Novel polyaminocarboxylate chelates derived from 3-aroylcoumarins

We have devised efficient reaction pathways to attach aminopolycarboxylate subunits to the 3-aroylcoumarin chromophore. Two series of compounds were thus prepared in which the chelating arms were directly bonded to the coumarin ring (series A) or to the 3-aroyl moiety (series B). The corresponding Eu(III) and Tb(III) chelates were easily formed and their photophysical properties measured. In all the cases, lanthanide emission lifetimes were in the range of ms. Unfortunately, quantum yields were relatively low. Measurement of T1 states gave too low range of values to sensitize Tb(III). In fact, the metal emission of Tb(III) chelates of series A was not observed. However, series B was able to sensitize both metals. The absorption/energy-transfer/emission mechanisms are discussed.