- Electrochemistry and spectroscopy of substituted [Ru(phen)3]2+ and [Ru(bpy)3]2+ complexes
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The metal-to-ligand charge transfer property of nitrogen-based ruthenium complexes earns it a central place in dye-sensitized solar cell and photo-catalytic H2O and CO2 reduction research and applications. Electronic and spectral tuning are conveniently done by altering substituents and ligands. Cyclic voltammograms and UV–visible spectra of a synthesized series of electronically altered phenanthroline and bipyridyl ruthenium complexes (ΔE°' > 1.4 V for RuII-III) were obtained and, amongst others, correlated with DFT computed HOMO energies and ionization potentials. A good linear relationship with R2 = 0.97 were found for the combined bipyridyl and phenanthrolinato ruthenium series, thereby providing a convenient computational tool for the theoretical prediction of associated redox potentials. TDDFT closely simulates spectral properties of these complexes, where λmax varies from 420 to 520 nm. The former wavelength is representative of the dione-phenanthroline and the latter of the dinitro-bipyridyl ruthenium complex.
- van der Westhuizen, Deidré,von Eschwege, Karel G.,Conradie, Jeanet
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- Electronic effects on reactivity and anticancer activity by half-sandwich N,N-chelated iridium(iii) complexes
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The synthesis and characterization of a series of organometallic half-sandwich N,N-chelated iridium(iii) complexes bearing a range of electron-donating and withdrawing substituents were described. The X-ray crystal structures of complexes 1, 3 and 5 have been determined. This work demonstrated how the aqueous chemistry, catalytic activity in converting coenzyme NADH to NAD+ and anticancer activity can be controlled and fine-tuned by the modification of the ligand electronic perturbations. In general, the introduction of an electron-withdrawing group (-Cl and-NO2) on the bipyridine ring resulted in increased anticancer activity, whereas an electron-donating group (-NH2,-OH and-OCH3) decreased the anticancer activity. Complex 6 bearing a strongly electron-withdrawing NO2 group displayed the highest anticancer activity (7.3 ± 1.2 μM), ca. three times as active as cisplatin in the A549 cell line. Notably, selective cytotoxicity for cancer cells over normal cells was observed for complexes 1 and 6. DNA binding does not seem to be the primary mechanism for cancer fighting. However, the aqueous chemistry, cell apoptosis and cell cycle, which show similar dependence on the ligand electronic perturbations as the anticancer activity, appear to together contribute to the anticancer potency of theses complexes. This work may provide an alternative strategy to enhance anticancer activity for these N,N-chelated organometallic half-sandwich iridium(iii) complexes.
- Guo, Lihua,Zhang, Hairong,Tian, Meng,Tian, Zhenzhen,Xu, Yanjian,Yang, Yuliang,Peng, Hongwei,Liu, Peng,Liu, Zhe
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supporting information
p. 16183 - 16192
(2018/10/04)
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- The synthesis of diethyl 2-(2,2 ′ -bipyridin-4-ylmethylene)malonate and diethyl 3,3 ′ -(2,2 ′ -bipyridine-4,4 ′ -diyl)diacrylate
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Abstract: The new acrylic acid derivatives diethyl 2-(2,2′-bipyridin-4-ylmethylene)malonate and diethyl 3,3′-(2,2′-bipyridine-4,4′-diyl)diacrylate which may be used for the introduction of metal coordination sites in polyacrylates were synthesized and characterized. Intermediates of the syntheses were prepared by improved synthetic protocols working under microwave conditions whenever it was advantageous for the resulting product in terms of reaction time and/or chemical yield. In addition, the crystal structure of one of the intermediates, 4,4′-dibromo-2,2′-bipyridine (6), is reported, in which molecules are arranged into infinite chains by C-H—Br interactions. Graphical Abstract: SYNOPSIS Synthesis and characterization of new 2,2’-bipyridine ligands with substituents related to acrylic acid esters are reported. These compounds offer the possibility to incorporate 2,2’-bipyridine ligands or coordination compounds derived from them into polyacrylate materials. [Figure not available: see fulltext.].
- Heintz, Katharina,G?rls, Helmar,Imhof, Wolfgang
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- Catalytic Conversions in Water. Part 22: Electronic Effects in the (Diimine)palladium(II)-Catalysed Aerobic Oxidation of Alcohols
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The electronic effects in the (diimine)Pd-(II)-catalysed aerobic oxidation of alcohols were investigated from the viewpoint of both the catalyst and the alcohol. A 'push-pull' mechanism is operative, where both electron-donating substituents on the benzyl alcohol (ρ = -0.58) and electron-withdrawing groups on the 4,4′-disubstituted-2,2′-bipyridine ligand (ρ = +0.18) increase the reaction rate. The results indicate partial reduction of the palladium centre in the transition state of the rate-limiting step.
- Ten Brink, Gerd-Jan,Arends, Isabel W. C. E.,Hoogenraad, Marcel,Verspui, Goeran,Sheldon, Roger A.
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p. 497 - 505
(2007/10/03)
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- Studies of 2,2'-Bipyridyl N,N'-Dioxides
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2,2'-Bipyridyl N,N'-dioxide, its derivatives substituted at the 4- and/or 4'-positions by methoxy, nitro, chloro, and bromo groups, and the corresponding N,N'-deoxygenated compounds have been synthesized.The N,N'-dioxides were examined in a number of refluxing solvents and under sublimation to investigate a potential liberation of singlet oxygen.All N,N'-dioxides were found to be stable under such conditions with no production of the corresponding N,N'-deoxygenated compounds.
- Wenkert, David,Woodward, R. B.
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p. 283 - 289
(2007/10/02)
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- SUBSTITUTED 2,2'-BIPYRIDINES AS LIGANDS. PREPARATION AND CHARACTERIZATION OF 4,4'-DISUBSTITUTED 2,2'-BIPYRIDINE DERIVATIVES OF THE HEXACARBONYLS OF CHROMIUM, MOLYBDENUM AND TUNGSTEN
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The preparation of cis- (M=Cr, Mo, W; biL is 4,4'-X2-2,2'-bipyridine; X=NMe2, NH2, OMe, CMe3, Me, H, Ph, CH=CHPh, Cl, CO2H, CO2Me, NO2) is reported.The ligands and complexes are characterized by spectroscopy (IR, electronic absorption and emission, NMR (1H, 13C, 15N, 95Mo)) and microanalysis.The variations observed in the spectroscopic properties of these complexes are strongly correlated with electronic substituent parameters of the group X.This is most apparent in the lowest energy (visible) absorption which changes by ca. 0.8 eV between the extremes of donor and off acceptor substituent used.
- Connor, Joseph P.,Overton, Colin
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p. 165 - 174
(2007/10/02)
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