- Threading of various 'U' shaped bidentate axles into a heteroditopic macrocyclic wheel: Via NiII/CuII templation
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The threading of 'U' shaped bent axles having diverse functionalities (Axle1-Axle10) is investigated by using a heteroditopic amido-amine macrocyclic (MC) wheel via NiII or CuII metal ion templation. These bent shaped axles are the derivatives of 4,4′-substituted 2,2′-bipyridine, which are composed of various terminal groups like alkene, alkyne, bromide, hydroxyl and azide. Such metallo [2]pseudorotaxanes are well characterised by ESI-MS, EPR and FT-IR spectroscopic studies, UV-Vis absorption studies, elemental analysis and single-crystal X-ray diffraction studies wherever possible. Experimental evidence supports 1:1:1 ternary complexation between MC, the metal ion and axle. The single crystal X-ray structures of three CuII templated ternary complexes (PR1′, PR3′ and PR7′) show the penta-coordination arrangement around the templating metal ion. Interestingly, judicious selection of chemical functionalities in the complementary wheel and axle components enables to show the existence of various covalent and non-covalent interactions.
- Nandi, Mandira,Santra, Saikat,Akhuli, Bidyut,Ghosh, Pradyut
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- Highly soluble dichloro, dibromo and dimethyl dioxomolybdenum(VI)- bipyridine complexes as catalysts for the epoxidation of olefins
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The reaction of solvent substituted MoO2X2(S) 2 (X = Cl, S = THF; X = Br, S = DMF) complexes with one equivalent of bidentate nitrogen donor ligands at room temperature leads within a few minutes to the quantitative formation of complexes of the type [MoO2X 2L2] (L = 4,4′-bis-methoxycarbonyl-2,2′- bipyridine, 5,5′-bis-methoxycarbonyl-2,2′-bipyridine, 4,4′-bis-ethoxycarbonyl-2,2′-bipyridine, 5,5′-bis- ethoxycarbonyl-2,2′-bipyridine). Treatment of the complexes [MoO 2Cl2L2] with Grignard reagents at low temperatures yields dimethylated complexes of the formula [MoO 2(CH3)2L2]. [MoO2Br 2(4,4′-bis-ethoxycarbonyl-2,2′-bipyridine)], [MoO 2Br2(5,5′-bis-methoxycarbonyl-2,2′-bipyridine) ] and [MoO2Br2(5,5′-bis-ethoxycarbonyl-2,2′- bipyridine)] have been exemplary examined by single crystal X-ray analysis. The complexes were applied as homogenous catalysts for the epoxidation of cyclooctene with tert-butyl hydroperoxide (TBHP) as oxidising agent under solvent-free conditions. The complexes containing L = Cl have been additionally investigated with room temperature ionic liquids (RTILs) as solvents. The catalytic activity of the [MoO2X2L2] complexes in olefin epoxidation with tert-butyl hydroperoxide is on average very good. The main advantage of the synthesised complexes in comparison to previously reported complexes is their high solubility. This good solubility is apparently the reason that the catalytic potential of the compounds can unfold. The turnover frequencies (TOFs) in RTILs are even higher, showing the performance of the catalysts under optimised conditions.
- Günyar, Alev,Betz, Daniel,Drees, Markus,Herdtweck, Eberhardt,Kühn, Fritz E.
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- Synthetic routes to ruthenium(II) species containing carboxylate-functionalized 2,2′-bipyridine ligands
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Two methods are reported for the incorporation of carboxylate substituents on polypyridyl ligands coordinated to ruthenium(II) centres. In the first, a precursor complex is synthesized with ethoxycarbonyl groups which are subsequently base-hydrolysed to produce the carboxylate in high yield (-CO2Et → -CO2H). In the second method, ruthenyl (RuIV=O) species were used to chemically catalyse the electochemical oxidation of methyl substituents on the ligands of a precursor complex to produce the target carboxylate species (-CH3 → -CO2H).
- Patterson, Bradley T.,Keene, F. Richard
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- Effect of the CF3 Substituents on the Charge-Transfer Kinetics of High-Efficiency Cyclometalated Ruthenium Sensitizers
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Six thiocyanate-free complexes, DUY1-DUY6, were synthesized, and their application in a dye-sensitized solar cell was studied to explore the effect of the CF3 substituent positioned in the ancillary ligand and the structure of the anchoring ligand on the physicochemical properties, charge-transfer kinetics, and photovoltaic properties of ruthenium sensitizers. When the electron-withdrawing groups were installed on the cyclometalating ligands and their π conjugation of the ancillary ligand was extended, the frontier orbital energy levels of the ruthenium complex appeared to be sufficient for effective electron injection and dye regeneration, at the same time having high light-harvesting ability. Two electron-withdrawing CF3 groups meta to the cyclometalated position reduce the electron density at the metal center less seriously than o-CF3 and p-CF3 groups. The sensitizers containing a m-CF3 group also reveal a more favorable distribution of β lowest unoccupied spin orbital for interaction between the oxidized dyes and the iodide ion, which promotes dye regeneration. The absorption profiles of DUY1-DUY4 adsorbed a TiO2 film extended to longer wavelength compared to those in an N,N-dimethylformamide solution, especially DUY1 and DUY2 dyes, which have λmax red shifts of up to 30 nm. The DUY2-dyed cell exhibited the highest efficiency of 9.03%, while the power conversion efficiencies of DUY1-, DUY3-, DUY4-, and N719-based devices were 7.40%, 7.01%, 8.92%, and 8.63%, respectively. DUY5 and DUY6 (the side products of DUY3 and DUY4) without anchoring groups have very weak physical adsorption on a TiO2 anode. The corresponding cells exhibit very low efficiency (0.1%), although both dyes have high light-harvesting ability and proper frontier orbital energy levels.
- Nguyen, The-Duy,Lin, Chun-Han,Wu, Chun-Guey
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- Selective Photoinactivation of Methicillin-Resistant Staphylococcus aureus by Highly Positively Charged RuII Complexes
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Ruthenium(II) polypyridyl complexes featuring peripheral quaternary ammonium structures were found to be able to selectively inactivate Gram-positive Staphylococcus aureus (S. aureus), including methicillin-resistant S. aureus (MRSA) upon visible light irradiation, but have low phototoxicity toward 293T cells, L02 cells and lack hemolysis toward rabbit red blood cells (RBC), exhibiting promising potential as a novel type of antimicrobial photodynamic therapy (aPDT) agents.
- Feng, Yang,Sun, Wei-Ze,Wang, Xue-Song,Zhou, Qian-Xiong
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- Copper(II)-directed synthesis of neutral heteroditopic [2]rotaxane ion-pair host systems incorporating hydrogen and halogen bonding anion binding cavities
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Neutral heteroditopic [2]rotaxane ion-pair host systems were synthesised via a Cu(ii) directed passive metal template strategy. Each rotaxane contains discrete, axle-separated interlocked binding sites for a guest anion and a transition metal countercatio
- Brown, Asha,Mennie, Katrina M.,Mason, Owen,White, Nicholas G.,Beer, Paul D.
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- Dye molecular structure device open-circuit voltage correlation in Ru(II) sensitizers with heteroleptic tridentate chelates for dye-sensitized solar cells
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Dicarboxyterpyridine chelates with π-conjugated pendant groups attached at the 5- or 6-position of the terminal pyridyl unit were synthesized. Together with 2,6-bis(5-pyrazolyl)pyridine, these were used successfully to prepare a series of novel heteroleptic, bis-tridentate Ru(II) sensitizers, denoted as TF-11-14. These dyes show excellent performance in dye-sensitized solar cells (DSCs) under AM1.5G simulated sunlight at a light intensity of 100 mW cm -2 in comparison with a reference device containing [Ru(Htctpy)(NCS)3][TBA]3 (N749), where H3tctpy and TBA are 4,4′,4″-tricarboxy-2,2′:6′,2″- terpyridine and tetra-n-butylammonium cation, respectively. In particular, the sensitizer TF-12 gave a short-circuit photocurrent of 19.0 mA cm-2, an open-circuit voltage (VOC) of 0.71 V, and a fill factor of 0.68, affording an overall conversion efficiency of 9.21%. The increased conjugation conferred to the TF dyes by the addition of the π-conjugated pendant groups increases both their light-harvesting and photovoltaic energy conversion capability in comparison with N749. Detailed recombination processes in these devices were probed by various spectroscopic and dynamics measurements, and a clear correlation between the device VOC and the cell electron lifetime was established. In agreement with several other recent studies, the results demonstrate that high efficiencies can also be achieved with Ru(II) sensitizers that do not contain thiocyanate ancillaries. This bis-tridentate, dual-carboxy anchor configuration thus serves as a prototype for future omnibearing design of highly efficient Ru(II) sensitizers suited for use in DSCs.
- Wu, Kuan-Lin,Li, Cheng-Hsuan,Chi, Yun,Clifford, John N.,Cabau, Lydia,Palomares, Emilio,Cheng, Yi-Ming,Pan, Hsiao-An,Chou, Pi-Tai
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- Stark effects after excited-state interfacial electron transfer at sensitized TiO2 nanocrystallites
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Photophysical studies were performed with [Ru(dtb)2(dcb)] (PF6)2 and cis-Ru(dcb)(dnb)(NCS)2, where dtb is 4,4′-(C(CH3)3)2-2,2′-bipyridine, dcb is 4,4′-(COOH)2-2,2′-bipyridine, and dnb is 4,4′-(CH3(CH2)8)2-2,2′- bipyridine), anchored to anatase TiO2 particles (-15 nm in diameter) interconnected in a mesoporous, 10 μm thick film immersed in Li +-containing CH3CN electrolytes with iodide or phenothiazine donors. Pulsed-laser excitation resulted in rapid excited-state injection and donor oxidation to yield TiO2(e-)s and oxidized donors, while the metal-to-ligand charge-transfer (MLCT) absorption spectrum of the Ru(II) coordination compounds differed from that which was initially excited. The spectral data were consistent with an underlying Stark effect and indicated that the surface electric field was not completely screened from the molecular sensitizer. The magnitude of the electric field was estimated to be -270 MV/m from Li+ titration experiments, corresponding to a -40 mV potential drop. With iodide donors, the amplitude of the Stark effect decreased over time periods where charge recombination was absent, behavior attributed to "screening" of the electric field by interfacial ionic reorganization. The screening kinetics were nonexponential but were well described by the Kohlrausch-Williams-Watts model, from which a characteristic rate constant, -o-1, of -1.5 - 10 5 s-1 was abstracted. At least seven other sensitizers and five different cations, as well as on SnO2 nanoparticle films, exhibited similar transient absorption behavior with iodide donor molecules indicating that the effect was quite general. In the presence of phenothiazine donors (or in the absence of an external donor), there was no clear evidence for screening, and the Stark effect disappeared concurrent with interfacial charge recombination. Complementary spectroelectrochemical studies of these same sensitized films displayed similar absorption spectra when the TiO2 thin film was partially reduced with a forward bias. Spectral modeling in the absence of donor molecules as well as studies of TiO2 thin films sensitized with two different Ru(II) compounds demonstrated that the electric field created by excited-state injection from one sensitizer influenced the absorption spectra of other sensitizers that had not undergone photoinduced electron injection.
- Ardo, Shane,Sun, Yali,Staniszewski, Aaron,Castellano, Felix N.,Meyer, Gerald J.
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- Two-dimensional emission quenching and charge separation using a Ru(II)-photosensitizer assembled with membrane-bound acceptors
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Novel syntheses of the bipyridine ligand 1, dcHb (dcHb = 4,4′-dicarboxy-2,2′-bipyridine), by anionic oxidation of 4,4′-dimethyl-2′,2-bipyridine (dmb) using molecular oxygen (4 atm), and of the sensitizer precursor 4, tris(4,4′-diethoxycarbonyl-2,2′-bipyridine)ruthenium(II) bis(triflate), from a chloride-free Ru(II) precursor 3b, RuII(DMSO)4(triflate)2-n(EtOH)n (n = 0-2, DMSO = dimethyl sulfoxide, triflate = OSO2CF3) are reported. The anionic sensitizer Ru(dcb)34- (5) was shown to bind to vesicles of lecithin when these were made positively charged by cationic bipyridinium electron acceptors. With cetylmethylviologen (CMV2+) as quencher, the time-resolved decay of the Ru(dcb)34- emission followed a model for diffusion-controlled quenching in two dimensions. However, the diffusion coefficient obtained from a fit to the data was very small, (6±2)×10-11 m2 s-1, comparable to values for amphiphiles in bilayers, even though Ru(dcb)34- diffuses in the water region at the vesicle surface. The quantum yield of primary charge separation was 0.06±0.02, which is significant, if not high, despite the large electrostatic attraction between the reactants. Attempts were made to increase the charge separation yield by the use of a monocationic acceptor. Possible extensions of the system are discussed, such as charge separation across the vesicle membrane and the covalent linking of a donor to the sensitizer.
- Hammarstrom,Norrby,Stenhagen,Martensson,Akermark,Almgren
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- New amide based iridium(III) complexes: Synthesis, characterization, photoluminescence and DFT/TD-DFT studies
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New iridium(iii) complexes with 2-(3-fluorophenyl)-4-methylpyridine as cyclometalated ligands and 2,2′-bipyridine-4,4′-dicarboxamide derivatives as ancillary ligands were synthesized and characterized by FTIR, NMR, MS, UV/Visible, and fluorescence spectroscopies and cyclic voltammetry. The effects of different solvents and substituents on the photophysical properties of the complexes have been investigated. The complexes show tunable photoluminescence wavelengths depending on solvent polarity in the 548 nm to 610 nm range where the emission colour can change from green to orange-red. The complexes exhibit high photoluminescence quantum yields between 0.41 and 0.75, which may be attributed to the change in the transition dipole moment originating from the amide group upon electronic excitation. The calculated HOMO and LUMO energy levels of complexes 1-7 are in the -5.51 to -5.60 eV and -3.37 to -3.40 eV ranges, respectively. The ground and excited state properties of 1 have been fully investigated by means DFT and TD-DFT methods respectively. The general trends of observed data have been successfully represented and quantified by computational data.
- Sahin, Cigdem,Goren, Aysen,Demir, Serkan,Cavus, Muhammet Serdar
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- A panchromatic, near infrared Ir(III) emitter bearing a tripodal C^N^C ligand as a dye for dye-sensitized solar cells
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The synthesis of a new complex of the form [Ir(C^N^C)(N^N)Cl] [where C^N^C = 2-(bis(4-(tert-butyl)phenyl)methyl)pyridinato (dtBubnpy, L1) and N^N is diethyl [2,2′-bipyridine-4,4′-dicarboxylate (deeb)] is reported. The crystal structure reveals an unusual tripodal tridentate C^N^C ligand forming three six-membered rings around the iridium center. The photophysical and electrochemical properties suggest the use of this complex as a dye in dye-sensitized solar cells. Time-Dependent Density Functional Theory (TD-DFT) calculations have been used to reveal the nature of the excited-states.
- Hierlinger, Claus,Flint, Heather V.,Cordes, David B.,Slawin, Alexandra M.Z.,Gibson, Elizabeth A.,Jacquemin, Denis,Guerchais, Véronique,Zysman-Colman, Eli
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- Prototypical cis-ruthenium(II) complexes present differential fluorescent staining in walled-cell models (yeasts)
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cis-Ru(deeb)3 2+ (R1; where deeb is 4,4′-diethanoate-2,2′-bipyridine) and cis-Ru(phen)3 2+ (R2; where phen is 1,10-phenanthroline) were synthesized. Although the presence of the cell wall (a structure that is present in yeasts and bacteria,) was previously described as a natural barrier that hampers the uptake of d6-based luminescent complexes, we previously demonstrated that rhenium(I) tricarbonyl complexes were useful to stain both yeasts and bacteria. Even though several studies of classical ruthenium(II) complexes can be found, none of those studies aimed to determine the potential of these compounds as biomarkers for walled cells, testing only cell lines that lack this permeability barrier. Walled cells exhibit a relatively rigid structure, mainly constituted by carbohydrates and proteins, and surround the plasma membrane. In this manuscript, we observed that both R1 and R2 exhibited very low cytotoxicity in different walled-cell models (including bacteria and yeasts). More importantly, we found that both R1 and R2 were able to fluorescently stain Candida albicans (yeast), with a simple and fast procedure, without the need of additional permeabilizer molecules and antibodies. Interestingly, R1 remained retained in a discrete central structure consistent with the cell nucleus, whereas R2 seemed to be accumulated in the cell wall. These results show that these two complexes can be used as biomarkers for walled cells as differential staining, supporting the fact that, as well as with rhenium(I) complexes, biomarkers properties can be modulated by changing the substituents in ruthenium(II)-derivative luminescent stains, even for walled cells.
- Carre?o, Alexander,Páez-Hernández, Dayán,Zú?iga, César,Ramírez-Osorio, Angélica,Nevermann, Jan,Rivera-Zaldívar, María Macarena,Otero, Carolina,Fuentes, Juan A.
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- Photo-induced electron transfer study of rhenium(I) bipyridyl complexes with covalently linked phenothiazine donor through different bridge
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A novel rhenium(I) bipyridyl complex 1a, [(4,4'-di-COOEt-bpy)Re(CO)3(py-NHCO-PTZ)PF6] and a model 1b, [(4,4'-di-COOEt-bpy)Re(CO)3(py-PTZ)PF6] (bpy is 2, 2'-bipyridine, py-NHCO-PTZ is phenothiazine-(10-carbonyl amide) pyridine and py-PTZ is 10-(4-picolyl) phenothiazine) were synthesized. Their photo-induced electron transfer (ET) reaction with electron acceptor methyl viologen (MV2+) in acetonitrile was studied by nanosecond laser flash photolysis at room temperature. Photoexcitation of 1 in the presence of MV2+ led to ET from the Re moiety to MV2+ generating Re(II) and methyl viologen radical (MV·+). Then Re(II) was reduced either by the charge recombination with MV·+ or by intramolecular ET from the attached PTZ, regenerating the photosensitizer Re(I) and forming the PTZ radical at 510 nm. In the case of 1b, the absorption for PTZ radical can be observed distinctly accompanied intermolecular ET, whereas not much difference at 510 nm can be detected for 1a on the time scale of the experiments. This demonstrates that the linking bridge plays a key role on the intramolecular ET in complex 1.
- Sun, Shiguo,Shi, Lei,Liu, Fengyu,Fan, Jiangli,Peng, Xiaojun
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- Control of Excited-State Supramolecular Assembly Leading to Halide Photorelease
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Ground- and excited-state control of halide supramolecular assembly was achieved through the preparation of a series of ester- and amide-functionalized ruthenium polypyridyl complexes in CH2Cl2. Hydrogen-bonding amide and alcohol groups on the receptor ligand were found to direct interactions with halide, while halide association with the ethyl ester groups was not observed. The various functional groups on the receptor ligands tuned the ground-state equilibrium constants over 2 orders of magnitude (1 × 105 to 1 × 107 M-1), and the fractional contribution of each hydrogen-bond donor to the total equilibrium constant was determined. Pulsed-laser excitation of the complexes resulted in excited-state localization on the ester- or amide-functionalized ligands. In the case where the excited state was oriented toward an associated halide ion (the amide complexes), an 80 ± 10 meV Coulombic repulsion was induced that lowered the excited-state equilibrium constant (K?eq) and resulted in halide photorelease. The rate constants for excited-state halide release (k?21) were determined, and the values varied based on the functional groups present in the receptor ligand. Complexes with more hydrogen-bonding donors had smaller rate constants for halide photorelease. In a complex without a specific receptor ligand, the excited-state dipole was not oriented toward the associated halide, and the excited state was therefore found to have a larger equilibrium constant for halide association than the ground state.
- Turlington, Michael D.,Troian-Gautier, Ludovic,Sampaio, Renato N.,Beauvilliers, Evan E.,Meyer, Gerald J.
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p. 3316 - 3328
(2019/05/25)
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- A water-soluble cyclometalated iridium(III) complex with fluorescent sensing capability for hypochlorite
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Herein, a novel cyclometalated iridium (III) complex (Ir-1) with good water-solubility was designed and synthesized to sensitively detect hypochlorite (ClO?) in aqueous buffer solution. The sensor Ir-1 was prepared by incorporating a methacrylate group into cyclometalated ligands, which was a specific response site toward ClO? through an oxidation process. Ir-1 displayed strong emission at 615 nm, while significant fluorescence quenching was observed upon addition of ClO? with a low detection limit of 0.41 μM. Moreover, probe Ir-1 exhibited a rapid response (? with high selectivity over potentially competing species. The sensing process was evidenced by NMR and MS characterization. Further application in bioimaging of ClO? was successfully performed in living HepG2 cells.
- Lu, Zhen,Shangguan, Mingqin,Jiang, Xingzong,Xu, Peiyao,Hou, Linxi,Wang, Tao
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- Dehydrogenative Synthesis of 2,2′-Bipyridyls through Regioselective Pyridine Dimerization
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2,2′-Bipyridyls have been utilized as indispensable ligands in metal-catalyzed reactions. The most streamlined approach for the synthesis of 2,2′-bipyridyls is the dehydrogenative dimerization of unfunctionalized pyridine. Herein, we report on the palladium-catalyzed dehydrogenative synthesis of 2,2′-bipyridyl derivatives. The Pd catalysis effectively works with an AgI salt as the oxidant in the presence of pivalic acid. A variety of pyridines regioselectively react at the C2-positions. This dimerization method is applicable for challenging substrates such as sterically hindered 3-substituted pyridines, where the pyridines regioselectively react at the C2-position. This reaction enables the concise synthesis of twisted 3,3′-disubstituted-2,2′-bipyridyls as an underdeveloped class of ligands.
- Yamada, Shuya,Kaneda, Takeshi,Steib, Philip,Murakami, Kei,Itami, Kenichiro
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supporting information
p. 8341 - 8345
(2019/04/30)
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- Thiocyanate-free ruthenium(II) sensitizers with a bi-imidazole ligand in dye-sensitized solar cells (DSSCs)
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In this study, tris-heteroleptic Ru(ii) sensitizers denoted as SD-15 and SD-16 with a 4,4′,5,5′-tetramethyl-1H,1′H-2,2′-bis-imidazole moiety as the ancillary ligand were designed, synthesized and characterized using FTIR-ATR, 1H-NMR and UV-vis spectrophotometry. Structural modulations resulted in a red shift in the low-energy metal-to-ligand charge transfer (MLCT) absorption peak. The novel bis-imidazole based Ru(ii) sensitizer was adsorbed on a TiO2 surface via -COOH anchoring groups. The band gap, and the ground and excited state oxidation potentials were measured. The photovoltaic performance of the as-fabricated solar cells was measured and showed that the presence of bis-imidazole provided more negative free energy for dye regeneration (-ΔGregeneration) and less driving force for electron injection (-ΔGinjection) into the conduction band edge of TiO2. Therefore, the use of SD-15 and SD-16 resulted in lower JSC values of 10.20 and 3.52 mA cm-2, respectively, than N719. The open-circuit photovoltage (VOC) of SD-15 and SD-16 was 0.58 and 0.52 V, respectively, less than N719 under the same experimental conditions due to the decreased eTiO2 lifetime of 0.71 ms compared to 8.8 ms of N719 for the injected electrons that was calculated using impedance measurements. Our efforts in this research program led to the development of more stable Ru(ii) complexes compared to N719 NCS-based complexes; however, the conversion efficiency was lower. Hence, the fine-tuning of bi-imidazole is needed to identify more efficient NCS-free Ru(ii) sensitizers for higher efficiency DSSCs.
- Ashraf, Saba,Akhtar, Javeed,Siddiqi, Humaira M.,El-Shafei, Ahmed
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supporting information
p. 6272 - 6277
(2017/07/17)
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- Directly Coupled Versus Spectator Linkers on Diimine PtII Acetylides—Change the Structure, Keep the Function?
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Modification of light-harvesting units with anchoring groups for surface attachment often compromises light-harnessing properties. Herein, a series of [donor–acceptor–anchor] platinum(II) diimine (bis-)acetylides was developed in order to systematically compare the effect of conjugated versus electronically decoupled modes of attachment of protected anchoring groups on the photophysical properties of light-harvesting units. The first examples of “decoupled” phosphonate diimine PtII complexes are reported, and their properties are compared and contrasted to those of carboxylate analogues studied by a diversity of methods. Ultrafast time-resolved IR and transient absorption spectroscopy revealed that all complexes have a charge-transfer (CT) lowest excited state with lifetimes between 2 and 14 ns. Vibrational signatures and dynamics of CT states were identified; the assignment of electronic states and their vibrational origin was aided by TDDFT calculations. Ultrafast energy redistribution accompanied by structural changes was directly captured in the CT states. A significant difference between the structures of the electronic ground and CT excited states, as well as differences in the structural reorganisation in the complexes bearing directly attached or electronically decoupled anchoring groups, was discovered. This work demonstrates that decoupling of the anchoring group from the light-harvesting core by a saturated spacer is an easy approach to combine surface attachment with high reduction potential and ten times longer lifetime of the CT excited state of the light-absorbing unit, and retain electron-transfer photoreactivity essential for light-harvesting applications.
- Archer, Stuart A.,Keane, Theo,Delor, Milan,Bevon, Elizabeth,Auty, Alexander J.,Chekulaev, Dimitri,Sazanovich, Igor V.,Towrie, Michael,Meijer, Anthony J. H. M.,Weinstein, Julia A.
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p. 18239 - 18251
(2017/12/07)
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- Synthesis and Characterization of a Series of Bis-homoleptic Cycloruthenates with Terdentate Ligands as a Family of Panchromatic Dyes
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A series of six homoleptic bis-cyclometalated ruthenium complexes, Ru(N^N^C)2, is reported where N^N^C is a 6-(2,4-difluoro-3-R3-phenyl)-4-R2-4′-R1-2,2′-bipyridine with R3 = -H or -CF3 and R2 and R1 = -COOEt or -CF3. An effective synthesis of the ligands and the complexes is described. The UV-visible absorption studies demonstrate that these complexes are panchromatic dyes absorbing up to 900 nm. Importantly, the onset of absorption depends only on the substitution on the metalated phenyl, whereas the intensity of absorption throughout the spectra is a function of substituents on both the phenyl and the bipyridine moieties. The same trend is observed in electrochemistry as the redox gap depends only on the substitution on the metalated phenyl, whereas the oxidation and reduction potentials are a function of substituents on both the phenyl and the bipyridine moieties. Preliminary tests as sensitizer for dye-sensitized solar cells demonstrate that the number of anchoring groups on the dye has a major influence on the device efficiency.
- Rees, Thomas W.,Liao, Jinfeng,Sinopoli, Alessandro,Male, Louise,Calogero, Giuseppe,Curchod, Basile F.E.,Baranoff, Etienne
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supporting information
p. 9903 - 9912
(2017/08/26)
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- Covalent hybrids based on Re(i) tricarbonyl complexes and polypyridine-functionalized polyoxometalate: Synthesis, characterization and electronic properties
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A series of [Re(CO)3Br(N^N)] (N^N = substituted 2,2′-bipyridine ligand) complexes based on polypyridine-functionalized Dawson polyoxometalate (1-3) has been synthesized. The new hybrids (4-6) were characterized by various analytical techniques, including absorption, vibrational and luminescence spectroscopies as well as electrochemistry. Both units, the polyoxometalate and the transition metal complex, retain their intrinsic properties. Their combination in the newly prepared hybrids results in improved photosensitization in the high-energy visible region. However, a complete quenching of the emission for the [Re(CO)3Br(N^N)] complexes is observed due to formation of a charge separated state, Re(ii)-POM-, as shown by quenching experiments as well as theoretical modelling via DFT.
- Auvray, Thomas,Santoni, Marie-Pierre,Hasenknopf, Bernold,Hanan, Garry S.
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supporting information
p. 10029 - 10036
(2017/08/10)
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- Correlation between the Structure and Catalytic Activity of [Cp*Rh(Substituted Bipyridine)] Complexes for NADH Regeneration
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A series of water-soluble half-sandwich [Cp*RhIII(N^N)Cl]+ (Cp* = pentamethylcyclopentadiene, N^N-substituted 2,2′-bipyridine) complexes containing electron-donating substituents around the 2,2′-bipyridyl ligand were synthesized and fully characterized for the regioselective reduction of nicotinamide coenzyme (NAD+). The influence of the positional effect of the substituents on the structural, electrochemical, and catalytic properties of the catalyst was systematically studied in detail. The catalytic efficiency of the substituted bipyridine Cp*RhIII complexes are inversely correlated with their redox potentials. The 5,5′-substituted bipyridine Cp*RhIII complex, which had the lowest reduction potential, most effectively regenerated NADH with a turnover frequency of 1100 h-1. Detailed kinetic studies on the generation of intermediate(s) provide valuable mechanistic insight into this catalytic cycle and help to direct the future design strategy of corresponding catalysts.
- Ganesan, Vinothkumar,Sivanesan, Dharmalingam,Yoon, Sungho
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p. 1366 - 1374
(2017/02/15)
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- A new bipyridyl cobalt complex for reductive dechlorination of pesticides
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Reductive dechlorinations are especially promising reactions for improving the biodegradability and hence decreasing the environmental impact of chlorinated organic pollutants. In this context, the catalytic activity of a bipyridyl cobalt complex containing two bipyridine ligands was examined for achieving clean electrochemical dehalogenation in aqueous media. The prepared [Co(bpy(CH2OH)2)2]2+ complex was found to exhibit high catalytic activity toward the dechlorination of chloroacetanilide herbicides. Based on preparative electrolyses, 2-electron reduction of the substrate was obtained with a dechlorination yield of 85%, underlining the selectivity and efficiency of the dehalogenation process. Cyclic voltammetry analyses highlighted the catalytic activity of the complex toward chloroacetanilide herbicides, as alachlor, metolachlor and metazachlor. An high apparent chemical rate constant k1 of 5000 mol-1 L s-1 is calculated for the first step of the cathodic reduction of alachlor, based on simulated cyclic voltammetry experiments.
- He,Fontmorin,Hapiot,Soutrel,Floner,Fourcade,Amrane,Geneste
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p. 313 - 320
(2016/05/24)
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- PT(IV) COMPLEXES CONTAINING 4,4'-DISUBSTITUTED-2,2'-BIPYRIDYL AND THEIR USE IN CANCER THERAPY
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Platinum-containing compounds for the treatment of disease, such as, for example, cancer, are provided herein. Specifically, platinum Pt(IV) complexes with a substituted 2,2'-bipyridine ring structure are provided, as are methods for using the complexes.
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Paragraph 00214; 00216
(2016/02/29)
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- A water-soluble and retrievable ruthenium-based probe for colorimetric recognition of Hg(II) and Cys
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A new ruthenium-based complex 1 [(bis(4,4′-dimethylphosphonic-2,2′-bipyridine) dithiocyanato ruthenium (II))] was developed as a colorimetric probe for the detection of Hg(II) and Cys (Cysteine). The obtained compound 1 can give interconversional color changes upon the alternating addition of Hg(II) and Cys in 100% aqueous solution. The specific coordination between NCS groups with Hg(II) can lead to the formation of 1-Hg2 + complex, which can induce a remarkable spectral changes of probe 1. Afterwards the formed 1-Hg2 + complex can act as effective colorimetric sensor for Cys. Owing to the stronger binding affinity of sulfhydryl group to Hg2 +, Cys can extract Hg2 + from 1-Hg2 + complex resulting in the release of 1 and the revival of absorption profile of the probe 1. By introducing the hydrophilic phosphonic acid groups, the proposed probe exhibited excellent water solubility. The limits of detection (LODs) of the assay for Hg2 + and Cys are calculated to be 15 nM and 200 nM, respectively.
- Cui, Yali,Hao, Yuanqiang,Zhang, Yintang,Liu, Baoxia,Zhu, Xu,Qu, Peng,Li, Deliang,Xu, Maotian
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p. 150 - 154
(2016/05/09)
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- Metal-based tris-bipyridyl complexes and uses thereof in electrochromic applications
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The present invention relates to metal-based tris-bipyridyl complexes, e.g., iron-based tris-bipyridyl complexes, and their use in fabrication of surface confined assemblies for electrochromic applications.
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Paragraph 0128; 0159
(2016/10/09)
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- Synthesis and characterization of an immobilizable photochemical molecular device for H2-generation
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With [RuII(bpyMeP)2tpphzPtCl2]2+ (4) a molecular photocatalyst has been synthesized for visible-light-driven H2-evolution. It contains the ligand bpyMeP (4,4′-bis(diethyl-(methylene)-phosphonate)-2,2′-bipyridine) with phosphate ester groups as precursors for the highly potent phosphonate anchoring groups, which can be utilized for immobilization of the catalyst on metal-oxide semiconductor surfaces. The synthesis was optimized with regard to high yields, bpyMeP was fully characterized and a solid-state structure could be obtained. Photophysical studies showed that the photophysical properties and the localization of the excited states are not altered compared to similar Ru-complexes without anchoring group precursors. (4) was even more active in homogenous catalysis experiments than [RuII(tbbpy)2tpphzPtCl2]2+ (6) with tbbpy (4,4′-bis(tbutyl)-2,2′-bipyridine) as peripheral ligands. After hydrolysis (4) was successfully immobilized on NiO, suggesting that an application in photoelectrosynthesis cells is feasible. This journal is
- Braumüller, Markus,Schulz, Martin,Sorsche, Dieter,Pfeffer, Michael,Schaub, Markus,Popp, Jürgen,Park, Byung-Wook,Hagfeldt, Anders,Dietzek, Benjamin,Rau, Sven
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supporting information
p. 5577 - 5586
(2015/03/30)
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- An improved procedure for the preparation of Ru(bpz)3(PF6)2 via a high-yielding synthesis of 2,2'-bipyrazine
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There has been a recent surge of interest in the use of transition metal polypyridyl complexes as visible light-absorbing photocatalysts for synthetic applications. Among the most attractive features of this approach is the availability of many known complexes with well-characterized photophysical and electrochemical properties. In particular, Ru(bpz)32+ is a powerful photooxidant that has proven to be uniquely suited for oxidatively induced photoredox transformations. We present here a straightforward and highyielding route to Ru(bpz)3(PF6)2 that features an improved Pd-catalyzed synthesis of the 2,2'-bipyrazine ligand that is amenable to gram-scale preparations.
- Schultz, Danielle M.,Sawicki, James W.,Yoon, Tehshik P.
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supporting information
p. 61 - 65
(2015/01/30)
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- Synthesis of bifunctional Ru complexes with 1,2-dithiolane and carboxylate-substituted ligands
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Abstract An N3-type, Ru heteroleptic complex, AK1, having one bipyridyl ligand modified with COOH groups for tethering to TiO2 and a second bipyridyl ligand modified with two lipoic acid units for binding to platinum, was synthesized. The photophysical and spectroelectrochemical properties were studied in solution, on TiO2, in a dye-sensitized solar cell and on a Pt wire electrode. The results showed that AK1 can produce a photocurrent on TiO2. Furthermore, AK1 binds to Pt via the lipoic acid ligand but not via the carboxylic acid group, and can be electrochemically addressed by the Pt via the lipoic acid linkage.
- Kopecky, Andrew,Liu, Guangliang,Agushi, Ardian,Agrios, Alexander G.,Galoppini, Elena
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p. 6271 - 6275
(2015/05/27)
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- Selective on/off switching at room temperature of a magnetic bistable {Fe2Co2} complex with single crystal-to-single crystal transformation via intramolecular electron transfer
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A cyano-bridged {Fe2Co2} complex shows reversible single crystal-to-single crystal transformation between diamagnetic and paramagnetic states switched specifically by losing and absorbing methanol at room temperature in the solid state. And the solvent loss form presents temperature- and pressure-induced intramolecular electron transfer behaviour.
- Cao, Li,Tao, Jun,Gao, Qian,Liu, Tao,Xia, Zhengcai,Li, Dongfeng
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supporting information
p. 1665 - 1667
(2014/02/14)
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- New bi-functional zinc catalysts based on robust and easy-to-handle N-chelating ligands for the synthesis of cyclic carbonates from epoxides and CO2 under mild conditions
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A series of novel zinc complexes were prepared by covalent linkage of various imidazolium-based ionic liquid moieties with the 2,2′-bipyridine ligand on the two sides of the 4,4′-position. The zinc(ii) complexes containing the rigid N-chelating ligand proved to be stable, highly efficient and easy-to-handle catalysts towards the synthesis of cyclic carbonate from epoxide and CO2 without the use of any co-catalyst or organic solvent. The catalysts can be easily recovered and reused without significant loss of activity and selectivity by control of the solvent. The kinetic study uncovered that the reaction was first-order with respect to the epoxide. Moreover, a plausible reaction mechanism was proposed, in which the zinc center could promote ring-opening of the epoxide for the synergetic effect with the anion X- in ILs. the Partner Organisations 2014.
- Luo, Rongchang,Zhou, Xiantai,Zhang, Wuying,Liang, Zhongxiu,Jiang, Jun,Ji, Hongbing
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supporting information
p. 4179 - 4189
(2014/09/30)
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- PHOTOELECTRIC CONVERSION ELEMENT THAT CONTAINS DYE CONSISTING OF BINUCLEAR RUTHENIUM COMPLEX HAVING SUBSTITUTED BIPYRIDYL GROUPS, AND PHOTOCHEMICAL CELL
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The present invention relates to a binuclear ruthenium complex dye having a higher absorption coefficient and capable of absorbing light of longer wavelength for realizing a photoelectric conversion element and a photochemical cell which may convert solar
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Paragraph 0076
(2013/03/26)
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- Synthesis of phosphonic acid derivatized bipyridine ligands and their ruthenium complexes
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Water-stable, surface-bound chromophores, catalysts, and assemblies are an essential element in dye-sensitized photoelectrosynthesis cells for the generation of solar fuels by water splitting and CO2 reduction to CO, other oxygenates, or hydrocarbons. Phosphonic acid derivatives provide a basis for stable chemical binding on metal oxide surfaces. We report here the efficient synthesis of 4,4′-bis(diethylphosphonomethyl)-2,2′- bipyridine and 4,4′-bis(diethylphosphonate)-2,2′-bipyridine, as well as the mono-, bis-, and tris-substituted ruthenium complexes, [Ru(bpy) 2(Pbpy)]2+, [Ru(bpy)(Pbpy)2]2+, [Ru(Pbpy)3]2+, [Ru(bpy)2(CPbpy)]2+, [Ru(bpy)(CPbpy)2]2+, and [Ru(CPbpy)3] 2+ [bpy = 2,2′-bipyridine; Pbpy = 4,4′-bis(phosphonic acid)-2,2′-bipyridine; CPbpy = 4,4′-bis(methylphosphonic acid)-2,2′-bipyridine].
- Norris, Michael R.,Concepcion, Javier J.,Glasson, Christopher R. K.,Fang, Zhen,Lapides, Alexander M.,Ashford, Dennis L.,Templeton, Joseph L.,Meyer, Thomas J.
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p. 12492 - 12501
(2013/11/19)
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- Functionalized bipyridyl rhodium complex capable of electrode attachment for regeneration of NADH
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A Rh(III) complex having a functionalized bpy-OH ligand that is potentially linkable to electrode surfaces was synthesized and fully characterized. The hydrido complex, which could be generated either electrochemically by cathodic reduction of the [η5-Cp*Rh(bpy-OH)Cl]Cl complex at -771 mV (versus Ag/AgCl) or chemically with formate, transformed NAD + efficiently into NADH with a TOF = 710 at 60 C.
- Sivanesan, Dharmalingam,Yoon, Sungho
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- Establishing dual electrogenerated chemiluminescence and multicolor electrochromism in functional ionic transition-metal complexes
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A combination of electrochromism and electroluminescence in functional materials could lead to single-layer dual electrochromic/electroluminescent (EC/EL) display devices, capable of simultaneous operation in emissive and reflective modes. Whereas such next generation displays could provide optimal visibility in any ambient lighting situation, materials available that exhibit such characteristics in the active layer are limited due to the required intrinsic multifunctionality (i.e., redox activity, electroluminescence, electrochromism, and ion conductivity) and to date can only be achieved via the rational design of ionic transition-metal complexes. Reported herein is the synthesis and characterization of a new family of acrylate-containing ruthenium (tris)bipyridine-based coordination complexes with multifunctional characteristics. Potential use of the presented compounds in EC/EL devices is established, as they are applied as cross-linked electrochromic films and electrochemiluminescent layers in light-emitting electrochemical cell devices. Electrochromic switching of the polymeric networks between yellow, orange, green, brown and transmissive states is demonstrated, and electrochemiluminescent devices based on the complexes synthesized show red-orange to deep red emission with λmax ranging from 680 to 722 nm and luminance up to 135 cd/m2. Additionally, a dual EC/EL device prototype is presented where light emission and multicolor electrochromism occur from the same pixel comprised of a single active layer, demonstrating a true combination of these properties in ionic transition-metal complexes.
- Puodziukynaite, Egle,Oberst, Justin L.,Dyer, Aubrey L.,Reynolds, John R.
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scheme or table
p. 968 - 978
(2012/03/07)
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- PHOTOELECTRIC CONVERSION DEVICE WHEREIN DYE CONSISTING OF BINUCLEAR RUTHENIUM COMPLEX HAVING SUBSTITUTED BIPYRIDYL GROUPS IS USED, AND PHOTOCHEMICAL CELL
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The present invention relates to a binuclear ruthenium complex dye having a substituted bipyridyl group and represented by the general formula (1): wherein R1, R2, R3 and R4 each independently represents a linear or branched alkyl group having 1 to 30 carbon atoms, with the proviso that at least one of R1 and R2 represents a linear or branched alkyl group having 10 to 30 carbon atoms and at least one of R3 and R4 represents a linear or branched alkyl group having 10 to 30 carbon atoms; X represents a counter ion; n represents a number of the counter ions needed to neutralize a charge of the complex; and proton(s) (H+) of one or more carboxyl groups (-COOH) may dissociate.
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Page/Page column 9
(2012/09/10)
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- 4,4'-DICARBOXY-2,2'-BIPYRIDINE DERIVED TRIDENTATE LIGAND, METAL COMPLEX CONTAINING THE SAME, AND APPLICATION THEREOF
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Disclosed is a 4,4′-dicarboxy-2,2′-bipyridine derived tridentate ligand represented by formula (I): wherein definitions of Y1, Y2, and R are the same as those defined in the specification. Also disclosed are a metal complex containing the aforesaid tridentate ligand and a dye-sensitized solar cell containing the metal complex.
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- High spectral response heteroleptic ruthenium (II) complexes as sensitizers for dye sensitized solar cells
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Heteroleptic ruthenium(II) bipyridyl complex, cis-Ru(II)(4,4'-bis(4-tert- butylstyryl)-2,2'-bipyridyl) (4,4'-dicarboxy-2,2'-bipyridyl) (NCS2) (H112) was synthesized and characterized by 1H-NMR, MASS, Spectrofluorometer and UV-Vis spectroscopes. The photo-voltaic performance of the sensitizer was evaluated in Dye Sensitized Solar Cell (DSSC) under irradiation of AM 1.5 G solar light and the photovoltaic characteristics were compared with those of reference cells of HRS1 and N719 fabricated under comparable conditions. Compared to N719, H112 sensitizer showed enhanced molar extinction coefficient and relatively better monochromatic incident photon-to-current conversion efficiency (IPCE) across the spectral range of 400 to 800 nm with solar energy-to-electrical conversion efficiency (η) of 2.43% [open circuit photovoltage (VOC) = 0.631V, short-circuit photocurrent density (JSC) = 8.96 mA/cm2, fill factor (ff) = 0.430], while η values of 2.51% (VOC = 0.651 V, JSC = 9.41mA/cm 2, ff = 0.410) and 2.74% (VOC = 0.705 V, JSC = 8.62 mA/cm2, ff = 0.455) were obtained for HRS1 and N719 sensitized solar cells respectively. The introduction of 4,4'-bis(4-tert-butylstyryl) moieties on one of the bipyridine moieties of N719 complex shows higher light absorption abilities, IPCE and JSC. Indian Academy of Sciences.
- Chandrasekharam,Srinivasarao,Suresh,Reddy, M. Anil,Raghavender,Rajkumar,Srinivasu,Reddy, P. Yella
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experimental part
p. 37 - 46
(2012/02/13)
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- Inhibition of histone demethylases by 4-Carboxy-2,2'-Bipyridyl compounds
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Exploiting epigenetics: 2-Oxoglutarate (2OG)-dependent histone lysine demethylases, such as JMJD2E, are potential therapeutic targets in a range of diseases. Through structure-activity relationship studies and analyses, we identified a potent 4-carboxy-2,2'-bipyridyl compound, which inhibits JMJD2E with an IC50 value of 110nM, representing a 66-fold improvement over the lead compound. These bipyridyl derivatives bind in the 2-oxoglutarate binding site.
- Chang, Kai-Hsuan,King, Oliver N. F.,Tumber, Anthony,Woon, Esther C. Y.,Heightman, Tom D.,Mcdonough, Michael A.,Schofield, Christopher J.,Rose, Nathan R.
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scheme or table
p. 759 - 764
(2012/01/06)
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- Convenient synthesis of functionalized 4,4′-disubstituted-2,2′- bipyridine with extended π-system for dye-sensitized solar cell applications
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Exploration of new ruthenium-based sensitizers for dye-sensitized solar cell (DSC) applications requires an easy access to multifunctionalized ligands for efficient screening of sensitizers' properties. Based on the Horner-Emmons-Wadsworth reaction, a convenient synthetic route for the extension of the π-system on 4,4′-disubstituted-2,2′-bipyridines was used to develop a novel series of functionalized 2,2′-bipyridine ligands with either electron-withdrawing or donating end-capping group. 1H NMR spectroscopy revealed that all the new bipyridyl ligands were obtained exclusively in their fully E isomers.
- Klein, Cédric,Baranoff, Etienne,Nazeeruddin, Md. Khaja,Gr?tzel, Michael
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scheme or table
p. 6161 - 6165
(2011/01/04)
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- Enhanced electrochemiluminescence efficiency of Ru(ii) derivative covalently linked carbon nanotubes hybrid
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The synthesized derivative Ru(bpy)3 covalently linked CNTs hybrid shows good electrochemical activity and ca. 17 times higher luminescence quantum efficiency than the adsorbed derivative Ru(bpy)3. The Ru-CNTs based ECL sensor exhibits high stability toward determination of TPA with a detection limit as low as 8.75 pM.
- Li, Jing,Guo, Li-Rong,Gao, Wei,Xia, Xing-Hua,Zheng, Li-Min
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supporting information; experimental part
p. 7545 - 7547
(2010/04/28)
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- Spectroscopic, electrochemical and computational study of Pt-diimine-dithiolene complexes: Rationalising the properties of solar cell dyes
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A series of [Pt(ii)(diimine)(dithiolate)] complexes of general formula [Pt{X,X′-(CO2R)2-bpy}(mnt)] (where X = 3, 4 or 5; R = H or Et, bpy = 2,2′-bipyridyl and mnt = maleonitriledithiolate), have been spectroscopically, electrochemically and computationally characterised and compared with the precursors [Pt{X,X′-(CO2R) 2-bpy}Cl2] and X,X′-(CO2R) 2-bpy. The study includes cyclic voltammetry, in situ EPR spectroelectrochemical studies of fluid solution and frozen solution samples, UV/Vis/NIR spectroelectrochemistry, hyrid DFT and TD-DFT calculations. The effect of changing the position of the bpy substituents from 3,3′ to 4,4′ and 5,5′ is discussed with reference to electronic changes seen within the different members of the family of molecules. The performance of the mnt complexes in dye-sensitised solar cells has been previously described and the superior performance of [Pt{3,3′-(CO2R)2-bpy} (mnt)] is now explained in terms of decreased electronic delocalisation through twisting of the bipyridyl ligand as supported by the EPR and computational results.
- Geary, Elaine A. M.,McCall, Keri L.,Turner, Andrew,Murray, Paul R.,McInnes, Eric J. L.,Jack, Lorna A.,Yellowlees, Lesley J.,Robertson, Neil
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scheme or table
p. 3701 - 3708
(2009/02/01)
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- Dehydrogenative coupling of 4-substituted pyridines catalyzed by diruthenium complexes
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Coupling reaction of 4-substituted pyridines via direct C-H bond activation was achieved by the use of diruthenium complexes 1 and 2. These reactions provide a variety of functionalized bipyridines in a selective manner without the formation of terpyridines. Copyright
- Kawashima, Takashi,Takao, Toshiro,Suzuki, Hiroharu
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p. 11006 - 11007
(2008/03/13)
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- Photophysical Properties of Polypyridyl Carbonyl Complexes of Rhenium(I)
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The photophysical properties of the metal to ligand charge transfer (m.l.c.t.) excited states of the complexes (X=NH2, NEt2, NHCOCH3, OCH3, CH3, H, Ph, Cl, CO2Et or NO2; bipy = bipyridine) vary systematically as the substituent X is varied.For the cases where m.l.c.t. states are lowest lying a quantitative correlation exists between ln(knr x 1 s) (knr is the rate constant for nonradiative decay) and the Franck-Condon factor calculated from parameters obtained by emission spectral fitting.The solvent reorganizational energy for has been determined to be 1100 cm-1 in EtOH-MeOH -(4:1 v/v) and 650 cm-1 in 2-methyltetrahydrofuran by a temperature dependent bandwidth study.Based on a comparative analysis of properties with related polybipyridyl complexes of RuII and OsII it has been concluded that: (1) the extent of distortion at the 4,4'-X2-bipy acceptor ligand correlates with the energy gap between the excited and ground states; these results are in agreement with an earlier correlation found for polypyridyl complexes of OsII; (2) the unusually large Stokes shift and the broadening of the vibronic components in absorption and emission spectra arise from a combination of increased solvent reorganizational energies and greater distortions in the low-frequency modes between the excited and ground states; and (3) the relatively short lifetimes for the complexes of ReI have as a major contributing factor the participation of a ν(CO) mode at ca. 2020-2040 cm-1 as an energy acceptor in non-radiative decay.
- Worl, Laura A.,Duesing, Rich,Chen, Pingyun,Ciana, Leopoldo Della,Meyer, Thomas J.
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p. 849 - 858
(2007/10/02)
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- Electrochemical and Spectral investigations of Ring-Substituted Bipyridine Complexes of Ruthenium
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A spectroelectrochemical study of a series of Ru complexes has been carried out by using an optically transparent thin-layer electrode (OTTLE).The visible spectra of the reduced complexes Ru(Bp5COOEt)3n (Bp5COOEt = 5,5'-bis(ethoxycarbonyl)-2,2'-bipyridine) and Ru(bpy)3n (bpy = bipyridine) appear to resemble the spectra of the corresponding ligand radical anion whereas the spectrum of Ru(Bp4COOEt)3n (Bp4COOEt = 4,4'-bis(ethoxycarbonyl)-2,2'-bipyridine) does not.In the near-IR two types of spectral behavior are observed once the complexes are reduced beyong the 2+ oxidation state: Type A complexes (e.g., Ru(bpy)3, Ru(Bp4Me)3 (Bp4Me = 4,4'-dimethyl-2,2'-bipyridine)) exhibit low-intensity (ε n, Ru(Bp4CONEt)3n (Bp4CONEt = 4,4'-bis(diethylcarbamyl)-2,2'-bipyridine)) exhibit broad bands of greater intensity (1000 ε 15000).Possible origins for type B behavior are discussed.Examination of electrochemical results reveals an almost perfect linear correlation when ligand reduction potentials are plotted against the 2+/1+ couple of the corresponding ruthenium complex (correlation coefficient = 0.9993).The thermodynamic applications of this observation are considered.Both the spectral and electrochemical data support a model of the reduced metal complex having electrons localized in ligand orbitals.
- Elliott, C. Michael,Hershenhart, Elise J.
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p. 7519 - 7526
(2007/10/02)
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