The complex Re(bpy)(CO)(3)(EtG)(+) (1) has been prepared and structurally characterized(EtG = 9-ethylguanine). The MLCT absorption maximum of the acetonitrile complex red-shifts 2400 cm(-1) upon binding of EtG, and the emission maximum shifts 2030 cm(-1). The quantum yield (0.054) and emission lifetime (170 ns) of 1 allow for an analysis of the electronic properties of the MLCT chromophore in terms of the energy-gap law, which may provide guidelines for the design of new emissive complexes. for nucleobase targeting.