Synthesis, characterization and relaxivity of DTPA double alkyl esters heterocyclic gadolinium(III) complexes

The DTPA ligand modified by heterocyclic compound and linked through double alkyl ester covalent bond was synthesized by acylation reaction between diethylenetriamine pentaacetic (DTPA) bisanhydride and a novel heterocyclic compound. The corresponding paramagnetic Gd(III) complex was gained by the reaction of the DTPA ligand with GdCl3.6H2O. The structure of the ligand and its Gd(III) complex was characterized by elemental analysis, FTIR and 1H NMR, and the longitudinal relaxivity (R1) was measured. Besides, the magnetic resonance imaging of the new Gd(III) complex in vitro was studied. The result suggested that the stability of the complex was well, and when the Gd(III) quantity was identical, the R1 of the Gd(III) complex (5.12 mmol x L(-1) x s(-1)) was higher than the clinical magnetic resonance imaging contrast agent Gd-DTPA (3.64 mmol x L(-1).