1
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Mato M, Bruzzese PC, Takahashi F, Leutzsch M, Reijerse EJ, Schnegg A, Cornella J. Oxidative Addition of Aryl Electrophiles into a Red-Light-Active Bismuthinidene. J Am Chem Soc 2023; 145:18742-18747. [PMID: 37603853 PMCID: PMC10472430 DOI: 10.1021/jacs.3c06651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Indexed: 08/23/2023]
Abstract
The oxidative addition of aryl electrophiles is a fundamental organometallic reaction widely applied in the field of transition metal chemistry and catalysis. However, the analogous version based on main group elements still remains largely underexplored. Here, we report the ability of a well-defined organobismuth(I) complex to undergo formal oxidative addition with a wide range of aryl electrophiles. The process is facilitated by the reactivity of both the ground and excited states of N,C,N-bismuthinidenes upon absorption of low-energy red light.
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Affiliation(s)
- Mauro Mato
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
| | - Paolo Cleto Bruzzese
- Max
Planck Institute for Chemical Energy Conversion, Stiftstrasse 34−36, Mülheim an der Ruhr 45470, Germany
| | - Fumiya Takahashi
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
| | - Markus Leutzsch
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
| | - Edward J. Reijerse
- Max
Planck Institute for Chemical Energy Conversion, Stiftstrasse 34−36, Mülheim an der Ruhr 45470, Germany
| | - Alexander Schnegg
- Max
Planck Institute for Chemical Energy Conversion, Stiftstrasse 34−36, Mülheim an der Ruhr 45470, Germany
| | - Josep Cornella
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
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2
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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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3
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Krause M, Maisuls I, Buss S, Strassert CA, Winter A, Schubert US, Nair SS, Dietzek-Ivanšić B, Klein A. Photophysical Study on the Rigid Pt(II) Complex [Pt(naphen)(Cl)] (Hnaphen = Naphtho[1,2-b][1,10]Phenanthroline and Derivatives. Molecules 2022; 27:molecules27207022. [PMID: 36296617 PMCID: PMC9606891 DOI: 10.3390/molecules27207022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/05/2022] [Accepted: 10/10/2022] [Indexed: 11/16/2022] Open
Abstract
The electrochemistry and photophysics of the Pt(II) complexes [Pt(naphen)(X)] (Hnaphen = naphtho[1,2-b][1,10]phenanthroline, X = Cl or C≡CPh) containing the rigid tridentate C^N^N-coordinating pericyclic naphen ligand was studied alongside the complexes of the tetrahydro-derivative [Pt(thnaphen)(X)] (Hthnaphen = 5,6,8,9-tetrahydro-naphtho[1,2-b][1,10]phenanthroline) and the N^C^N-coordinated complex [Pt(bdq)(Cl)] (Hbdq = benzo[1,2-h:5,4-h’]diquinoline. The cyclic voltammetry showed reversible reductions for the C^N^N complexes, with markedly fewer negative potentials (around −1.6 V vs. ferrocene) for the complexes containing the naphen ligand compared with the thnaphen derivatives (around −1.9 V). With irreversible oxidations at around +0.3 V for all of the complexes, the naphen made a difference in the electrochemical gap of about 0.3 eV (1.9 vs. 2.2 eV) compared with thnaphen. The bdq complex was completely different, with an irreversible reduction at around −2 V caused by the N^C^N coordination pattern, which lacked a good electron acceptor such as the phenanthroline unit in the C^N^N ligand naphen. Long-wavelength UV-Vis absorption bands were found around 520 to 530 nm for the C^N^N complexes with the C≡CPh coligand and were red-shifted when compared with the Cl derivatives. The N^C^N-coordinated bdq complex was markedly blue-shifted (493 nm). The steady-state photoluminescence spectra showed poorly structured emission bands peaking at around 630 nm for the two naphen complexes and 570 nm for the thnaphen derivatives. The bdq complex showed a pronounced vibrational structure and an emission maximum at 586 nm. Assuming mixed 3LC/3MLCT excited states, the vibronic progression for the N^C^N bdq complex indicated a higher LC character than assumed for the C^N^N-coordinated naphen and thnaphen complexes. The blue-shift was a result of the different N^C^N vs. C^N^N coordination. The photoluminescence lifetimes and quantum yields ΦL massively increased from solutions at 298 K (0.06 to 0.24) to glassy frozen matrices at 77 K (0.80 to 0.95). The nanosecond time-resolved study on [Pt(naphen)(Cl)] showed a phosphorescence emission signal originating from the mixed 3LC/3MLCT with an emission lifetime of around 3 µs.
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Affiliation(s)
- Maren Krause
- University of Cologne, Faculty of Mathematics and Natural Sciences, Department of Chemistry, Institute for Inorganic Chemistry, Greinstrasse 6, 50939 Köln, Germany
| | - Iván Maisuls
- Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, CeNTech, CiMIC, SoN, Heisenbergstr. 11, 48149 Münster, Germany
| | - Stefan Buss
- Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, CeNTech, CiMIC, SoN, Heisenbergstr. 11, 48149 Münster, Germany
| | - Cristian A. Strassert
- Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, CeNTech, CiMIC, SoN, Heisenbergstr. 11, 48149 Münster, Germany
| | - Andreas Winter
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstr. 10, 07743 Jena, Germany
- Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, 07743 Jena, Germany
| | - Ulrich S. Schubert
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstr. 10, 07743 Jena, Germany
- Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, 07743 Jena, Germany
| | - Shruthi S. Nair
- Institute for Physical Chemistry (IPC), Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
- Leibniz Institute for Photonic Technologies Jena (IPHT), Albert-Einstein-Str. 9, 07745 Jena, Germany
| | - Benjamin Dietzek-Ivanšić
- Institute for Physical Chemistry (IPC), Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
- Leibniz Institute for Photonic Technologies Jena (IPHT), Albert-Einstein-Str. 9, 07745 Jena, Germany
- Correspondence: (B.D.-I.); (A.K.); Tel.: +49-221-470-4006 (A.K.)
| | - Axel Klein
- University of Cologne, Faculty of Mathematics and Natural Sciences, Department of Chemistry, Institute for Inorganic Chemistry, Greinstrasse 6, 50939 Köln, Germany
- Correspondence: (B.D.-I.); (A.K.); Tel.: +49-221-470-4006 (A.K.)
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4
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Herr P, Schwab A, Kupfer S, Wenger OS. Deep‐Red Luminescent Molybdenum(0) Complexes with Bi‐ and Tridentate Isocyanide Chelate Ligands. CHEMPHOTOCHEM 2022. [DOI: 10.1002/cptc.202200052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Patrick Herr
- University of Basel: Universitat Basel Department of Chemistry SWITZERLAND
| | - Alexander Schwab
- Friedrich-Schiller-Universität Jena: Friedrich-Schiller-Universitat Jena Institute of Physical Chemistry GERMANY
| | - Stephan Kupfer
- Friedrich-Schiller-Universität Jena: Friedrich-Schiller-Universitat Jena Institute of Physical Chemistry GERMANY
| | - Oliver S. Wenger
- Universität Basel Departement für Chemie St. Johanns-Ring 19 4056 Basel SWITZERLAND
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5
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Rupp MT, Shevchenko N, Hanan GS, Kurth DG. Enhancing the photophysical properties of Ru(II) complexes by specific design of tridentate ligands. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2021.214127] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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6
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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7
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Bera MK, Ninomiya Y, Higuchi M. Stepwise introduction of three different transition metals in metallo-supramolecular polymer for quad-color electrochromism. Commun Chem 2021; 4:56. [PMID: 36697515 PMCID: PMC9814570 DOI: 10.1038/s42004-021-00495-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 03/26/2021] [Indexed: 01/28/2023] Open
Abstract
Metallo-supramolecular polymers (MSPs) show unique electrochemical and optical properties, that are different to organic polymers, caused by electronic interactions between metals and ligands. For the development of quad-color electrochromic materials, here we report the stepwise introduction of three different transition metal ions into an MSP, utilizing the different complexation abilities of the transition metals. An MSP with Os(II), Ru(II), and Fe(II) (polyOsRuFe) was synthesized via a stepwise synthetic route through the formation of an Os(II) complex first, followed by the introduction of Ru(II) to the Os(II) complex, and finally the attachment of Fe(II) to the Os(II)-Ru(II) complex to produce the polymer. This synthetic procedure was extended to fabricate MSPs that comprised Co(II)/Ru(II)/Os(II) and Zn(II)/Ru(II)/Os(II). The synthesized MSPs showed a broad optical and electrochemical window due to the coupling of three heterometallic segments into the polymer. Introducing acetate anion as the counter anion greatly enhanced the solubility of polyOsRuFe in methanol. A thin film of polyOsRuFe was prepared on ITO/glass by spin-coating the methanol solution, and its reversible quad-color electrochromism was demonstrated.
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Affiliation(s)
- Manas Kumar Bera
- grid.21941.3f0000 0001 0789 6880Electronic Functional Macromolecules Group, Research Center for Functional Materials, National Institute for Materials Science (NIMS), Tsukuba Ibaraki, Japan
| | - Yoshikazu Ninomiya
- grid.21941.3f0000 0001 0789 6880Electronic Functional Macromolecules Group, Research Center for Functional Materials, National Institute for Materials Science (NIMS), Tsukuba Ibaraki, Japan
| | - Masayoshi Higuchi
- grid.21941.3f0000 0001 0789 6880Electronic Functional Macromolecules Group, Research Center for Functional Materials, National Institute for Materials Science (NIMS), Tsukuba Ibaraki, Japan
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8
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Cerfontaine S, Troian-Gautier L, Duez Q, Cornil J, Gerbaux P, Elias B. MLCT Excited-State Behavior of Trinuclear Ruthenium(II) 2,2'-Bipyridine Complexes. Inorg Chem 2021; 60:366-379. [PMID: 33351615 DOI: 10.1021/acs.inorgchem.0c03004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Four trinuclear ruthenium(II) polypyridyl complexes were synthesized, and a detailed investigation of their excited-state properties was performed. The tritopic sexi-pyridine bridging ligands were obtained via para or meta substitution of a central 2,2'-bipyridine fragment. A para connection between the 2,2'-bipyridine chelating moieties of the bridging ligand led to a red-shifted MLCT absorption band in the visible part of the spectra, whereas the meta connection induced a broadening of the LC transitions in the UV region. A convergent energy transfer from the two peripheral metal centers to the central Ru(II) moiety was observed for all trinuclear complexes. These complexes were in thermal equilibrium with an upper-lying 3MLCT excited state over the investigated range of temperatures. For all complexes, deactivation via the 3MC excited state was absent at room temperature. Importantly, the connection in the para position for both central and peripheral 2,2'-bipyridines of the bridging ligand resulted in a trinuclear complex (Tpp) that absorbed more visible light, had a longer-lived excited state, and had a higher photoluminescence quantum yield than the parent [Ru(bpy)3]2+, despite its red-shifted photoluminescence. This behavior was attributed to the presence of a highly delocalized excited state for Tpp.
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Affiliation(s)
- Simon Cerfontaine
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Ludovic Troian-Gautier
- Laboratoire de Chimie Organique, Université libre de Bruxelles (ULB), CP 160/06, 50 avenue F.D. Roosevelt, 1050 Brussels, Belgium.,Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Quentin Duez
- Organic Synthesis and Mass Spectrometry Laboratory, University of Mons - UMONS, 23 Place du Parc, B-7000 Mons, Belgium.,Laboratory for Chemistry of Novel Materials, Center of Innovation and Research in Materials and Polymers (CIRMAP) - University of Mons (UMONS), Place du Parc 23, B-7000 Mons, Belgium
| | - Jérôme Cornil
- Laboratory for Chemistry of Novel Materials, Center of Innovation and Research in Materials and Polymers (CIRMAP) - University of Mons (UMONS), Place du Parc 23, B-7000 Mons, Belgium
| | - Pascal Gerbaux
- Organic Synthesis and Mass Spectrometry Laboratory, University of Mons - UMONS, 23 Place du Parc, B-7000 Mons, Belgium
| | - Benjamin Elias
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
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9
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Paul A, Ganguly T, Bar M, Baitalik S. Controlling the Direction of Intercomponent Energy Transfer by Appropriate Placement of Metals in Long-Lived Trinuclear Complexes of Fe(II), Ru(II), and Os(II). Inorg Chem 2021; 60:412-422. [PMID: 33350308 DOI: 10.1021/acs.inorgchem.0c03067] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In this work, we report the synthesis, photophysics, and electrochemistry of a new array of trinuclear complexes, [(bpy)2Os(d-HIm-t)M(t-HIm-d)Os(bpy)2]6+ (M = FeII, RuII, and OsII), based on a previously reported bipyridine-terpyridine type bridge (d-HIm-t). Photophysical behavior of in situ generated trinuclear OsZnOs complex {[(bpy)2Os(d-HIm-t)Zn(t-HIm-d)Os(bpy)2]6+} was also investigated to understand the complicated photophysics of trinuclear array. Complexes display very rich redox properties demonstrating multiple metal-based oxidation and ligand-based reduction couples. The triads exhibit strong absorption throughout the entire UV-vis spectral region and also emit in the near-infrared domain (NIR) with a sufficiently long lifetime at ambient temperature. Intercomponent energy transfer, either from the periphery to the center or from the center to the periphery, depending upon the relative position of metals, was convincingly demonstrated through steady-state emission and lifetime measurements of the triads together with respective model complexes. Interestingly, Fe2+ does not worsen the emission behavior of the OsFeOs system to a great extent. Present trinuclear complexes act as a visible light absorbing antenna by funneling the absorbed light to the subunit(s) with the lowest energy excited state.
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Affiliation(s)
- Animesh Paul
- Inorganic Chemistry Section, Department of Chemistry, Jadavpur University Kolkata 700032, India
| | - Tanusree Ganguly
- Inorganic Chemistry Section, Department of Chemistry, Jadavpur University Kolkata 700032, India
| | - Manoranjan Bar
- Inorganic Chemistry Section, Department of Chemistry, Jadavpur University Kolkata 700032, India
| | - Sujoy Baitalik
- Inorganic Chemistry Section, Department of Chemistry, Jadavpur University Kolkata 700032, India
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10
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Ravetz B, Tay NES, Joe CL, Sezen-Edmonds M, Schmidt MA, Tan Y, Janey JM, Eastgate MD, Rovis T. Development of a Platform for Near-Infrared Photoredox Catalysis. ACS Cent Sci 2020; 6:2053-2059. [PMID: 33274281 PMCID: PMC7706074 DOI: 10.1021/acscentsci.0c00948] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Indexed: 05/05/2023]
Abstract
Over the past decade, chemists have embraced visible-light photoredox catalysis due to its remarkable ability to activate small molecules. Broadly, these methods employ metal complexes or organic dyes to convert visible light into chemical energy. Unfortunately, the excitation of widely utilized Ru and Ir chromophores is energetically wasteful as ∼25% of light energy is lost thermally before being quenched productively. Hence, photoredox methodologies require high-energy, intense light to accommodate said catalytic inefficiency. Herein, we report photocatalysts which cleanly convert near-infrared (NIR) and deep red (DR) light into chemical energy with minimal energetic waste. We leverage the strong spin-orbit coupling (SOC) of Os(II) photosensitizers to directly access the excited triplet state (T1) with NIR or DR irradiation from the ground state singlet (S0). Through strategic catalyst design, we access a wide range of photoredox, photopolymerization, and metallaphotoredox reactions which usually require 15-50% higher excitation energy. Finally, we demonstrate superior light penetration and scalability of NIR photoredox catalysis through a mole-scale arene trifluoromethylation in a batch reactor.
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Affiliation(s)
- Benjamin
D. Ravetz
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Nicholas E. S. Tay
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
| | - Candice L. Joe
- Chemical
Process Development, Bristol Myers Squibb, 1 Squibb Drive, New Brunswick, New Jersey 08903, United States
- E-mail:
| | - Melda Sezen-Edmonds
- Chemical
Process Development, Bristol Myers Squibb, 1 Squibb Drive, New Brunswick, New Jersey 08903, United States
| | - Michael A. Schmidt
- Chemical
Process Development, Bristol Myers Squibb, 1 Squibb Drive, New Brunswick, New Jersey 08903, United States
| | - Yichen Tan
- Chemical
Process Development, Bristol Myers Squibb, 1 Squibb Drive, New Brunswick, New Jersey 08903, United States
| | - Jacob M. Janey
- Chemical
Process Development, Bristol Myers Squibb, 1 Squibb Drive, New Brunswick, New Jersey 08903, United States
| | - Martin D. Eastgate
- Chemical
Process Development, Bristol Myers Squibb, 1 Squibb Drive, New Brunswick, New Jersey 08903, United States
| | - Tomislav Rovis
- Department
of Chemistry, Columbia University, New York, New York 10027, United States
- E-mail:
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11
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Sárosiné Szemes D, Keszthelyi T, Papp M, Varga L, Vankó G. Quantum-chemistry-aided ligand engineering for potential molecular switches: changing barriers to tune excited state lifetimes. Chem Commun (Camb) 2020; 56:11831-11834. [PMID: 33021253 DOI: 10.1039/d0cc04467a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Substitution of terpyridine at the 4' position with electron withdrawing and donating groups is used to tune the quintet lifetime of its iron(ii) complex. DFT calculations suggest that the energy barrier between the quintet and singlet states can be altered significantly upon substitution, inducing a large variation of the lifetime of the photoexcited quintet state. This prediction was experimentally verified by transient optical absorption spectroscopy and good agreement with the trend expected from the calculations was found. This demonstrates that the potential energy landscape can indeed be rationally tailored by relevant modifications based on DFT predictions. This result should pave the way to advancing efficient theory-based ligand engineering of functional molecules to a wide range of applications.
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12
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Musib D, Raza MK, Martina K, Roy M. Mn(I)-based photoCORMs for trackable, visible light-induced CO release and photocytotoxicity to cancer cells. Polyhedron 2019; 172:125-31. [DOI: 10.1016/j.poly.2019.04.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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13
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Paul A, Bar M, Deb S, Baitalik S. Long-Lived Trimetallic Complexes of Fe(II), Ru(II), and Os(II) Based on a Heteroditopic Bipyridine-Terpyridine Bridge: Synthesis, Photophysics, and Electronic Energy Transfer. Inorg Chem 2019; 58:10065-10077. [PMID: 31313934 DOI: 10.1021/acs.inorgchem.9b01217] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Synthesis, characterization, and investigation of photophysical and redox behaviors of a new class of homo- and heterotrimetallic complexes of composition [(bpy/phen)2Ru(dipy-Hbzim-tpy)M(tpy-Hbzim-dipy)Ru(bpy/phen)2]6+ (M = FeII, RuII, and OsII) derived from a conjugated heteroditopic bipyridine-terpyridine bridge were carried out in this work. Trimetallic RuZnRu complexes of composition [(bpy/phen)2Ru(dipy-Hbzim-tpy)Zn(tpy-Hbzim-dipy)Ru(bpy/phen)2]6+ were also synthesized in situ as their photophysical properties are of particular interest in demonstrating the absorption and emission spectra of the complexes in the presence of a metal (Zn2+) that has neither metal-to-ligand charge transfer (MLCT) nor metal-centered (3MC) states. Complexes display intense absorption bands spanning almost the entire UV and visible region. The complexes also exhibit rich electrochemical behaviors with a number of metal-centered reversible oxidation and ligand-centered reduction waves. All complexes are luminescent at room temperature, and time-resolved emission spectral studies indicate that peripheral RuII-centered emissive 3MLCT states are quantitatively quenched, by intramolecular energy transfer to the low lying 3MLCT (for central Ru and Os) or 3MC states of the FeII center (nonluminescent). Interestingly, Fe(II) does not adversely deteriorate the photophysics of the RuFeRu assembly. Thus, multicomponent complexes in the present work can serve as well-organized light-harvesting antennas as the light absorbed by multiple chromophoric subunits is efficiently channeled to the distinct component having the lowest-energy excited state.
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Affiliation(s)
- Animesh Paul
- Inorganic Chemistry Section, Department of Chemistry , Jadavpur University , Kolkata 700 032 , India
| | - Manoranjan Bar
- Inorganic Chemistry Section, Department of Chemistry , Jadavpur University , Kolkata 700 032 , India
| | - Sourav Deb
- Inorganic Chemistry Section, Department of Chemistry , Jadavpur University , Kolkata 700 032 , India
| | - Sujoy Baitalik
- Inorganic Chemistry Section, Department of Chemistry , Jadavpur University , Kolkata 700 032 , India
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14
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Mede T, Jäger M, Schubert US. High-Yielding Syntheses of Multifunctionalized Ru II Polypyridyl-Type Sensitizer: Experimental and Computational Insights into Coordination. Inorg Chem 2019; 58:9822-9832. [PMID: 31322344 DOI: 10.1021/acs.inorgchem.9b00847] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
RuII complexes based on functionalized 2,6-di(quinolin-8-yl)pyridine (dqp) ligands feature excellent photophysical and geometrical properties, thus suggesting dqp ligands as ideal surrogates for 2,2'-bipyridine (bpy) or 2,2':6',2″-terpyridine (tpy). However, the synthesis of multifunctionalized [Ru(dqp)2]2+-based complexes is often low-yielding, which has hampered their practical value to date. In this study, a universal high-yielding route was explored and corroborated by a mechanistic investigation based on 1H NMR, MS, and density functional theory. With application of high-boiling but less-coordinating solvents (i.e., DMF) during the coordination of dqp by the precursor [Ru(dqp)(MeCN)3]2+, the required reaction temperature is lowered considerably (by 30 °C). In comparison to tpy, the reaction rate for dqp is further reduced which is assigned to the higher steric demand upon the coordination process. Namely, the onset of coordination of a tpy derivative at 60 °C and of dqp at 90 °C is significantly milder than in previous protocols. The versatility of the procedure is demonstrated by the high-yielding syntheses of multifunctionalized RuII complexes reaching up to 90%, whereby the presence of hydroxyl groups and losses during purification may lower the isolated yields substantially. In addition, the same strategy of high-boiling but less-coordinating solvents enabled a milder one-pot protocol to prepare [Ru(dqp)2]2+ from a [Ru(MeCN)6]2+ source, i.e., without the need for in situ reduction or halide abstraction as typical for RuIIICl3 hydrate. Hence, the developed protocol benefits from an improved thermal tolerance of sensitive functional groups, which may be applicable also to related polypyridyl-type ligands.
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Affiliation(s)
- Tina Mede
- Laboratory of Organic and Macromolecular Chemistry (IOMC) , Friedrich Schiller University Jena , Humboldtstraße 10 , 07743 Jena , Germany
| | - Michael Jäger
- 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 7a , 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 7a , 07743 Jena , Germany
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15
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16
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Zedler L, Krieck S, Kupfer S, Dietzek B. Resonance Raman Spectro-Electrochemistry to Illuminate Photo-Induced Molecular Reaction Pathways. Molecules 2019; 24:molecules24020245. [PMID: 30634707 PMCID: PMC6358810 DOI: 10.3390/molecules24020245] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/04/2019] [Accepted: 01/05/2019] [Indexed: 11/16/2022] Open
Abstract
Electron transfer reactions play a key role for artificial solar energy conversion, however, the underlying reaction mechanisms and the interplay with the molecular structure are still poorly understood due to the complexity of the reaction pathways and ultrafast timescales. In order to investigate such light-induced reaction pathways, a new spectroscopic tool has been applied, which combines UV-vis and resonance Raman spectroscopy at multiple excitation wavelengths with electrochemistry in a thin-layer electrochemical cell to study [RuII(tbtpy)₂]2+ (tbtpy = tri-tert-butyl-2,2':6',2''-terpyridine) as a model compound for the photo-activated electron donor in structurally related molecular and supramolecular assemblies. The new spectroscopic method substantiates previous suggestions regarding the reduction mechanism of this complex by localizing photo-electrons and identifying structural changes of metastable intermediates along the reaction cascade. This has been realized by monitoring selective enhancement of Raman-active vibrations associated with structural changes upon electronic absorption when tuning the excitation wavelength into new UV-vis absorption bands of intermediate structures. Additional interpretation of shifts in Raman band positions upon reduction with the help of quantum chemical calculations provides a consistent picture of the sequential reduction of the individual terpyridine ligands, i.e., the first reduction results in the monocation [(tbtpy)Ru(tbtpy•)]⁺, while the second reduction generates [(tbtpy•)Ru(tbtpy•)]0 of triplet multiplicity. Therefore, the combination of this versatile spectro-electrochemical tool allows us to deepen the fundamental understanding of light-induced charge transfer processes in more relevant and complex systems.
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Affiliation(s)
- Linda Zedler
- Department Functional Interfaces, Leibniz Institute of Photonic Technology Jena, Albert-Einstein-Strasse 9, 07745 Jena, Germany.
| | - Sven Krieck
- Institute of Inorganic and Analytical Chemistry, Friedrich-Schiller-University Jena, Humboldtstrasse 8, 07743 Jena, Germany.
| | - Stephan Kupfer
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743 Jena, Germany.
| | - Benjamin Dietzek
- Department Functional Interfaces, Leibniz Institute of Photonic Technology Jena, Albert-Einstein-Strasse 9, 07745 Jena, Germany.
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743 Jena, Germany.
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17
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Luo Y, Wächtler M, Barthelmes K, Winter A, Schubert US, Dietzek B. Direct detection of the photoinduced charge-separated state in a Ru(ii) bis(terpyridine)-polyoxometalate molecular dyad. Chem Commun (Camb) 2018; 54:2970-2973. [PMID: 29399681 DOI: 10.1039/c7cc09181h] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Observation of photoinduced intramolecular charge-separation is difficult for photosensitizer-POM dyads because of rapid backward electron transfer. We report here for the first time on a long-lived charge-separated state (τ = 470 ns) observed in a Ru(ii) bis(terpyridine)-based dyad. Charge-separation occurs despite virtually no driving force and the short intrinsic excited-state lifetime of the photosensitizer.
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Affiliation(s)
- Yusen Luo
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, Jena 07743, Germany and Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Straβe 9, Jena 07745, Germany.
| | - Maria Wächtler
- Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Straβe 9, Jena 07745, Germany.
| | - Kevin Barthelmes
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstraβe 10, Jena 07743, Germany and Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, Jena 07743, Germany
| | - Andreas Winter
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstraβe 10, Jena 07743, Germany and Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, Jena 07743, Germany
| | - Ulrich S Schubert
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstraβe 10, Jena 07743, Germany and Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, Jena 07743, Germany
| | - Benjamin Dietzek
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, Jena 07743, Germany and Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Straβe 9, Jena 07745, Germany. and Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, Jena 07743, Germany
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18
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Mondal PC, Singh V, Manna AK, Zharnikov M. Covalently Assembled Monolayers of Homo- and Heteroleptic Fe II -Terpyridyl Complexes on SiO x and ITO-Coated Glass Substrates: An Experimental and Theoretical Study. Chemphyschem 2017; 18:3407-3415. [PMID: 28905521 DOI: 10.1002/cphc.201700918] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 09/09/2017] [Indexed: 11/07/2022]
Abstract
Well-defined FeII -terpyridyl monolayers were fabricated on SiOx and conductive ITO-coated glass substrates through covalent-bond formation between the metallo-organic complexes and a preassembled coupling layer. Three different homo- and heteroleptic complexes with terminal pyridyl, amine, and phenyl groups were tested. All the films were found to be densely packed and homogeneous, and consist of molecules standing upright. They exhibited high thermal (up to ≈220 °C) and temporal (up to 5 h at 100 °C) stability. The UV/Vis spectra of the monolayers showed pronounced metal-to-ligand charge-transfer bands with a significant redshift compared with the solution spectra of the metallo-ligands with a pendant pyridyl group quaternized with the coupling layer, whereas the shift was significantly smaller when the coupling layer was bonded to the primary amine (-NH2 ) group of the complex. Cyclic voltammograms of the monolayers showed reversible, one-electron redox behavior and suggested strong electronic coupling between the confined molecules and the underlying substrate. Analysis of the electrochemistry data allowed us to estimate the charge-transfer rate constant between the metal center and the substrate. Additionally, detailed quantum-chemical calculations were performed to support and rationalize the experimentally observed photophysical properties of the FeII -terpyridyl complexes both in the solution state and when bound to a SiOx -based substrate.
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Affiliation(s)
- Prakash Chandra Mondal
- Department of Chemistry, University of Delhi, Delhi-, 110007, India.,Present address: National Institute of Nanotechnology, University of Alberta, Edmonton-, T6G 2M9, AB, Canada
| | - Vikram Singh
- Centre for Nanoscience and Nanotechnology, Panjab University, Chandigarh-, 160015, India
| | - Arun K Manna
- Department of Chemistry, Indian Institute of Technology, Tirupati, Tirupati-, 517506, AP, India
| | - Michael Zharnikov
- Applied Physical Chemistry, Heidelberg University, Im Neuenheimer Feld 253, 69120, Heidelberg, Germany
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19
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Kübel J, Wächtler M, Dietzek B. Excitation Power Modulates Energy-Transfer Dynamics in a Supramolecular Ru II -Fe II -Ru II Triad. Chemphyschem 2017; 18:2899-2907. [PMID: 28799732 DOI: 10.1002/cphc.201700710] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Indexed: 11/09/2022]
Abstract
Multichromophoric arrays are key to light harvesting in natural and artificial photosynthesis. A trinuclear, symmetric RuII -FeII -RuII triad may resemble a light-harvesting model system in which excitation energy from donor units (Ru-terpyridine fragments) is efficiently transferred to the acceptor (the Fe-terpyridine fragment). The photoinduced dynamics after simultaneous excitation of more than a single chromophoric unit (donor/acceptor) at varying excitation fluence is investigated in this contribution. Data suggests that energy transfer is decelerated if the acceptor states (on the FeII unit) are not depopulated fast enough. As a consequence, the lifetime of a high-lying excited state (centered on either of the RuII units) is prolonged. A kinetic model is suggested to account for this effect. Although the proposed model is specifically adopted to account for the experimental data reported here, it might be generalized to other situations in which multiple energy or electron donors are covalently linked to a single acceptor site, a situation of interest in contemporary artificial photosynthesis.
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Affiliation(s)
- Joachim Kübel
- Research Department Functional Interfaces, Leibniz Institute of Photonic Technology (IPHT) Jena e.V., Albert-Einstein-Str. 9, 07745, Jena, Germany.,Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany.,Department of Chemistry and Molecular Biology, University of Gothenburg, 40530, Gothenburg, Sweden
| | - Maria Wächtler
- Research Department Functional Interfaces, Leibniz Institute of Photonic Technology (IPHT) Jena e.V., Albert-Einstein-Str. 9, 07745, Jena, Germany
| | - Benjamin Dietzek
- Research Department Functional Interfaces, Leibniz Institute of Photonic Technology (IPHT) Jena e.V., Albert-Einstein-Str. 9, 07745, Jena, Germany.,Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany.,Center for Energy and Environmental Chemistry (CEEC), Friedrich Schiller University Jena, Philosophenweg 7, 07743, Jena, Germany
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20
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Laramée-Milette B, Hanan GS. Going against the flow: Os(ii)-to-Ru(ii) energy transfer in rod-like polypyridyl chromophore. Chem Commun (Camb) 2017; 53:10496-10499. [PMID: 28787049 DOI: 10.1039/c7cc03541a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The judicious design of a unique mixed-metal Ru-Os molecular rod led to the first photoinduced energy transfer from osmium-to-ruthenium in a polypyridyl complex. The absorbed light is directed from the osmium metal center to the peripheral ruthenium moieties, where only the low energy luminescence from the heteroleptic ruthenium phen-hpp complex was observed.
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Affiliation(s)
- Baptiste Laramée-Milette
- Département de chimie, Université de Montréal, 5155 Ch. de la rampe, Pavillon J.-A. Bombardier, H3T2B1, Montréal, QC, Canada.
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21
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Affiliation(s)
- Carlito S. Ponseca
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Pavel Chábera
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Jens Uhlig
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Petter Persson
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Villy Sundström
- Division
of Chemical Physics, Chemical Center, and ‡Theoretical Chemistry Division,
Chemical Center, Lund University, Box 124, Lund SE-221 00, Sweden
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22
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Manbeck GF, Fujita E, Brewer KJ. Tetra- and Heptametallic Ru(II),Rh(III) Supramolecular Hydrogen Production Photocatalysts. J Am Chem Soc 2017; 139:7843-7854. [DOI: 10.1021/jacs.7b02142] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Gerald F. Manbeck
- Chemistry
Division, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Etsuko Fujita
- Chemistry
Division, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Karen J. Brewer
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
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23
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Luo Y, Barthelmes K, Wächtler M, Winter A, Schubert US, Dietzek B. Energy versus Electron Transfer: Controlling the Excitation Transfer in Molecular Triads. Chemistry 2017; 23:4917-4922. [PMID: 28198051 DOI: 10.1002/chem.201700413] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Indexed: 01/23/2023]
Abstract
The photochemistry of RuII coordination compounds is generally discussed to originate from the lowest lying triplet metal-to-ligand charge-transfer state (3 MLCT). However, when heteroleptic complexes are considered, for example, in the design of molecular triads for efficient photoinduced charge separation, a complex structure of 1 MLCT states, which can be populated in a rather narrow spectral window (typically around 450 nm) is to be considered. In this contribution we show that the localization of MLCT excited states on different ligands can affect the following ps to ns decay pathways to an extent that by tuning the excitation wavelength, intermolecular energy transfer from a RuII -terpyridine unit to a fullerene acceptor can be favored over electron transfer within the molecular triad. These results might have important implications for the design of molecular dyads, triads, pentads and so forth with respect to a specifically targeted response of these complexes to photoexcitation.
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Affiliation(s)
- Yusen Luo
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743, Jena, Germany.,Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Strasse 9, 07745, Jena, Germany
| | - Kevin Barthelmes
- Jena Center for Soft Matter (JCSM), Friedrich-Schiller-University Jena, Philosophenweg 7, 07743, Jena, Germany.,Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich-Schiller-University Jena, Humboldtstrasse 10, 07743, Jena, Germany
| | - Maria Wächtler
- Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Strasse 9, 07745, Jena, Germany
| | - Andreas Winter
- Jena Center for Soft Matter (JCSM), Friedrich-Schiller-University Jena, Philosophenweg 7, 07743, Jena, Germany.,Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich-Schiller-University Jena, Humboldtstrasse 10, 07743, Jena, Germany
| | - Ulrich S Schubert
- Jena Center for Soft Matter (JCSM), Friedrich-Schiller-University Jena, Philosophenweg 7, 07743, Jena, Germany.,Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich-Schiller-University Jena, Humboldtstrasse 10, 07743, Jena, Germany
| | - Benjamin Dietzek
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743, Jena, Germany.,Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Strasse 9, 07745, Jena, Germany.,Jena Center for Soft Matter (JCSM), Friedrich-Schiller-University Jena, Philosophenweg 7, 07743, Jena, Germany
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24
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Abstract
The photophysics and photochemistry of transition metal complexes (TMCs) has long been a hot field of interdisciplinary research. Rich metal-based redox processes, together with a high variety in electronic configurations and excited-state dynamics, have rendered TMCs excellent candidates for interconversion between light, chemical, and electrical energies in intramolecular, supramolecular, and interfacial arrangements. In specific applications such as photocatalytic organic synthesis, photoelectrochemical cells, and light-driven supramolecular motors, light absorption by a TMC-based photosensitizer and subsequent excited-state energy or electron transfer constitute essential steps. In this context, TMCs based on rare and expensive metals, such as ruthenium and iridium, are frequently employed as photosensitizers, which is obviously not ideal for large-scale implementation. In the search for abundant and environmentally benign solutions, six-coordinate Fe(II) complexes (Fe(II)L6) have been widely considered as highly desirable alternatives. However, not much success has been achieved due to the extremely short-lived triplet metal-to-ligand charge transfer ((3)MLCT) excited state that is deactivated by low-lying metal-centered (MC) states on a 100 fs time scale. A fundamental strategy to design useful Fe-based photosensitizers is thus to destabilize the MC states relative to the (3)MLCT state by increasing the ligand field strength, with special focus on making eg σ* orbitals on the Fe center energetically less accessible. Previous efforts to directly transplant successful strategies from Ru(II)L6 complexes unfortunately met with limited success in this regard, despite their close chemical kinship. In this Account, we summarize recent promising results from our and other groups in utilizing strongly σ-donating N-heterocyclic carbene (NHC) ligands to make strong-field Fe(II)L6 complexes with significantly extended (3)MLCT lifetimes. Already some of the first homoleptic bis(tridentate) complexes incorporating (CNHC^Npyridine^CNHC)-type ligands gratifyingly resulted in extension of the (3)MLCT lifetime by more than 2 orders of magnitude compared to the parental [Fe(tpy)2](2+) (tpy = 2,2':6',2″-terpyridine) complex. Quantum chemical (QC) studies also revealed that the (3)MC instead of the (5)MC state likely dictates the deactivation of the (3)MLCT state, a behavior distinct from traditional Fe(II)L6 complexes but rather resembling Ru analogues. A heteroleptic Fe(II) NHC complex featuring mesoionic bis(1,2,3-triazol-5-ylidene) (btz) ligands also delivered a 100-fold elongation of the (3)MLCT lifetime relative to its parental [Fe(bpy)3](2+) (bpy = 2,2'-bipyridine) complex. Again, a Ru-like deactivation mechanism of the (3)MLCT state was indicated by QC studies. With a COOH-functionalized homoleptic complex, a record (3)MLCT lifetime of 37 ps was recently observed on an Al2O3 nanofilm. As a proof of concept, it was further demonstrated that the significant improvement in the (3)MLCT lifetime indeed benefits efficient light harvesting with Fe(II) NHC complexes. For the first time, close-to-unity electron injection from the lowest-energy (3)MLCT state to a TiO2 nanofilm was achieved by a stable Fe(II) complex. This is in complete contrast to conventional Fe(II)L6-derived photosensitizers that could only make use of high-energy photons. These exciting results significantly broaden the understanding of the fundamental photophysics and photochemistry of d(6) Fe(II) complexes. They also open up new possibilities to develop solar energy-converting materials based on this abundant, inexpensive, and intrinsically nontoxic element.
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Affiliation(s)
- Yizhu Liu
- Centre
for Analysis and Synthesis, Lund University, Box 124, 22100 Lund, Sweden
- Department
of Chemical Physics, Lund University, Box 124, 22100 Lund, Sweden
| | - Petter Persson
- Theoretical
Chemistry Division, Lund University, Box 124, 22100 Lund, Sweden
| | - Villy Sundström
- Department
of Chemical Physics, Lund University, Box 124, 22100 Lund, Sweden
| | - Kenneth Wärnmark
- Centre
for Analysis and Synthesis, Lund University, Box 124, 22100 Lund, Sweden
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25
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Abstract
A theoretical-guided design concept aiming to achieve highly efficient unidirectional charge transfer and multi-charge separation upon successive photoexcitation for light-harvesting dyes in the scope of supramolecular photocatalysts is presented. Four 4H-imidazole-ruthenium(ii) complexes incorporating a biimidazole-based electron-donating ligand sphere have been designed based on the well-known 4H-imidazole-ruthenium(ii) polypyridyl dyes. The quantum chemical evaluation, performed at the density functional and time-dependent density functional level of theory, revealed extraordinary unidirectional charge transfer bands from the near-infrared to the ultraviolet region of the absorption spectrum upon multi-photoexcitation. Spectro-electrochemical simulations modeling photoexcited intermediates determined the outstanding multi-electron storage capacity for this novel class of black dyes. These remarkable photochemical and photophysical properties are found to be preserved upon site-specific protonation rendering 4H-imidazole-ruthenium(ii) biimidazole dyes ideal for light-harvesting applications in the field of solar energy conversion.
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Affiliation(s)
- Stephan Kupfer
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743 Jena, Germany.
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