Multifaceted Deactivation Dynamics of Fe(II) <i>N</i>-Heterocyclic Carbene Photosensitizers

Lindh, Linnea; Pascher, Torbjörn; Persson, Samuel; Goriya, Yogesh; Wärnmark, Kenneth; Uhlig, Jens; Chábera, Pavel; Persson, Petter; Yartsev, Arkady

doi:10.1021/acs.jpca.3c06983

Cited by 7 publications

(6 citation statements)

References 74 publications

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“…Traditionally, considerable focus has been placed on copper(I), primarily because of its completely filled 3d 10 subshell. − This particular electron configuration, responsible for the semiprecious chemical character of copper(I), precludes the presence of energetically low-lying metal-centered (MC) states that can negatively affect the photophysical and photochemical behavior of charge transfer (CT) excited states. , Consequently, long-lived and brightly luminescent CT excited states in copper(I) complexes are comparatively easily accessible, − because they are less susceptible to unwanted nonradiative relaxation involving metal-centered (MC) states. This stands in strong contrast to their d 8 (Ni II ) ,− or d 6 (Cr 0 , Mn I , Fe II , Co III ) − counterparts, where low-lying MC states can be present.…”

Section: Introductionmentioning

confidence: 64%

Iron(III) Carbene Complexes with Tunable Excited State Energies for Photoredox and Upconversion

Wellauer,

Ziereisen,

Sinha

et al. 2024

J. Am. Chem. Soc.

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Substituting precious elements in luminophores and photocatalysts by abundant first-row transition metals remains a significant challenge, and iron continues to be particularly attractive owing to its high natural abundance and low cost. Most iron complexes known to date face severe limitations due to undesirably efficient deactivation of luminescent and photoredox-active excited states. Two new iron(III) complexes with structurally simple chelate ligands enable straightforward tuning of ground and excited state properties, contrasting recent examples, in which chemical modification had a minor impact. Crude samples feature two luminescence bands strongly reminiscent of a recent iron(III) complex, in which this observation was attributed to dual luminescence, but in our case, there is clear-cut evidence that the higher-energy luminescence stems from an impurity and only the red photoluminescence from a doublet ligand-to-metal charge transfer ( 2 LMCT) excited state is genuine. Photoinduced oxidative and reductive electron transfer reactions with methyl viologen and 10-methylphenothiazine occur with nearly diffusion-limited kinetics. Photocatalytic reactions not previously reported for this compound class, in particular the C−H arylation of diazonium salts and the aerobic hydroxylation of boronic acids, were achieved with low-energy red light excitation. Doublet−triplet energy transfer (DTET) from the luminescent 2 LMCT state to an anthracene annihilator permits the proof of principle for triplet−triplet annihilation upconversion based on a molecular iron photosensitizer. These findings are relevant for the development of iron complexes featuring photophysical and photochemical properties competitive with noble-metal-based compounds.

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Section: Introductionmentioning

confidence: 64%

Iron(III) Carbene Complexes with Tunable Excited State Energies for Photoredox and Upconversion

Wellauer,

Ziereisen,

Sinha

et al. 2024

J. Am. Chem. Soc.

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“…The general shape of the equations is very similar, but in Maxwell-Bloch equations, the evolution of the off-diagonal density matrix elements is added. Both explicit dynamics approaches successfully disentangled complex dynamics in various pump-probe experiments [5,10,35,36].…”

Section: General Considerationsmentioning

confidence: 99%

“…We start with the same system described generally by a 2 × 2 density matrix (Equation ( 38)). Before the pump, the molecular system is described by a wavefunction from Equation (35) and right after the pumping, by a wavefunction from Equation (36). Equivalently, they are given by a density matrix from Equations ( 40) and (49), respectively.…”

Section: Coherent Oscillations With Decaymentioning

confidence: 99%

Inverse Problems in Pump–Probe Spectroscopy

Tikhonov,

Garg,

Schnell

2024

Photochem

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Ultrafast pump–probe spectroscopic studies allow for deep insights into the mechanisms and timescales of photophysical and photochemical processes. Extracting valuable information from these studies, such as reactive intermediates’ lifetimes and coherent oscillation frequencies, is an example of the inverse problems of chemical kinetics. This article describes a consistent approach for solving this inverse problem that avoids the common obstacles of simple least-squares fitting that can lead to unreliable results. The presented approach is based on the regularized Markov Chain Monte-Carlo sampling for the strongly nonlinear parameters, allowing for a straightforward solution of the ill-posed nonlinear inverse problem. The software to implement the described fitting routine is introduced and the numerical examples of its application are given. We will also touch on critical experimental parameters, such as the temporal overlap of pulses and cross-correlation time and their connection to the minimal reachable time resolution.

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“…Both explicit dynamics approaches successfully disentangled complex dynamics in various pump-probe experiments. [5,10,35,36] However, modeling the rate dynamics explicitly is rather complicated and time-consuming. First, the cost of solving the differential equations is higher than many other numerical problems.…”

Section: General Considerationsmentioning

confidence: 99%

Inverse Problems in Pump-Probe Spectroscopy

Tikhonov,

Garg,

Schnell

2024

Preprint

View full text Add to dashboard Cite

Ultrafast pump-probe spectroscopic studies allow for deep insights into the mechanisms and timescales of photophysical and photochemical processes. Extracting valuable information from these studies, such as reactive intermediates' lifetimes and coherent oscillation frequencies, is an example of the inverse problems of chemical kinetics. This article describes a consistent approach for solving this inverse problem that avoids the common obstacles of simple least-squares fitting that can lead to unreliable results. The presented approach is based on the regularized Markov Chain Monte Carlo sampling for the strongly nonlinear parameters, allowing for a straightforward solution of the ill-posed nonlinear inverse problem. The software to implement the described fitting routine is introduced and the numerical examples of its application are given. We will also touch on critical experimental parameters, such as the temporal overlap of pulses and cross-correlation time and their connection to the minimal reachable time resolution.

show abstract

Multifaceted Deactivation Dynamics of Fe(II) N-Heterocyclic Carbene Photosensitizers

Cited by 7 publications

References 74 publications

Iron(III) Carbene Complexes with Tunable Excited State Energies for Photoredox and Upconversion

Iron(III) Carbene Complexes with Tunable Excited State Energies for Photoredox and Upconversion

Inverse Problems in Pump–Probe Spectroscopy

Inverse Problems in Pump-Probe Spectroscopy

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