A NEW NONIONIC MACROCYCLIC GADOLINIUM(III) CHELATE AS A POTENTIAL MAGNETIC-RESONANCE-IMAGING CONTRAST AGENT

A new Gd-III complex of a 17-membered macrocycle with three pendant ca rboxymethyl groups has been synthesized; the ligand has been obtained in a single step from diethylenetriaminepentaacetic dianhydride (pente tic dianhydride) and 1,4-butanediamine (putrescine). An X-ray crystal analysis has shown that the complex is a nonionic metal chelate with a coordinated water molecule. The near-zero electrical conductivity, 1 Omega(-1) cm(2) mol-l, of a 1 mM solution indicated that the metal che late is essentially undissociated. The NMR TI relaxivity is 2.5 s(-1) mM(-1) at a resonance field of 64 MHz, and 3.4 s(-1) mM(-1) at 250 MHz . This new Gd-III complex is a potentially important magnetic resonanc e imaging contrast agent.