Cover Picture: Photo-Chromium: Sensitizer for Visible-Light-Induced Oxidative C−H Bond Functionalization-Electron or Energy Transfer? (ChemPhotoChem 8/2017)
Distinct photodynamics of κ-N and κ-C pseudoisomeric iron(ii) complexes
Two closely related FeII complexes with 2,6-bis(1-ethyl-1H-1,2,3-triazol-4yl)pyridine and 2,6-bis(1,2,3-triazol-5-ylidene)pyridine ligands are presented to gain new insights into the photophysics of bis(tridentate) iron(II) complexes. The [Fe(N^N^N)2]2+ pseudoisomer sensitizes singlet oxygen through a MC state with nanosecond lifetime after MLCT excitation, while the bis(tridentate) [Fe(C^N^C)2]2+ pseudoisomer possesses a similar 3MLCT lifetime as the tris(bidentate) [Fe(C^C)2(N^N)]2+ complexes with four mesoionic carbenes. Financial support from the Deutsche Forschungsge-meinschaft [DFG, Priority Program SPP 2102] "Light-controlled reactivity of metal complexes" (BA 4467/7-1, LO 714/11-1, …
Gold(II) Porphyrins in Photoinduced Electron Transfer Reactions
Chemistry - a European journal 25(23), 5940 - 5949 (2019). doi:10.1002/chem.201900050
Higher MLCT lifetime of carbene iron(ii) complexes by chelate ring expansion
Combining strong σ-donating N-heterocyclic carbene ligands and π-accepting pyridine ligands with a high octahedricity in rigid iron(ii) complexes increases the 3MLCT lifetime from 0.15 ps in the prototypical [Fe(tpy)2]2+ complex to 9.2 ps in [Fe(dpmi)2]2+12+. The tripodal CNN ligand dpmi (di(pyridine-2-yl)(3-methylimidazol-2-yl)methane) forms six-membered chelate rings with the iron(ii) centre leading to close to 90° bite angles and enhanced iron-ligand orbital overlap.
Green-Light Activation of Push-Pull Ruthenium(II) Complexes.
Abstract Synthesis, characterization, electrochemistry, and photophysics of homo‐ and heteroleptic ruthenium(II) complexes [Ru(cpmp)2]2+ (22+) and [Ru(cpmp)(ddpd)]2+ (32+) bearing the tridentate ligands 6,2’’‐carboxypyridyl‐2,2’‐methylamine‐pyridyl‐pyridine (cpmp) and N,N’‐dimethyl‐N,N’‐dipyridin‐2‐ylpyridine‐2,6‐diamine (ddpd) are reported. The complexes possess one (32+) or two (22+) electron‐deficient dipyridyl ketone fragments as electron‐accepting sites enabling intraligand charge transfer (ILCT), ligand‐to‐ligand charge transfer (LL'CT) and low‐energy metal‐to‐ligand charge transfer (MLCT) absorptions. The latter peak around 544 nm (green light). Complex 22+ shows 3MLCT phosphorescenc…
Ground- and Excited-State Properties of Iron(II) Complexes Linked to Organic Chromophores
Two new bichromophoric complexes, [Fe(bim-ant)2]2+ and [Fe(bim-pyr)2]2+ ([H2-bim]2+ = 1,1′-(pyridine-2,6-diyl)bis(3-methyl-1H-imidazol-3-ium); ant = 9-anthracenyl; pyr = 1-pyrenyl), are investigate...
Photo-Chromium: Sensitizer for Visible-Light-Induced Oxidative C−H Bond Functionalization-Electron or Energy Transfer?
The chromium(III) sensitizer [Cr(ddpd)2]3+ - based on an earth-abundant metal center - possesses a unique excited state potential energy landscape (ddpd = N,N'-dimethyl-N,N'-dipyridine-2-ylpyridine-2,6-diamine). The very large energy gap between the redox active and substitutionally labile 4T2 state and the long-lived low-energy 2E spin-flip state enables a selective, efficient sensitization of triplet dioxygen to give singlet dioxygen. Ultrafast intersystem crossing after the Franck Condon point from the 4T2 to the 2E excited state within 3.5 ps precludes intermolecular electron transfer pathways from the ultrashort-lived excited 4T2 state. This specific excited state reactivity enables a …
Cover Feature: Excited‐State Kinetics of an Air‐Stable Cyclometalated Iron(II) Complex (Chem. Eur. J. 51/2019)
A Vanadium(III) Complex with Blue and NIR-II Spin-Flip Luminescence in Solution.
Luminescence from Earth-abundant metal ions in solution at room temperature is a very challenging objective due to the intrinsically weak ligand field splitting of first-row transition metal ions, which leads to efficient nonradiative deactivation via metal-centered states. Only a handful of 3d
Ultrafast and long-time excited state kinetics of an NIR-emissive vanadium(iii) complex I: synthesis, spectroscopy and static quantum chemistry.
In spite of intense, recent research efforts, luminescent transition metal complexes with Earth-abundant metals are still very rare owing to the small ligand field splitting of 3d transition metal complexes and the resulting non-emissive low-energy metal-centered states. Low-energy excited states decay efficiently non-radiatively, so that near-infrared emissive transition metal complexes with 3d transition metals are even more challenging. We report that the heteroleptic pseudo-octahedral d2-vanadium(iii) complex VCl3(ddpd) (ddpd = N,N′-dimethyl-N,N′-dipyridine-2-yl-pyridine-2,6-diamine) shows near-infrared singlet → triplet spin–flip phosphorescence maxima at 1102, 1219 and 1256 nm with a …
Excited-State Kinetics of an Air-Stable Cyclometalated Iron(II) Complex.
The complex class [Fe(N^N^C)(N^N^N)]+ with an Earth-abundant metal ion has been repeatedly suggested as a chromophore and potential photosensitizer on the basis of quantum chemical calculations. Synthesis and photophysical properties of the parent complex [Fe(pbpy)(tpy)]+ (Hpbpy=6-phenyl-2,2'-bipyridine and tpy=2,2':6',2''-terpyridine) of this new chromophore class are now reported. Ground-state characterization by X-ray diffraction, electrochemistry, spectroelectrochemistry, UV/Vis, and X-ray spectroscopy in combination with DFT calculations proves the high impact of the cyclometalating ligand on the electronic structure. The photophysical properties are significantly improved compared to …
Cover Feature: Green‐Light Activation of Push–Pull Ruthenium(II) Complexes (Chem. Eur. J. 30/2020)
CCDC 1958562: Experimental Crystal Structure Determination
Related Article: Matthias Dorn, Jens Kalmbach, Pit Boden, Ayla Päpcke, Sandra Gómez, Christoph Förster, Felix Kuczelinis, Luca M. Carrella, Laura A. Büldt, Nicolas H. Bings, Eva Rentschler, Stefan Lochbrunner, Leticia González, Markus Gerhards, Michael Seitz, Katja Heinze|2020|J.Am.Chem.Soc.|142|7947|doi:10.1021/jacs.0c02122
CCDC 2050317: Experimental Crystal Structure Determination
Related Article: Philipp Dierks, Ayla Kruse, Olga S. Bokareva, Mohammed J. Al-Marri, Jens Kalmbach, Marc Baltrun, Adam Neuba, Roland Schoch, Stephan Hohloch, Katja Heinze, Michael Seitz, Oliver Kühn, Stefan Lochbrunner, Matthias Bauer|2021|Chem.Commun.|57|6640|doi:10.1039/D1CC01716K
CCDC 1904835: Experimental Crystal Structure Determination
Related Article: Jakob Steube, Lukas Burkhardt, Ayla Päpcke, Johannes Moll, Peter Zimmer, Roland Schoch, Christoph Wölper, Katja Heinze, Stefan Lochbrunner, Matthias Bauer|2019|Chem.-Eur.J.|25|11826|doi:10.1002/chem.201902488
CCDC 2049729: Experimental Crystal Structure Determination
Related Article: Philipp Dierks, Ayla Kruse, Olga S. Bokareva, Mohammed J. Al-Marri, Jens Kalmbach, Marc Baltrun, Adam Neuba, Roland Schoch, Stephan Hohloch, Katja Heinze, Michael Seitz, Oliver Kühn, Stefan Lochbrunner, Matthias Bauer|2021|Chem.Commun.|57|6640|doi:10.1039/D1CC01716K
CCDC 1852838: Experimental Crystal Structure Determination
Related Article: Johannnes Moll, Cui Wang, Ayla Päpcke, Christoph Förster, Ute Resch-Genger, Stefan Lochbrunner, Katja Heinze|2020|Chem.-Eur.J.|26|6820|doi:10.1002/chem.202000871