Tuning pGa with chelating agents related to (o-hydroxybenzyl)iminodiacetic acid

Gallium complexes with R-(o-hydroxybenzyl)iminodiacetate ligands (Lx) have been synthesized and their thermodynamic constants determined in aqueous solution by potentiometric titration. These quantitative results were also confirmed by H-1 and F-19 NMR spectroscopy. An X-ray study of GaL3 (R = NO2) showed that the gallium((III)) ion is hexacoordinate with two H2O molecules in cis positions. The ability of the ligands to chelate Ga-III was evaluated. at physiological pH and ionic strength from the pGa values. Among the different ligands studied, L6 (R = OMe) has a pGa value two orders of magnitude higher than that of the complex between Ga and the blood serum protein transferrin. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).