Ab initio simulation of a gadolinium-based magnetic resonance imaging contrast agent in aqueous solution.

The first ab initio molecular dynamics simulation of a Gd(III)-based contrast agent in explicit aqueous solution at ambient conditions as used in the actual magnetic resonance imaging of human bodies is presented. The description of the structure of this chelate complex is considerably improved with respect to typical force fields and ab initio calculations in continuum solvent models if the open 4f shell of Gd is included explicitly. The solvation-shell structure is revealed to be anionic and includes a rather short hydrogen bond donated by the hydroxypropyl arm.