We report in this work the synthesis and spectroscopic, electrochemical, spectroelectrochemical, and photophysical characterization of a novel series of ruthenium polypyridyl complexes with 4-methyl-2,2'-bipyridine-4'-carbonitrile (Mebpy-CN) as an auxiliary ligand of general formula [Ru(bpy)3-x(Mebpy-CN)x](PF6)2 (x = 1-3) (with bpy = 2,2'-bipyridine). A significant increase in the lifetime and quantum yield of emission of the lowest (3)MLCT excited state is disclosed when going from x = 1 to x = 3, evidencing an improvement of the photosensitizing properties with respect to [Ru(bpy)3](PF6)2. Furthermore, quenching by molecular oxygen of (3)MLCT excited states of the three complexes produced singlet molecular oxygen ((1)O2) with quantum yield values higher than that of [Ru(bpy)3](2+) in CH3CN. The structure of the complex with x = 1 has been determined by X-ray diffraction. The photoconductivity of ZnO nanowires covered with this same complex is increased by an order of magnitude, pointing to its feasibility as a component of a DSSC. A new dinuclear complex with Mebpy-CN as a bridging ligand has also been prepared and characterized by physicochemical techniques. The derived mixed-valent species of formula [(bpy)2Ru(II)(Mebpy-CN)Ru(III)(NH3)5](5+) displays a considerable metal-metal electronic coupling due to the delocalization effect of a nitrile group in the 4' position of the bpy ring.

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We report a combined computational and experimental study of efficient QTM suppression in {Cr3Dy3} triangle-in-triangle SMMs.

Novel mono‐ and dinuclear tricarbonylrhenium(I) complexes of formula [Re(Mebpy‐CN)(CO)3Cl] (1), [Re(Mebpy‐CN)(CO)3(CH3CN)](PF6) (2), and [(CH3CN)(CO)3Re(Mebpy‐CN)Ru(NH3)5](PF6)3 (3), in which Mebpy‐CN = 4‐methyl‐2,2′‐bipyridine‐4′‐carbonitrile, were prepared and characterized by spectroscopic, photophysical, and computational techniques. The complete structure of complex 2 was determined by X‐ray diffraction. The increased conjugation in the bipyridyl ring owing to the nitrile substituent increases the emission quantum yields of the 3MLCT (metal‐to‐ligand charge‐transfer) lowest‐lying excited states of 1 and 2 with respect to the corresponding bpy complexes (bpy = 2,2′‐bipyridine). The mixed‐valent species of formula [(CH3CN)(CO)3Re(Mebpy‐CN)Ru(NH3)5]4+ (4) was prepared in situ and as a mixed salt; the charge recombination from its metal‐to‐metal charge‐transfer (MMCT) excited state is predicted to lie in the Marcus inverted region. The electronic structures and optical properties of all the reported complexes calculated by DFT and TD‐DFT methods agree reasonably well with experimental results.

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Dye-sensitized ZnO nanowire (NW) electrodes were fabricated using Ru polypyridyl complexes that use nitrile instead of carboxylic group as anchoring unit to the NW surfaces. The complexes formula is [Ru(bpy) 3−x (Mebpy-CN) x ] 2+ (x =1−3, bpy = 2,2'-bipyridine, Mebpy-CN = 4-methyl-2,2'bipyridine-4'-carbonitrile). The ZnO NWs were grown by a vapor transport method on insulating SiO 2 /Si substrates. The sensitized ZnO NW electrodes were studied by electron microscopy, Raman and PL spectroscopies, and spectral and relaxation photocurrent measurements. The Raman spectra confirm that the complexes were effectively anchored to the ZnO NWs through one of the pendant nitrile groups of the bipyridyl ligands. The nanostructured morphology of the NW electrodes was maintained so that their light trapping characteristics were preserved. The Ru complexes were found to be excellent sensitizers of the ZnO NWs, improving by orders of magnitude their photocurrent in the visible region. The Fe-based complex of formula [Fe(Mebpy-CN) 3 ](PF 6) 2 was also tested; however it did not show any sensitizing effect. An order of magnitude shortening of the persistent photocurrent relaxation times (after the illumination is interrupted) was found to occur upon successful sensitization of the ZnO NWs with the Ru complexes. This effect is interpreted in terms of hole traps at  eV above the ZnO valence band edge, which are loweredby 50-60 meV in the soaked samples due to screening of the trap centers provided by the extra photoexcited charge carriers transferred from the sensitizing complex to the NWs.