1,10-Diaza-4,7,13,16-tetraoxacyclooctadecane-1,10-bis(malonate), a ligand with high Sr2+/Ca2+ and Pb2+/Zn2+ selectivities in aqueous solution

The stability constants of the complexes of 1,10-diaza-4,7,13,16-tetraoxacyclooctadecane-1,10-bis(malonate) formed with alkaline-earths, lanthanides, zinc, cadmium and lead are larger for larger metal ions, which is manifested in unusually high Sr2+/Ca2+ and Pb2+/Zn2+ selectivities in aqueous solution.