uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Steric influence on the excited-state lifetimes of ruthenium complexes with bipyridyl-alkanylene-pyridyl ligands.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
Show others and affiliations
2008 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 47, no 9, 3540-3548 p.Article in journal (Refereed) Published
Abstract [en]

The structural effect on the metal-to-ligand charge transfer (MLCT) excited-state lifetime has been investigated in bis-tridentate Ru(II)-polypyridyl complexes based on the terpyridine-like ligands [6-(2,2'-bipyridyl)](2-pyridyl)methane (1) and 2-[6-(2,2'-bipyridyl)]-2-(2-pyridyl)propane (2). A homoleptic ([Ru(2)(2)](2+)) and a heteroleptic complex ([Ru(ttpy)(2)](2+)) based on the new ligand 2 have been prepared and their photophysical and structural properties studied experimentally and theoretically and compared to the results for the previously reported [Ru(1)(2)](2+). The excited-state lifetime of the homoleptic Ru-II complex with the isopropylene-bridged ligand 2 was found to be 50 times shorter than that of the corresponding homoleptic Ru-II complex of ligand 1, containing a methylene bridge. A comparison of the ground-state geometries of the two homoleptic complexes shows that steric interactions involving the isopropylene bridges make the coordination to the central Ru-II ion less octahedral in [Ru(2)(2)](2+) than in [Ru(1)(2))(2+). Calculations indicate that the structural differences in these complexes influence their ligand field splittings as well as the relative stabilities of the triplet metal-to-ligand charge transfer ((MLCT)-M-3) and metal-centered ((MC)-M-3) excited states. The large difference in measured excited-state lifetimes for the two homoleptic Ru-II complexes is attributed to a strong influence of steric interactions on the ligand field strength, which in turn affects the activation barriers for thermal conversion from (MLCT)-M-3 states to short-lived (MC)-M-3 states.

Place, publisher, year, edition, pages
ACS , 2008. Vol. 47, no 9, 3540-3548 p.
National Category
Inorganic Chemistry Analytical Chemistry
Research subject
Analytical Chemistry
URN: urn:nbn:se:uu:diva-95085DOI: 10.1021/ic7019457ISI: 000255380500018PubMedID: 18402440OAI: oai:DiVA.org:uu-95085DiVA: diva2:169161
Available from: 2006-11-09 Created: 2006-11-09 Last updated: 2011-03-21Bibliographically approved
In thesis
1. Tuning of the Excited State Properties of Ruthenium(II)-Polypyridyl Complexes
Open this publication in new window or tab >>Tuning of the Excited State Properties of Ruthenium(II)-Polypyridyl Complexes
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Processes where a molecule absorbs visible light and then converts the solar energy into chemical energy are important in many biological systems, such as photosynthesis and also in many technical applications e.g. photovoltaics. This thesis describes a part of a multidisciplinary project, aiming at a functional mimic of the natural photosynthesis, with the overall goal of production of a renewable fuel from sun and water. More specific, the thesis is focused on design and photophysical characterization of new photosensitizers, i.e. light absorbers that should be capable of transferring electrons to an acceptor and be suitable building blocks for supramolecular rod-like donor-photosensitizer-acceptor arrays.

The excited state lifetime, the excited state energy and the geometry are important properties for a photosensitizer. The work presented here describes a new strategy to obtain longer excited state lifetimes of the geometrically favorable Ru(II)-bistridentate type complexes, without a concomitant substantial decrease in excited state energy. The basic idea is that a more octahedral coordination around the Ru will lead to longer excited state lifetimes. In the first generation of new photosensitizers a 50-fold increase of the excited state lifetime was observed, going from 0.25 ns for the model complex to 15 ns for the best photosensitizer. The second generation goes another step forward, to an excited state lifetime of 810 ns. Furthermore, the third generation of new photosensitizers show excited state lifetimes in the 0.45 - 5.5 microsecond region at room temperature, a significant improvement. In addition, the third generation of photosensitizers are suitable for further symmetric attachment of electron donor and acceptor motifs, and it is shown that the favorable properties are maintained upon the attachment of anchoring groups. The reactivity of the excited state towards light-induced reactions is proved and the photostability is sufficient so the new design strategy has proven successful.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2006. 79 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 237
Physical chemistry, Artificial photosynthesis, Ruthenium(II), Bistridentate complexes, Excited state lifetime, Linear donor-photosenstizer-acceptor arrays, Temperature dependence, Excited state decay, Fysikalisk kemi
urn:nbn:se:uu:diva-7230 (URN)91-554-6707-5 (ISBN)
Public defence
2006-12-01, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:30
Available from: 2006-11-09 Created: 2006-11-09 Last updated: 2011-06-10Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textPubMed

Search in DiVA

By author/editor
Bergquist, Jonas
By organisation
Department of Photochemistry and Molecular ScienceDepartment of Quantum ChemistryAnalytical ChemistryDepartment of Biochemistry and Organic Chemistry
In the same journal
Inorganic Chemistry
Inorganic ChemistryAnalytical Chemistry

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 526 hits
ReferencesLink to record
Permanent link

Direct link