Temperature Dependence of Nonradiative Decay

Claude, Juan Pablo; Meyer, Thomas J.

doi:10.1021/j100001a010

Cited by 108 publications

(133 citation statements)

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“…The details of this analysis are described elsewhere, 31,33,34 but essentially, the emission envelope is modeled as a sum of Gaussians spaced by the average vibrational mode coupled to the transition. E 0 then corresponds to the highest energy Gaussian and gives the relative vertical positions of the excited-and ground-state potential surfaces, i.e., the 3 MLCT/ 1 A 1 gap.…”

Section: Resultsmentioning

confidence: 99%

Static and Time-Resolved Spectroscopic Studies of Low-Symmetry Ru(II) Polypyridyl Complexes

Curtright

McCusker

1999

J. Phys. Chem. A

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The spectroscopic and electrochemical properties of a series of four Ru II polypyridyl complexes are reported. Compounds of the form [Ru(dmb) x (dea) 3-x ] 2+ (x ) 0-3), where dmb is 4,4′-dimethyl-2,2′-bipyridine and dea is 4,4′-bis(diethylamino)-2,2′-bipyridine, have been prepared and studied using static and time-resolved electronic and vibrational spectroscopies as a prelude to femtosecond spectroscopic studies of excited-state dynamics. Static electronic spectra in CH 3 CN solution reveal a systematic shift of the MLCT absorption envelope from a maximum of 458 nm in the case of [Ru(dmb) 3 ] 2+ to 518 nm for [Ru(dea) 3 ] 2+ with successive substitutions of dea for dmb, suggesting a dea-based chromophore as the lowest-energy species. However, analysis of static and time-resolved emission data indicates an energy gap ordering of [Ru(dmb) , at variance with the electronic structures inferred from the absorption spectra. Nanosecond time-resolved electronic absorption and time-resolved step-scan infrared data are used to resolve this apparent conflict and confirm localization of the long-lived 3 MLCT state on dmb in all three complexes where this ligand is present, thus making the dea-based excited state unique to [Ru-(dea) 3 ] 2+ . Electrochemical studies further reveal the origin of this result, where a strong influence of the dea ligand on the oxidative Ru II/III couple, due to π donation from the diethylamino substituent, is observed. The electronic absorption spectra are then reexamined in light of the now well-determined excited-state electronic structure. The results serve to underscore the importance of complete characterization of the electronic structures of transition metal complexes before embarking on ultrafast studies of their excited-state properties.

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Section: Resultsmentioning

confidence: 99%

Static and Time-Resolved Spectroscopic Studies of Low-Symmetry Ru(II) Polypyridyl Complexes

Curtright

McCusker

1999

J. Phys. Chem. A

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“…The 0-0 energy of the luminescent level, E 0 , is Ϸ 2.8 eV for 1 and Ϸ 2.7 eV for both 2 and 3. This indicates that at 77 K, the luminescent state is deactivated via coupling with the same type of vibrational modes, which are likely to be C-N or C-C skeleton vibrations, [24][25][26][27] with a similar extent of electronic delocalisation for all three cases. According to previous assignments for the 3 LC emission for 1, [1,10,11] this suggests that at 77 K the nature of the emitting state in 2 and 3 is likewise 3 LC.…”

Section: Optical Spectroscopymentioning

confidence: 88%

Luminescent Iridium(III)‐Terpyridine Complexes – Interplay of Ligand Centred and Charge Transfer States

et al. 2005

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Electrochemical properties, ground state absorption spectra, luminescence spectra and lifetimes (at room temperature and 77 K) as well as transient absorption spectra are reported herein for newly synthesized iridium(III) complexes in which benzamide units are appended to the coordinated terpyridine fragments. The nature of the luminescent excited states (Φ < 2 × 10–3 and τ in the microsecond range, in air‐equilibrated acetonitrile at 298 K) is discussed with regards to the ligand‐centred (3LC) or charge transfer (3CT) nature. At room temperature, the excited state, a predominantly ligand‐centred triplet (3LC) for the iridium(III) terpyridine compounds, is switched for the benzamide‐containing complexes to a charge transfer state (3CT). Intense absorption in the visible range, high energy content, long excited states lifetimes at 298 and 77 K and good luminescence yields make these complexes very promising as photosensitisers (P). The CT nature of the excited states of the benzamide‐containing complexes makes them ideal components for the construction of rigid, linear arrays of the Donor‐P‐Acceptor type for charge separation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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“…This value is higher for the Re complexes due to a contribution to the average mode from the high-energy, totally symmetric CO stretch at ∼2030-2040 cm -1 (Table 3). 19,23 DFT Calculations. Density functional calculations were performed on [Re(bpy)(CO) 3 (4-Etpy)] + in both the ground and excited states.…”

Section: Cis-[os(pp) 2 (Co)(l)] N+ Ground-and Excited-state ν(Co)mentioning

confidence: 99%

Application of Time-Resolved Infrared Spectroscopy to Electronic Structure in Metal-to-Ligand Charge-Transfer Excited States

et al. 2002

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Infrared data in the nu(CO) region (1800-2150 cm(-1), in acetonitrile at 298 K) are reported for the ground (nu(gs)) and polypyridyl-based, metal-to-ligand charge-transfer (MLCT) excited (nu(es)) states of cis-[Os(pp)2(CO)(L)](n)(+) (pp = 1,10-phenanthroline (phen) or 2,2'-bipyridine (bpy); L = PPh3, CH(3)CN, pyridine, Cl, or H) and fac-[Re(pp)(CO)3(4-Etpy)](+) (pp = phen, bpy, 4,4'-(CH3)2bpy, 4,4'-(CH3O)2bpy, or 4,4'-(CO2Et)2bpy; 4-Etpy = 4-ethylpyridine). Systematic variations in nu(gs), nu(es), and Delta(nu) (Delta(nu) = nu(es) - nu(gs)) are observed with the excited-to-ground-state energy gap (E(0)) derived by a Franck-Condon analysis of emission spectra. These variations can be explained qualitatively by invoking a series of electronic interactions. Variations in dpi(M)-pi(CO) back-bonding are important in the ground state. In the excited state, the important interactions are (1) loss of back-bonding and sigma(M-CO) bond polarization, (2) pi(pp*-)-pi(CO) mixing, which provides the orbital basis for mixing pi(CO)- and pi(4,4'-X(2)bpy)-based MLCT excited states, and (3) dpi(M)-pi(pp) mixing, which provides the orbital basis for mixing pipi- and pi(4,4'-X(2)bpy*-)-based MLCT states. The results of density functional theory (DFT) calculations on the ground and excited states of fac-[Re(I)(bpy)(CO)3(4-Etpy)](+) provide assignments for the nu(CO) modes in the MLCT excited state. They also support the importance of pi(4,4'-X2bpy*-)-pi(CO) mixing, provide an explanation for the relative intensities of the A'(2) and A' ' excited-state bands, and provide an explanation for the large excited-to-ground-state nu(CO) shift for the A'(2) mode and its relative insensitivity to variations in X.

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Temperature Dependence of Nonradiative Decay

Cited by 108 publications

References 1 publication

Static and Time-Resolved Spectroscopic Studies of Low-Symmetry Ru(II) Polypyridyl Complexes

Static and Time-Resolved Spectroscopic Studies of Low-Symmetry Ru(II) Polypyridyl Complexes

Luminescent Iridium(III)‐Terpyridine Complexes – Interplay of Ligand Centred and Charge Transfer States

Application of Time-Resolved Infrared Spectroscopy to Electronic Structure in Metal-to-Ligand Charge-Transfer Excited States

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