Synthesis, characterization and relaxivity validations of Gd(III) complex of DOTA tetrahydrazide as MRI contrast agent

Abstract

We report a novel Gadolinium(III) complex of (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetra(acetohydrazide) (Gd(III)L1) as a potential contrast agent for high resolution images in MRI and its molecular structure prediction by DFT calculations. The DOTA tetrahydrazide ligand framework (L1) was synthesized by the reaction of 1,4,7,10-tetraazacyclododecane (cyclen) with bromo derivative of conjugated t-butyl carbazate and followed by the subsequent cleavage of Boc moieties. The corresponding Gd(III) complex was prepared in an aqueous medium with the adjustment of pH to 7.0. The Gd(III)L1 complex shows the longitudinal relaxivity of 4.9 mM−1s−1 and transverse relaxivity of 6.2 mM−1s−1 at 37 ⁰C. The as-prepared complex Gd(III)L1 displays the enhanced intensity of T1 weighted phantom MR images with various concentrations at 7.0 T MRI scanner, which pave the way to achieve higher resolution images in MRI.