The water exchange process was accelerated for nine-coordinate, monohydrated macrocyclic Gd^III complexes by inducing steric compression around the water binding site; the increased steric crowding was achieved by replacing an ethylene bridge of DOTA⁴⁻ by a propylene bridge; in addition to the optimal water exchange rate, the stability of [Gd(TRITA)(H₂O)]⁻ is sufficiently high to ensure safe medical use which makes it a potential synthon for the development of high relaxivity, macromolecular MRI contrast agents.