MACROCYCLIC DILACTAMS WITH PENDANT ACIDIC FUNCTIONS AS DISCRIMINATINGAGENTS FOR LANTHANIDE IONS

N,N'-bis(carboxymethyl) macrocyclic dilactams were synthesized in good to high yields from diamines and dianhydrides. Their ligand protonati on and lanthanide complex stability constants were measured by a poten tiometric method in aqueous solution. The lanthanide discriminating po wer of 12- and 18-membered macrocyclic dilactams derived from EDTA and EGTA measured by their stability constants were compared with other m acrocyclic compounds like diaminocrown-ethers and dilactones. In tile dilactam series the Eu3+ complex was found to be the most stable for t he ligand derived from o-phenylene diamine and ETGA dianhydride.