Spectroscopic Studies of Ruthenium(II) Complexes. Assignment of the Luminescence

Abstract

Absorption and emission spectra of nine (4d)6 ruthenium(II) complexes dissolved in rigid glasses are reported. Tris(bipyridine), tris(o-phenanthroline), bis(tripyridine), and a series of cis-substituted bis(bipyridine) complexes of ruthenium(II) were synthesized. The cis substituents were cyanide, ethylenediamine, pyridine, oxalate, and chloride chosen for their order in the spectrochemical series. On the basis of the structures of the emission spectra, their energy relationships with charge-transfer absorption bands, and the lack of correlation between the energies of emission and predictions from crystal-field theory, it is proposed that the intense luminescence observed from all the complexes under excitation by ultraviolet light is charge transfer in nature.

Electronic Properties and Structure of Assemblies of CdSe Nanocrystal Quantum Dots and Ru‐Polypyridine Complexes Probed by Steady State and Time‐Resolved Photoluminescence

“…[29][30][31][32] The PL spectra of the complexes 1 and 2 are characterized by a broad PL band with a peak at 610-650 nm, which is due to radiative relaxation of the metalto-ligand charge transfer (MLCT) state. [ 33,34 ] The most notable effect of adding complex 2 to the solution of NQDs, observed in Figure 1 a and b, is a dramatic quenching of the NQD band-edge PL at 520 nm, which correlates with a signifi cant enhancement of PL in the spectral region of complex emission at λ > 600 nm. In contrast, the results summarized in Figure 1 c show no evidence of NQD PL quenching or enhancement of complex PL in the NQD/ 1 mixture.…”

Theoretical Studies on Photophysical Properties and Mechanism of Phosphorescence in [fac‐Ir(2‐phenylpyridine)3]

“…Several models including spin-orbit coupling have been proposed for understanding the photophysical properties of MLCT states in transition-metal compounds. Electronic absorption spectra in [M(bpy) 3 proaches to ab inito calculation of phosphorescent properties of transition-metal compounds, such as excitation energies, oscillator strengths, and zfs, is using a response function containing the electric dipole and spin-orbit operators for multi-configurational self-consistent field (MCSCF) wave functions. 30 However, the application of this method is limited to small molecules due to a limited number of active spaces (valence orbitals) and therefore photophysical properties of phosphorescent states in transition-metal compounds are not yet readily available.…”

“…[20][21] The strong phosphorescence of these compounds originates from intensity borrowing of the transition dipole moments of singlet excited states via spin-orbit interaction. Among luminescent cyclometalated Ir(III) compounds, [fac-Ir(ppy) 3 ] have attracted the greatest interest 22 and the photophysical properties such as zero-field splitting (zfs) have been investigated. 23 The electronic structures in the ground state and the excitation energies were studied by…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Recently, increasing attention has been paid to developing phosphorescent dopants for organic light emitting diodes (OLEDs), such as Pt(II) or Ir(III) compounds which exhibit intense MLCT phosphorescence. [16][17][18] The MLCT phosphorescence of these compounds is characterized by a large radiative rate constant (~10 6 s -1 ) at ambient temperature.…”

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The photophysical properties of [fac-Ir(ppy) 3 ] have been studied using time-dependent density functional theory with one-center spin-orbit coupling approximation. The phosphorescent state of [fac-Ir(ppy) 3 ] was characterized by a mixture of 40% 3 MLCT and 58% intra-and inter-ligand 3 pp* with charge distribution being partially localized to a single ligand.

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