Singlet energy transfer to azoalkanes

Engel, Paul S.; Fogel, Laurence D.; Steel, Colin

doi:10.1021/ja00809a001

Cited by 21 publications

(16 citation statements)

References 4 publications

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“…In the average mode approximation, multiple modes are represented by an average frequency, pω, and dimensionless displacement, S, given by 23,[25][26][27][28] Eq 21 is obtained by assuming that the individual vibronic peaks are well-represented as Gaussians with half-widths greater than the spread in vibrational frequencies. When the sum over j included all coupled modes, the average frequency was ∼1350 cm -1 , the progression observed in low-temperature emission.…”

Section: Resultsmentioning

confidence: 99%

Time-Dependent Raman Analysis of Metal-to-Ligand Charge Transfer Excited States: Application to Radiative and NonRadiative Decay

et al. 2003

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The photophysical properties of the emitting metal-to-ligand charge transfer (MLCT) excited states of the complexes, [Os(bpy) 3 ] 2+ , [Os(bpy) 2 (py) 2 ] 2+ , and [Os(bpy)(py) 4 ] 2+ (bpy ) 4-4′-bipyridine, py ) pyridine) have been characterized in aqueous solution at room temperature by absorption, emission, and Raman spectroscopies and by emission lifetimes and emission quantum yields. A spectroscopic model has been developed by using the time-dependent theory of Raman scattering, taking into account interference effects on resonance Raman profiles arising from interactions between the different ligands. A model based on the cylindrical model of Sension and Strauss provides a good fit to the data. The mode-specific vibrational parameters obtained from the spectroscopic analysis are used to calculate the vibrational contributions to the radiative and nonradiative decay rate constants for each of the complexes. These results and the experimental rate constants were used to calculate vibrationally induced electronic coupling matrix elements (V k ) for nonradiative decay and also transition moments, M, for radiative decay. For radiative decay, the average transition moment for the three complexes was 0.05Å, and for nonradiative decay, the average value of V k was 910 cm -1 . Within a reasonable margin of error, the Franck-Condon contributions are in agreement with values obtained in a previous study that used the single mode approximation and a Franck-Condon analysis of emission spectra.

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Section: Resultsmentioning

confidence: 99%

Time-Dependent Raman Analysis of Metal-to-Ligand Charge Transfer Excited States: Application to Radiative and NonRadiative Decay

et al. 2003

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“…This inverted effect has previously been observed for intermolecular singlet-singlet energy transfer between aromatics and azoalkanes. [22][23][24] In essence, we have reached the inverted region, where energy transfer is slowed down, regardless of favourable thermodynamics, due to decreased Franck-Condon overlap between the initial and final states, akin to the Marcus inverted region for electron transfer. 41 The dominant quantities are the spectral overlap integrals (J ) of the donor emission and the acceptor absorption, which enter directly the expressions (eqn.…”

Section: Rate and Efficiency Of Singlet-singlet Energy Transfermentioning

confidence: 97%

“…170 M Ϫ1 cm Ϫ1 in hydrocarbon solvents. 24 for the intermolecular energy transfer between DBO and benzene (J ex = 2.0 × 10 Ϫ7 cm) or naphthalene (J ex = 6.8 × 10 Ϫ5 cm) in isooctane. f Intermolecular fluorescence quenching rate constants of benzene or naphthalene by DBO in isooctane taken from ref.…”

Section: Absorption Propertiesmentioning

confidence: 99%

“…f Intermolecular fluorescence quenching rate constants of benzene or naphthalene by DBO in isooctane taken from ref. 24.…”

Section: Absorption Propertiesmentioning

confidence: 99%

“…flexibility and intra-chromophore distances, has provided valuable insights into the mechanistic details of this basic photophysical process. 20, 21 Although azoalkanes have been the subject of intermolecular energy-transfer studies, [22][23][24][25] the only intramolecular study deals with triplet-triplet energy transfer from carbonyl chromophores to azoalkanes. 26 Morrison and co-workers have introduced the dimethylphenylsiloxy (DPSO) group as an antenna for singlet-singlet energy transfer (SSET) to keto functions in steroidal molecules.…”

Section: Introductionmentioning

confidence: 99%

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Intramolecular singlet–singlet energy transfer in antenna-substituted azoalkanes

Pischel

Huang

Nau

2004

Photochem Photobiol Sci

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Two novel azoalkane bichromophores and related model compounds have been synthesised and photophysically characterised. Dimethylphenylsiloxy (DPSO) or dimethylnaphthylsiloxy (DNSO) serve as aromatic donor groups (antenna) and the azoalkane 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) as the acceptor. The UV spectral window of DBO (250-300 nm) allows selective excitation of the donor. Intramolecular singlet-singlet energy transfer to DBO is highly efficient and proceeds with quantum yields of 0.76 with DPSO and 0.99 with DNSO. The photophysical and spectral properties of the bichromophoric systems suggest that energy transfer occurs through diffusional approach of the donor and acceptor within a van der Waals contact at which the exchange mechanism is presumed to dominate. Furthermore, akin to the behaviour of electron-transfer systems in the Marcus inverted region, a rate of energy transfer 2.5 times slower was observed for the system with the more favourable energetics, i.e. singlet-singlet energy transfer from DPSO proceeded slower than from DNSO, although the process is more exergonic for DPSO (-142 kJ mol(-1) for DPSO versus-67 kJ mol(-1) for DNSO).

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Stowell

1975

PATAI'S Chemistry of Functional Groups

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Singlet energy transfer to azoalkanes

Cited by 21 publications

References 4 publications

Time-Dependent Raman Analysis of Metal-to-Ligand Charge Transfer Excited States: Application to Radiative and NonRadiative Decay

Time-Dependent Raman Analysis of Metal-to-Ligand Charge Transfer Excited States: Application to Radiative and NonRadiative Decay

Intramolecular singlet–singlet energy transfer in antenna-substituted azoalkanes

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