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Zobel JP, Radatz H, González L. Photodynamics of the Molecular Ruby [Cr(ddpd) 2] 3. Molecules 2023; 28:molecules28041668. [PMID: 36838661 PMCID: PMC9968007 DOI: 10.3390/molecules28041668] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 02/12/2023] Open
Abstract
The introduction of strong-field ligands can enable luminescence in first-row transition-metal complexes. In this way, earth-abundant near-infrared emitters can be obtained using early 3d metals. A prime example is the molecular ruby [Cr(ddpd)2]3+ (ddpd = N,N'-dimethyl-N,N'-dipyridin-2-ylpyridine-2,6-diamine) that can achieve high phosphorescence quantum yields at room temperature in aqueous solution. To understand these remarkable properties, here, we simulate its photodynamics in water using trajectory surface hopping on linear vibronic coupling potentials parametrized from multiconfigurational CASSCF/CASPT2 calculations. We find that after excitation to the second absorption band, a relaxation cascade through metal-centered states occurs. After an initial back-and-forth intersystem crossing with higher-lying doublet states, the complex relaxes through a manifold of quartet metal-centered states to the low-lying doublet metal-centered states which are responsible for the experimentally observed emission. These electronic processes are driven by an elongation of the Cr-ligand bond lengths as well as the twisting motion of the trans-coordinated pyridine units in the ddpd ligands. The low-lying doublet states are reached within 1-2 ps and are close in geometry to the doublet minima, thus explaining the high phosphorescence quantum yield of the molecular ruby [Cr(ddpd)2]3+.
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Bürgin TH, Glaser F, Wenger OS. Shedding Light on the Oxidizing Properties of Spin-Flip Excited States in a Cr III Polypyridine Complex and Their Use in Photoredox Catalysis. J Am Chem Soc 2022; 144:14181-14194. [PMID: 35913126 PMCID: PMC9376921 DOI: 10.1021/jacs.2c04465] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
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The photoredox activity of well-known RuII complexes
stems from metal-to-ligand charge transfer (MLCT) excited states,
in which a ligand-based electron can initiate chemical reductions
and a metal-centered hole can trigger oxidations. CrIII polypyridines show similar photoredox properties, although they
have fundamentally different electronic structures. Their photoactive
excited state is of spin-flip nature, differing from the electronic
ground state merely by a change of one electron spin, but with otherwise
identical d-orbital occupancy. We find that the driving-force dependence
for photoinduced electron transfer from 10 different donors to a spin-flip
excited state of a CrIII complex is very similar to that
for a RuII polypyridine, and thereby validate the concept
of estimating the redox potential of d3 spin-flip excited
states in analogous manner as for the MLCT states of d6 compounds. Building on this insight, we use our CrIII complex for photocatalytic reactions not previously explored with
this compound class, including the aerobic bromination of methoxyaryls,
oxygenation of 1,1,2,2-tetraphenylethylene, aerobic hydroxylation
of arylboronic acids, and the vinylation of N-phenyl
pyrrolidine. This work contributes to understanding the fundamental
photochemical properties of first-row transition-metal complexes in
comparison to well-explored precious-metal-based photocatalysts.
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Affiliation(s)
- Tobias H Bürgin
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Felix Glaser
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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Riesner M, Fainblat R, Budniak AK, Amouyal Y, Lifshitz E, Bacher G. Temperature dependence of Fano resonances in CrPS4. J Chem Phys 2022; 156:054707. [DOI: 10.1063/5.0079298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Affiliation(s)
- Maurizio Riesner
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Duisburg 47057, Germany
| | - Rachel Fainblat
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Duisburg 47057, Germany
| | - Adam K. Budniak
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion–Institute of Technology, Haifa 3200003, Israel
| | - Yaron Amouyal
- Department of Materials Science and Engineering, Technion–Israel Institute of Technology, Haifa 3200003, Israel
| | - Efrat Lifshitz
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion–Institute of Technology, Haifa 3200003, Israel
| | - Gerd Bacher
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Duisburg 47057, Germany
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Kitzmann WRR, Ramanan C, Naumann R, Heinze K. Molecular Ruby: Exploring the Excited State Landscape. Dalton Trans 2022; 51:6519-6525. [DOI: 10.1039/d2dt00569g] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The discovery of the highly NIR-luminescent Molecular Ruby [Cr(ddpd)2]3+ 13+ (ddpd = N,N’-dimethyl-N,N’-dipyridine-2-ylpyridine-2,6-diamine) has been a milestone in the development of earth-abundant luminophors and has led to important new impulses...
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Wegeberg C, Wenger OS. Luminescent First-Row Transition Metal Complexes. JACS AU 2021; 1:1860-1876. [PMID: 34841405 PMCID: PMC8611671 DOI: 10.1021/jacsau.1c00353] [Citation(s) in RCA: 101] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Indexed: 05/25/2023]
Abstract
Precious and rare elements have traditionally dominated inorganic photophysics and photochemistry, but now we are witnessing a paradigm shift toward cheaper and more abundant metals. Even though emissive complexes based on selected first-row transition metals have long been known, recent conceptual breakthroughs revealed that a much broader range of elements in different oxidation states are useable for this purpose. Coordination compounds of V, Cr, Mn, Fe, Co, Ni, and Cu now show electronically excited states with unexpected reactivity and photoluminescence behavior. Aside from providing a compact survey of the recent conceptual key advances in this dynamic field, our Perspective identifies the main design strategies that enabled the discovery of fundamentally new types of 3d-metal-based luminophores and photosensitizers operating in solution at room temperature.
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Grupe M, Boden P, Di Martino‐Fumo P, Gui X, Bruschi C, Israil R, Schmitt M, Nieger M, Gerhards M, Klopper W, Riehn C, Bizzarri C, Diller R. Time-Resolved Spectroscopy and Electronic Structure of Mono-and Dinuclear Pyridyl-Triazole/DPEPhos-Based Cu(I) Complexes. Chemistry 2021; 27:15251-15270. [PMID: 34550622 PMCID: PMC8597052 DOI: 10.1002/chem.202102760] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Indexed: 12/20/2022]
Abstract
Chemical and spectroscopic characterization of the mononuclear photosensitizers [(DPEPhos)Cu(I)(MPyrT)]0/+ (CuL, CuLH) and their dinuclear analogues (Cu2 L', Cu2 L'H2 ), backed by (TD)DFT and high-level GW-Bethe-Salpeter equation calculations, exemplifies the complex influence of charge, nuclearity and structural flexibility on UV-induced photophysical pathways. Ultrafast transient absorption and step-scan FTIR spectroscopy reveal flattening distortion in the triplet state of CuLH as controlled by charge, which also appears to have a large impact on the symmetry of the long-lived triplet states in Cu2 L' and Cu2 L'H2 . Time-resolved luminescence spectroscopy (solid state), supported by transient photodissociation spectroscopy (gas phase), confirm a lifetime of some tens of μs for the respective triplet states, as well as the energetics of thermally activated delayed luminescence, both being essential parameters for application of these materials based on earth-abundant copper in photocatalysis and luminescent devices.
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Affiliation(s)
- Merten Grupe
- Department of PhysicsTU KaiserslauternErwin-Schrödinger-Straße 4667663KaiserslauternGermany
| | - Pit Boden
- Department of ChemistryTU KaiserslauternErwin-Schrödinger-Straße 5267663KaiserslauternGermany
| | - Patrick Di Martino‐Fumo
- Department of ChemistryTU KaiserslauternErwin-Schrödinger-Straße 5267663KaiserslauternGermany
| | - Xin Gui
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 276131KarlsruheGermany
| | - Cecilia Bruschi
- Institute of Organic Chemistry (IOC)Karlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 676131KarlsruheGermany
| | - Roumany Israil
- Department of ChemistryTU KaiserslauternErwin-Schrödinger-Straße 5267663KaiserslauternGermany
| | - Marcel Schmitt
- Department of ChemistryTU KaiserslauternErwin-Schrödinger-Straße 5267663KaiserslauternGermany
| | - Martin Nieger
- Department of ChemistryUniversity of HelsinkiA.I. Virtasen aukio 100014HelsinkiFinland
| | - Markus Gerhards
- Department of ChemistryTU KaiserslauternErwin-Schrödinger-Straße 5267663KaiserslauternGermany
- Research Center OPTIMASErwin-Schrödinger-Straße 4667663KaiserslauternGermany
| | - Wim Klopper
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 276131KarlsruheGermany
| | - Christoph Riehn
- Department of ChemistryTU KaiserslauternErwin-Schrödinger-Straße 5267663KaiserslauternGermany
- Research Center OPTIMASErwin-Schrödinger-Straße 4667663KaiserslauternGermany
| | - Claudia Bizzarri
- Institute of Organic Chemistry (IOC)Karlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 676131KarlsruheGermany
| | - Rolf Diller
- Department of PhysicsTU KaiserslauternErwin-Schrödinger-Straße 4667663KaiserslauternGermany
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Reichenauer F, Wang C, Förster C, Boden P, Ugur N, Báez-Cruz R, Kalmbach J, Carrella LM, Rentschler E, Ramanan C, Niedner-Schatteburg G, Gerhards M, Seitz M, Resch-Genger U, Heinze K. Strongly Red-Emissive Molecular Ruby [Cr(bpmp) 2] 3+ Surpasses [Ru(bpy) 3] 2. J Am Chem Soc 2021; 143:11843-11855. [PMID: 34296865 DOI: 10.1021/jacs.1c05971] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gaining chemical control over the thermodynamics and kinetics of photoexcited states is paramount to an efficient and sustainable utilization of photoactive transition metal complexes in a plethora of technologies. In contrast to energies of charge transfer states described by spatially separated orbitals, the energies of spin-flip states cannot straightforwardly be predicted as Pauli repulsion and the nephelauxetic effect play key roles. Guided by multireference quantum chemical calculations, we report a novel highly luminescent spin-flip emitter with a quantum chemically predicted blue-shifted luminescence. The spin-flip emission band of the chromium complex [Cr(bpmp)2]3+ (bpmp = 2,6-bis(2-pyridylmethyl)pyridine) shifted to higher energy from ca. 780 nm observed for known highly emissive chromium(III) complexes to 709 nm. The photoluminescence quantum yields climb to 20%, and very long excited state lifetimes in the millisecond range are achieved at room temperature in acidic D2O solution. Partial ligand deuteration increases the quantum yield to 25%. The high excited state energy of [Cr(bpmp)2]3+ and its facile reduction to [Cr(bpmp)2]2+ result in a high excited state redox potential. The ligand's methylene bridge acts as a Brønsted acid quenching the luminescence at high pH. Combined with a pH-insensitive chromium(III) emitter, ratiometric optical pH sensing is achieved with single wavelength excitation. The photophysical and ground state properties (quantum yield, lifetime, redox potential, and acid/base) of this spin-flip complex incorporating an earth-abundant metal surpass those of the classical precious metal [Ru(α-diimine)3]2+ charge transfer complexes, which are commonly employed in optical sensing and photo(redox) catalysis, underlining the bright future of these molecular ruby analogues.
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Affiliation(s)
- Florian Reichenauer
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Cui Wang
- Division Biophotonics, Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, 12489 Berlin, Germany.,Institut für Chemie und Biochemie, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany
| | - Christoph Förster
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Pit Boden
- Department of Chemistry and Research Center Optimas, University Kaiserslautern, Erwin-Schrödinger-Straße, 67663 Kaiserslautern, Germany
| | - Naz Ugur
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Ricardo Báez-Cruz
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Jens Kalmbach
- Institute of Inorganic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Luca M Carrella
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Eva Rentschler
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Charusheela Ramanan
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Gereon Niedner-Schatteburg
- Department of Chemistry and Research Center Optimas, University Kaiserslautern, Erwin-Schrödinger-Straße, 67663 Kaiserslautern, Germany
| | - Markus Gerhards
- Department of Chemistry and Research Center Optimas, University Kaiserslautern, Erwin-Schrödinger-Straße, 67663 Kaiserslautern, Germany
| | - Michael Seitz
- Institute of Inorganic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Ute Resch-Genger
- Division Biophotonics, Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Str. 11, 12489 Berlin, Germany
| | - Katja Heinze
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
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