We investigated the relaxation dynamics of bis(2-phenylpyridinato-)(2,2'-bipyridine)iridium(III), [Ir(ppy)(2)bpy](+) using the technique of time-resolved spectroscopy. In the visible emission spectra this molecule exhibits triple phosphorescence: displaying blue, green, and orange bands. From the dependence of spectral shifts with polarity of solvent, decay lifetimes, and the results of calculations using time-dependent density functional theory, we assigned these three emitting states to be triplet interligand charge-transfer ((3)LLCT), metal-to-ligand ppy charge transfer ((3)MLCT(ppy)), and metal-to-ligand bpy charge transfer ((3)MLCT(bpy)) states. The blue states were formed promptly after excitation at wavelength 355 nm; the one lying at higher energy decaying with a time coefficient 0.79-2.56 ns is assigned to be a triplet MLCT, and the other at lower energy decaying in 1.5-2.8 μs is assigned to (3)LLCT(A), A symmetry. This decay time coefficient of (3)LLCT(A) decreases with increasing dielectric constant of the solvent indicating this state mixing of some MLCT character. The green state (3)MLCT(ppy) decays in 0.13-4.8 ns to a nearby intermediate state either (3)MLCT(ppy) or (3)MLCT(bpy). The orange state (3)MLCT(bpy) is coupled to the intermediate state to have a rise time about 0.36-0.84 ns and decays in 425-617 ns. Although many triplet states exist in a small energy range, they couple weakly to display triple emission. All (3)LLCT and (3)MCLT states are coupled to the singlet (1)LLCT manifold directly and/or indirectly and contribute to the emission in the visible range.

The Raman and infrared spectra of fac-tris(2-phenylpyridinato-N,C2 )iridium(III), Ir(ppy) 3 and surface-enhanced resonance Raman spectra of bis(2-phenyl pyridinato-) (2,2 bipyridine) iridium (III), [Ir(ppy) 2 (bpy)] + cation were recorded in the wavenumber range 150-1700 cm −1 , and complete vibrational analyses of Ir(ppy) 3 and [Ir(ppy) 2 (bpy)] + were performed. Most of the vibrational wavenumbers were calculated with density-functional theory agree with experimental data. On the basis of the results of calculation and comparison of the spectra of both complexes and their analogue [Ru(bpy) 3 ] 2+ , we assign the vibrational wavenumbers for metal-ligand modes; metal-ligand stretching wavenumbers are 277/307 and 261/236 cm −1 for Ir(ppy) 3 , and 311/324, 257/270, 199/245 cm −1 for [Ir(ppy) 2 bpy] + . Surface-enhanced Raman scattering spectra of [Ir(ppy) 2 bpy] 2+ were measured at two wavelengths on the red and blue edges of the low-energy metal-to-ligand charge-transfer band. According to the enhanced Raman intensities for the vibrational modes of both ligands ppy and bpy, the unresolved charge-transfer band is deduced to consist of charge-transfer transitions from the triplet metal to both ligands ppy and bpy.

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