Synthesis and Evaluation of Neutral Gd(III), Mn(II) Complexes From DTPA-Bisamide Derivative as Potential MRI Contrast Agents

A strong chelating ligand was synthesized through the modification of DTPA by bioactive 5-fluorouracil derivatives and characterized by means of mass spectra, Fourier transform infrared spectra, elemental analysis, and nuclear magnetic resonance spectroscopy. Its complexes of Gd(III) and Mn(II) were designed as potential MRI contrast agents. Thermodynamic stability constant of the complexes indicated that they were stable enough to prevent the metal ions from releasing. Relaxivity studies showed that the two complexes provided higher T1-weighted relaxivity than that of commercial contrast agent Gd-DTPA and the Mn(II) complex owned much higher T2-weighted relaxation property. Both the Gd(III) and Mn(II) complexes had the advantage of becoming promising T1-weighted MRI contrast agents.