The exchange of several other cations for the Na+ ions in Na3[Eu(2,6-p
yridinedicarboxylato)3] was investigated using Eu3+ ion luminescence s
pectroscopy. Monovalent, divalent, and trivalent metal ions, as well a
s the monovalent ammonium ion, replaced the Na+ ion via mass action to
form various salts with the Eu(2,6-pyridinedicarboxylato)33- complex
anion. The detection of the cation exchange was achieved because of th
e sensitivity of Eu3+ ion luminescence to the near environment of the
Eu3+ ion.