Synthesis, Characterization, Thermodynamics Stability Constant, and Relaxation Properties of Neutral Gadolinium(III) Complex With Derivatives From Diethylene Triamine Pentaacetic Acid and m-hydroxybenzoyl Hydrazine

Abstract

A novel ligand, diethylenetriamine-N,N″-bis(acetyl-m-hydroxybenzoyl hydrazine)-N, N′, N″-triacetic acid (H3L), was synthesized and characterized on the basis of elemental analysis, molar conductivities, 1H NMR, FAB-MS, TG-DTA analysis, and IR methods. Its complex of Gd(III) holding promise of magnetic resonance imaging(MRI) was synthesized, and relaxivity of GdL and Gd(DTPA)2– used as compare were determined in water solution, respectively. The relaxivity of GdL (R1 = 6.02 L·mmol–1·s–1) was larger than that of Gd(DTPA)2–(R1 = 4.34L·mmol–1·s–1). The relaxivity of GdL had also been investigated in human serum albumin (HSA) solution, the relaxivity of GdL was enhanced from 6.02 L·mmol–1·s–1 in water solution to 7.10 L·mmol–1·s–1 in HSA solution. In addition, thermodynamics stability constant of GdL complex was determined. The results showed that GdL is a prospective MRI contrast agent, although the thermodynamic stability constant of GdL complex(K GdL = 1019.92) was a little less than that of Gd(DTPA)2–(KGd-DTPA = 1020.73).