Spectral imaging in microscopy aids evaluation of the luminescent probe behaviour of europium complexes

In a series of structurally related cationic Eu(III) triamide complexes, the analysis of variations in emission lifetime and spectral signature as a function of probe environment has elucidated the nature of changes to probe speciation. The cationic complexes exhibit an intrinsic tendency to localise in cellular nucleoli or the lysosomes, providing key information in the design and evaluation of related targeted probes. Each of the three complexes studied possesses a coordinated water molecule in aqueous media, that is absent in organic solvents or is displaced by the addition of protein. The complex observed in cellulo is probably a protein-bound Eu complex.