Département de chimie moléculaire

A [Ru(bpy)3]2+-like complex (L1) bearing two free terpyridine groups at the 5 and 5' positions of the same bipyridine, linked by the rigid and linear 2,5-di-Me phenylene bridges has been synthesized to open access to two classes of linear mol. wires with photosensitive properties: a bimetallic coordination polymer and an inorg. triad. In this Research Article, we report on the synthesis and characterization of the resulting [{\{}RuII{\_}FeII{\}}n]4n+ alternated bimetallic polymer and the [CoIII{\_}RuII{\_}FeII]7+ triad based on the building block L1. The [{\{}RuII{\_}FeII{\}}n]4n+ polymer is fully characterized in soln. Cyclic voltammetry and emission lifetime measurements show that the bridging ligand allows interaction between the metal centers in the excited state despite the lack of interactions in the ground state. Under visible irradn., the polymer can be fully oxidized in the presence of a sacrificial electron acceptor in soln. Thin robust films of the polymer are easily obtained on ITO by a simple electrochem. procedure based on an electroredn. adsorption process. The ITO/[{\{}RuII{\_}FeII{\}}n]4n+-modified electrode behaves as a photocathode under irradn. in the presence of ArN2+. The magnitude of the photocurrent is dependent on the film thickness, probably limited by the diffusion of charge in thicker film. On the other hand L1 is also used to construct a well-ordered triad in assocn. with Co(III) and Fe(II) metallic centers as electron acceptor and donor, resp. The metallic triad is anchored on ITO or on a SiO2 wafer, starting from a terpyridine phosphonate modified surface. AFM images prove the presence of the triad in a linear upward orientation. Irradn. of the ITO/[CoIII{\_}RuII{\_}FeII]7+ modified surface in the presence of triethanolamine in CH3CN induces the generation of an anodic photocurrent of around 30 $μ$A.cm-2. The photocurrent d. generated by the ITO/[CoIII{\_}RuII{\_}FeII]7+ electrode, appears to be more stable than in the case of ITO/[{\{}RuII{\_}FeII{\}}n]4n+ because of the presence of the anchoring group. Moreover, this photocurrent magnitude represents an enhancement of 30{%} compared to our previous triad ( Dalton Trans. 2014, 43, 12156-12159), proving the advantage of a linear and rigid spacer for the construction of such mol. assemblies with photoinduced charge transfer abilities.