Knowledge Bank

An analysis of the crystal field splitting of the f to f electronic transitions of $Eu+3$ complexed in solution with the crown ethers 15-crown-5 or benzo-15-crown-5 reveals that there is little distortion from $C5v$ geometry. Highly specific and different quenching of europium fluorescence is found to take place in each europium-crown complex . While our studies support the formation of 1:1 complexes in solution, the interpretation is found to complicated by time-dependent processes. More complicated splitting pattern occur for the crown-complexed neodymium transitions. Large changes in extinction coefficient are also observed for the complexed neodymium transitions suggesting that these may be useful model systems for studying the coupling mechanisms by which the La Porte forbidden transitions gain intensity in the rare earth ions.