Ligand LH2, composed of two bipyridylcarboxylate fragments linked to an amino butyl chain, reacts with europium and terbium to form luminescent complexes in water at neutral pH. When testing these unsaturated complexes as anion sensors with NO3-, HPO42-, AMP, ADP, and ATP, a marked selectivity is observed for HPO42- and ATP(4-) at PH = 7.0. The interaction of these anions with the complex was investigated by means of absorption and emission spectroscopies. With ATP(4-), ES-MS and P-31 NMR experiments revealed the formation of a [Ln.L.(ATPp)](3-) ternary species.