Synthesis and relaxation properties of two non-ion complexes of gadolinium(III) and manganese(II) with derivatives from diethylene triamine pentaacetic acid and isoniazid

In this paper, two novel ligands (H3L1, H2L2) have been synthesized from diethylene triamine pentaacetic acid (DTPA) and isoniazid in different conditions. H3L1 has three carboxylic groups, and H2L2 has two carboxylic groups. Their non-ion complexes of GdL1 and MnL2 holding promise of magnetic resonance imaging (MRI) are synthesized, and relaxivity of complexes are determined, respectively. The relaxivity of GdL1 (R1 = 6.07 L·mmol−1·s−1) and MnL2 (R1 = 6.94 L·mmol−1·s−1) are larger than that of Gd(DTPA)2− (R1 = 4.34 L·mmol− 1·s−1). It is more significative that relaxivity of MnL2 is larger than that of GdL1. The results showed that two non-ion complexes are prospective MRI contrast agents.