic resonance imaging, and the development of new contrast agents remains a highly active field. A key requisite for contrast agents is high thermodynamic stability of the complex to ensure that the Gd(III) ion is not released in the body. Here we utilized published stability constants spanning 20 orders of magnitude to develop empirical expressions based on structural descriptors to predict the Gd(III)-ligand formation constant as well as pGd at pH 7.4. We then tested the predictive power of these expressions and found excellent agreement with a mean deviation of 1.0 log K units. The magnitudes of the structural descriptors are useful for guiding ligand design for Gd(III), and the empirical stability constant expressions can be used to screen potential ligands. This methodology is readily extended to other aqueous metal ion systems.