Light harvesting and directional energy transfer in long-lived homo- and heterotrimetallic complexes of Fe(II), Ru(II), and Os(II).

A new family of trimetallic complexes of the form [(bpy)2 M(phen-Hbzim-tpy)M'(tpy-Hbzim-phen)M(bpy)2](6+) (M=Ru(II), Os; M'=Fe(II), Ru(II), Os; bpy=2,2'-bipyridine) derived from heteroditopic phenanthroline-terpyridine bridge 2-{4-[2,6-di(pyridin-2-yl) pyridine-4-yl]phenyl}-1H-imidazole[4,5-f][1,10]phenanthroline (phen-Hbzim-tpy) were prepared and fully characterized. Zn(2+) was used to prepare mixed-metal trimetallic complexes in situ by coordinating with the free tpy site of the monometallic precursors. The complexes show intense absorptions throughout the UV/Vis region and also exhibit luminescence at room temperature.

Ru(II) and Os(II) complexes based on terpyridyl-imidazole ligand rigidly linked to pyrene: synthesis, structure, photophysics, electrochemistry, and anion-sensing studies.

We report in this work a new family of bis-tridentate ruthenium(II) and osmium(II) complexes bearing a terpyridyl ligand rigidly link to pyrenyl-benzimidazole moiety (tpy-HImzPy = 10-(4-[2,2':6',2''-terpyridine]terpyridin-4'-yl-phenyl)-9H-9,11-diaza-cyclopenta[e]pyrene) along with other tridentate ligands such as 4'-(2-naphthyl)-2,2':6',2″-terpyridine (tpy-NaPh) and 2,6-bis(benzimidazole-2-yl)pyridine (H2pbbzim). All the complexes are thoroughly characterized by their elemental analysis, ESI mass spectrometry, and (1)H NMR spectroscopy. The molecular structures of two complexes [Ru(tpy-HImzPy)2](ClO4)2 (3) and [(pbbzim)Ru(tpy-HImzPy)] (2a) in the solid state were determined by X-ray crystallography.

Photoinduced intramolecular energy transfer and anion sensing studies of isomeric RuIIOsII complexes derived from an asymmetric phenanthroline-terpyridine bridge.

Two heterobimetallic Ru(II)-Os(II) complexes of compositions [(bpy)2M(II)(phen-Hbzim-tpy)M'(II)(tpy-PhCH3)](4+), where M(II) = Ru and M'(II) = Os (4) and M(II) = Os and M'(II) = Ru (5), phen-Hbzim-tpy = 2-(4-(2,6-di(pyridin-2-yl)pyridine-4-yl)phenyl)-1H-imidazole[4,5][1,10]phenanthroline, bpy = 2,2'-bipyridine, and tpy-PhCH3 = 4'-(4-methylphenyl)-2,2':6',2''-terpyridine have been synthesized and characterized by elemental analyses, ESI mass spectrometry, and (1)H NMR and UV-vis absorption spectroscopy. The absorption spectra, redox behavior, and luminescence properties of the complexes have been thoroughly investigated and compared with that of monometallic model compounds [(bpy)2M(II)(phen-Hbzim-tpy)](2+) [M(II) = Ru (1) and M(II) = Os (2)] and [(phen-Hbzim-tpy)Ru(II)(tpy-PhCH3)](2+) (3). The complexes display very intense, ligand-centered absorption bands in the UV and moderately intense MLCT bands in the visible regions.

Photoinduced electron and energy transfer and pH-induced modulation of the photophysical properties in homo- and heterobimetallic complexes of ruthenium(II) and rhodium(III) based on a heteroditopic phenanthroline-terpyridine bridge.

Homo- and heterobimetallic complexes of compositions [(bpy)2Ru(II)(phen-Hbzim-tpy)Ru(II)(tpy/tpy-PhCH3/H2pbbzim)](4+) and [(bpy)2Ru(II)(phen-Hbzim-tpy)Rh(III)(tpy-PhCH3/H2pbbzim)](5+), where phen-Hbzim-tpy = 2-[4-(2,6-dipyridin-2-ylpyridin-4-yl)phenyl]-1H-imidazole[4,5-f][1,10]phenanthroline, bpy = 2,2'-bipyridine, tpy = 2,2':6',2"-terpyridine, tpy-PhCH3 = 4'-(4-methylphenyl)-2,2':6',2"-terpyridine, and H2pbbzim = 2,6-bis(benzimidazol-2-yl)pyridine, have been synthesized and characterized by elemental analyses, electrospray ionization mass spectrometry, and (1)H NMR spectroscopy. The absorption spectra, redox behavior, and luminescence properties of these bimetallic complexes have been thoroughly investigated and compared with those of monometallic [(bpy)2Ru(II)(phen-Hbzim-tpy)](2+) and [(tpy-PhCH3)Rh(III)(tpy-Hbzim-phen)](3+) model compounds. The electrochemistry of the complexes shows a reversible Ru(II/III) oxidation in the anodic region and an irreversible Rh(III/I) reduction and several ligand-based reductions in the cathodic region.

Luminescent bis-tridentate ruthenium(II) and osmium(II) complexes based on terpyridyl-imidazole ligand: synthesis, structural characterization, photophysical, electrochemical, and solvent dependence studies.

Homo- and heteroleptic bis-tridentate ruthenium(II) and osmium(II) complexes of compositions [(tpy-PhCH(3))Ru(tpy-HImzPh(3))](ClO(4))(2) (1), [(H(2)pbbzim)Ru(tpy-HImzPh(3))] (ClO(4))(2) (2) and [M(tpy-HImzPh(3))(2)](ClO(4))(2) [M = Ru(II) (3) and Os(II) (4)], where tpy-PhCH(3) = p-methylphenyl terpyridine, H(2)pbbzim = 2,6-bis(benzimidazole-2-yl)pyridine and tpy-HImzPh(3) = 4'-[4-(4,5-diphenyl-1H-imidazol-2-yl)-phenyl]-[2,2':6',2'']terpyridine, have been synthesized and characterized by using standard analytical and spectroscopic techniques. These compounds were designed to increase the room temperature excited-state lifetimes of bisterpyridine-type ruthenium(II) and osmium(II) complexes. The X-ray crystal structures of two homoleptic complexes 3 and 4 have been determined and show that both the compounds crystallized in orthorhombic form with space group Fddd.

Synthesis, structural characterization, photophysical, electrochemical, and anion-sensing studies of luminescent homo- and heteroleptic ruthenium(II) and osmium(II) complexes based on terpyridyl-imidazole ligand.

A series of hetero- and homoleptic tridentate ruthenium(II) and osmium(II) complexes of compositions [(tpy-PhCH(3))Ru(tpy-HImzphen)](ClO(4))(2) (1), [(H(2)pbbzim)Ru(tpy-HImzphen)](ClO(4))(2) (2), and [M(tpy-HImzphen)(2)](ClO(4))(2) [M = Ru(II) (3) and Os(II) (4)], where tpy-PhCH(3) = 4'-(4-methylphenyl)-2,2':6',2"-terpyridine, H(2)pbbzim = 2,6-bis(benzimidazole-2-yl)pyridine and tpy-HImzphen = 2-(4-[2,2':6',2"]terpyridine-4'-yl-phenyl)-1H-phenanthro[9,10-d]imidazole, have been synthesized and characterized by using standard analytical and spectroscopic techniques. X-ray crystal structures of three complexes 2, 3, and 4 have been determined. The absorption spectra, redox behavior, and luminescence properties of the complexes have been thoroughly investigated.

A terpyridyl-imidazole (tpy-HImzPh3) based bifunctional receptor for multichannel detection of Fe2+ and F- ions.

The X-ray crystal structures of the tridentate ligand, 4'-[4-(4,5-diphenyl-1H-imidazol-2-yl)-phenyl]-[2,2':6',2'']terpyridine (tpy-HImzPh(3)) and its bis-homoleptic iron(ii) complex of composition [Fe(tpy-HImzPh(3))(2)](2+) have been determined, showing that the ligand crystallized in a monoclinic form with the space group P2(1)/c while its Fe(II) complex crystallizes in an orthorhombic form with space group Fddd. Both the anion and cation binding properties of the receptor were thoroughly investigated in dimethylformamide-acetonitrile (1 : 9) solution using absorption, emission, and (1)H NMR spectral studies which revealed that the receptor acts as a sensor for both F(-) and Fe(2+). In the presence of excess F(-) ion, deprotonation of the imidazole N-H fragment of the receptor occurs, an event which is signaled by the development of a yellow color visible with the naked eye.

Synthesis, characterization, photophysical, and anion-binding studies of luminescent heteroleptic bis-tridentate ruthenium(II) complexes based on 2,6-bis(benzimidazole-2-yl)pyridine and 4'-substituted 2,2':6',2'' terpyridine derivatives.

A series of heteroleptic tridentate ruthenium(II) complexes of composition [(H(2)pbbzim)Ru(tpy-X)](PF(6))(2) (1-7), where H(2)pbbzim = 2,6-bis(benzimidazole-2-yl)pyridine and tpy-X = 4'-substituted terpyridine ligands with X = H, p-methyl phenyl (PhCH(3)), p-bromomethylphenyl (PhCH(2)Br), p-dibromomethylphenyl (PhCHBr(2)), p-cyanomethylphenyl (PhCH(2)CN), p-triphenylphosphonium methylphenyl bromide (PhCH(2)PPh(3)Br), and 4'-phenylformyl (PhCHO) groups, has been synthesized and characterized by using standard analytical and spectroscopic techniques. These compounds were designed to increase the excited-state lifetime of ruthenium(II) bisterpyridine-type complexes. The X-ray crystal structure of a representative compound 2, which crystallized with monoclinic space group P2(1)/c, has been determined.

Ru(II) and Os(II) mixed-chelates derived from imidazole-4,5-dicarboxylic acid and 2,2'-bipyridine as colorimetric sensors for anions: synthesis, characterization and binding studies.

Mixed-ligand monometallic ruthenium(II) and osmium(II) complexes of composition [(bipy)(2)M(H(2)Imdc)](ClO(4)), where H(3)Imdc = imidazole-4,5-dicarboxylic acid and bipy = 2,2'-bipyridine, have been synthesized and characterized using standard analytical and spectroscopic techniques. The X-ray crystal structures of the ruthenium(II) complexes, [(bipy)(2)Ru(H(2)Imdc)](ClO(4)) (1) and its corresponding N-H deprotonated form [(bipy)(2)Ru(HImdc)] (3) have been determined. Compound 1 crystallizes in monoclinic form with space group P2(1)/c while 3 is obtained in triclinic form with the space group P1.

Monometallic and bimetallic ruthenium(II) complexes derived from 4,5-bis(benzimidazol-2-yl)imidazole (H3Imbzim) and 2,2'-bipyridine as colorimetric sensors for anions: synthesis, characterization, and binding studies.

Mixed-ligand monometallic and bimetallic ruthenium(II) complexes of compositions [(bpy)(2)Ru(H(3)Imbzim)](ClO(4))(2) x 2 H(2)O (1) and [(bpy)(2)Ru(H(2)Imbzim)Ru(bpy)(2)](ClO(4))(3) x CH(2)Cl(2) (2), where H(3)Imbzim = 4,5-bis(benzimidazol-2-yl)imidazole and bpy = 2,2'-bipyridine, have been synthesized and characterized using standard analytical and spectroscopic techniques. The X-ray crystal structures of both compounds have been determined and showed that 1 crystallized in the triclinic form with space group P1 and 2 is in the monoclinic form with space group P2(1)/m. The anion binding properties of complexes 1 and 2, as well as those of the parent H(3)Imbzim, were thoroughly investigated in an acetonitrile solution using absorption, emission, and (1)H NMR spectral studies, which revealed that both of the metalloreceptors act as sensors for F(-), for AcO(-), and, to some extent, for H(2)PO(4)(-).