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Control over Excited State Intramolecular Proton Transfer and Photoinduced Tautomerization: Influence of the Hydrogen-Bond Geometry
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
Department of Chemistry, Yale University.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
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2015 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 17, 6362-6366 p.Article in journal (Refereed) Published
Abstract [en]

The influence of H-bond geometry on thedynamics of excited state intramolecular proton transfer(ESIPT) and photoinduced tautomerization in a series ofphenol-quinoline compounds is investigated. Control overthe proton donor–acceptor distance (dDA) and dihedralangle between the proton donor–acceptor subunits isachieved by introducing methylene backbone straps ofincreasing lengths to link the phenol and quinoline. Wedemonstrate that a long dDA correlates with a higher barrierfor ESIPT, while a large dihedral angle opens highlyefficient deactivation channels after ESIPT, preventing theformation of the fully relaxed tautomer photoproduct.

Place, publisher, year, edition, pages
2015. Vol. 21, no 17, 6362-6366 p.
Keyword [en]
excited state, fluorescence, hydrogen bonds, intramolecular proton transfer, phenols, tautomerism
National Category
Organic Chemistry
URN: urn:nbn:se:uu:diva-251468DOI: 10.1002/chem.201500244ISI: 000352796100008OAI: oai:DiVA.org:uu-251468DiVA: diva2:806218
Available from: 2015-04-19 Created: 2015-04-19 Last updated: 2015-07-07Bibliographically approved
In thesis
1. Synthesis of Biomimetic Systems for Proton and Electron Transfer Reactions in the Ground and Excited State
Open this publication in new window or tab >>Synthesis of Biomimetic Systems for Proton and Electron Transfer Reactions in the Ground and Excited State
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A detailed understanding of natural photosynthesis provides inspiration for the development of sustainable and renewable energy sources, i.e. a technology that is capable of converting solar energy directly into chemical fuels. This concept is called artificial photosynthesis. The work described in this thesis contains contributions to the development of artificial photosynthesis in two separate areas.

The first one relates to light harvesting with a focus on the question of how electronic properties of photosensitizers can be tuned to allow for efficient photo-induced electron transfer processes. The study is based on a series of bis(tridentate)ruthenium(II) polypyridyl complexes, the geometric properties of which make them highly appealing for the construction of linear donor-photosensitizer-acceptor arrangements for efficient vectorial photo-induced electron transfer reactions. The chromophores possess remarkably long lived 3MLCT excited states and it is shown that their excited-state oxidation strength can be altered by variations of the ligand scaffold over a remarkably large range of 900 mV.

The second area of relevance to natural and artificial photosynthesis that is discussed in this thesis relates to the coupled movement of protons and electrons. The delicate interplay between these two charged particles regulates thermodynamic and kinetic aspects in many key elementary steps of natural photosynthesis, and further studies are needed to fully understand this concept. The studies are based on redox active phenols with intramolecular hydrogen bonds to quinolines. The compounds thus bear a strong resemblance to the tyrosine/histidine couple in photosystem II, i.e. the water-plastoquinone oxidoreductase enzyme in photosynthesis. The design of the biomimetic models is such that the distance between the proton donor and acceptor is varied, enabling studies on the effect the proton transfer distance has on the rate of proton-coupled electron transfer reactions. The results of the studies have implications for the development of artificial photosynthesis, in particular in connection with redox leveling, charge accumulation, as well as electron and proton transfer.

In addition to these two contributions, the excited-state dynamics of the intramolecular hydrogen-bonded phenols was investigated, thereby revealing design principles for technological applications based on excited-state intramolecular proton transfer and photoinduced tautomerization.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 104 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1258
Solar energy conversion, artificial photosynthesis, hydrogen bonds, excited state intramolecular proton transfer, tautomerization, proton-coupled electron transfer, photosensitizer, ruthenium complex.
National Category
Organic Chemistry Physical Chemistry Inorganic Chemistry
Research subject
Chemistry with specialization in Organic Chemistry
urn:nbn:se:uu:diva-251471 (URN)978-91-554-9253-3 (ISBN)
Public defence
2015-06-12, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:00 (English)
Available from: 2015-05-22 Created: 2015-04-19 Last updated: 2015-07-07

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Parada, Giovanny A.Glover, Starla D.Hammarström, LeifOtt, SaschaZietz, Burkhard
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