N-2-(Azol-1(2)-yl)ethyliminodiacetic acids: a novel series of Gd(III) chelators as T2relaxation agents for magnetic resonance imaging

The synthesis, physicochemical properties, and toxicological implications of a novel series of N-2-(azol-1(2)-yl)ethyliminodiacetic acids, useful as contrast agents for magnetic resonance imaging are reported. Compounds were prepared by alkylation of methyl iminodiacetate with N-2-bromoethylazoles and subsequent hydrolysis. Stability constants of the corresponding Gd(III) complexes and T1and T2relaxivities were determined and interpreted in terms of optimized geometries obtained by semiempirical PM3 calculations. Compounds show increased T2relaxivity and decreased toxicity in vitro as compared to EDTA-Gd(III) complexes.