The new chromophore-quencher tricarbonylrhenium(I) complexes [Re(4,4Ј-X 2 -bpy)(CO) 3 -salts and characterized by spectroscopic, electrochemical, and photophysical techniques. In contrast to previously reported species with X = Me or H, these complexes emit at room temperature in CH 3 CN. The recovery of luminescence can thus be ascribed to the change of energy levels induced by adding electron-withdrawing substituents to the 2,2Ј-bipyridine ring, since the emissive Re II (X 2 bpy -) excited state becomes much lower in energy than the Re II (PCA -) non-emissive excited state. For the mononuclear and symmetric dinuclear rhenium(I) complexes with X = CO 2 Me, consecutive