Photoinduced Electron Transfer in Linear Triarylamine–Photosensitizer–Anthraquinone Triads with Ruthenium(II), Osmium(II), and Iridium(III)

Hankache, Jihane; Niemi, Marja; Lemmetyinen, Helge; Wenger, Oliver S.

doi:10.1021/ic300558s

Cited by 66 publications

(69 citation statements)

References 72 publications

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“…(See also Figure 2 for an enhanced view of the 300 to 800 nm region.) 43,50,51 Importantly, the integrated intensity of these 3 , similar to that observed within a single group of bands in the 1 MLCT transitions. One is then tempted to assign the 590 nm band to a higher vibronic band of the 3 MLCT transition having its origin at ∼665 nm.…”

Section: Resultssupporting

confidence: 72%

Ultrafast Relaxation Dynamics of Osmium–Polypyridine Complexes in Solution

Bräm¹,

Messina²,

Baranoff

et al. 2013

J. Phys. Chem. C

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We present steady-state absorption and emission spectroscopy and femtosecond broadband photoluminescence up-conversion spectroscopy studies of the electronic relaxation of Os(dmbp) 3 (Os1) and Os(bpy) 2 (dpp) (Os2) in ethanol, where dmbp is 4,4′-dimethyl-2,2′-biypridine, bpy is 2,2′-biypridine, and dpp is 2,3-dipyridyl pyrazine. In both cases, the steady-state phosphorescence is due to the lowest 3 MLCT state, whose quantum yield we estimate to be ≤5.0 × 10. For Os1, the steady-state phosphorescence lifetime is 25 ns. In both complexes, the photoluminescence excitation spectra map the absorption spectrum, pointing to an excitation wavelength-independent quantum yield. The ultrafast studies revealed a short-lived (≤100 fs) fluorescence, which stems from the lowest singlet metal-to-ligand-charge-transfer ( 1 MLCT) state and decays by intersystem crossing to the manifold of 3 MLCT states. In addition, Os1 exhibits a 50 ps lived emission from an intermediate triplet state at an energy ∼2000 cm −1 above that of the long-lived (25 ns) phosphorescence. In Os2, the 1 MLCT− 3 MLCT intersystem crossing is faster than that in Os1, and no emission from triplet states is observed other than the lowest one. These observations are attributed to a higher density of states or a smaller energy spacing between them compared with Os1. They highlight the importance of the energetics on the rate of intersystem crossing.

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Section: Resultssupporting

confidence: 72%

Ultrafast Relaxation Dynamics of Osmium–Polypyridine Complexes in Solution

Bräm¹,

Messina²,

Baranoff

et al. 2013

J. Phys. Chem. C

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“…[18] Basic transient absorption studies of triad II (involving single excitation) were made in prior work. [15‐18] The two‐color pump‐pump probe experiments reported herein were performed on an LP920‐KS instrument from Edinburgh Instruments using the frequency‐doubled output of a Quantel Brilliant b laser for the first excitation, and a Quantel Brilliant laser equipped with an OPO from Opotek for the second excitation. Synchronization of the two lasers occurred with a 9520 digital delay pulse generator from Quantum Composers .…”

Section: Methodsmentioning

confidence: 99%

Pump‐Pump‐Probe Spectroscopy of a Molecular Triad Monitoring Detrimental Processes for Photoinduced Charge Accumulation

Kuss‐Petermann

Wenger

2016

Helvetica Chimica Acta

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Controlling light-induced accumulation of electrons or holes is desirable in view of multi-electron redox chemistry, for example for the formation of solar fuels or for photoredox catalysis in general. Excitation with multiple photons is usually required for electron or hole accumulation, and consequently pump-pump-probe spectroscopy becomes a valuable spectroscopic tool. In this work, we excited a triarylamine-Ru(bpy)3 2+ -anthraquinone triad (bpy = 2,2'-bipyridine) with two temporally delayed laser pulses of different color and monitored the resulting photoproducts. Absorption of the first photon by the Ru(bpy)3 2+ photosensitizer generated a triarylamine radical cation and an anthraquinone radical anion by intramolecular electron transfer. Subsequent selective excitation of either one of these two radical ion species then induced rapid reverse electron transfer to yield the triad in its initial (ground) state. This shows in direct manner that after absorption of a first photon and formation of the primary photoproducts, the absorption of a second photon can lead to unproductive electron transfer events that counteract further charge accumulation. In principle, this problem is avoidable by careful excitation wavelength selection in combination with good molecular design.

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“…[38] Three ligand-based reduction waves for 2 and 3 correspond to the successive reduction of the three diimine ligands as also observed for the Ru(bpy) 3 2+ complex. Only two reduction waves are observed for 4 within the voltage range of the solvent.…”

Section: Resultsmentioning

confidence: 75%

A facile and versatile methodology for cysteine specific labeling of proteins with octahedral polypyridyl d6 metal complexes

Dwaraknath

Tran

Dao

et al. 2014

Journal of Inorganic Biochemistry

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We have synthesized and characterized four octahedral polypyridyl d6 metal complexes bearing the 5,6-epoxy-5,6-dihydro-[1,10]phenanthroline ligand (L1) as cysteine specific labeling reagents. The proposed synthetic pathways allow the preparation of the metal complexes containing Re(I), Ru(II), Os(II) and Ir(III) while preserving the epoxide functionality. The complexes were characterized by 1H and 13C NMR, mass spectrometry, UV-visible and luminescence spectroscopies as well as cyclic voltammetry. As proof of concept, a set of non-native single cysteine P450 BM3 heme domain mutants previously developed in our laboratory was used to study the labeling reaction. We demonstrate that the proposed labels can selectively react, often in high yield, with cysteine residues of the protein via the nucleophilic thiol ring opening of the epoxide moiety. In addition, under basic conditions, subsequent loss of a water molecule led to the aromatization of the phenanthroline ring on the protein-bound label compounds, as observed by mass spectrometry and luminescence measurements.

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Photoinduced Electron Transfer in Linear Triarylamine–Photosensitizer–Anthraquinone Triads with Ruthenium(II), Osmium(II), and Iridium(III)

Cited by 66 publications

References 72 publications

Ultrafast Relaxation Dynamics of Osmium–Polypyridine Complexes in Solution

Ultrafast Relaxation Dynamics of Osmium–Polypyridine Complexes in Solution

Pump‐Pump‐Probe Spectroscopy of a Molecular Triad Monitoring Detrimental Processes for Photoinduced Charge Accumulation

A facile and versatile methodology for cysteine specific labeling of proteins with octahedral polypyridyl d6 metal complexes

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