Perturbation of luminophore properties

An interesting aspect of the above (and related) systems is the fact that the photophysical properties of the luminophoric unit, while maintaining most of their characteristic features, are somewhat perturbed by the presence of the attached chromophoric component. For example, while the emission quantum yields and lifetimes are 3.3x10 and 310 ms for the isolated Cr(cyclam)(CN)2 component, they become 5.3x10 and 260 ms in the 

NC-Cr(cyclam)-CN-Ru(bpy)2-NC-Cr(cyclam)-CN complex [72]. Given the unitary efficiency of population of the emitting state in both systems, this indicates that the radiative rate constant of Cr(III) phosphorescence increases from 10 s to 20 s upon attachment of the chromophoric unit. This behavior seems to be quite general, as all the other Ru(II)-Cr(ni) complexes studied [69,87,88] exhibit radiative (and non radiative) rate constants for deactivation of the Cr(III) doublet which are larger than those of the free chromophore. 

An experimental check of this picture has been attempted using the 

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