Macrocyclic dilactams with pendant acidic functions as discriminating agents for lanthanide ions
Résumé
N,N′-bis(carboxymethyl) macrocyclic dilactams were synthesized in good to high yields from diamines and dianhydrides. Their ligand protonation and lanthanide complex stability constants were measured by a potentiometric method in aqueous solution. The lanthanide discriminating power of 12- and 18-membered macrocyclic dilactams derived from EDTA and EGTA measured by their stability constants were compared with other macrocyclic compounds like diaminocrown-ethers and dilactones. In the dilactam series the Eu3+ complex was found to be the most stable for the ligand derived from o-phenylene diamine and EGTA dianhydride.