Model of the iron hydrogenase active site covalently linked to a ruthenium photosensitizer: Synthesis and photophysical properties

Sascha Ott, Magnus Borgström, Mikael Kritikos, Reiner Lomoth, Jonas Bergquist, Björn Åkermark, Leif Hammarström, Licheng Sun

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Abstract

A model of the iron hydrogenase active site with the structure [μ-ADT)Fe2(CO)6] (ADT = azadithiolate (S-CH 2-NR-CH2-S), (2: R = 4-bromophenyl, 3: R = 4-iodophenyl)) has been assembled and covalently linked to a [Ru(terpy)2] 2+ photosensitizer. This trinuclear complex 1 represents one synthetic step toward the realization of our concept of light-driven proton reduction. A rigid phenylacetylene tether has been incorporated as the linking unit in 1 in order to prolong the lifetime of the otherwise short-lived [Ru(terpy)2]2+ excited state. The success of this strategy is demonstrated by comparison of the photophysical properties of 1 and of two related ruthenium complexes bearing acetylenic terpyridine ligands, with those of [Ru(terpy)2]2+. IR and electrochemical studies reveal that the nitrogen heteroatom of the ADT bridge has a marked influence on the electronic properties of the [Fe2(CO)6] core. Using the Rehm-Weller equation, the driving force for an electron transfer from the photoexcited *[Ru(terpy)2]2+ to the diiron site in 1 was calculated to be uphill by 0.59 eV. During the construction of the trinuclear complex 1, n-propylamine has been identified as a decarbonylation agent on the [(μ-ADT)Fe2(CO)6] portion of the supermolecule. Following this procedure, the first azadithiolate-bridged dinuclear iron complex coordinated by a phosphine ligand [(μ-ADT)Fe 2(CO)5PPh3] (4, R = 4-bromophenyl) was synthesized.

Original languageEnglish
Pages (from-to)4683-4692
Number of pages10
JournalInorganic Chemistry
Volume43
Issue number15
DOIs
Publication statusPublished - Jul 26 2004

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ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Ott, S., Borgström, M., Kritikos, M., Lomoth, R., Bergquist, J., Åkermark, B., ... Sun, L. (2004). Model of the iron hydrogenase active site covalently linked to a ruthenium photosensitizer: Synthesis and photophysical properties. Inorganic Chemistry, 43(15), 4683-4692. https://doi.org/10.1021/ic0303385