title: Electron-, proton-, and photon-induced spectroscopic changes in chromophore-quencher tricarbonyl(2,2'-bipyridine)rhenium(I) complexes with 4,4'-azobis(pyridine).
abstract: We report in this work the synthesis and characterization of new mono- and dinuclear complexes of formulas: [Re(bpy)(CO)(3)(4,4'-azpy)](CF(3)SO(3)), 1 (bpy = 2,2'-bipyridine, 4,4'-azpy = 4,4'-azobis(pyridine)); [(bpy)(CO)(3)Re(4,4'-azpy)Ru(NH(3))(5)](PF(6))(3).CH(3)CN.6H(2)O, 2 and the heterodinuclear species [(bpy)(CO)(3)Re(4,4'-azpy)Ru(NH(3))(5)](4+), 3 (obtained in situ by electrochemical oxidation of 2). The molecular structure of 1 has been determined by X-ray diffraction. We also report the effect of controlled potential electrolysis, protonation, and light excitation on the absorption and emission properties of these complexes. In particular, complex 1, which is almost non-emissive at room temperature, recovers luminescence either by reduction of coordinated 4,4'-azpy or by trans- to cis-photoisomerization. The detected emission of 1 at 77 K is due to decay from a Re --> bpy metal-to-ligand charge transfer excited state. Time dependent density functional theory calculations support the interpretation of the photophysical changes induced by external stimuli.
authors.affiliation: INQUINOA-CONICET, Instituto de Química Física, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 491, (T4000INI) San Miguel de Tucumán, Argentina.
authors.forename: Gaston
authors.initials: G
authors.lastname: Pourrieux
authors.forename: Florencia
authors.initials: F
authors.lastname: Fagalde
authors.forename: Isabel
authors.initials: I
authors.lastname: Romero
authors.forename: Xavier
authors.initials: X
authors.lastname: Fontrodona
authors.forename: Teodor
authors.initials: T
authors.lastname: Parella
authors.forename: Néstor E
authors.initials: NE
authors.lastname: Katz
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D004583:Electrons; D008024:Ligands; D008027:Light; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D017785:Photons; D011725:Pyridines / Q000737:chemistry*
chemical_list: C550638:4,4'-azobis(pyridine); D001391:Azo Compounds; D008024:Ligands; D009942:Organometallic Compounds; D011725:Pyridines; C550637:tricarbonyl(2,2'-bipyridine)rhenium(I)