Energy- and electron-transfer processes are very important for artificial photosynthesis and a variety of other applications. [(bpy)(2)Ru(PAP)Os(bpy)(2)](4+) and its oxidized form [(bpy)(2)Ru(PAP)Os(bpy)(2)](5+) perform efficient photoinduced energy- and electron-transfer processes, respectively (k(en) = 5.2 x 10(7) s(-1), k(et) = 7.2 x 10(6) s(-1)). The introduction of appropriate donor and acceptor units on the Ru2+ center can improve the lifetime of the excited state, resulting in a much longer and efficient storage of energy. Nonempirical (density functional) calculations and experimental data are used to predict the best donor and acceptor ligands for improving electron-and energy-transfer processes. Such a result can be extended to all polynuclear complexes where electronic coupling between the metal centers is very weak.