Computational insight into a mechanistic overview of water exchange kinetics and thermodynamic stabilities of bis and tris-aquated complexes of lanthanides.

A thorough investigation of Ln complexes with more than one inner-sphere water molecule is crucial for designing high relaxivity contrast agents (CAs) used in magnetic resonance imaging (MRI). This study accomplished a comparative stability analysis of two hexadentate (Hcbda and Hdpaa) and two heptadentate (Hpeada and Htpaa) ligands with Ln ions. The higher stability of the hexadentate Hcbda and heptadentate Hpeada ligands has been confirmed by the binding affinity and Gibbs free energy analysis in aqueous solution.