1
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Witas K, Nair SS, Maisuradze T, Zedler L, Schmidt H, Garcia-Porta P, Rein ASJ, Bolter T, Rau S, Kupfer S, Dietzek-Ivanšić B, Sorsche DU. Beyond the First Coordination Sphere─Manipulating the Excited-State Landscape in Iron(II) Chromophores with Protons. J Am Chem Soc 2024; 146:19710-19719. [PMID: 38990184 PMCID: PMC11273614 DOI: 10.1021/jacs.4c00552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 06/14/2024] [Accepted: 06/17/2024] [Indexed: 07/12/2024]
Abstract
Molecular transition metal chromophores play a central role in light harvesting and energy conversion. Recently, earth-abundant transition-metal-based chromophores have begun to challenge the dominance of platinum group metal complexes in this area. However, the development of new chromophores with optimized photophysical properties is still limited by a lack of synthetic methods, especially with respect to heteroleptic complexes with functional ligands. Here, we demonstrate a facile and efficient method for the combination of strong-field carbenes with the functional 2,2'-bibenzimidazole ligand in a heteroleptic iron(II) chromophore complex. Our approach yields two isomers that differ predominantly in their excited-state lifetimes based on the symmetry of the ligand field. Deprotonation of both isomers leads to a significant red-shift of the metal-to-ligand charge transfer (MLCT) absorption and a shortening of excited-state lifetimes. Femtosecond transient absorption spectroscopy in combination with quantum chemical simulations and resonance Raman spectroscopy reveals the complex relationship between protonation and photophysical properties. Protonation is found to tip the balance between MLCT and metal-centered (MC) excited states in favor of the former. This study showcases the first example of fine-tuning of the excited-state landscape in an iron(II) chromophore through second-sphere manipulations and provides a new perspective to the challenge of excited-state optimizations in 3d transition metal chromophores.
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Affiliation(s)
- Kamil Witas
- Institute
for Inorganic Chemistry 1, Ulm University
(UUlm), Albert-Einstein-Allee 11, Ulm 89081, Germany
| | - Shruthi Santhosh Nair
- Research
Department Functional Interfaces, Leibniz
Institute of Photonic Technology (Leibniz-IPHT), Albert-Einstein-Straße 9, Jena 07745, Germany
- Institute
for Physical Chemistry, Friedrich-Schiller-Universität
Jena (FSU Jena), Lessingstraße 4, Jena 07743, Germany
| | - Tamar Maisuradze
- Institute
for Physical Chemistry, Friedrich-Schiller-Universität
Jena (FSU Jena), Lessingstraße 4, Jena 07743, Germany
| | - Linda Zedler
- Research
Department Functional Interfaces, Leibniz
Institute of Photonic Technology (Leibniz-IPHT), Albert-Einstein-Straße 9, Jena 07745, Germany
- Institute
for Physical Chemistry, Friedrich-Schiller-Universität
Jena (FSU Jena), Lessingstraße 4, Jena 07743, Germany
| | - Heiner Schmidt
- Research
Department Functional Interfaces, Leibniz
Institute of Photonic Technology (Leibniz-IPHT), Albert-Einstein-Straße 9, Jena 07745, Germany
- Institute
for Physical Chemistry, Friedrich-Schiller-Universität
Jena (FSU Jena), Lessingstraße 4, Jena 07743, Germany
| | - Pablo Garcia-Porta
- Institute
for Inorganic Chemistry 1, Ulm University
(UUlm), Albert-Einstein-Allee 11, Ulm 89081, Germany
| | | | - Tim Bolter
- Institute
for Inorganic Chemistry 1, Ulm University
(UUlm), Albert-Einstein-Allee 11, Ulm 89081, Germany
| | - Sven Rau
- Institute
for Inorganic Chemistry 1, Ulm University
(UUlm), Albert-Einstein-Allee 11, Ulm 89081, Germany
| | - Stephan Kupfer
- Institute
for Physical Chemistry, Friedrich-Schiller-Universität
Jena (FSU Jena), Lessingstraße 4, Jena 07743, Germany
| | - Benjamin Dietzek-Ivanšić
- Research
Department Functional Interfaces, Leibniz
Institute of Photonic Technology (Leibniz-IPHT), Albert-Einstein-Straße 9, Jena 07745, Germany
- Institute
for Physical Chemistry, Friedrich-Schiller-Universität
Jena (FSU Jena), Lessingstraße 4, Jena 07743, Germany
| | - Dieter U. Sorsche
- Institute
for Inorganic Chemistry 1, Ulm University
(UUlm), Albert-Einstein-Allee 11, Ulm 89081, Germany
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2
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Losada IB, Persson P. Photoredox matching of earth-abundant photosensitizers with hydrogen evolving catalysts by first-principles predictions. J Chem Phys 2024; 160:074302. [PMID: 38375904 DOI: 10.1063/5.0174837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 01/09/2024] [Indexed: 02/21/2024] Open
Abstract
Photoredox properties of several earth-abundant light-harvesting transition metal complexes in combination with cobalt-based proton reduction catalysts have been investigated computationally to assess the fundamental viability of different photocatalytic systems of current experimental interest. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations using several GGA (BP86, BLYP), hybrid-GGA (B3LYP, B3LYP*), hybrid meta-GGA (M06, TPSSh), and range-separated hybrid (ωB97X, CAM-B3LYP) functionals were used to calculate relevant ground and excited state reduction potentials for photosensitizers, catalysts, and sacrificial electron donors. Linear energy correction factors for the DFT/TD-DFT results that provide the best agreement with available experimental reference results were determined in order to provide more accurate predictions. Among the selection of functionals, the B3LYP* and TPSSh sets of correction parameters were determined to give the best redox potentials and excited states energies, ΔEexc, with errors of ∼0.2 eV. Linear corrections for both reduction and oxidation processes significantly improve the predictions for all the redox pairs. In particular, for TPSSh and B3LYP*, the calculated errors decrease by more than 0.5 V against experimental values for catalyst reduction potentials, photosensitizer oxidation potentials, and electron donor oxidation potentials. Energy-corrected TPSSh results were finally used to predict the energetics of complete photocatalytic cycles for the light-driven activation of selected proton reduction cobalt catalysts. These predictions demonstrate the broader usefulness of the adopted approach to systematically predict full photocycle behavior for first-row transition metal photosensitizer-catalyst combinations more broadly.
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Affiliation(s)
- Iria Bolaño Losada
- Division of Computational Chemistry, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Petter Persson
- Division of Computational Chemistry, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
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3
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Wang C, Wegeberg C, Wenger OS. First-Row d 6 Metal Complex Enables Photon Upconversion and Initiates Blue Light-Dependent Polymerization with Red Light. Angew Chem Int Ed Engl 2023; 62:e202311470. [PMID: 37681516 DOI: 10.1002/anie.202311470] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/07/2023] [Accepted: 09/08/2023] [Indexed: 09/09/2023]
Abstract
Photosensitizers for sensitized triplet-triplet annihilation upconversion (sTTA-UC) often rely on precious heavy metals, whereas coordination complexes based on abundant first-row transition metals are less common. This is mainly because long-lived triplet excited states are more difficult to obtain for 3d metals, particularly when the d-subshell is only partially filled. Here, we report the first example of sTTA-UC based on a 3d6 metal photosensitizer yielding an upconversion performance competitive with precious metal-based analogues. Using a newly developed Cr0 photosensitizer featuring equally good photophysical properties as an OsII benchmark complex in combination with an acetylene-decorated anthracene annihilator, red-to-blue upconversion is achievable. The upconversion efficiency under optimized conditions is 1.8 %, and the excitation power density threshold to reach the strong annihilation limit is 5.9 W/cm2 . These performance factors, along with high photostability, permit the initiation of acrylamide polymerization by red light, based on radiative energy transfer between delayed annihilator fluorescence and a blue light absorbing photo-initiator. Our study provides the proof-of-concept for photon upconversion with elusive first-row analogues of widely employed precious d6 metal photosensitizers, and for their application in photochemical reactions triggered by excitation wavelengths close to near-infrared.
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Affiliation(s)
- Cui Wang
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
- Current address: Department of Biology and Chemistry, Osnabrück University, Barbarastraße 7, 49076, Osnabrück, Germany
| | - Christina Wegeberg
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
- Current address: Division of Chemical Physics, Department of Chemistry, Lund University Box 124, 22100, Lund, Sweden
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
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4
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Sinha N, Wenger OS. Photoactive Metal-to-Ligand Charge Transfer Excited States in 3d 6 Complexes with Cr 0, Mn I, Fe II, and Co III. J Am Chem Soc 2023; 145:4903-4920. [PMID: 36808978 PMCID: PMC9999427 DOI: 10.1021/jacs.2c13432] [Citation(s) in RCA: 39] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Many coordination complexes and organometallic compounds with the 4d6 and 5d6 valence electron configurations have outstanding photophysical and photochemical properties, which stem from metal-to-ligand charge transfer (MLCT) excited states. This substance class makes extensive use of the most precious and least abundant metal elements, and consequently there has been a long-standing interest in first-row transition metal compounds with photoactive MLCT states. Semiprecious copper(I) with its completely filled 3d subshell is a relatively straightforward and well explored case, but in 3d6 complexes the partially filled d-orbitals lead to energetically low-lying metal-centered (MC) states that can cause undesirably fast MLCT excited state deactivation. Herein, we discuss recent advances made with isoelectronic Cr0, MnI, FeII, and CoIII compounds, for which long-lived MLCT states have become accessible over the past five years. Furthermore, we discuss possible future developments in the search for new first-row transition metal complexes with partially filled 3d subshells and photoactive MLCT states for next-generation applications in photophysics and photochemistry.
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Affiliation(s)
- Narayan Sinha
- 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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Curtin GM, Jakubikova E. Extended π-Conjugated Ligands Tune Excited-State Energies of Iron(II) Polypyridine Dyes. Inorg Chem 2022; 61:18850-18860. [DOI: 10.1021/acs.inorgchem.2c02362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Gregory M. Curtin
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Elena Jakubikova
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
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Yarranton JT, McCusker JK. Ligand-Field Spectroscopy of Co(III) Complexes and the Development of a Spectrochemical Series for Low-Spin d 6 Charge-Transfer Chromophores. J Am Chem Soc 2022; 144:12488-12500. [PMID: 35749670 DOI: 10.1021/jacs.2c04945] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A study of a series of six-coordinate Co(III) complexes has been carried out to quantify spectroscopic parameters for a range of ligands that are commonly employed to realize strong charge-transfer absorptions in low-spin, d6 systems. Identification of any three ligand-field transitions allows for the determination of the splitting parameter (10 Dq) as well as the Racah B and C parameters for a given compound. The data revealed a relatively small spread in the magnitude of 10 Dq, ranging from ca. 23 000 cm-1 in the case of [Co(pyrro-bpy)3]3+ (where pyrro-bpy is 4,4'-dipyrrolidinyl-2,2'-bipyridine) to ca. 26 000 cm-1 for [Co(terpy)2]3+ (where terpy is 2,2':6',2″-terpyridine). Significantly, trends across the series suggest that polypyridyl ligands behave as net π-donors when interacting with Co(III), in contrast to the net π-accepting character they exhibit when bound to second- and third-row metals. The influence of strong σ donation associated with carbene-based ligands was evident from the data acquired for [Co(BMeImPy)2]3+ (where BMeImPy is 3,3'-(pyridine-2,6-diyl)bis(1-methyl-1H-3-imidazolium)), where a 10 Dq value of ca. 30 000 cm-1 was determined. Spectroscopic data were also analyzed for [Fe(bpy)3]2+ using the results on [Co(bpy)3]3+ as a reference point. A value for 10 Dq of 21 000 cm-1 was estimated, indicating a reduction in the ligand-field strength of ca. 3000 cm-1 upon replacing Co(III) with Fe(II). We suggest that this approach of taking advantage of the blueshift of the charge-transfer feature in Co(III) complexes to reveal otherwise obscured ligand-field bands can be a useful tool for the development of new ligand systems to expand the photofunctionality of first-row transition-metal-based chromophores.
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Affiliation(s)
- Jonathan T Yarranton
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824, United States
| | - James K McCusker
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824, United States
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Dierks P, Vukadinovic Y, Bauer M. Photoactive iron complexes: more sustainable, but still a challenge. Inorg Chem Front 2022. [DOI: 10.1039/d1qi01112j] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
With the “Criticality Score” used as a benchmark for sustainability – potentials, strategies and challenges are discussed to replace noble metal compounds in photosensitizers by the sustainable alternative iron.
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Affiliation(s)
- Philipp Dierks
- Faculty of Science, Chemistry Department and Center for Sustainable Systems Design, Paderborn University, 33098 Paderborn, Germany
| | - Yannik Vukadinovic
- Faculty of Science, Chemistry Department and Center for Sustainable Systems Design, Paderborn University, 33098 Paderborn, Germany
| | - Matthias Bauer
- Faculty of Science, Chemistry Department and Center for Sustainable Systems Design, Paderborn University, 33098 Paderborn, Germany
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Abstract
In this Frontier article, recently discovered chromium(0) and manganese(i) complexes emitting from metal-to-ligand charge transfer (MLCT) excited states are highlighted. Chelating isocyanide ligands give access to this new class of 3d6 emitters with MLCT lifetimes in (or close to) the nanosecond regime in solution at room temperature. Although the so far achievable luminescence quantum yields in these open-shell complexes are yet comparatively low, the photophysical properties of the new chromium(0) and manganese(i) isocyanides are reminiscent of those of well-known ruthenium(ii) polypyridines. Our findings provide insight into how undesired nonradiative MLCT deactivation in 3d6 complexes can be counteracted, and they seem therefore relevant for the further development of new luminescent first-row transition metal complexes based on iron(ii) and cobalt(iii) in addition to chromium(0) and manganese(i). In this Frontier article, recently discovered chromium(0) and manganese(i) complexes emitting from metal-to-ligand charge transfer (MLCT) excited states are highlighted.![]()
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Affiliation(s)
- Christina Wegeberg
- 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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9
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Temperton RH, Guo M, D'Acunto G, Johansson N, Rosemann NW, Prakash O, Wärnmark K, Schnadt J, Uhlig J, Persson P. Resonant X-ray photo-oxidation of light-harvesting iron (II/III) N-heterocyclic carbene complexes. Sci Rep 2021; 11:22144. [PMID: 34772983 PMCID: PMC8590020 DOI: 10.1038/s41598-021-01509-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 10/25/2021] [Indexed: 11/12/2022] Open
Abstract
Two photoactive iron N-heterocyclic carbene complexes \documentclass[12pt]{minimal}
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\begin{document}$${[\hbox {Fe}^{{{\rm{II}}}}(\hbox {btz})_2(\hbox {bpy})]^{2+}}$$\end{document}[FeII(btz)2(bpy)]2+ and \documentclass[12pt]{minimal}
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\begin{document}$${[\hbox {Fe}^{{\rm{III}}}(\hbox {btz})_3]^{3+}}$$\end{document}[FeIII(btz)3]3+, where btz is 3,3’-dimethyl-1,1’-bis(p-tolyl)-4,4’-bis(1,2,3-triazol-5-ylidene) and bpy is 2,2’-bipyridine, have been investigated by Resonant Photoelectron Spectroscopy (RPES). Tuning the incident X-ray photon energy to match core-valence excitations provides a site specific probe of the electronic structure properties and ligand-field interactions, as well as information about the resonantly photo-oxidised final states. Comparing measurements of the Fe centre and the surrounding ligands demonstrate strong mixing of the Fe \documentclass[12pt]{minimal}
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\begin{document}$${\hbox {t}_{{\rm{2g}}}}$$\end{document}t2g levels with occupied ligand \documentclass[12pt]{minimal}
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\begin{document}$$\pi$$\end{document}π orbitals but weak mixing with the corresponding unoccupied ligand orbitals. This highlights the importance of \documentclass[12pt]{minimal}
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\begin{document}$$\pi$$\end{document}π-accepting and -donating considerations in ligand design strategies for photofunctional iron carbene complexes. Spin-propensity is also observed as a final-state effect in the RPES measurements of the open-shell \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {Fe}^{{\rm{III}}}$$\end{document}FeIII complex. Vibronic coupling is evident in both complexes, where the energy dispersion hints at a vibrationally hot final state. The results demonstrate the significant impact of the iron oxidation state on the frontier electronic structure and highlights the differences between the emerging class of \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {Fe}^{{\rm{III}}}$$\end{document}FeIII photosensitizers from those of more traditional \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {Fe}^{{\rm{II}}}$$\end{document}FeII complexes.
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Affiliation(s)
- Robert H Temperton
- MAX IV Laboratory, Lund University, Box 118, 221 00, Lund, Sweden.,School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK.,Lund Institute of Advanced Neutron and X-ray Science, IDEON Building: Delta 5, Scheelevägen 19, 223 70, Lund, Sweden
| | - Meiyuan Guo
- Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, 221 00, Lund, Sweden
| | - Giulio D'Acunto
- Division of Synchrotron Radiation Research, Department of Physics, Lund University, Box 118, 221 00, Lund, Sweden
| | - Niclas Johansson
- Division of Synchrotron Radiation Research, Department of Physics, Lund University, Box 118, 221 00, Lund, Sweden
| | - Nils W Rosemann
- Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, 221 00, Lund, Sweden
| | - Om Prakash
- Department of Chemistry, Centre for Analysis and Synthesis, Lund University, Box 124, 221 00, Lund, Sweden
| | - Kenneth Wärnmark
- Department of Chemistry, Centre for Analysis and Synthesis, Lund University, Box 124, 221 00, Lund, Sweden
| | - Joachim Schnadt
- MAX IV Laboratory, Lund University, Box 118, 221 00, Lund, Sweden. .,Lund Institute of Advanced Neutron and X-ray Science, IDEON Building: Delta 5, Scheelevägen 19, 223 70, Lund, Sweden. .,Division of Synchrotron Radiation Research, Department of Physics, Lund University, Box 118, 221 00, Lund, Sweden.
| | - Jens Uhlig
- Lund Institute of Advanced Neutron and X-ray Science, IDEON Building: Delta 5, Scheelevägen 19, 223 70, Lund, Sweden. .,Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, 221 00, Lund, Sweden.
| | - Petter Persson
- Lund Institute of Advanced Neutron and X-ray Science, IDEON Building: Delta 5, Scheelevägen 19, 223 70, Lund, Sweden. .,Division of Theoretical Chemistry, Department of Chemistry, Lund University, Box 124, 221 00, Lund, Sweden.
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10
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Napierała S, Kubicki M, Wałęsa-Chorab M. Toward Electrochromic Metallopolymers: Synthesis and Properties of Polyazomethines Based on Complexes of Transition-Metal Ions. Inorg Chem 2021; 60:14011-14021. [PMID: 34396778 PMCID: PMC8456411 DOI: 10.1021/acs.inorgchem.1c01249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Indexed: 11/29/2022]
Abstract
The tridentate ligand L and its complexes with transition-metal ions have been prepared and characterized. The polycondensation reactions of transition-metal complexes with different dialdehydes led to the formation of transition-metal-complex-based polyazomethines, which have been obtained by on-substrate polymerization, and their electrochemical and electrochromic performance have been investigated. The most interesting properties are exhibited by polymers of Fe(II) and Cu(II) ions obtained by the reaction of the appropriate complexes with a triphenylamine-based dialdehyde. Fe(II) polymer P1 undergoes a reversible oxidation/reduction process and a color change from orange to gray due to the oxidation of Fe(II) to Fe(III) ions concomitant with the oxidation of the triphenylamine group. Its electrochromic properties such as long-term stability, switching times, and coloration efficiencies have been investigated, providing evidence of the utility of the on-substrate polycondensation reaction in the formation of thin films of electrochromic metallopolymers.
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Affiliation(s)
- Sergiusz Napierała
- Faculty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego
8, 61-614 Poznań, Poland
| | - Maciej Kubicki
- Faculty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego
8, 61-614 Poznań, Poland
| | - Monika Wałęsa-Chorab
- Faculty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego
8, 61-614 Poznań, Poland
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11
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Huber‐Gedert M, Nowakowski M, Kertmen A, Burkhardt L, Lindner N, Schoch R, Herbst‐Irmer R, Neuba A, Schmitz L, Choi T, Kubicki J, Gawelda W, Bauer M. Fundamental Characterization, Photophysics and Photocatalysis of a Base Metal Iron(II)-Cobalt(III) Dyad. Chemistry 2021; 27:9905-9918. [PMID: 33884671 PMCID: PMC8362051 DOI: 10.1002/chem.202100766] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Indexed: 12/13/2022]
Abstract
A new base metal iron-cobalt dyad has been obtained by connection between a heteroleptic tetra-NHC iron(II) photosensitizer combining a 2,6-bis[3-(2,6-diisopropylphenyl)imidazol-2-ylidene]pyridine with 2,6-bis(3-methyl-imidazol-2-ylidene)-4,4'-bipyridine ligand, and a cobaloxime catalyst. This novel iron(II)-cobalt(III) assembly has been extensively characterized by ground- and excited-state methods like X-ray crystallography, X-ray absorption spectroscopy, (spectro-)electrochemistry, and steady-state and time-resolved optical absorption spectroscopy, with a particular focus on the stability of the molecular assembly in solution and determination of the excited-state landscape. NMR and UV/Vis spectroscopy reveal dissociation of the dyad in acetonitrile at concentrations below 1 mM and high photostability. Transient absorption spectroscopy after excitation into the metal-to-ligand charge transfer absorption band suggests a relaxation cascade originating from hot singlet and triplet MLCT states, leading to the population of the 3 MLCT state that exhibits the longest lifetime. Finally, decay into the ground state involves a 3 MC state. Attachment of cobaloxime to the iron photosensitizer increases the 3 MLCT lifetime at the iron centre. Together with the directing effect of the linker, this potentially makes the dyad more active in photocatalytic proton reduction experiments than the analogous two-component system, consisting of the iron photosensitizer and Co(dmgH)2 (py)Cl. This work thus sheds new light on the functionality of base metal dyads, which are important for more efficient and sustainable future proton reduction systems.
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Affiliation(s)
- Marina Huber‐Gedert
- Department ChemieUniversität PaderbornWarburger Straße 10033098PaderbornGermany
| | - Michał Nowakowski
- Department ChemieUniversität PaderbornWarburger Straße 10033098PaderbornGermany
| | - Ahmet Kertmen
- Faculty of PhysicsAdam Mickiewicz University Poznańul. Uniwersytetu Poznańskiego 2Poznań61-614Poland
| | - Lukas Burkhardt
- Department ChemieUniversität PaderbornWarburger Straße 10033098PaderbornGermany
| | - Natalia Lindner
- Faculty of PhysicsAdam Mickiewicz University Poznańul. Uniwersytetu Poznańskiego 2Poznań61-614Poland
| | - Roland Schoch
- Department ChemieUniversität PaderbornWarburger Straße 10033098PaderbornGermany
| | - Regine Herbst‐Irmer
- Institut für Anorganische ChemieUniversität GöttingenTammannstraße 437077GöttingenGermany
| | - Adam Neuba
- Department ChemieUniversität PaderbornWarburger Straße 10033098PaderbornGermany
| | - Lennart Schmitz
- Department ChemieUniversität PaderbornWarburger Straße 10033098PaderbornGermany
| | | | - Jacek Kubicki
- Faculty of PhysicsAdam Mickiewicz University Poznańul. Uniwersytetu Poznańskiego 2Poznań61-614Poland
| | - Wojciech Gawelda
- Faculty of PhysicsAdam Mickiewicz University Poznańul. Uniwersytetu Poznańskiego 2Poznań61-614Poland
- Department of ChemistryUniversidad Autónoma de MadridCampus Universitario28049MadridSpain
- IMDEA-NanocienciaCalle Faraday 928049MadridSpain
| | - Matthias Bauer
- Department ChemieUniversität PaderbornWarburger Straße 10033098PaderbornGermany
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12
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Nair SS, Bysewski OA, Kupfer S, Wächtler M, Winter A, Schubert US, Dietzek B. Excitation Energy-Dependent Branching Dynamics Determines Photostability of Iron(II)-Mesoionic Carbene Complexes. Inorg Chem 2021; 60:9157-9173. [PMID: 34081456 DOI: 10.1021/acs.inorgchem.1c01166] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Photoactive metal complexes containing earth-abundant transition metals recently gained interest as photosensitizers in light-driven chemistry. In contrast to the traditionally employed ruthenium or iridium complexes, iron complexes developed to be promising candidates despite the fact that using iron complexes as photosensitizers poses an inherent challenge associated with the low-lying metal-centered states, which are responsible for ultrafast deactivation of the charge-transfer states. Nonetheless, recent developments of strongly σ-donating carbene ligands yielded highly promising systems, in which destabilized metal-centered states resulted in prolonged lifetimes of charge-transfer excited states. In this context, we introduce a series of novel homoleptic Fe-triazolylidene mesoionic carbene complexes. The excited-state properties of the complexes were investigated by time-resolved femtosecond transient absorption spectroscopy and quantum chemical calculations. Pump wavelength-dependent transient absorption reveals the presence of distinct excited-state relaxation pathways. We relate the excitation-wavelength-dependent branching of the excited-state dynamics into various reaction channels to solvent-dependent photodissociation following the population of dissociative metal centered states upon excitation at 400 nm.
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Affiliation(s)
- Shruthi S Nair
- Department Functional Interfaces, Leibniz Institute of Photonic Technology (Leibniz-IPHT), Albert-Einstein-Strasse 9, 07745 Jena, Germany.,Institute of Physical Chemistry, Friedrich-Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
| | - Oliver A Bysewski
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich-Schiller University Jena, Humboldtstrasse 10, 07743 Jena, Germany.,Center for Energy and Environmental Chemistry Jena (CEEC-Jena), Friedrich-Schiller University Jena, Philosophenweg, 07743 Jena, Germany
| | - Stephan Kupfer
- Institute of Physical Chemistry, Friedrich-Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
| | - Maria Wächtler
- Department Functional Interfaces, Leibniz Institute of Photonic Technology (Leibniz-IPHT), Albert-Einstein-Strasse 9, 07745 Jena, Germany.,Institute of Physical Chemistry, Friedrich-Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany.,Abbe Center of Photonics, Friedrich Schiller University Jena, Philosophenweg, 07745 Jena, Germany
| | - Andreas Winter
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich-Schiller University Jena, Humboldtstrasse 10, 07743 Jena, Germany.,Center for Energy and Environmental Chemistry Jena (CEEC-Jena), Friedrich-Schiller University Jena, Philosophenweg, 07743 Jena, Germany
| | - Ulrich S Schubert
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich-Schiller University Jena, Humboldtstrasse 10, 07743 Jena, Germany.,Center for Energy and Environmental Chemistry Jena (CEEC-Jena), Friedrich-Schiller University Jena, Philosophenweg, 07743 Jena, Germany
| | - Benjamin Dietzek
- Department Functional Interfaces, Leibniz Institute of Photonic Technology (Leibniz-IPHT), Albert-Einstein-Strasse 9, 07745 Jena, Germany.,Institute of Physical Chemistry, Friedrich-Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
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13
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Li X, Zhao J, Shi WJ, Bai S, Han YF. Synthesis, Characterization, and Structural Transformation of Picolyl-Functionalized Polynuclear Silver(I)– and Gold(I)–N-Heterocyclic Carbene Complexes. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00119] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Xin Li
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, People’s Republic of China
| | - Jing Zhao
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, People’s Republic of China
| | - Wen-Jie Shi
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, People’s Republic of China
| | - Sha Bai
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, People’s Republic of China
| | - Ying-Feng Han
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, People’s Republic of China
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14
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Doettinger F, Yang Y, Schmid MA, Frey W, Karnahl M, Tschierlei S. Cross-Coupled Phenyl- and Alkynyl-Based Phenanthrolines and Their Effect on the Photophysical and Electrochemical Properties of Heteroleptic Cu(I) Photosensitizers. Inorg Chem 2021; 60:5391-5401. [PMID: 33764043 DOI: 10.1021/acs.inorgchem.1c00416] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
With the aims of increasing the antenna system and improving the photophysical properties of Cu(I)-based photosensitizers, the backbone of 2,9-dimethyl-1,10-phenanthroline was selectively extended in the 5,6-position. Applying specifically tailored Suzuki-Miyaura and "chemistry-on-the-complex" Sonogashira cross-coupling reactions enabled the development of two sets of structurally related diimine ligands with a broad variety of different phenyl- and alkynyl-based substituents. The resulting 11 novel heteroleptic Cu(I) complexes, including five solid-state structures, were studied with respect to their structure-property relationships. Both sets of substituents are able to red-shift the absorption maxima and to increase the absorptivity. For the alkynyl-based complexes, this is accompanied by a significant anodic shift of the reduction potentials. The phenyl-based substituents strongly influence the emission wavelength and quantum yield of the resulting Cu(I) complexes and lead to an increase in the emission lifetime of up to 504 ns, which clearly indicates competition with the benchmark system [(xantphos)Cu(bathocuproine)]PF6.
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Affiliation(s)
- Florian Doettinger
- Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.,Department of Energy Conversion, Institute of Physical and Theoretical Chemistry, Technische Universität Brauschweig, Gaußstraße 17, 38106 Braunschweig, Germany
| | - Yingya Yang
- Department of Energy Conversion, Institute of Physical and Theoretical Chemistry, Technische Universität Brauschweig, Gaußstraße 17, 38106 Braunschweig, Germany
| | - Marie-Ann Schmid
- Department of Energy Conversion, Institute of Physical and Theoretical Chemistry, Technische Universität Brauschweig, Gaußstraße 17, 38106 Braunschweig, Germany
| | - Wolfgang Frey
- Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Michael Karnahl
- Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Stefanie Tschierlei
- Department of Energy Conversion, Institute of Physical and Theoretical Chemistry, Technische Universität Brauschweig, Gaußstraße 17, 38106 Braunschweig, Germany
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15
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Xie W, Li R, Wang CQ. Crystal structure of catena-poly[triqua-bis( μ
2-4-carboxy-2-(1 H-tetrazol-1-yl)-1 H-imidazole-5-carboxylato-k 3
N, O: O′)barium(II)] tetrahydrate, C 14H 14BaN 12O 15. Z KRIST-NEW CRYST ST 2021. [DOI: 10.1515/ncrs-2020-0487] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Abstract
C14H14BaN12O15, monoclinic, C2/c (no. 15), a = 21.787(4) Å, b = 6.7594(11) Å, c = 18.143(3) Å, β = 102.456(2)°, V = 2609.0(8) Å3, Z = 4, R
gt
(F) = 0.0209, wR
ref
(F
2) = 0.0567, T = 296(2) K.
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Affiliation(s)
- Wei Xie
- Yangzhou Polytechnic Institute , 225127, Yangzhou , Jiangsu , P. R. China
| | - Rui Li
- Yangzhou Polytechnic Institute , 225127, Yangzhou , Jiangsu , P. R. China
| | - Chuan-Qi Wang
- School of Chemical Engineering, Henan Technical Institute , 450042, Zhengzhou , Henan , P. R. China
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16
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Bilger JB, Kerzig C, Larsen CB, Wenger OS. A Photorobust Mo(0) Complex Mimicking [Os(2,2'-bipyridine) 3] 2+ and Its Application in Red-to-Blue Upconversion. J Am Chem Soc 2021; 143:1651-1663. [PMID: 33434435 DOI: 10.1021/jacs.0c12805] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Osmium(II) polypyridines are a well-known class of complexes with luminescent metal-to-ligand charge-transfer (MLCT) excited states that are currently experiencing a revival due to their application potential in organic photoredox catalysis, triplet-triplet annihilation upconversion, and phototherapy. At the same time, there is increased interest in the development of photoactive complexes made from Earth-abundant rather than precious metals. Against this background, we present a homoleptic Mo(0) complex with a new diisocyanide ligand exhibiting different bite angles and a greater extent of π-conjugation than previously reported related chelates. This new design leads to deep red emission, which is unprecedented for homoleptic arylisocyanide complexes of group 6 metals. With a 3MLCT lifetime of 56 ns, an emission band maximum at 720 nm, and a photoluminescence quantum yield of 1.5% in deaerated toluene at room temperature, the photophysical properties are reminiscent of the prototypical [Os(2,2'-bipyridine)3]2+ complex. Under 635 nm irradiation with a cw-laser, the new Mo(0) complex sensitizes triplet-triplet annihilation upconversion of 9,10-diphenylanthracene (DPA), resulting in delayed blue fluorescence with an anti-Stokes shift of 0.93 eV. The photorobustness of the Mo(0) complex and the upconversion quantum yield are high enough to generate a flux of upconverted light that can serve as a sufficiently potent irradiation source for a blue-light-driven photoisomerization reaction. These findings are relevant in the greater contexts of designing new luminophores and photosensitizers for use in red-light-driven photocatalysis, photochemical upconversion, light-harvesting, and phototherapy.
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Affiliation(s)
- Jakob B Bilger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Christoph Kerzig
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Christopher B Larsen
- 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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17
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Zobel JP, Bokareva OS, Zimmer P, Wölper C, Bauer M, González L. Intersystem Crossing and Triplet Dynamics in an Iron(II) N-Heterocyclic Carbene Photosensitizer. Inorg Chem 2020; 59:14666-14678. [PMID: 32869981 PMCID: PMC7581298 DOI: 10.1021/acs.inorgchem.0c02147] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
![]()
The electronic excited
states of the iron(II) complex [FeII(tpy)(pyz-NHC)]2+ [tpy = 2,2′:6′,2″-terpyridine; pyz-NHC
= 1,1′-bis(2,6-diisopropylphenyl)pyrazinyldiimidazolium-2,2′-diylidene]
and their relaxation pathways have been theoretically investigated.
To this purpose, trajectory surface-hopping simulations within a linear
vibronic coupling model including a 244-dimensional potential energy
surface (PES) with 20 singlet and 20 triplet coupled states have been
used. The simulations show that, after excitation to the lowest-energy
absorption band of predominant metal-to-ligand charge-transfer character
involving the tpy ligand, almost 80% of the population undergoes intersystem
crossing to the triplet manifold in about 50 fs, while the remaining
20% decays through internal conversion to the electronic ground state
in about 300 fs. The population transferred to the triplet states
is found to deactivate into two different regions of the PESs, one
where the static dipole moment is small and shows increased metal-centered
character and another with a large static dipole moment, where the
electron density is transferred from the tpy to pyz-NHC ligand. Coherent
oscillations of 400 fs are observed between these two sets of triplet
populations, until the mixture equilibrates to a ratio of 60:40. Finally,
the importance of selecting suitable normal modes is highlighted—a
choice that can be far from straightforward in transition-metal complexes
with hundreds of degrees of freedom. Trajectory
surface-hopping simulations with a linear vibronic coupling model
reveal the competition of major intersystem crossing versus minor
internal conversion dynamics in an iron(II) N-heterocyclic carbene
dye. The triplet population bifurcates into two regions of the potential
energy surfaces, characterized by small and large static dipole moments
due to different electronic character and showing coherent oscillations
of 400 fs until both triplet populations coexist in a mixture of 60:40.
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Affiliation(s)
- J Patrick Zobel
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währingerstraße 19, 1090 Vienna, Austria
| | - Olga S Bokareva
- Institute of Physics, Rostock University, Albert Einstein Straße 23-24, 18059 Rostock, Germany
| | - Peter Zimmer
- Faculty of Science, Chemistry Department and Center for Sustainable Systems Design (CSSD), Paderborn University, Warburger Straße 100, 33098 Paderborn, Germany
| | - Christoph Wölper
- Department for X-Ray Diffraction, Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 7, D-45117 Essen, Germany
| | - Matthias Bauer
- Faculty of Science, Chemistry Department and Center for Sustainable Systems Design (CSSD), Paderborn University, Warburger Straße 100, 33098 Paderborn, Germany
| | - Leticia González
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währingerstraße 19, 1090 Vienna, Austria.,Vienna Research Platform on Accelerating Photoreaction Discovery, University of Vienna, Währingerstr. 19, 1090 Vienna, Austria
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