Trinuclear Gd(III) Metal Complex with Amide Core Display Remarkable Enhancement in Relaxivity

Abstract

New trinuclear gadolinium(III) complex having 2-bromoisovaleric acid pendant arm is reported. The longitudinal relaxivity (r_1p) of the complex is 23.17 mM⁻¹ s⁻¹ which correspond to a “per Gd” relaxivity of 7.72 mM⁻¹ s⁻¹. The transverse relaxivity (r_2p) of the complex is 24.79 mM⁻¹ s⁻¹ which correspond to a “per Gd” value of 8.26. The complex exhibit r_1p and r_2p values of 29.19 and 35.20, respectively, in the presence of HSA. The complex also shows pH dependant relaxivity which is an added advantage of the complex for utilization in cancer cell magnetic resonance imaging. The higher relaxivity values in water and HSA indicates a compact solution structure for the complexes and a restricted internal motion about the amide spacer.