Maximizing the relaxivity of HSA-bound gadolinium complexes by simultaneous optimization of rotation and water exchange

Two new GdEGTA (EGTA = ethylene glycol-bis(2-aminoethylether)-N,N,N?, N?-tetraacetic acid) derivatives incorporating aromatic moieties into the oxoethylenic bridge have been prepared and characterised, their conjugates to HSA investigated and an unprecedented high relaxivity, close to that predicted by theory, interpreted in terms of the combined effect of restricted local rotation and fast rate of water exchange. © The Royal Society of Chemistry.