The 77 K absorption, emission, excitation, photoselection, and time-resolved emission spectra and emission lifetimes were obtained in aprotic and protic systems for the series of complexes [ R U (~~~) , ( H D P A )~-, ]~' ( n = 0-3) and [Ru-(phen),(HDPA)3-,,]2' ( n = 0-3). The n = 2 species have d-A* MLCT emission characteristics indicative of the Ru-bpy and Ru-phen chromophores as do the n = 1 species in water, but in weak hydrogen-bonding solvents, as well as aprotic solvents, a second emission is observed producing a dual luminescence for the n = 1 species. This second emission is assigned to an nHDPA-Abpy* (or nHDPA-A hen*) interligand charge-transfer (ILCT) process. The absorption spectra for the deprotonated species [Ru(bpy),(DPA-),_,]("l~+ ( n = 1, 2) were also obtained, and the absence of emission up to 800 nm for these complexes is discussed in terms of available emitting states and metal perturbations.

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Steady-state excitation photoselection (SSExP), 77 K absorption, and 77 K emission spectra are presented for cisand trans-[Ru(bpy)2(py)2](C104)2 (bpy = 2,2'-bipyridine; py = pyridine), trans-[Ru(bpy)2(mdpp)2](PF6)2 (mdpp = methyldiphenylphosphine), trans-[Ru(bpy)2(tpp)2](C104)2 (tpp = triphenylphosphine), and [Ru(bpy)2(dppe)](PF6)2 (dppe = l,2-bis(diphenylphosphino)ethane) in ethanol glass. SSExP supports the results of the recent interchromophoric coupling model for the SSExP of ruthenium-bipyridine complexes. Independent evidence of excitonic interaction between the chromophores of such species is obtained from the electronic spectroscopy of trans complexes.

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