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From organic mixed valence to photoinduced proton-coupled multi-electron transfer

Applicant Wenger Oliver
Number 146231
Funding scheme Project funding
Research institution Institut für Anorganische Chemie Universität Basel
Institution of higher education University of Basel - BS
Main discipline Inorganic Chemistry
Start/End 01.10.2013 - 31.05.2018
Approved amount 481'258.00
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All Disciplines (3)

Discipline
Inorganic Chemistry
Physical Chemistry
Organic Chemistry

Keywords (4)

laser spectroscopy; electron transfer; photochemistry; coordination chemistry

Lay Summary (German)

Lead
Protonengekoppelte Elektronenübertragungsreaktionen spielen eine wichtige Rolle in der Photosynthese. Die lichtinduzierte Übertragung einzelner Elektronen von einem Reaktionspartner auf einen anderen ist mittlerweile recht gut verstanden. Im Hinblick auf eine künstliche Photosynthese scheint jedoch ein besseres Verständnis von protonengekoppelten Elektronenübertragungsreaktionen wünschenswert.
Lay summary

Inhalt und Ziel des Forschungsprojekts

Im Rahmen dieses Forschungsvorhabens sollen grundlegende Aspekte des lichtinduzierten protonengekoppelten Elektronentransfers an geeigneten chemischen Modellsystemen, die eigens dafür hergestellt werden, systematisch mit optisch-spektroskopischen und elektrochemischen Methoden untersucht werden. Ein wichtiges Ziel dabei ist die Ermittlung der Triebkraft- und Distanzabhängigkeit der Geschwindigkeitskonstanten von protonengekoppelten Elektronenübertragungen. Des Weiteren sollen molekulare Systeme hergestellt und untersucht werden, in denen nach Lichtanregung nicht nur einzelne, sondern zwei oder mehrere Elektronen von einem Reaktionspartner auf einen anderen übertragen werden können.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

Dieses Forschungsvorhaben soll neue Erkenntnisse im Hinblick auf die Umwandlung von Sonnenenergie in chemisch gespeicherte Energie liefern. Ein mögliches langfristiges Ziel dieser Grundlagenforschung ist die künstliche Photosynthese.
Direct link to Lay Summary Last update: 28.03.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Circular Photoinduced Electron Transfer in a Donor-Acceptor- Acceptor Triad
Larsen Christopher B., Wenger Oliver S. (2018), Circular Photoinduced Electron Transfer in a Donor-Acceptor- Acceptor Triad, in Angew. Chem. Int. Ed., 57, 841-845.
Electron Transfer around a Molecular Corner
Schmidt Hauke C., Larsen Christopher B., Wenger Oliver S. (2018), Electron Transfer around a Molecular Corner, in Angew. Chem. Int. Ed., 57, 10.1002/an.
Exploiting Potential Inversion for Photoinduced Multielectron Transfer and Accumulation of Redox Equivalents in a Molecular Heptad
Nomrowski Julia, Wenger Oliver S. (2018), Exploiting Potential Inversion for Photoinduced Multielectron Transfer and Accumulation of Redox Equivalents in a Molecular Heptad, in J. Am. Chem. Soc., 140, 10.1021/ja.
Exceptionally Long-Lived Photodriven Multi-Electron Storage without Sacrificial Reagents
Kuss-Petermann Martin, Wenger Oliver S. (2017), Exceptionally Long-Lived Photodriven Multi-Electron Storage without Sacrificial Reagents, in Chem. Eur. J., 23, 10808-10814.
Intramolecular Light-Driven Accumulation of Reduction Equivalents by Proton-Coupled Electron Transfer
Kuss-Petermann Martin, Orazietti Margherita, Neuburger Markus, Hamm Peter, Wenger Oliver S. (2017), Intramolecular Light-Driven Accumulation of Reduction Equivalents by Proton-Coupled Electron Transfer, in J. Am. Chem. Soc., 139, 5225-5232.
Photoinduced Electron Transfer Coupled to Donor Deprotonation and Acceptor Protonation in a Molecular Triad Mimicking Photosystem II
Pannwitz Andrea, Wenger Oliver S. (2017), Photoinduced Electron Transfer Coupled to Donor Deprotonation and Acceptor Protonation in a Molecular Triad Mimicking Photosystem II, in J. Am. Chem. Soc., 139, 13308-13311.
Pump-Pump-Probe Spectroscopy of a Molecular Triad Monitoring Detrimental Processes for Photoinduced Charge Accumulation
Kuss-Petermann Martin, Wenger Oliver S. (2017), Pump-Pump-Probe Spectroscopy of a Molecular Triad Monitoring Detrimental Processes for Photoinduced Charge Accumulation, in Helv. Chim. Acta, 100, e1600283.
Charge Transfer Pathways in Three Isomers of Naphthalene-Bridged Organic Mixed Valence Compounds
Schmidt Hauke C., Spulber Mariana, Neuburger Markus, Palivan Cornelia G., Meuwly Markus, Wenger Oliver S. (2016), Charge Transfer Pathways in Three Isomers of Naphthalene-Bridged Organic Mixed Valence Compounds, in J. Org. Chem., 81, 595-602.
Electron Accumulation in a Molecular Pentad
Orazietti Margherita, Kuss-Petermann Martin, Hamm Peter, Wenger Oliver S. (2016), Electron Accumulation in a Molecular Pentad, in Angew. Chem. Int. Ed., 55, 9407-9410.
Electron Transfer Rate Maxima at Large Donor−Acceptor Distances
Kuss-Petermann Martin, Wenger Oliver S. (2016), Electron Transfer Rate Maxima at Large Donor−Acceptor Distances, in J. Am. Chem. Soc., 138, 1349-1358.
Increasing Electron Transfer Rates with Increasing Donor-Acceptor Distance
Kuss-Petermann Martin, Wenger Oliver S. (2016), Increasing Electron Transfer Rates with Increasing Donor-Acceptor Distance, in Angew. Chem. Int. Ed., 55, 815-819.
Photoinduced Electron Transfer in an Anthraquinone-[Ru(bpy)3]2+-Oligotriarylamine-[Ru(bpy)3]2+- Anthraquinone Pentad
Bonn Annabell G., Yushchenko Oleksandr, Vauthey Eric, Wenger Oliver S. (2016), Photoinduced Electron Transfer in an Anthraquinone-[Ru(bpy)3]2+-Oligotriarylamine-[Ru(bpy)3]2+- Anthraquinone Pentad, in Inorg. Chem., 55, 2894-2899.
Proton coupled electron transfer from the excited state of a ruthenium(II) pyridylimidazole complex
Pannwitz Andrea, Wenger Oliver S. (2016), Proton coupled electron transfer from the excited state of a ruthenium(II) pyridylimidazole complex, in Phys. Chem. Chem. Phys., 18, 11374-11382.
Reaction Rate Maxima at Large Distances between Reactants
Kuss-Petermann Martin, Wenger Oliver S. (2016), Reaction Rate Maxima at Large Distances between Reactants, in Chimia, 70, 177-181.
Unusual Distance Dependences of Electron Transfer Rates
Kuss-Petermann Martin, Wenger Oliver S. (2016), Unusual Distance Dependences of Electron Transfer Rates, in Phys. Chem. Chem. Phys., 18, 18657-18664.
Charge Transfer Emission in Oligotriarylamine−Triarylborane Compounds
Bonn Annabell G., Wenger Oliver S. (2015), Charge Transfer Emission in Oligotriarylamine−Triarylborane Compounds, in J. Org. Chem., 80, 4097-4107.
Dependence of Reaction Rates for Bidirectional PCET on the Electron Donor−Electron Acceptor Distance in Phenol−[Ru(2,2′-Bipyridine)3]2+ Dyads
Chen Jing, Kuss-Petermann Martin, Wenger Oliver S. (2015), Dependence of Reaction Rates for Bidirectional PCET on the Electron Donor−Electron Acceptor Distance in Phenol−[Ru(2,2′-Bipyridine)3]2+ Dyads, in J. Phys. Chem. B, 119, 2263-2273.
Fluoride binding to an organoboron wire controls photoinduced electron transfer
Chen Jing, Wenger Oliver S. (2015), Fluoride binding to an organoboron wire controls photoinduced electron transfer, in Chem. Sci., 6, 3582-3592.
Photoinduced Charge Accumulation by Metal Ion-Coupled Electron Transfer
Bonn Annabell G., Wenger Oliver S. (2015), Photoinduced Charge Accumulation by Metal Ion-Coupled Electron Transfer, in Phys. Chem. Chem. Phys., 17, 24001-24010.
Photoinduced Charge Accumulation in Molecular Systems
Bonn Annabell G., Wenger Oliver S. (2015), Photoinduced Charge Accumulation in Molecular Systems, in Chimia, 69, 17-21.
Photoinduced PCET in Ruthenium−Phenol Systems: Thermodynamic Equivalence of Uni- and Bidirectional Reactions
Nomrowski Julia, Wenger Oliver S. (2015), Photoinduced PCET in Ruthenium−Phenol Systems: Thermodynamic Equivalence of Uni- and Bidirectional Reactions, in Inorg. Chem., 54, 3680-3687.
Tetramethoxybenzene is a Good Building Block for Molecular Wires: Insights from Photoinduced Electron Transfer
Heinz Luisa G., Yushchenko Oleksandr, Neuburger Markus, Vauthey Eric, Wenger Oliver S. (2015), Tetramethoxybenzene is a Good Building Block for Molecular Wires: Insights from Photoinduced Electron Transfer, in J. Phys. Chem. A, 119, 5676-5684.
Charge Delocalization in an Organic Mixed Valent Bithiophene Is Greater Than in a Structurally Analogous Biselenophene
Jahnke Ann Christin, Proppe Jonny, Spulber Mariana, Palivan Cornelia G., Herrmann Carmen, Wenger Oliver S. (2014), Charge Delocalization in an Organic Mixed Valent Bithiophene Is Greater Than in a Structurally Analogous Biselenophene, in J. Phys. Chem. A, 118, 11293-11303.
Distance Dependence of Bidirectional Concerted Proton–Electron Transfer in Phenol-[Ru(2,2'-bipyridine)3]2+ Dyads
Chen Jing, Kuss-Petermann Martin, Wenger Oliver S. (2014), Distance Dependence of Bidirectional Concerted Proton–Electron Transfer in Phenol-[Ru(2,2'-bipyridine)3]2+ Dyads, in Chem. Eur. J., 20, 4098-4104.
Electronic coupling mediated by furan, thiophene, selenophene and tellurophene in a homologous series of organic mixed valence compounds
Jahnke Ann Christin, Spulber Mariana, Neuburger Markus, Palivan Cornelia G., Wenger Oliver S. (2014), Electronic coupling mediated by furan, thiophene, selenophene and tellurophene in a homologous series of organic mixed valence compounds, in Chem. Commun., 50, 10883-10886.
Long-range proton-coupled electron transfer in phenol–[Ru(2,2'-bipyrazine)3]2+ dyads
Bronner Catherine, Wenger Oliver S. (2014), Long-range proton-coupled electron transfer in phenol–[Ru(2,2'-bipyrazine)3]2+ dyads, in Phys. Chem. Chem. Phys., 16, 3617-3622.
Photoinduced Electron Transfer in Rhenium(I)−Oligotriarylamine Molecules
Bonn Annabell G., Neuburger Markus, Wenger Oliver S. (2014), Photoinduced Electron Transfer in Rhenium(I)−Oligotriarylamine Molecules, in Inorg. Chem., 53, 11075-11085.
Mechanistic Diversity in Proton-Coupled Electron Transfer between Thiophenols and Photoexcited [Ru(2,2′-Bipyrazine)3]2+
Kuss-Petermann Martin, Wenger Oliver S. (2013), Mechanistic Diversity in Proton-Coupled Electron Transfer between Thiophenols and Photoexcited [Ru(2,2′-Bipyrazine)3]2+, in J. Phys. Chem. Lett., 4, 2535-2539.

Collaboration

Group / person Country
Types of collaboration
Peter Hamm, Universität Zürich Switzerland (Europe)
- Publication
Prof. Carmen Herrmann, University of Hamburg Germany (Europe)
- Publication
Cornelia G. Palivan, Universität Basel Switzerland (Europe)
- Publication
Eric Vauthey, Université de Genève Switzerland (Europe)
- Publication
Markus Meuwly, Universität Basel Switzerland (Europe)
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Seminar, Université de Montréal Individual talk From Photoinduced Electron Transfer and Photoredox Catalysis to New Photosensitizers 15.03.2018 Montreal, Canada Wenger Oliver;
Molecular biradicals: structure, properties and reactivity Talk given at a conference Biradicals from Photoinduced Electron Transfer in Donor-Bridge-Acceptor Compounds 27.02.2018 Würzburg, Germany Wenger Oliver;
Frontiers in Photochemistry Talk given at a conference Proton-Coupled Electron Transfer Reactions for Light-Driven Accumulation of Redox Equivalents 18.02.2018 Cancun, Mexico Wenger Oliver;
Seminar, Ecole nomale supérieure de Lyon Individual talk Photoinduced Electron Transfer and Luminescent Metal Complexes 31.01.2018 Lyon, France Wenger Oliver;
Institutsseminar, Westfälische Wilhemls-Universität Münster Individual talk From Photoinduced Electron Transfer to Charge Accumulation and New Photosensitizers 18.01.2018 Münster, Germany Wenger Oliver;
GDCh Vortrag, Friedrich-Alexander-Universität Erlangen Individual talk From Photoinduced Electron Transfer to Charge Accumulation and New Photosensitizers 21.12.2017 Erlangen, Germany Wenger Oliver;
Seminar, City University of Hong Kong Individual talk From Photoinduced Electron Transfer to Charge Accumulation and New Photosensitizers 24.11.2017 Hongkong, Hongkong Wenger Oliver;
Seminar, The University of Hong Kong Individual talk From Photoinduced Electron Transfer to Charge Accumulation and New Photosensitizers 23.11.2017 Hongkong, Hongkong Wenger Oliver;
Seminar, Southern University of Science and Technology, SUSTECH Individual talk From Photoinduced Electron Transfer to Charge Accumulation and New Photosensitizers 21.11.2017 Shenzhen, China Wenger Oliver;
Solchem 2017 Talk given at a conference From Photoinduced Electron Transfer to Charge Accumulation and New Photosensitizers 08.10.2017 Ulm, Germany Wenger Oliver;
Institutsseminar, Université de Paris-Saclay Individual talk From Photoinduced Electron Transfer to Charge Accumulation and New Photosensitizers 05.10.2017 Paris-Saclay, France Wenger Oliver;
Seminar, University of Padova Individual talk From Photoinduced Electron Transfer to Charge Accumulation and New Photosensitizers 28.09.2017 Padua, Italy Wenger Oliver;
International Symposium on Photophysics and Photochemistry of Coordination Compounds Talk given at a conference Luminescent Cr(0), Mo(0) and Ni(0) Isocyanide Chelate Complexes and Their Applications 09.07.2017 Oxford, Great Britain and Northern Ireland Herr Patrick; Malzkuhn Sabine; Wenger Oliver;
International Conference on Hydrogen Atom Transfer Talk given at a conference From Single Electron Transfer to Multi-Electron Multi-Proton Photochemistry in Donor-Acceptor Compounds 02.07.2017 Monteporzio Catone, Italy Wenger Oliver;
From Photoinduced Electron Transfer to New Luminophores, Photocatalysis and Artificial Photosynthesis Individual talk Departementsseminar, Universität Bern 15.06.2017 Bern, Switzerland Wenger Oliver;
Kolloquium in Anorganischer Chemie, Universität Stuttgart Individual talk From Photoinduced Electron and Proton Transfer to New Luminophores, Photocatalysis and Artificial Photosynthesis 16.05.2017 Stuttgart, Germany Wenger Oliver;
Kavli Meeting Talk given at a conference Electron tunneling through organic molecules 14.05.2017 Chicheley Hall, Great Britain and Northern Ireland Wenger Oliver;
Seminarvortrag, Université de Paris-Diderot Individual talk From photoinduced electron transfer to light-driven charge accumulation and new photosensitizers 21.01.2017 Paris, France Wenger Oliver;
Vorstellungsvortrag, Universität Regensburg Individual talk Photoinduced electron and proton transfer with metal complexes and organic molecules 27.10.2016 Regensburg, Germany Wenger Oliver;
Seminarvortrag, Queen Mary University of London Individual talk Photoinduced electron and proton transfer with metal complexes and organic molecules 21.10.2016 London, Great Britain and Northern Ireland Wenger Oliver;
Seminarvortrag, École nationale supérieure de chimie de Mulhouse Individual talk Photoinduced Electron Transfer with Metal Complexes and Organic Molecules 29.09.2016 Mulhouse, France Wenger Oliver;
EuCheMS Chemistry Congress Talk given at a conference Photoinduced Accumulation of Reduction Equivalents for Sustainable Solar Energy Conversion 11.09.2016 Sevilla, Spain Wenger Oliver;
COST action CM1202 Final Action Meeting Talk given at a conference Photoinduced long-range electron transfer across molecular bridges and wires 04.09.2016 Milazzo, Italy Wenger Oliver;
International Conference on Coordination Chemistry Talk given at a conference Photoinduced long-range electron transfer across molecular bridges and wires 03.07.2016 Brest, France Pannwitz Andrea; Wenger Oliver;
Swiss NanoConvention Talk given at a conference Photoinduced long-range electron transfer across molecular bridges and wires 30.06.2016 Basel, Switzerland Wenger Oliver;
Seminar, Kyoto University Individual talk Long-range electron transfer across molecular bridges and wires 27.06.2016 Kyoto, Japan Wenger Oliver;
2nd International Symposium on Chemical Energy Conversion Processes Talk given at a conference Light-driven charge accumulation and other fundamental processes for solar energy conversion 22.05.2016 Fukuoka, Japan Wenger Oliver;
Kolloquium in Anorganischer Chemie Individual talk Light-driven charge accumulation and other fundamental processes for solar energy conversion 17.05.2016 Göttingen, Germany Wenger Oliver;
Molecules and Materials for Arficial Photosynthesis Conference Talk given at a conference Light-driven charge accumulation in molecular systems 25.02.2016 Cancun, Mexico Wenger Oliver;
Central European Conference on Photochemistry Talk given at a conference Increasing rates for phototriggered electron transfer with increasing donor-acceptor distance 14.02.2016 Bad Hofgastein, Austria Wenger Oliver;
Institutsvortrag Université de Strasbourg Individual talk Photoinduced electron and proton transfer with metal complexes and organic molecules 10.12.2015 Strasbourg, France Wenger Oliver;
Institutsvortrag ETH Zürich Individual talk Photoinduced electron and proton transfer with metal complexes and organic molecules 10.11.2015 Zürich, Switzerland Wenger Oliver;
KOPO, Tagung über Konjugierte Oligomere und Polymere Talk given at a conference Fluoride binding to an organoboron wire controls photoinduced long-range electron transfer 27.09.2015 Würzburg, Germany Chen Jing; Wenger Oliver;
Molesco workshop Talk given at a conference Photoinduced long-range electron transfer in donor-bridge-acceptor compounds 15.09.2015 Regensburg, Germany Wenger Oliver;
COST action CM1202 Progress Meeting Talk given at a conference Photoinduced charge accumulation in molecular systems 02.09.2015 Gdansk, Poland Wenger Oliver;
27th International Conference on Photochemistry Talk given at a conference Photoinduced proton-coupled electron transfer and charge accumulation in molecular systems 28.06.2015 Jeju Island, Korean Republic (South Korea) Wenger Oliver;
98th Canadian Chemistry Conference and Exhibition Talk given at a conference Photoinduced electron transfer and charge accumulation in molecular systems 13.06.2015 Ottawa, Canada Chen Jing; Wenger Oliver;
International Conference of Computational Methods in Sciences and Engineering Talk given at a conference Photoinduced Electron and Proton Transfer with Metal Complexes and Organic Molecules 20.03.2015 Athen, Greece Wenger Oliver;
Kolloquium in Anorganischer Chemie Individual talk Photoinduced Electron and Proton Transfer with Metal Complexes and Organic Molecules 09.12.2014 Mainz, Germany Wenger Oliver;
GDCh Seminar Individual talk Photoinduced Electron and Proton Transfer with Metal Complexes and Organic Molecules 23.10.2014 Ulm, Germany Wenger Oliver;
24th Lecture Conference on Photochemistry (GDCh) Talk given at a conference Proton-Coupled Electron Transfer with Photoexcited Metal Complexes 29.09.2014 Köln, Germany Kuss-Petermann Martin; Wenger Oliver;
Wöhler-Tagung der GDCh Talk given at a conference Proton-coupled electron transfer with photoexcited d6 metal complexes 24.09.2014 Saarbrücken, Germany Kuss-Petermann Martin; Wenger Oliver;
Seminar, Paul Scherrer Institut Individual talk Photoinduced Electron and Proton Transfer with Metal Complexes and Organic Molecules 12.09.2014 Villigen, Switzerland Wenger Oliver;
LightChEC Symposium and Summer School Talk given at a conference Long-range electron transfer 09.09.2014 Les Diablerets, Switzerland Kuss-Petermann Martin; Wenger Oliver;
Fall 2014 American Chemical Society National Meeting Talk given at a conference Proton-Coupled Electron Transfer with Photoexcited Metal Complexes 10.08.2014 San Francisco, CA, United States of America Kuss-Petermann Martin; Wenger Oliver;
Fall 2014 American Chemical Society National Meeting Talk given at a conference Long-range electron tunneling and proton-coupled electron transfer with photoexcited ruthenium(II), rhenium(I) and iridium(III) complexes 10.08.2014 San Francisco, CA, United States of America Chen Jing; Kuss-Petermann Martin; Wenger Oliver;
Fall 2014 American Chemical Society National Meeting Talk given at a conference Charge-delocalization in mixed-valent chalcogenophenes 10.08.2014 San Francisco, CA, United States of America Wenger Oliver; Jahnke Ann Christin;
International Conference on Coordination Chemistry Talk given at a conference Light-Driven Proton-Coupled Electron Transfer with Metal Complexes for Solar Energy Conversion 21.07.2014 Singapur, Singapore Kuss-Petermann Martin; Wenger Oliver;
International Conference on Hydrogen Atom Transfer Talk given at a conference Proton-coupled electron transfer with photoexcited metal complexes 22.06.2014 Monteporzio Catone, Italy Wenger Oliver; Kuss-Petermann Martin;
2nd International Conference on Proton-Coupled Electron Transfer Talk given at a conference Mechanistic studies of PCET with photoexcited metal complexes 15.06.2014 Uppsala, Sweden Kuss-Petermann Martin; Wenger Oliver;
Spring 2014 American Chemical Society National Meeting Talk given at a conference Thiophene- and phenylene-based molecular wires in organic mixed-valence compounds 16.03.2014 Dallas, TX, United States of America Jahnke Ann Christin; Wenger Oliver;
Spring 2014 American Chemical Society National Meeting Talk given at a conference Light-driven proton-coupled electron transfer with photoexcited metal complexes 16.03.2014 Dallas, TX, United States of America Wenger Oliver;
European Symposium on Current Challenges in Supramolecular Artificial Photosynthesis Talk given at a conference Light-driven proton-coupled electron transfer with metal complexes for solar energy conversion 12.03.2014 Jena, Germany Wenger Oliver; Pannwitz Andrea;
Central European Conference on Photochemistry Talk given at a conference Proton-Coupled Electron Transfer with Photoexcited Metal Complexes 09.02.2014 Bad Hofgastein, Austria Wenger Oliver;
Institutsseminar, Universität Zürich Individual talk Photoinduced electron and proton transfer with metal complexes and organic molecules 21.11.2013 Zürich, Switzerland Wenger Oliver;
Departmental Seminar, Université de Genève Individual talk Photoinduced electron and proton transfer with metal complexes and organic molecules 13.11.2013 Genf, Switzerland Wenger Oliver;
Inorganic Chemistry Seminar, University of Oxford Individual talk Photoinduced electron and proton transfer with metal complexes and organic molecules 22.10.2013 Oxford, Great Britain and Northern Ireland Wenger Oliver;


Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
Seniorenuni, Volkshochschule beider Basel Talk 11.04.2016 Basel, Switzerland Wenger Oliver;


Associated projects

Number Title Start Funding scheme
157777 High-end X-ray diffraction instrumentation for chemical crystallography 01.06.2015 R'EQUIP
110611 Long-Range Electron Tunneling and Proton-Coupled Electron Transfer 01.10.2006 SNSF Professorships
178760 Photoactive Metal Complexes from Earth-Abundant Elements and Multi-Electron Photochemistry in Donor-Acceptor Compounds 01.08.2018 Project funding
157687 Picosecond Transient Absorption Setup for Detection of Short-Lived Photoproducts and Excited States in Molecular Systems 01.11.2015 R'EQUIP

Abstract

Biological systems readily perform photoinduced proton-coupled multi-electron transfer reactions in fuel-forming processes, but no man-made system can even approximate their performance. Activation of small inert molecules such as H2O, CO2, or N2 to chemically more useful molecules (e. g., H2, HCOOH, or NH3) seems possible only via concerted transfer of multiple protons and electrons. Furthermore, these reactions usually require significant energy input. Solar light would be a particularly clean and abundant energy source for this purpose. The proposed research aims at understanding light-driven transfers of electrons and protons at the most fundamental level. This research is therefore directly relevant in the context of artificial photosynthesis, but the generation of fuels from solar light is not the primary goal of this 36-month project. The priority is on understanding some important fundamental aspects of light-to-chemical energy conversion in artificial model systems that will be synthesized specifically for this purpose. Toward this end, three lines of research with different focal points will be pursued.Sub-project 1 addresses the question over how many molecular units an electron can be delocalized in a given “molecular wire”. This research is important in order to be able to transport charge carriers over long distances. For artificial photosynthesis it will be necessary to achieve efficient spatial separation between electrons and holes. It is proposed to focus on oligo-selenophenes and oligo-tellurophenes which represent poorly explored classes of materials (Scheme 1a), particularly when compared to oligo-thiophenes which have already found use in numerous applications.Sub-project 2 focuses on the coupling of proton transfer to photoinduced electron transfer (Scheme 1b). An important goal is to elucidate under what circumstances the photoinduced transfer of an electron and a proton can occur in a concerted manner, and under what conditions the two particles preferably transfer in a stepwise (consecutive) fashion. This is important for example because photo-reduction of CO2 only appears thermodynamically feasible when occurring in concert with proton transfer. Another important goal of sub-project 2 is to explore the possibility of photoinduced long-range electron/proton transfers which formally correspond to hydrogen-atom transfer (HAT) reactions. Dyads and triads specifically designed for this purpose will be synthesized and investigated electrochemically and by transient absorption spectroscopy.In sub-project 3 molecular triads comprised of a donor (D), a sensitizer (S), and an acceptor (A) will be synthesized and investigated. In such triads long-lived charge-separated states of the type D+-S-A- are commonly accessible after photoexcitation. However, these simple charge-separated states are of limited use for further (secondary) chemistry because many of the most interesting chemical transformations require multiple electrons or holes. Therefore, sub-project 3 aims at the photo-generation of doubly charge-separated states of the type D2+-S-A2- (Scheme 1c) through stepwise two-photon excitation, similar to the photon upconversion processes explored by the applicant in the course of his Ph. D. research. In parallel, a molecular pentad offering the possibility for photoinduced two-electron reduction coupled to twofold protonation of an anthraquinone moiety will be synthesized. The three lines of research are to be pursued by 3 individual coworkers, and all of them will follow the “make-and-measure” philosophy of the applicant’s group, i. e., synthetic work will be complemented by electrochemical and optical spectroscopic experiments.
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