- Chromium(VI) oxide-mediated oxidation of polyalkyl-polypyridines to polypyridine-polycarboxylic acids with periodic acid
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4,4′-Dicarboxy-2,2′-bipyridine was synthesized quantitatively by chromium(VI) oxide-mediated oxidation of 4,4′-dimethyl-2,2′-bipyridine or 4,4′-diethyl-2,2′-bipyridine with periodic acid as the terminal oxidant in sulfuric acid. 5,5′-Dicarboxy-2,2′-bipyridine and 6,6’-dicarboxy-2,2′-bipyridine were also synthesized by the method from the corresponding dimethyl bipyridines in excellent yields. 4,4′,4″-Tricarboxy-2,2′:6′,2″-terpyridine was obtained in 80% yield from 4,4′,4″-triethyl-2,2′:6′,2″-terpyridine, and 4,4′,4″,4′″-tetracarboxy-2,2′:6′,2″:6″,2′″-quaterpyridine was obtained in 72% yield from 4,4′,4″,4′″-tetraethyl-2,2′:6′,2″:6″,2′″-quaterpyridine by the same procedure.
- Yamazaki, Shigekazu
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supporting information
p. 2210 - 2218
(2019/06/25)
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- Method for preparing 2,2'-bipyridine and its derivatives
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The invention discloses a method for preparing 2,2'-bipyridine and its derivatives. The method is characterized in that the 2,2'-bipyridine represented by formula II is generated through dehydrogenation coupling of pyridine represented by formula I, or its derivative, in the presence of an additive under the action of a supported catalyst, wherein R in the formula I and the formula II is H, a C1-C2 alkyl group, Cr or Br. The method has the advantages of extensive applicability of the raw material, high atom utilization rate, and high activity, long life and few byproducts in the catalyst.
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Paragraph 0049; 0051
(2018/06/15)
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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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- Synthesis of triruthenium complexes containing a triply bridging pyridyl ligand and its transformations to face-capping pyridine and perpendicularly coordinated pyridyl ligands
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Unlike the reactions of carbonyl clusters with pyridine leading to the formation of μ-pyridyl complexes, the reaction of the triruthenium pentahydrido complex {Cp*Ru(μ-H)}3(μ3-H) 2 (Cp* = η5-C5Me5) (1) with pyridines provided μ3-η2(//)-pyridyl complexes, (Cp*Ru)3(μ-H)4(μ3- η2(//)-RC5H3N) (2a, R = H; 2b, R = 4-COOMe; 2c, R = 4-COOEt; 2d, R = 4-Me; 2e, R = 5-Me), in which the molecular plane of the pyridyl group was tilted with respect to the Ru3 plane. Electron-rich metal centers of the trimetallic core enabled back-donation to the pyridyl group, which caused the additional π-coordination of the C=N bond. The electron-rich metal centers of 2a-2c also promoted further transformation into face-capping pyridine complexes {Cp*Ru(μ-H)} 3(μ3-η2:η2: η2-RC5H4N) (3a, R = H; 3b, R = 4-COOMe; 3c, R = 4-COOEt) upon heating. In contrast, the thermolysis of 2d did not afford a face-capping picoline complex because of the poor electron-accepting ability of the picolyl moiety. Instead, the coordinatively unsaturated μ3- picolyl complex (Cp*Ru)3(μ-H)2(μ3- η2-4-Me-C5H3N) (4d) was obtained. Owing to its unsaturated nature, 4d can react with γ-picoline to yield 4,4′-dimethyl-2,2′-bipyridine. Although the reaction rate was slow, complex 1 catalyzed the dehydrogenative coupling of 4-substituted pyridines containing an electron-donating group. The protonation of 2a also afforded the coordinatively unsaturated pyridyl complex [(Cp*Ru)3(μ-H) 2(μ3-H)(μ3-η2: η2(⊥)-C5H4N)]+ (5a), but the coordination mode of the pyridyl group in 5a was completely different from that in 4d. The pyridyl moiety in 5a was coordinated on one of the Ru-Ru bonds in a perpendicular fashion. The methylation of the face-capping pyridine complex 3a, which led to the formation of the N-methyl pyridinium complex [(Cp*Ru)3(μ-H)3 (μ3- η2:η2:η2-C5H 5NMe)]+ (7b) was also examined. NMR studies on 7b as well as X-ray diffraction studies suggested enhanced back-donation to the pyridinium moiety because of the localized cationic charge on the nitrogen atom.
- Takao, Toshiro,Kawashima, Takashi,Kanda, Hideyuki,Okamura, Rei,Suzuki, Hiroharu
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experimental part
p. 4817 - 4831
(2012/10/08)
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- A more efficient synthesis of 4,4′,4″-tricarboxy-2,2′: 6′,2″-terpyridine
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We report in this paper a new route for the synthesis of 4,4′,4″-tricarboxy-2,2′:6′,2″-terpyridine. This synthetic pathway has a lower ecological impact with respect to yield, atom economy, solvent and chemicals used and wastes generated when compared to a previously reported method. In addition it uses furfural, which can be obtained from renewable sources. The title compound can be used to prepare complexes that are valuable for applications in Dye Sensitized Solar Cells.
- Dehaudt, Jeremy,Husson, Jerome,Guyard, Laurent
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scheme or table
p. 3337 - 3340
(2012/01/15)
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- Engineering of efficient panchromatic sensitizers for nanocrystalline TiO2-based solar cells
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A new series of panchromatic ruthenium(II) sensitizers derived from carboxylated terpyridyl complexes of tris-thiocyanato Ru(II) have been developed. Black dye containing different degrees of protonation {(C2H5)3NH}[Ru(H3tcterpy)(NCS) 3] 1, {(C4H9)4N}2[Ru(H2 tcterpy)(NCS)3] 2, {(C4H9)4N}3[Ru(Htcterpy)(NCS) 3] 3, and {(C4H9)4N}4[Ru(tcterpy)(NCS) 3] 4 (tcterpy = 4,4′,4″-tricarboxy-2,2′:6′,2″-terpyridine) have been synthesized and fully characterized by UV-vis, emission. IR, Raman, NMR, cyclic voltammetry, and X-ray diffraction studies. The crystal structure of complex 2 confirms the presence of a RuIIN6 central core derived from the terpyridine ligand and three N-bonded thiocyanates. Intermolecular H-bonding between carboxylates on neighboring terpyridines gives rise to 2-D H-bonded arrays. The absorption and emission maxima of the black dye show a bathochromic shift with decreasing pH and exhibit pH-dependent excited-state lifetimes. The red-shift of the emission maxima is due to better π-acceptor properties of the acid form that lowers the energy of the CT excited state. The low-energy metal-to-ligand charge-transfer absorption band showed marked solvatochromism due to the presence of thiocyanate ligands. The Ru(II)/(III) oxidation potential of the black dye and the ligand-based reduction potential shifted cathodically with decreasing number of protons and showed more reversible character. The adsorption of complex 3 from methoxyacetonitrile solution onto transparent TiO2 films was interpreted by a Langmuir isotherm yielding an adsorption equilibrium constant, Kads, of (1.0 ± 0.3) × 105 M-1. The amount of dye adsorbed at monolayer saturation was (na = 6.9 ± 0.3) × 10-8 mol/mg of TiO2, which is around 30% less than that of the cis-di(thiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylate) ruthenium(II) complex. The black dye, when anchored to nanocrystalline TiO2 films achieves very efficient sensitization over the whole visible range extending into the near-IR region up to 920 nm, yielding over 80% incident photon-to-current efficiencies (IPCE). Solar cells containing the black dye were subjected to analysis by a photovoltaic calibration laboratory (NREL, U.S.A.) to determine their solar-to-electric conversion efficiency under standard AM 1.5 sunlight. A short circuit photocurrent density obtained was 20.5 mA/cm2, and the open circuit voltage was 0.72 V corresponding to an overall conversion efficiency of 10.4%.
- Nazeeruddin,Pechy,Renouard,Zakeeruddin,Humphry-Baker,Cointe,Liska,Cevey,Costa,Shklover,Spiccia,Deacon,Bignozzi,Graetzel
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p. 1613 - 1624
(2007/10/03)
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