Towards longer-lived metal-to-ligand charge transfer states of iron(ii) complexes: an N-heterocyclic carbene approach

Liu, Yizhu; Harlang, Tobias; Canton, Sophie E.; Chábera, Pavel; Suárez‐Alcántara, K.; Fleckhaus, André; Vithanage, Dimali A.; Göransson, Erik; Corani, Alice; Lomoth, Reiner; Sundström, Villy; Wärnmark, Kenneth

doi:10.1039/c3cc43833c

Cited by 221 publications

(514 citation statements)

References 22 publications

Supporting

Mentioning

465

Contrasting

Unclassified

Order By: Relevance

“…The dynamics are dominated by two main processes. The first is an ultrafast ISC from 1 MLCT→ 3 MLCT, which has a time constant of ∼100 fs 24 in excellent agreement with previous experimental observations 11 . The rapid nature of this step is a result of the close energetic proximity of the 1 MLCT and 3 MLCT states, which promotes strong mixing and leads to efficient population transfer.…”

Section: Simulating the X-ray Spectrasupporting

confidence: 89%

“…As the dynamics progresses the spectrum begins to exhibit increasing characteristics of the 3 MC spectrum. There are also clear 300 fs oscillations in the transient signal, consistent with those observed in the transient absorption study 11,24 . As assigned above, this corresponds to the wavepacket motion along the ν 6 breathing mode 24 and consequently it is similar to the widely reported wavepacket dynamics of [Fe(bipy) 3 ] 2+ 9 .…”

Section: Femtosecond X-ray Spectroscopysupporting

confidence: 85%

“…This is followed by a slower component consistent with a time constant ≥4 ps consistent with ref. 11 . This population transfer ( 3 MLCT→ 3 MC) step is between two triplet states and therefore can occur through two mechanisms, nonadiabatic or spin-orbit coupling.…”

Section: Photoexcited Decay Of [Fe(bmip) 2 ] 2+mentioning

confidence: 99%

“…11 , femtosecond X-ray spectroscopic studies are unlikely to shed significantly new insight on the photoexcited decay mechanisms. Here, one should bear in mind that the strength of X-ray spectroscopy is providing a local interpretation around the absorbing atom.…”

Section: X-ray Absorption Near-edge Structure (Xanes)mentioning

confidence: 99%

See 3 more Smart Citations

Probing spin–vibronic dynamics using femtosecond X-ray spectroscopy

et al. 2016

View full text Add to dashboard Cite

Ultrafast pump-probe spectroscopy within the X-ray regime is now possible owing to the development of X-ray Free Electrons Lasers (X-FELs) and is opening new opportunities for the direct probing of femtosecond evolution of the nuclei, the electronic and spin degrees of freedom. In this contribution we use wavepacket dynamics of the photoexcited decay of a new Fe(ii) complex, [Fe(bmip)2]2+ (bmip = 2,6-bis(3-methyl-imidazole-1-ylidine)pyridine), to simulate the experimental observables associated with femtosecond Fe K-edge X-ray Absorption Near-Edge Structure (XANES) and X-ray emission (XES) spectroscopy. We show how the evolution of the nuclear wavepacket is translated into the spectroscopic signal and the sensitivity of these approaches for following excited state dynamics.

show abstract

Section: Simulating the X-ray Spectrasupporting

confidence: 89%

Section: Femtosecond X-ray Spectroscopysupporting

confidence: 85%

Section: Photoexcited Decay Of [Fe(bmip) 2 ] 2+mentioning

confidence: 99%

Section: X-ray Absorption Near-edge Structure (Xanes)mentioning

confidence: 99%

See 2 more Smart Citations

Probing spin–vibronic dynamics using femtosecond X-ray spectroscopy

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Recently, as shown by Wärnmark and coworkers, N-heterocyclic carbenes (NHC) have been proven to promote notable improvements of 3 MLCT lifetimes, thanks to strong σ-donating effects inducing the destabilization of MC states [25][26][27][28]. While no DSSCs have been built from the newly designed complexes, this work has fostered the revival of research towards the development of iron-based sensitizers for DSSCs, which has been almost asleep since the pioneering works by Ferrere using the Fe(dcbpy) 2 (CN) 2 dye [14].…”

Section: Introductionmentioning

confidence: 99%

NHC-Based Iron Sensitizers for DSSCs

et al. 2018

View full text Add to dashboard Cite

Nanostructured dye-sensitized solar cells (DSSCs) are promising photovoltaic devices because of their low cost and transparency. Ruthenium polypyridine complexes have long been considered as lead sensitizers for DSSCs, allowing them to reach up to 11% conversion efficiency. However, ruthenium suffers from serious drawbacks potentially limiting its widespread applicability, mainly related to its potential toxicity and scarcity. This has motivated continuous research efforts to develop valuable alternatives from cheap earth-abundant metals, and among them, iron is particularly attractive. Making iron complexes applicable in DSSCs is highly challenging due to an ultrafast deactivation of the metal-ligand charge-transfer (MLCT) states into metal-centered (MC) states, leading to inefficient injection into TiO 2 . In this review, we present our latest developments in the field using Fe(II)-based photosensitizers bearing N-heterocyclic carbene (NHC) ligands, and their use in DSSCs. Special attention is paid to synthesis, photophysical, electrochemical, and computational characterization.

show abstract

Hot Branching Dynamics in a Light‐Harvesting Iron Carbene Complex Revealed by Ultrafast X‐ray Emission Spectroscopy

et al. 2019

Self Cite

View full text Add to dashboard Cite

Iron N‐heterocyclic carbene (NHC) complexes have received a great deal of attention recently because of their growing potential as light sensitizers or photocatalysts. We present a sub‐ps X‐ray spectroscopy study of an FeIINHC complex that identifies and quantifies the states involved in the deactivation cascade after light absorption. Excited molecules relax back to the ground state along two pathways: After population of a hot 3MLCT state, from the initially excited 1MLCT state, 30 % of the molecules undergo ultrafast (150 fs) relaxation to the 3MC state, in competition with vibrational relaxation and cooling to the relaxed 3MLCT state. The relaxed 3MLCT state then decays much more slowly (7.6 ps) to the 3MC state. The 3MC state is rapidly (2.2 ps) deactivated to the ground state. The 5MC state is not involved in the deactivation pathway. The ultrafast partial deactivation of the 3MLCT state constitutes a loss channel from the point of view of photochemical efficiency and highlights the necessity to screen transition‐metal complexes for similar ultrafast decays to optimize photochemical performance.

show abstract

Towards longer-lived metal-to-ligand charge transfer states of iron(ii) complexes: an N-heterocyclic carbene approach

Abstract: A 9 ps (3)MLCT lifetime was achieved by a Fe(II) complex based on C(NHC)^N(py)^C(NHC) pincer ligands. This is the longest known so far for any kind of complexes of this abundant metal, and increased by almost two orders of magnitude compared to the reference Fe(II) bis-terpyridine complex.

Cited by 221 publications

References 22 publications

Probing spin–vibronic dynamics using femtosecond X-ray spectroscopy

Probing spin–vibronic dynamics using femtosecond X-ray spectroscopy

NHC-Based Iron Sensitizers for DSSCs

Hot Branching Dynamics in a Light‐Harvesting Iron Carbene Complex Revealed by Ultrafast X‐ray Emission Spectroscopy

Contact Info

Product

Resources

About