1
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Singh Z, Chiong JD, Ricardo-Noordberg JF, Kamal S, Majewski MB. Charge separation in a copper(I) donor-chromophore-acceptor assembly for both photoanode and photocathode sensitization. Dalton Trans 2024. [PMID: 39258478 DOI: 10.1039/d4dt01681e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2024]
Abstract
A copper(I) donor-chromophore-acceptor triad bearing 1,8-napthalenemonoimide as the electron acceptor and triphenylamine as the electron donor was synthesized. Photophysical and electrochemical characterization suggest stepwise photoinduced charge separation upon excitation of the copper(I)-based metal-to-ligand charge transfer (MLCT) transition. Analyses of femtosecond transient absorption data of the triad show that intersystem crossing from the 1MLCT to the 3MLCT state is followed by two electron-transfer steps with time constants of 20 ps and 722 ps yielding a presumed final charge-separated state with a radical cation on the donor and radical anion on the acceptor that has an 18 ns lifetime in acetonitrile. Finally, this triad was anchored onto n-type (ZnO) and p-type (NiO) semiconductor surfaces to construct a photoanode and photocathode respectively. Successful photocurrent generation from both electrodes upon white light illumination confirms the potential utilization of such systems in dye-sensitized photoelectrochemical cells.
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Affiliation(s)
- Zujhar Singh
- Department of Chemistry and Biochemistry and Centre for NanoScience Research, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, H4B 1R6, Canada.
| | - Joseph D Chiong
- Department of Chemistry and Biochemistry and Centre for NanoScience Research, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, H4B 1R6, Canada.
| | - Joseph F Ricardo-Noordberg
- Department of Chemistry and Biochemistry and Centre for NanoScience Research, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, H4B 1R6, Canada.
| | - Saeid Kamal
- Department of Chemistry and Laboratory for Advanced Spectroscopy and Imaging Research (LASIR), The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Marek B Majewski
- Department of Chemistry and Biochemistry and Centre for NanoScience Research, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, H4B 1R6, Canada.
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2
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Knoll S, Zens C, Maisuradze T, Schmidt H, Kupfer S, Zedler L, Dietzek-Ivanšić B, Streb C. Light-Induced Charge Separation in Covalently Linked BODIPY-Quinone-Alkyne Dyads. Chemistry 2024; 30:e202303250. [PMID: 38411403 DOI: 10.1002/chem.202303250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 02/23/2024] [Accepted: 02/27/2024] [Indexed: 02/28/2024]
Abstract
Visible light-induced charge separation and directional charge transfer are cornerstones for artificial photosynthesis and the generation of solar fuels. Here, we report synthetic access to a series of noble metal-free donor-acceptor dyads based on bodipy light-absorbers and redox-active quinone/anthraquinone charge storage sites. Peripheral functionalization of the quinone/anthraquinone units with alkynes primes the dyads for integration into a range of light-harvesting systems, e. g., by Cu-catalyzed cycloadditions (CLICK chemistry) or Pd-catalyzed C-C cross-coupling reactions. Initial photophysical, electrochemical and theoretical analyses reveal the principal processes during the light-induced charge separation in the reported dyads.
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Affiliation(s)
- Sebastian Knoll
- Institute of Inorganic Chemistry I, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Clara Zens
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
| | - Tamar Maisuradze
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
| | - Heiner Schmidt
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Stephan Kupfer
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
| | - Linda Zedler
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Benjamin Dietzek-Ivanšić
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Carsten Streb
- Institute of Inorganic Chemistry I, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128, Mainz, Germany
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3
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Bürgin T, Ogawa T, Wenger OS. Better Covalent Connection in a Molecular Triad Enables More Efficient Photochemical Energy Storage. Inorg Chem 2023; 62:13597-13607. [PMID: 37562775 PMCID: PMC10445269 DOI: 10.1021/acs.inorgchem.3c02008] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Indexed: 08/12/2023]
Abstract
Numerous studies have explored the kinetics of light-induced charge separation and thermal charge recombination in donor-acceptor compounds, but quantum efficiencies have rarely been investigated. Here, we report on two essentially isomeric molecular triads, both comprising a π-extended tetrathiafulvalene (ExTTF) donor, a ruthenium(II)-based photosensitizer, and a naphthalene diimide (NDI) acceptor. The key difference between the two triads is how the NDI acceptor is connected. Linkage at the NDI core provides stronger electronic coupling to the other molecular components than connection via the nitrogen atoms of NDI. This change in molecular connectivity is expected to accelerate both energy-storing charge separation and energy-wasting charge recombination processes, but it is not a priori clear how this will affect the triad's ability to store photochemical energy; any gain resulting from faster charge separation could potentially be (over)compensated by losses through accelerated charge recombination. The new key insight emerging from our study is that the quantum yield for the formation of a long-lived charge-separated state increases by a factor of 5 when going from nitrogen- to core-connected NDI, providing the important proof of concept that better molecular connectivity indeed enables more efficient photochemical energy storage. The physical origin of this behavior seems to root in different orbital connectivity pathways for charge separation and charge recombination, as well as in differences in the relevant orbital interactions depending on NDI connection. Our work provides guidelines for how to discriminate between energy-storing and energy-wasting electron transfer reactions in order to improve the quantum yields for photochemical energy storage and solar energy conversion.
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Affiliation(s)
- Tobias
H. Bürgin
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, Basel 4056, Switzerland
| | - Tomohiro Ogawa
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, Basel 4056, Switzerland
- Graduate
School of Science and Engineering, University
of Toyama, Toyama 930-8555, Japan
| | - Oliver S. Wenger
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, Basel 4056, Switzerland
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4
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Accumulation of mono-reduced [Ir(piq) 2(LL)] photosensitizers relevant for solar fuels production. Photochem Photobiol Sci 2022; 21:1433-1444. [PMID: 35595935 DOI: 10.1007/s43630-022-00233-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 04/13/2022] [Indexed: 10/18/2022]
Abstract
A series of nine [Ir(piq)2(LL)]+.PF6- photosensitizers, where piqH = 1-phenylisoquinoline, was developed and investigated for excited-state electron transfer with sacrificial electron donors that included triethanolamine (TEOA), triethylamine (TEA) and 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH) in acetonitrile. The photosensitizers were obtained in 57-82% yield starting from the common [Ir(piq)2µ-Cl]2 precursor and were all characterized by UV-Vis absorption as well as by steady-state, time-resolved spectroscopies and electrochemistry. The excited-state lifetimes ranged from 250 to 3350 ns and excited-state electron transfer quenching rate constants in the 109 M-1 s-1 range were obtained when BIH was used as electron donor. These quenching rate constants were three orders of magnitude higher than when TEA or TEOA was used. Steady-state photolysis in the presence of BIH showed that the stable and reversible accumulation of mono-reduced photosensitizers was possible, highlighting the potential use of these Ir-based photosensitizers in photocatalytic reactions relevant for solar fuels production.
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5
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Ir(III)-Naphthoquinone complex as a platform for photocatalytic activity. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY 2022. [DOI: 10.1016/j.jpap.2021.100098] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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6
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Keller S, Hankache J, Yushchenko O, Lawson Daku LM, Sun Q, Ding J, Decurtins S, Vauthey E, Häner R, Hauser A, Liu S. Intramolecular Charge‐Transfer Dynamics in Benzodifuran‐Based Triads. Helv Chim Acta 2021. [DOI: 10.1002/hlca.202100099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Stephan Keller
- Department of Chemistry Biochemistry and Pharmaceutical Sciences University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
| | - Jihane Hankache
- Department of Physical Chemistry University of Geneva 30 Quai Ernest Ansermet CH-1211 Geneva Switzerland
| | - Oleksandr Yushchenko
- Department of Physical Chemistry University of Geneva 30 Quai Ernest Ansermet CH-1211 Geneva Switzerland
| | - Latévi Max Lawson Daku
- Department of Physical Chemistry University of Geneva 30 Quai Ernest Ansermet CH-1211 Geneva Switzerland
| | - Qinchao Sun
- Department of Physical Chemistry University of Geneva 30 Quai Ernest Ansermet CH-1211 Geneva Switzerland
| | - Jie Ding
- Department of Physical Chemistry University of Geneva 30 Quai Ernest Ansermet CH-1211 Geneva Switzerland
| | - Silvio Decurtins
- Department of Chemistry Biochemistry and Pharmaceutical Sciences University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
| | - Eric Vauthey
- Department of Physical Chemistry University of Geneva 30 Quai Ernest Ansermet CH-1211 Geneva Switzerland
| | - Robert Häner
- Department of Chemistry Biochemistry and Pharmaceutical Sciences University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
| | - Andreas Hauser
- Department of Physical Chemistry University of Geneva 30 Quai Ernest Ansermet CH-1211 Geneva Switzerland
| | - Shi‐Xia Liu
- Department of Chemistry Biochemistry and Pharmaceutical Sciences University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
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7
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Kranz C, Wächtler M. Characterizing photocatalysts for water splitting: from atoms to bulk and from slow to ultrafast processes. Chem Soc Rev 2021; 50:1407-1437. [DOI: 10.1039/d0cs00526f] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
This review provides a comprehensive overview on characterisation techniques for light-driven redox-catalysts highlighting spectroscopic, microscopic, electrochemical and spectroelectrochemical approaches.
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Affiliation(s)
- Christine Kranz
- Ulm University
- Institute of Analytical and Bioanalytical Chemistry
- 89081 Ulm
- Germany
| | - Maria Wächtler
- Leibniz Institute of Photonic Technology
- Department Functional Interfaces
- 07745 Jena
- Germany
- Friedrich Schiller University Jena
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8
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Singh Z, Donnarumma PR, Majewski MB. Molecular Copper(I)-Copper(II) Photosensitizer-Catalyst Photoelectrode for Water Oxidation. Inorg Chem 2020; 59:12994-12999. [PMID: 32909755 DOI: 10.1021/acs.inorgchem.0c01670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Copper(II)-based electrocatalysts for water oxidation in aqueous solution have been studied previously, but photodriving these systems still remains a challenge. In this work, a bis(diimine)copper(I)-based donor-chromophore-acceptor system is synthesized and applied as the light-harvesting component of a photoanode. This molecular assembly was integrated onto a zinc oxide nanowire surface, and upon photoexcitation, chronoamperometric studies reveal that the integrated triad can inject electrons directly into the conduction band of zinc oxide, generating oxidizing equivalents that are then transferred to a copper(II) water oxidation catalyst in aqueous solution, yielding O2 from water with a Faradaic efficiency of 76%.
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Affiliation(s)
- Zujhar Singh
- Department of Chemistry and Biochemistry and Centre for NanoScience Research Concordia University 7141 Sherbrooke Street West, Montreal, Quebec H4B 1R6, Canada
| | - P Rafael Donnarumma
- Department of Chemistry and Biochemistry and Centre for NanoScience Research Concordia University 7141 Sherbrooke Street West, Montreal, Quebec H4B 1R6, Canada
| | - Marek B Majewski
- Department of Chemistry and Biochemistry and Centre for NanoScience Research Concordia University 7141 Sherbrooke Street West, Montreal, Quebec H4B 1R6, Canada
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9
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Chen WH, Zhou Z, Luo GF, Neumann E, Marjault HB, Stone D, Nechushtai R, Willner I. Photosensitized H 2 Evolution and NADPH Formation by Photosensitizer/Carbon Nitride Hybrid Nanoparticles. NANO LETTERS 2019; 19:9121-9130. [PMID: 31729224 DOI: 10.1021/acs.nanolett.9b04375] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The broadband C3N4 semiconductor absorbs in the UV region, λ = 330-380 nm, a feature limiting its application for light-to-energy conversion. The unique surface adsorption properties of C3N4 allow, however, the binding of a photosensitizer, operating in the visible-solar spectrum to the surface of C3N4. Coupling of the energy levels of the photosensitizer with the energy levels of C3N4 allows effective photoinduced electron-transfer quenching and subsequent charge separation in the hybrid structures. Two methods to adsorb a photosensitizer on the C3N4 nanoparticles are described. One is exemplified by the adsorption of Zn(II)-protoporphyrin IX on C3N4 using π-π interactions. The second method utilizes the specific binding interactions of single-stranded nucleic acids on C3N4 and involves the binding of a Ru(II)-tris-bipyridine-modified nucleic acid on the C3N4 nanoparticles. Effective electron-transfer quenching of the photoexcited photosensitizers by C3N4 proceeds in the two hybrid systems. The two hybrid photosystems induce the effective photosensitized reduction of N,N'-dimethyl-4,4'-bipyridinium, MV2+, to MV+•, in the presence of Na2EDTA as a sacrificial electron donor. The generation of MV+• is ca. 5-fold higher as compared to the formation of MV+• in the presence of the photosensitizer alone (in the absence of C3N4). The effective generation of MV+• in the photosystems is attributed to the efficient quenching of the photosensitizers, followed by effective charge separation of the electrons in the conduction band of C3N4 and the holes in the oxidized photosensitizer. The subsequent transfer of the conduction-band electrons to MV2+ and the oxidation of Na2EDTA by the oxidized photosensitizers lead to the effective formation of MV+•. The photogenerated MV+• by the two hybrid photosystems is used to catalyze H2 evolution in the presence of Pt nanoparticle catalysts and to mediate the reduction of NADP+ to NADPH, in the presence of ferredoxin-NADP+ reductase, FNR. The ability to couple the photogenerated NADPH to drive NADP+-dependent biocatalytic transformations is demonstrated.
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Affiliation(s)
- Wei-Hai Chen
- Institute of Chemistry and Center for Nanoscience and Nanotechnology , The Hebrew University of Jerusalem , Jerusalem 91904 , Israel
| | - Zhixin Zhou
- Institute of Chemistry and Center for Nanoscience and Nanotechnology , The Hebrew University of Jerusalem , Jerusalem 91904 , Israel
| | - Guo-Feng Luo
- Institute of Chemistry and Center for Nanoscience and Nanotechnology , The Hebrew University of Jerusalem , Jerusalem 91904 , Israel
| | - Ehud Neumann
- Institute of Life Science , The Hebrew University of Jerusalem , Jerusalem 91904 , Israel
| | | | - David Stone
- Institute of Chemistry and Center for Nanoscience and Nanotechnology , The Hebrew University of Jerusalem , Jerusalem 91904 , Israel
| | - Rachel Nechushtai
- Institute of Life Science , The Hebrew University of Jerusalem , Jerusalem 91904 , Israel
| | - Itamar Willner
- Institute of Chemistry and Center for Nanoscience and Nanotechnology , The Hebrew University of Jerusalem , Jerusalem 91904 , Israel
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10
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Skaisgirski M, Larsen CB, Kerzig C, Wenger OS. Stepwise Photoinduced Electron Transfer in a Tetrathiafulvalene‐Phenothiazine‐Ruthenium Triad. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201900453] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Michael Skaisgirski
- 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
| | - Christoph Kerzig
- 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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11
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Neumann S, Kerzig C, Wenger OS. Quantitative insights into charge-separated states from one- and two-pulse laser experiments relevant for artificial photosynthesis. Chem Sci 2019; 10:5624-5633. [PMID: 31293747 PMCID: PMC6553010 DOI: 10.1039/c9sc01381d] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 05/01/2019] [Indexed: 01/25/2023] Open
Abstract
Charge-separated states (CSSs) are key intermediates in photosynthesis and solar energy conversion. However, the factors governing the formation efficiencies of CSSs are still poorly understood, and light-induced electron-hole recombinations as deactivation pathways competing with desired charge accumulations are largely unexplored. This greatly limits the possibility to perform efficient multi-electron transfer, which is essential for artificial photosynthesis. We present a systematic investigation of two donor-sensitizer-acceptor triads (with different donor-acceptor distances) capable of storing as much as 2.0 eV in their CSSs upon the absorption of a visible photon. Using quantitative one- and two-pulse laser flash photolysis, we provide deep insights into both the CSS formation quantum yield, which can reach up to 80%, and the fate of the CSS upon further (secondary) excitation with green photons. The triad with shorter intramolecular distances shows a remarkable excitation wavelength dependence of the CSS formation quantum yield, and the CSS of this triad undergoes more efficient light-induced charge recombination than the longer equivalent by about one order of magnitude, whilst thermal charge recombination shows the exact opposite behavior. The unexpected results of our detailed photophysical study can be rationalized by detrimental singlet charge transfer states or structural considerations, and could significantly contribute to the future design of CSS precursors for accumulative multi-electron transfer and artificial photosynthesis.
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Affiliation(s)
- Svenja Neumann
- 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 . ;
| | - Oliver S Wenger
- Department of Chemistry , University of Basel , St. Johanns-Ring 19 , 4056 Basel , Switzerland . ;
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12
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Keller SG, Pannwitz A, Schwizer F, Klehr J, Wenger OS, Ward TR. Light-driven electron injection from a biotinylated triarylamine donor to [Ru(diimine)3](2+)-labeled streptavidin. Org Biomol Chem 2018; 14:7197-201. [PMID: 27411288 DOI: 10.1039/c6ob01273f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Electron transfer from a biotinylated electron donor to photochemically generated Ru(iii) complexes covalently anchored to streptavidin is demonstrated by means of time-resolved laser spectroscopy. Through site-selective mutagenesis, a single cysteine residue was engineered at four different positions on streptavidin, and a Ru(ii) tris-diimine complex was then bioconjugated to the exposed cysteines. A biotinylated triarylamine electron donor was added to the Ru(ii)-modified streptavidins to afford dyads localized within a streptavidin host. The resulting systems were subjected to electron transfer studies. In some of the explored mutants, the phototriggered electron transfer between triarylamine and Ru(iii) is complete within 10 ns, thus highlighting the potential of such artificial metalloenzymes to perform photoredox catalysis.
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Affiliation(s)
- Sascha G Keller
- Department of Chemistry, University of Basel, Spitalstrasse 51, CH-4056 Basel, Switzerland.
| | - Andrea Pannwitz
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland.
| | - Fabian Schwizer
- Department of Chemistry, University of Basel, Spitalstrasse 51, CH-4056 Basel, Switzerland.
| | - Juliane Klehr
- Department of Chemistry, University of Basel, Spitalstrasse 51, CH-4056 Basel, Switzerland.
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland.
| | - Thomas R Ward
- Department of Chemistry, University of Basel, Spitalstrasse 51, CH-4056 Basel, Switzerland.
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13
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Schnaubelt L, Petzold H, Dmitrieva E, Rosenkranz M, Lang H. A solvent- and temperature-dependent intramolecular equilibrium of diamagnetic and paramagnetic states in Co complexes bearing triaryl amines. Dalton Trans 2018; 47:13180-13189. [PMID: 30178800 DOI: 10.1039/c8dt02538j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Complexes [Co(L)2](ClO4)2 (L = o-substituted 2-(pyridine-2-yl)-1,10-phenanthrolines 1a-c) containing three redox active centres (a Co2+ ion and two triaryl amine (Tara) units) have been synthesised. The order of oxidation steps in [Co(L)2](ClO4)2 (L = 1a-c) was determined using cyclic voltammetry and EPR/UV-vis-NIR spectroelectrochemistry. In acetonitrile solutions, at room temperature, the first oxidation is Co-centred followed by the Tara oxidation at more anodic potentials. The order of oxidation is inverted in solutions of the less polar solvent dichloromethane. The Co3+/2+-centred redox event leads to a spin transition between the paramagnetic high-spin (HS) Co2+ and the diamagnetic low-spin (LS) Co3+ state, which was proven using 1H NMR and EPR spectroscopy. After one-electron oxidation of [Co(L)2](ClO4)2, an equilibrium between the diamagnetic [Co3+(L)]3+ and paramagnetic [Co2+(L)(L+)]3+ state in [Co(L)2]3+ (L = 1a-c) was found. Cyclic voltammetry showed enhanced intermolecular electron transfer between the [Co2+(L)2]2+ and [Co3+(L)2]3+ redox states mediated by [Co2+(L)(L+)]3+. Variable temperature vis-NIR spectroscopy of in situ generated [Co(L)2]3+ revealed a temperature-dependent redox equilibrium between the [Co3+(L)2]3+ and the [Co2+(L+)(L)]3+ states (L = 1a-c). Magnetic coupling between the HS-Co2+ ion and the Tara+ radical in [HS-Co2+(L+)(L)]3+ (L = 1a,c) was deduced from broad and undetectable lines observed in the corresponding EPR spectra. Complete oxidation to [LS-Co3+(L+)2]5+ (L = 1a,c) leads to characteristic EPR spectra of Tara biradicals with non-interacting spins.
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Affiliation(s)
- Linda Schnaubelt
- Technische Universität Chemnitz, Faculty of Natural Sciences, Institute of Chemistry, Inorganic Chemistry, 09107 Chemnitz, Germany.
| | - Holm Petzold
- Technische Universität Chemnitz, Faculty of Natural Sciences, Institute of Chemistry, Inorganic Chemistry, 09107 Chemnitz, Germany.
| | - Evgenia Dmitrieva
- Center of Spectroelectrochemistry, Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany
| | - Marco Rosenkranz
- Center of Spectroelectrochemistry, Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069 Dresden, Germany
| | - Heinrich Lang
- Technische Universität Chemnitz, Faculty of Natural Sciences, Institute of Chemistry, Inorganic Chemistry, 09107 Chemnitz, Germany.
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14
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Nomrowski J, Wenger OS. Exploiting Potential Inversion for Photoinduced Multielectron Transfer and Accumulation of Redox Equivalents in a Molecular Heptad. J Am Chem Soc 2018; 140:5343-5346. [PMID: 29652485 DOI: 10.1021/jacs.8b02443] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Photoinduced multielectron transfer and reversible accumulation of redox equivalents is accomplished in a fully integrated molecular heptad composed of four donors, two photosensitizers, and one acceptor. The second reduction of the dibenzo[1,2]dithiin acceptor occurs more easily than the first by 1.3 V, and this potential inversion facilitates the light-driven formation of a two-electron reduced state with a lifetime of 66 ns in deaerated CH3CN. The quantum yield for formation of this doubly charge-separated photoproduct is 0.5%. In acidic oxygen-free solution, the reduction product is a stable dithiol. Under steady-state photoirradiation, our heptad catalyzes the two-electron reduction of an aliphatic disulfide via thiolate-disulfide interchange. Exploitation of potential inversion for the reversible light-driven accumulation of redox equivalents in artificial systems is unprecedented and the use of such a charge-accumulated state for multielectron photoredox catalysis represents an important proof-of-concept.
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Affiliation(s)
- Julia Nomrowski
- 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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15
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Schlotthauer T, Schroot R, Glover S, Hammarström L, Jäger M, Schubert US. A multidonor-photosensitizer-multiacceptor triad for long-lived directional charge separation. Phys Chem Chem Phys 2018; 19:28572-28578. [PMID: 29034949 DOI: 10.1039/c7cp05593e] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The modular assembly of a directional photoredox-active multidonor-photosensitizer-multiacceptor (Dn-P-Am) architecture is presented. The triad assembly features a central Ru(ii) sensitizer equipped with pendant polymer chains consisting of multiple triarylamine (pTARA) and naphthalene diimide (pNDI) units, respectively. Upon excitation, the efficient formation (>96%) of charge separation (CS) was observed featuring similar CS lifetimes (400 ns) as related molecular triads. In contrast, a significant additional longer-lived CS component (2400 ns, 30%) is observed indicating multiple contributing pathways.
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Affiliation(s)
- Tina Schlotthauer
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstraße 10, 07743 Jena, Germany.
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16
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Jacques A, Auvray T, Bevernaegie R, Loiseau F, Cibian M, Hanan GS, Kirsch-De Mesmaeker A, Elias B. Proton sensitive charge-transfer excited states in bis-terdentate cyclometalated Ir(III) complexes: Spectroscopic and theoretical investigation. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2017.10.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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17
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Whittemore TJ, White TA, Turro C. New Ligand Design Provides Delocalization and Promotes Strong Absorption throughout the Visible Region in a Ru(II) Complex. J Am Chem Soc 2017; 140:229-234. [PMID: 29260869 DOI: 10.1021/jacs.7b09389] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The new Ru(II)-anthraquinone complex [Ru(bpy)2(qdpq)](PF6)2 (Ru-qdpq; bpy = 2,2'-bipyridine; qdpq = 2,3-di(2-pyridyl)naphtho[2,3-f]quinoxaline-7,12-quinone) possesses a strong 1MLCT Ru → qdpq absorption with a maximum at 546 nm that tails into the near-IR and is significantly red-shifted relative to that of the related complex [Ru(bpy)2(qdppz)](PF6)2 (Ru-qdppz; qdppz = naphtho[2,3-a]dipyrido[3,2-h:2',3'-f]phenazine-5,18-dione), with λmax = 450 nm. Ru-qdppz possesses electronically isolated proximal and distal qdppz-based excited states; the former is initially generated and decays to the latter, which repopulates the ground state with τ = 362 ps. In contrast, excitation of Ru-qdpq results in the population of a relatively long-lived (τ = 19 ns) Ru(dπ) → qdpq(π*) 3MLCT excited state where the promoted electron is delocalized throughout the qdpq ligand. Ultrafast spectroscopy, used together with steady-state absorption, electrochemistry, and DFT calculations, indicates that the unique coordination modes of the qdpq and qdppz ligands impart substantially different electronic communication throughout the quinone-containing ligand, affecting the excited state and electron transfer properties of these molecules. These observations create a pathway to synthesize complexes with red-shifted absorptions that possess long-lived, redox-active excited states that are useful for various applications, including solar energy conversion and photochemotherapy.
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Affiliation(s)
- Tyler J Whittemore
- Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States
| | - Travis A White
- Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States
| | - Claudia Turro
- Department of Chemistry and Biochemistry, The Ohio State University , Columbus, Ohio 43210, United States
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18
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Keller SG, Pannwitz A, Mallin H, Wenger OS, Ward TR. Streptavidin as a Scaffold for Light-Induced Long-Lived Charge Separation. Chemistry 2017; 23:18019-18024. [PMID: 29024136 DOI: 10.1002/chem.201703885] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Indexed: 01/03/2023]
Abstract
Long-lived photo-driven charge separation is demonstrated by assembling a triad on a protein scaffold. For this purpose, a biotinylated triarylamine was added to a RuII -streptavidin conjugate bearing a methyl viologen electron acceptor covalently linked to the N-terminus of streptavidin. To improve the rate and lifetime of the electron transfer, a negative patch consisting of up to three additional negatively charged amino acids was engineered through mutagenesis close to the biotin-binding pocket of streptavidin. Time-resolved laser spectroscopy revealed that the covalent attachment and the negative patch were beneficial for charge separation within the streptavidin hosted triad; the charge separated state was generated within the duration of the excitation laser pulse, and lifetimes up to 3120 ns could be achieved with the optimized supramolecular triad.
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Affiliation(s)
- Sascha G Keller
- Department of Chemistry, University of Basel, Mattenstrasse 24a, CH-4002, Basel, Switzerland
| | - Andrea Pannwitz
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056, Basel, Switzerland
| | - Hendrik Mallin
- Department of Chemistry, University of Basel, Mattenstrasse 24a, CH-4002, Basel, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056, Basel, Switzerland
| | - Thomas R Ward
- Department of Chemistry, University of Basel, Mattenstrasse 24a, CH-4002, Basel, Switzerland
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19
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Kuss-Petermann M, Wenger OS. Exceptionally Long-Lived Photodriven Multi-Electron Storage without Sacrificial Reagents. Chemistry 2017; 23:10808-10814. [DOI: 10.1002/chem.201701456] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Martin Kuss-Petermann
- 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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20
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Kuss-Petermann M, Orazietti M, Neuburger M, Hamm P, Wenger OS. Intramolecular Light-Driven Accumulation of Reduction Equivalents by Proton-Coupled Electron Transfer. J Am Chem Soc 2017; 139:5225-5232. [PMID: 28362497 DOI: 10.1021/jacs.7b01605] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The photochemistry of a molecular pentad composed of a central anthraquinone (AQ) acceptor flanked by two Ru(bpy)32+ photosensitizers and two peripheral triarylamine (TAA) donors was investigated by transient IR and UV-vis spectroscopies in the presence of 0.2 M p-toluenesulfonic acid (TsOH) in deaerated acetonitrile. In ∼15% of all excited pentad molecules, AQ is converted to its hydroquinone form (AQH2) via reversible intramolecular electron transfer from the two TAA units (τ = 65 ps), followed by intermolecular proton transfer from TsOH (τ ≈ 3 ns for the first step). Although the light-driven accumulation of reduction equivalents occurs through a sequence of electron and proton transfer steps, the resulting photoproduct decays via concerted PCET (τ = 4.7 μs) with an H/D kinetic isotope effect of 1.4 ± 0.2. Moreover, the reoxidation of AQH2 seems to take place via a double electron transfer step involving both TAA+ units rather than sequential single electron transfer events. Thus, the overall charge-recombination reaction seems to involve a concerted proton-coupled two-electron oxidation of AQH2. The comparison of experimental data obtained in neat acetonitrile with data from acidic solutions suggests that the inverted driving-force effect can play a crucial role for obtaining long-lived photoproducts resulting from multiphoton, multielectron processes. Our pentad provides the first example of light-driven accumulation of reduction equivalents stabilized by PCET in artificial molecular systems without sacrificial reagents. Our study provides fundamental insight into how light-driven multielectron redox chemistry, for example the reduction of CO2 or the oxidation of H2O, can potentially be performed without sacrificial reagents.
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Affiliation(s)
- Martin Kuss-Petermann
- Department of Chemistry, University of Basel , St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Margherita Orazietti
- Department of Chemistry, University of Zurich , Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Markus Neuburger
- Department of Chemistry, University of Basel , St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Peter Hamm
- Department of Chemistry, University of Zurich , Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel , St. Johanns-Ring 19, 4056 Basel, Switzerland
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21
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Heinz LG, Wenger OS. Photoinduced electron transfer in a triarylamine-organoboron-Ru(2,2′-bipyridine) 3 2+ compound. CR CHIM 2017. [DOI: 10.1016/j.crci.2015.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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22
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Kuss-Petermann M, Wenger OS. Pump-Pump-Probe Spectroscopy of a Molecular Triad Monitoring Detrimental Processes for Photoinduced Charge Accumulation. Helv Chim Acta 2016. [DOI: 10.1002/hlca.201600283] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Oliver S. Wenger
- Department of Chemistry; University of Basel; St. Johanns-Ring 19 CH-4056 Basel
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23
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Barthelmes K, Winter A, Schubert US. Dyads and Triads Based on Phenothiazine, Bis(terpyridine)ruthenium(II) Complexes, and Fullerene. Eur J Inorg Chem 2016. [DOI: 10.1002/ejic.201600793] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Kevin Barthelmes
- Laboratory of Organic and Macromolecular Chemistry (IOMC); Friedrich Schiller University Jena; Humboldtstr. 10 07743 Jena Germany
- Jena Center for Soft Matter (JCSM); Friedrich Schiller University Jena; Philosophenweg 7 07743 Jena Germany
- Center for Energy and Environmental Chemistry Jena (CEEC Jena); Friedrich Schiller University Jena; Philosophenweg 7a 07743 Jena Germany
| | - Andreas Winter
- Laboratory of Organic and Macromolecular Chemistry (IOMC); Friedrich Schiller University Jena; Humboldtstr. 10 07743 Jena Germany
- Jena Center for Soft Matter (JCSM); Friedrich Schiller University Jena; Philosophenweg 7 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
- Jena Center for Soft Matter (JCSM); Friedrich Schiller University Jena; Philosophenweg 7 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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24
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Rajeswari A, Ramdass A, Muthu Mareeswaran P, Velayudham M, Rajagopal S. Electron transfer reactions of osmium(II) complexes with phenols and phenolic acids. J Mol Struct 2016. [DOI: 10.1016/j.molstruc.2016.02.088] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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Farran R, Jouvenot D, Gennaro B, Loiseau F, Chauvin J, Deronzier A. Photoinduced Charge Separation within Metallo-supramolecular Wires Built around a [Ru(bpy)3](2+)-Bisterpyridine Linear Entity. ACS APPLIED MATERIALS & INTERFACES 2016; 8:16136-16146. [PMID: 27280969 DOI: 10.1021/acsami.6b05082] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A [Ru(bpy)3](2+)-like complex (L1) bearing two free terpyridine groups at the 5 and 5' positions of the same bipyridine, linked by the rigid and linear 2,5-dimethyl phenylene bridges has been synthesized to open access to two classes of linear molecular wires with photosensitive properties: a bimetallic coordination polymer and an inorganic triad. In this Research Article, we report on the synthesis and characterization of the resulting [{Ru(II_)Fe(II)}n](4n+) alternated bimetallic polymer and the [Co(III_)Ru(II_)Fe(II)](7+) triad based on the building block L1. The [{Ru(II_)Fe(II)}n](4n+) polymer is fully characterized in solution. Cyclic voltammetry and emission lifetime measurements show that the bridging ligand allows interaction between the metal centers in the excited state despite the lack of interactions in the ground state. Under visible irradiation, the polymer can be fully oxidized in the presence of a sacrificial electron acceptor in solution. Thin robust films of the polymer are easily obtained on ITO by a simple electrochemical procedure based on an electroreduction adsorption process. The ITO/[{Ru(II_)Fe(II)}n](4n+)-modified electrode behaves as a photocathode under irradiation in the presence of ArN2(+). The magnitude of the photocurrent is dependent on the film thickness, probably limited by the diffusion of charge in thicker film. On the other hand L1 is also used to construct a well-ordered triad in association with Co(III) and Fe(II) metallic centers as electron acceptor and donor, respectively. The metallic triad is anchored on ITO or on a SiO2 wafer, starting from a terpyridine phosphonate modified surface. AFM images prove the presence of the triad in a linear upward orientation. Irradiation of the ITO/[Co(III_)Ru(II_)Fe(II)](7+) modified surface in the presence of triethanolamine in CH3CN induces the generation of an anodic photocurrent of around 30 μA.cm(-2). The photocurrent density generated by the ITO/[Co(III_)Ru(II_)Fe(II)](7+) electrode, appears to be more stable than in the case of ITO/[{Ru(II_)Fe(II)}n](4n+) because of the presence of the anchoring group. Moreover, this photocurrent magnitude represents an enhancement of 30% compared to our previous triad ( Dalton Trans. 2014 , 43 , 12156 - 12159 ), proving the advantage of a linear and rigid spacer for the construction of such molecular assemblies with photoinduced charge transfer abilities.
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Affiliation(s)
- Rajaa Farran
- Université de Grenoble-Alpes , Département de Chimie Moléculaire, UMR CNRS 5250, CS 40700, Grenoble 38058 cedex 9, France
| | - Damien Jouvenot
- Université de Grenoble-Alpes , Département de Chimie Moléculaire, UMR CNRS 5250, CS 40700, Grenoble 38058 cedex 9, France
| | - Béatrice Gennaro
- Université de Grenoble-Alpes , Département de Chimie Moléculaire, UMR CNRS 5250, CS 40700, Grenoble 38058 cedex 9, France
| | - Frédérique Loiseau
- Université de Grenoble-Alpes , Département de Chimie Moléculaire, UMR CNRS 5250, CS 40700, Grenoble 38058 cedex 9, France
| | - Jérôme Chauvin
- Université de Grenoble-Alpes , Département de Chimie Moléculaire, UMR CNRS 5250, CS 40700, Grenoble 38058 cedex 9, France
| | - Alain Deronzier
- Université de Grenoble-Alpes , Département de Chimie Moléculaire, UMR CNRS 5250, CS 40700, Grenoble 38058 cedex 9, France
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26
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Orazietti M, Kuss‐Petermann M, Hamm P, Wenger OS. Lichtgetriebene Elektronenakkumulation in einer molekularen Pentade. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201604030] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Margherita Orazietti
- Departement für ChemieUniversität Zürich Winterthurerstrasse 190 8057 Zürich Schweiz
| | | | - Peter Hamm
- Departement für ChemieUniversität Zürich Winterthurerstrasse 190 8057 Zürich Schweiz
| | - Oliver S. Wenger
- Departement für ChemieUniversität Basel St. Johanns-Ring 19 4056 Basel Schweiz
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27
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Orazietti M, Kuss-Petermann M, Hamm P, Wenger OS. Light-Driven Electron Accumulation in a Molecular Pentad. Angew Chem Int Ed Engl 2016; 55:9407-10. [PMID: 27336756 DOI: 10.1002/anie.201604030] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Indexed: 11/10/2022]
Abstract
Accumulation and temporary storage of redox equivalents with visible light as an energy input is of pivotal importance for artificial photosynthesis because key reactions, such as CO2 reduction or water oxidation, require the transfer of multiple redox equivalents. We report on the first purely molecular system, in which a long-lived charge-separated state (τ≈870 ns) with two electrons accumulated on a suitable acceptor unit can be observed after excitation with visible light. Importantly, no sacrificial reagents were employed.
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Affiliation(s)
- Margherita Orazietti
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Martin Kuss-Petermann
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
| | - Peter Hamm
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland.
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28
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Majewski MB, Smith JG, Wolf MO, Patrick BO. Long‐Lived, Emissive Excited States in Direct and Amide‐Linked Thienyl‐Substituted Ru
II
Complexes. Eur J Inorg Chem 2016. [DOI: 10.1002/ejic.201501436] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Marek B. Majewski
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada, http://https://groups.chem.ubc.ca/wolf/
| | - Jeremy G. Smith
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada, http://https://groups.chem.ubc.ca/wolf/
| | - Michael O. Wolf
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada, http://https://groups.chem.ubc.ca/wolf/
| | - Brian O. Patrick
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada, http://https://groups.chem.ubc.ca/wolf/
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29
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Flamigni L. Functional Arrays for Light Energy Capture and Charge Separation. CHEM REC 2016; 16:1067-81. [DOI: 10.1002/tcr.201500295] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Lucia Flamigni
- Istituto ISOF-CNR; Via P. Gobetti 101 40129 Bologna Italy
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30
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Bonn AG, Yushchenko O, Vauthey E, Wenger OS. Photoinduced Electron Transfer in an Anthraquinone–[Ru(bpy)3]2+–Oligotriarylamine–[Ru(bpy)3]2+–Anthraquinone Pentad. Inorg Chem 2016; 55:2894-9. [DOI: 10.1021/acs.inorgchem.5b02757] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Annabell G. Bonn
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Oleksandr Yushchenko
- Department of Physical
Chemistry, University of Geneva, 30 quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Eric Vauthey
- Department of Physical
Chemistry, University of Geneva, 30 quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Oliver S. Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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31
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Kuss-Petermann M, Wenger OS. Electron Transfer Rate Maxima at Large Donor-Acceptor Distances. J Am Chem Soc 2016; 138:1349-58. [PMID: 26800279 DOI: 10.1021/jacs.5b11953] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Because of their low mass, electrons can transfer rapidly over long (>15 Å) distances, but usually reaction rates decrease with increasing donor-acceptor distance. We report here on electron transfer rate maxima at donor-acceptor separations of 30.6 Å, observed for thermal electron transfer between an anthraquinone radical anion and a triarylamine radical cation in three homologous series of rigid-rod-like donor-photosensitizer-acceptor triads with p-xylene bridges. Our experimental observations can be explained by a weak distance dependence of electronic donor-acceptor coupling combined with a strong increase of the (outer-sphere) reorganization energy with increasing distance, as predicted by electron transfer theory more than 30 years ago. The observed effect has important consequences for light-to-chemical energy conversion.
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Affiliation(s)
- Martin Kuss-Petermann
- 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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32
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Kuss-Petermann M, Wenger OS. Unusual distance dependences of electron transfer rates. Phys Chem Chem Phys 2016; 18:18657-64. [DOI: 10.1039/c6cp03124b] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
There are regimes in which electron transfer rates increase with increasing donor–acceptor distance, leading to rate maxima at large donor–acceptor separations.
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33
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Lian ZY, Yuan J, Yan MQ, Liu Y, Luo X, Wu QG, Liu SH, Chen J, Zhu XL, Yu GA. 2-Aryl-indenylphosphine ligands: design, synthesis and application in Pd-catalyzed Suzuki–Miyaura coupling reactions. Org Biomol Chem 2016; 14:10090-10094. [DOI: 10.1039/c6ob01675h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A focused library of phosphine ligands was constructed for structural optimization. The catalyst can be used to perform the Suzuki–Miyaura cross-coupling reaction of aryl and heteroaryl chlorides.
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34
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Yan MQ, Yuan J, Pi YX, Liang JH, Liu Y, Wu QG, Luo X, Liu SH, Chen J, Zhu XL, Yu GA. Pd-indenyl-diphosphine: an effective catalyst for the preparation of triarylamines. Org Biomol Chem 2016; 14:451-454. [DOI: 10.1039/c5ob01934f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A new Buchwald-type diphosphine ligand has been developed for applications in Pd-catalyzed amination reactions towards the preparation of triarylamines. The catalyst can be used to perform the amination of an adverse array of aryl and heteroaryl chlorides.
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35
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Schmidt HC, Spulber M, Neuburger M, Palivan CG, Meuwly M, Wenger OS. Charge Transfer Pathways in Three Isomers of Naphthalene-Bridged Organic Mixed Valence Compounds. J Org Chem 2015; 81:595-602. [DOI: 10.1021/acs.joc.5b02427] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hauke C. Schmidt
- Department of Chemistry, University of Basel, St. Johanns-Ring
19, Spitalstrasse 51, and Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Mariana Spulber
- Department of Chemistry, University of Basel, St. Johanns-Ring
19, Spitalstrasse 51, and Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Markus Neuburger
- Department of Chemistry, University of Basel, St. Johanns-Ring
19, Spitalstrasse 51, and Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Cornelia G. Palivan
- Department of Chemistry, University of Basel, St. Johanns-Ring
19, Spitalstrasse 51, and Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, St. Johanns-Ring
19, Spitalstrasse 51, and Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Oliver S. Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring
19, Spitalstrasse 51, and Klingelbergstrasse 80, CH-4056 Basel, Switzerland
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36
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Büldt LA, Prescimone A, Neuburger M, Wenger OS. Photoredox Properties of Homoleptic d6Metal Complexes with the Electron-Rich 4,4′,5,5′-Tetramethoxy-2,2′-bipyridine Ligand. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201500670] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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37
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Bonn AG, Wenger OS. Photoinduced charge accumulation by metal ion-coupled electron transfer. Phys Chem Chem Phys 2015; 17:24001-10. [PMID: 26312416 DOI: 10.1039/c5cp04718h] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An oligotriarylamine (OTA) unit, a Ru(bpy)3(2+) photosensitizer moiety (Ru), and an anthraquinone (AQ) entity were combined to a molecular dyad (Ru-OTA) and a molecular triad (AQ-Ru-OTA). Pulsed laser excitation at 532 nm led to the formation of charge-separated states of the type Ru(-)-OTA(+) and AQ(-)-Ru-OTA(+) with lifetimes of ≤10 ns and 2.4 μs, respectively, in de-aerated CH3CN at 25 °C. Upon addition of Sc(OTf)3, very long-lived photoproducts were observed. Under steady-state irradiation conditions using a flux of (6.74 ± 0.21) × 10(15) photons per second at 450 nm, the formation of twofold oxidized oligotriarylamine (OTA(2+)) was detected in aerated CH3CN containing 0.02 M Sc(3+), as demonstrated unambiguously by comparison with UV-Vis absorption spectra obtained in the course of chemical oxidation with Cu(2+). Photodriven charge accumulation on the OTA unit of Ru-OTA and AQ-Ru-OTA is possible due to the lowering of the O2 reduction potential caused by the interaction of superoxide with the strong Lewis acid Sc(3+). The presence of the anthraquinone unit in AQ-Ru-OTA accelerates the rate-determining reaction step for charge accumulation by a factor of 10 compared to the Ru-OTA dyad. This is attributed to the formation of Sc(3+)-stabilized anthraquinone radical anion intermediates in the triad. Possible mechanistic pathways leading to charge accumulation are discussed. Photodriven charge accumulation is of key importance for solar fuels because their production will have to rely on multi-electron chemistry rather than single-electron reaction steps. Our study is the first to demonstrate that metal ion-coupled electron transfer (MCET) can be exploited to accumulate charges on a given molecular unit using visible light as an energy input. The approach of using a combination of intra- and intermolecular electron transfer reactions which are enabled by MCET is conceptually novel, and the fundamental insights gained from our study are relevant in the greater context of solar energy conversion.
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Affiliation(s)
- Annabell G Bonn
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.
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Chen J, Wenger OS. Fluoride binding to an organoboron wire controls photoinduced electron transfer. Chem Sci 2015; 6:3582-3592. [PMID: 29511520 PMCID: PMC5659175 DOI: 10.1039/c5sc00964b] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 04/20/2015] [Indexed: 12/28/2022] Open
Abstract
We demonstrate that the rates for long-range electron transfer can be controlled actively by tight anion binding to a rigid rod-like molecular bridge. Electron transfer from a triarylamine donor to a photoexcited Ru(bpy)32+ acceptor (bpy = 2,2'-bipyridine) across a 2,5-diboryl-1,4-phenylene bridge occurs within less than 10 ns in CH2Cl2 at 22 °C. Fluoride anions bind with high affinity to the organoboron bridge due to strong Lewis base/Lewis acid interactions, and this alters the electronic structure of the bridge drastically. Consequently, a large tunneling barrier is imposed on photoinduced electron transfer from the triarylamine to the Ru(bpy)32+ complex and hence this process occurs more than two orders of magnitude more slowly, despite the fact that its driving force is essentially unaffected by fluoride addition. Electron transfer rates in proteins could potentially be regulated via a similar fundamental principle, because interactions between charged amino acid side chains and counter-ions can modulate electronic couplings between distant redox partners. In artificial donor-bridge-acceptor compounds, external stimuli have been employed frequently to control electron transfer rates, but the approach of exploiting strong Lewis acid/Lewis base interactions to regulate the tunneling barrier height imposed by a rigid rod-like molecular bridge is conceptually novel and broadly applicable, because it is largely independent of the donor and the acceptor, and because the effect is not based on a change of the driving-force for electron transfer. The principle demonstrated here can potentially be used to switch between conducting and insulating states of molecular wires between electrodes.
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Affiliation(s)
- Jing Chen
- Department of Chemistry , University of Basel , St. Johanns-Ring 19 , CH-4056 Basel , Switzerland .
- Xiamen Institute of Rare Earth Materials , Chinese Academy of Sciences , Xiamen 361021 , People's Republic of China
- Key Laboratory of Design and Assembly of Functional Nanostructures , Fujian Provincial Key Laboratory of Nanomaterials , Fujian Institute of Research on the Structure of Matter , Chinese Academy of Sciences , People's Republic of China
| | - Oliver S Wenger
- Department of Chemistry , University of Basel , St. Johanns-Ring 19 , CH-4056 Basel , Switzerland .
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Heinz LG, Yushchenko O, Neuburger M, Vauthey E, Wenger OS. Tetramethoxybenzene is a Good Building Block for Molecular Wires: Insights from Photoinduced Electron Transfer. J Phys Chem A 2015; 119:5676-84. [DOI: 10.1021/acs.jpca.5b03649] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Luisa G. Heinz
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland
| | - Oleksandr Yushchenko
- Department
of Physical Chemistry, University of Geneva, 30 quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland
| | - Markus Neuburger
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland
| | - Eric Vauthey
- Department
of Physical Chemistry, University of Geneva, 30 quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland
| | - Oliver S. Wenger
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland
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40
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Preiß J, Jäger M, Rau S, Dietzek B, Popp J, Martínez T, Presselt M. How Does Peripheral Functionalization of Ruthenium(II)-Terpyridine Complexes Affect Spatial Charge Redistribution after Photoexcitation at the Franck-Condon Point? Chemphyschem 2015; 16:1395-404. [DOI: 10.1002/cphc.201500223] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Indexed: 02/06/2023]
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41
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Nie HJ, Yao CJ, Sun MJ, Zhong YW, Yao J. Ruthenium-bis-terpyridine Complex with Two Redox-Asymmetric Amine Substituents: Potential-Controlled Reversal of the Direction of Charge-Transfer. Organometallics 2014. [DOI: 10.1021/om500904k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Hai-Jing Nie
- Beijing National Laboratory
for Molecular Sciences, CAS Key Laboratory of Photochemistry, Institute
of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Chang-Jiang Yao
- Beijing National Laboratory
for Molecular Sciences, CAS Key Laboratory of Photochemistry, Institute
of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Meng-Jia Sun
- Beijing National Laboratory
for Molecular Sciences, CAS Key Laboratory of Photochemistry, Institute
of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Yu-Wu Zhong
- Beijing National Laboratory
for Molecular Sciences, CAS Key Laboratory of Photochemistry, Institute
of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Jiannian Yao
- Beijing National Laboratory
for Molecular Sciences, CAS Key Laboratory of Photochemistry, Institute
of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
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42
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Bonn AG, Neuburger M, Wenger OS. Photoinduced Electron Transfer in Rhenium(I)–Oligotriarylamine Molecules. Inorg Chem 2014; 53:11075-85. [DOI: 10.1021/ic501620g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Annabell G. Bonn
- Department of Chemistry, University of Basel, St. Johanns-Ring
19, CH-4056 Basel, Switzerland
| | - Markus Neuburger
- Department of Chemistry, University of Basel, St. Johanns-Ring
19, CH-4056 Basel, Switzerland
| | - Oliver S. Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring
19, CH-4056 Basel, Switzerland
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43
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Lee SH, Chan CTL, Wong KMC, Lam WH, Kwok WM, Yam VWW. Synthesis and photoinduced electron transfer in platinum(ii) bis(N-(4-ethynylphenyl)carbazole)bipyridine fullerene complexes. Dalton Trans 2014; 43:17624-34. [DOI: 10.1039/c4dt01397b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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44
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Chen J, Kuss-Petermann M, Wenger OS. Dependence of Reaction Rates for Bidirectional PCET on the Electron Donor–Electron Acceptor Distance in Phenol–Ru(2,2′-Bipyridine)32+ Dyads. J Phys Chem B 2014; 119:2263-73. [DOI: 10.1021/jp506087t] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jing Chen
- Department of Chemistry, University of Basel, St. Johanns-Ring
19, CH-4056 Basel, Switzerland
| | - Martin Kuss-Petermann
- Department of Chemistry, University of Basel, St. Johanns-Ring
19, CH-4056 Basel, Switzerland
| | - Oliver S. Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring
19, CH-4056 Basel, Switzerland
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45
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Lee SH, Chan CTL, Wong KMC, Lam WH, Kwok WM, Yam VWW. Design and Synthesis of Bipyridine Platinum(II) Bisalkynyl Fullerene Donor–Chromophore–Acceptor Triads with Ultrafast Charge Separation. J Am Chem Soc 2014; 136:10041-52. [DOI: 10.1021/ja5040073] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Sai-Ho Lee
- Department
of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China
| | - Chris Tsz-Leung Chan
- Department
of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong
Kong, P.R. China
| | - Keith Man-Chung Wong
- Department
of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China
| | - Wai Han Lam
- Department
of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China
| | - Wai-Ming Kwok
- Department
of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong
Kong, P.R. China
| | - Vivian Wing-Wah Yam
- Department
of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China
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Dwaraknath S, Tran NH, Dao T, Colbert A, Mullen S, Nguyen A, Cortez A, Cheruzel L. A facile and versatile methodology for cysteine specific labeling of proteins with octahedral polypyridyl d⁶ metal complexes. J Inorg Biochem 2014; 136:154-60. [PMID: 24468675 PMCID: PMC4058400 DOI: 10.1016/j.jinorgbio.2013.12.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 12/30/2013] [Accepted: 12/31/2013] [Indexed: 01/02/2023]
Abstract
We have synthesized and characterized four octahedral polypyridyl d(6) metal complexes bearing the 5,6-epoxy-5,6-dihydro-[1,10]phenanthroline ligand (L1) as cysteine specific labeling reagents. The proposed synthetic pathways allow the preparation of the metal complexes containing Re(I), Ru(II), Os(II) and Ir(III) while preserving the epoxide functionality. The complexes were characterized by (1)H and (13)C NMR, mass spectrometry, UV-visible and luminescence spectroscopies as well as cyclic voltammetry. As proof of concept, a set of non-native single cysteine P450 BM3 heme domain mutants previously developed in our laboratory was used to study the labeling reaction. We demonstrate that the proposed labels can selectively react, often in high yield, with cysteine residues of the protein via the nucleophilic thiol ring opening of the epoxide moiety. In addition, under basic conditions, subsequent loss of a water molecule led to the aromatization of the phenanthroline ring on the protein-bound label compounds, as observed by mass spectrometry and luminescence measurements.
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Affiliation(s)
- Sudharsan Dwaraknath
- San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States
| | - Ngoc-Han Tran
- San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States
| | - Thanh Dao
- San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States
| | - Alexander Colbert
- San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States
| | - Sarah Mullen
- San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States
| | - Angelina Nguyen
- San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States
| | - Alejandro Cortez
- San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States
| | - Lionel Cheruzel
- San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States.
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Farran R, Jouvenot D, Loiseau F, Chauvin J, Deronzier A. Photoelectric conversion at a [Ru(bpy)3]2+-based metallic triad anchored on ITO surface. Dalton Trans 2014; 43:12156-9. [DOI: 10.1039/c4dt01884b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A tri-metallic triad was built on ITO by a stepwise procedure, exhibiting photocurrent properties.
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Affiliation(s)
- Rajaa Farran
- Université Grenoble Alpes
- DCM
- 38041 Grenoble Cedex 9, France
| | | | | | - Jérôme Chauvin
- Université Grenoble Alpes
- DCM
- 38041 Grenoble Cedex 9, France
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Nguyen MH, Nguyen VH, Yip JHK. Sequence-Specific Synthesis of Platinum-Conjugated Trichromophoric Energy Cascades of Anthracene, Tetracene, and Pentacene and Fluorescent “Black Chromophores”. Organometallics 2013. [DOI: 10.1021/om400578t] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Minh-Hai Nguyen
- Department
of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543
| | - Van Ha Nguyen
- Department
of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543
| | - John H. K. Yip
- Department
of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543
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Abstract
Proton-coupled electron transfer (PCET) plays a crucial role in many enzymatic reactions and is relevant for a variety of processes including water oxidation, nitrogen fixation, and carbon dioxide reduction. Much of the research on PCET has focused on transfers between molecules in their electronic ground states, but increasingly researchers are investigating PCET between photoexcited reactants. This Account describes recent studies of excited-state PCET with d(6) metal complexes emphasizing work performed in my laboratory. Upon photoexcitation, some complexes release an electron and a proton to benzoquinone reaction partners. Others act as combined electron-proton acceptors in the presence of phenols. As a result, we can investigate photoinduced PCET involving electron and proton transfer in a given direction, a process that resembles hydrogen-atom transfer (HAT). In other studies, the photoexcited metal complexes merely serve as electron donors or electron acceptors because the proton donating and accepting sites are located on other parts of the molecular PCET ensemble. We and others have used this multisite design to explore so-called bidirectional PCET which occurs in many enzymes. A central question in all of these studies is whether concerted proton-electron transfer (CPET) can compete kinetically with sequential electron and proton transfer steps. Short laser pulses can trigger excited-state PCET, making it possible to investigate rapid reactions. Luminescence spectroscopy is a convenient tool for monitoring PCET, but unambiguous identification of reaction products can require a combination of luminescence spectroscopy and transient absorption spectroscopy. Nevertheless, in some cases, distinguishing between PCET photoproducts and reaction products formed by simple photoinduced electron transfer (ET) (reactions that don't include proton transfer) is tricky. Some of the studies presented here deal directly with this important problem. In one case study we employed a cyclometalated iridium(III) complex. Our other studies with ruthenium(II) complexes and phenols focused on systematic variations of the reaction free energies for the CPET, ET, and proton transfer (PT) steps to explore their influence on the overall PCET reaction. Still other work with rhenium(I) complexes concentrated on the question of how the electronic structure of the metal-to-ligand charge transfer (MLCT) excited states affects PCET. We used covalent rhenium(I)-phenol dyads to explore the influence of the electron donor-electron acceptor distance on bidirectional PCET. In covalent triarylamine-Ru(bpy)₃²⁺/Os(bpy)₃²⁺-anthraquinone triads (bpy = 2,2'-bipyridine), hydrogen-bond donating solvents significantly lengthened the lifetimes of photogenerated electron/hole pairs because of hydrogen-bonding to the quinone radical anion. Until now, comparatively few researchers have investigated this variation of PCET: the strengthening of H-bonds upon photoreduction.
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Affiliation(s)
- Oliver S. Wenger
- Departement Chemie, Universität Basel, Spitalstrasse 51, CH-4056 Basel, Switzerland
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