Electrochemical and Photophysical Properties of Ruthenium(II) Bipyridyl Complexes with Pendant Alkanethiol Chains in Solution and Anchored to Metal Surfaces

Abstract

Luminescent ruthenium trisbipyridine complexes containing one or two mercapto-alkyl chain(s) on one of the bipyridyl units have been synthesized through a new strategy. The electrochemical and photophysical properties, determined in solution and in the solid state were compared. Deposition on electrode surfaces (gold, platinum and indium tin oxide) was realized by self-assembly and the resulting adsorbed layers were characterized by electrochemistry and fluorescence confocal microscopy. Voltammetric measurements of the films, in aqueous and in acetonitrile solution, allowed the determination of the surface coverages and the oxidation potentials of the complexes. The effect of the number of chains and the chain length in the complexes is highlighted. Emission of the adsorbed complexes was strongly quenched by the metallic surfaces, while confocal microscopy images showed aggregate formation on a m length scale. The latter results provide considerable insight into the nature of the adsorbed layers and support deductions from the voltammetric data.

Luminescent acetylthiol derivative tripodal osmium(II) and iridium(III) complexes: Spectroscopy in solution and on surfaces

“…The origin of quenching on Au is attributed to a photoinduced electron transfer from the redox-active Os core to the electron-deficient Au surface. Similar effects with Ru tripod were observed by us, as well as other groups, with different Ru complexes on Au [24,31,[59][60][61][62][63]. Using the quenched and unquenched lifetimes, we can estimate the electron-transfer rate using the following equation:…”

“…Traditionally, various organic molecules functionalized with thiols have been investigated for this purpose. However, recently there has been some interest toward employing organometallic complexes containing Ru [21][22][23][24] and Os [21,[25][26][27][28][29][30][31][32][33] metal ions and ligands derivatized with thiols and amino groups for SAM formation. High stability coupled with very good photophysical and electrochemical behavior, as well as the possibility to have multielectron processes make them appealing candidates over conventional organic molecules.…”

Variation of the Viologen Electron Relay in Cyclodextrin‐Based Self‐Assembled Systems for Photoinduced Hydrogen Evolution from Water

“…These results confirm the essential role of the viologen for the electronic communication between the photosensitizer and the catalyst, in which hydrogen is probably formed according to Equation (1). This is somewhat surprising because it has been shown37 that Pt and Au surfaces can quench the excited state of the related Ru‐bpy by electron transfer from the photoexcited complex to the surface. For the combination of Ir‐ada and Pt‐βCD nanoparticles, the close proximity of these two components by supramolecular interactions apparently cannot compensate for the absence of the viologen relay.…”

Photochromic Molecules as Building Blocks for Molecular Electronics

“…3-bromo-2-methyl-5-thiopheneboronic acid (10) are coupled together by a Suzuki reaction to get the precursor 11. A second coupling reaction between 11 and perfluorocyclopentene leads to the desired bridging ligand 12 in moderate yield.…”

“…It is well known that the preparation of SAMs is a difficult task if the molecular units, which build up the layer, contain bulky substituents. [10] We have recently developed so-called 'tripods', able to bind via three S-Au bonds to gold surfaces. [11] The tripods are composed by a tetrahedral silicon core, decorated with three thiol-containing legs, and a rigid connection to the head part of the molecule.…”