The hydrolysis of 4,7-diphenyl-1,10-phenanthroline-2,9-dicarboxylic acid (DPPDA) esters is induced by lanthanide(III) ions. As the related 2,6-pyridinedicarboxylic acid esters are not cleaved, the effect is traced back on improved complexation of the lanthanides by the DPPDA esters. Time-resolved. fluorescence spectroscopic and electrospray mass spectrometric investigations on the esters provide information on the progress of the reactions. (C) 2008 Elsevier B.V. All rights reserved.