Photoelectrochemical behavior of multimetallic assemblies based on [Ru(bpy)3]2+-terpyridine building block: [Ru(II)–M–Ru(II)]+ in solution and [Ru(II)–M]+ dyad anchored on ITO (M = Co(III), Fe(II))

Photoactive Molecular Dyads [Ru(bpy)3–M(ttpy)2]n+ on Gold (M = Co(III), Zn(II)): Characterization, Intrawire Electron Transfer, and Photoelectric Conversion

“…As a consequence, the magnitude of the current photogenerated by Au/[Zn II –Ru II ] 4+ is only half of that generated by Au/[Co III –Ru II ] 5+ . We found that for Au/[Co III –Ru II ] 5+ , the density of photocurrent is similar to the value obtained with the dyad built on ITO via a phosphonate terpyridine self-assembled layer. , The similarities prove that in such assemblies the [Ru­(bpy) 3 ] 2+ photosensitive unit is maintained sufficiently far from the electrode to limit the quenching of [Ru­(bpy) 3 ] 2+ * by gold. Au/[Co III –Ru II ] 5+ exhibits an energy-conversion efficiency estimated to η = 3.5 × 10 –4 %.…”

“…The results indicate a strong quenching of the Ru­(II)* subunit by the cobalt one. This quenching process was already discussed and attributed to an efficient electron-transfer reaction between the Ru­(II)* subunits and the Co­(III) center leading to [Ru III -Co II –Ru II ] 7+ transient species. , The rate of the photoinduced electron-transfer process was estimated to be 9 × 10 6 s –1 . Moreover, in the presence of a sacrificial electron donor, such as triethanolamine (TEOA) or triphenylphosphine, continuous irradiation of [Ru II –Co III –Ru II ] 7+ generates quantitatively the reduced [Ru II –Co II –Ru II ] 6+ species.…”

“…Among the different SAMs, those incorporating ruthenium complexes derived from 2,2′-bipyridine (bpy) or 1,10-phenanthroline are of particular interest because of their unique combination of photophysical and electrochemical properties. − Aiming to reach a system that can generate a charge-separated species on surface under visible light irradiation, our group has designed a series of [Ru­(bpy) 3 ] 2+ cores bearing one or two free terpyridines. These metalloligands can be associated with first-row transition metals to prepare supramolecular photoactive polymers , in solution, or in a stepwise mode to afford inorganic dyads and triads on a transparent electrode, such as indium tin oxide (ITO). − We have notably grafted dyads and triads using a Ru­(II) metalloligand in association with Co­(III) and/or Fe­(II) as electron-acceptor or electron-donor subunits, respectively. Under visible light irradiation and in the presence of sacrificial acceptor like a diazonium salt, the Ru II –Fe II dyad on ITO behaves as a photocathode .…”

“…These metalloligands can be associated with first-row transition metals to prepare supramolecular photoactive polymers , in solution, or in a stepwise mode to afford inorganic dyads and triads on a transparent electrode, such as indium tin oxide (ITO). − We have notably grafted dyads and triads using a Ru­(II) metalloligand in association with Co­(III) and/or Fe­(II) as electron-acceptor or electron-donor subunits, respectively. Under visible light irradiation and in the presence of sacrificial acceptor like a diazonium salt, the Ru II –Fe II dyad on ITO behaves as a photocathode . Meanwhile, the Ru II –Co III dyad anchored on ITO is able to generate an anodic photocurrent in the presence of triethanolamine as sacrificial donor .…”

“…Under visible light irradiation and in the presence of sacrificial acceptor like a diazonium salt, the Ru II –Fe II dyad on ITO behaves as a photocathode . Meanwhile, the Ru II –Co III dyad anchored on ITO is able to generate an anodic photocurrent in the presence of triethanolamine as sacrificial donor . Moreover, the magnitude of the photocurrent is significantly increased when the three subunits (electron acceptor–photosensitizer–electron donor) are linked in a well-organized assembly .…”