Attachment of a Hydrogen-Bonding Carboxylate Side Chain to an FeFe -Hydrogenase Model Complex: Influence on the Catalytic Mechanism
2010 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 16, no 8, 2537-2546 p.Article in journal (Refereed) Published
Azapropanedithiolate (adt)-bridged model complexes of [FeFe]-hydrogenase bearing a carboxylic acid functionality have been designed with the aim of decreasing the potential for reduction of protons to hydrogen. Protonation of the bisphosphine complexes 4-6 has been studied by in situ IR and NMR spectroscopy, which revealed that protonation with triflic acid most likely takes place first at the N-bridge for complex 4 but at the Fe Fe bond for complexes 5 and 6. Using an excess of acid, the diprotonated species could also be observed, but none of the protonated species was sufficiently stable to be isolated in a pure state. Electrochemical studies have provided an insight into the catalytic mechanisms under strongly acidic conditions, and have also shown that complexes 3 and 6 are electro-active in aqueous solution even in the absence of acid, presumably due to hydrogen bonding. Hydrogen evolution, driven by visible light, has been observed for three-component systems consisting of [Ru(bpy)(3)](2+), complex 1, 2, or 3, and ascorbic acid in CH3CN/D2O solution by on-line mass spectrometry.
Place, publisher, year, edition, pages
2010. Vol. 16, no 8, 2537-2546 p.
electrochemistry, electron transfer, enzyme model, iron-hydrogenase, proton reduction, active-site models, fe-only hydrogenase, coupled electron-transfer, iron hydrogenase, electrochemical properties, structure/function, relationships, proton reduction, generation, activation, ligands
IdentifiersURN: urn:nbn:se:kth:diva-19317DOI: 10.1002/chem.200902278ISI: 000275685800026ScopusID: 2-s2.0-77049106133OAI: oai:DiVA.org:kth-19317DiVA: diva2:337364
FunderSwedish Research CouncilKnut and Alice Wallenberg Foundation
QC 201101142010-08-052010-08-052011-01-14Bibliographically approved