- Spin Crossover Behavior in a Homologous Series of Iron(II) Complexes Based on Functionalized Bipyridyl Ligands
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A series of bulky substituted bipyridine-related iron(II) complexes [Fe(H2Bpz2)2(L)] (pz = pyrazolyl) were prepared, where L = 5,5′-dimethyl-2,2′-bipyridine (bipy-CH3, 1), L = dimethyl-2,2′-bipyridyl-5,5′-dicarboxylate (MeObpydc, 2), L = diethyl-2,2′-bipyridyl-5,5′-dicarboxylate (EtObpydc, 3), or L = diisopropyl-2,2′-bipyridine-5,5′-dicarboxylate (i-PrObpydc, 4). The crystal structures of five new iron(II) complexes were determined by X-ray diffraction: those of 1, 3, and 4 and two modifications of 3 (3B) and 4 (4B). Complexes 1 and 3B display incomplete spin crossover (SCO) behavior because of a freezing-in effect, whereas 3 and 4B undergo gradual and incomplete SCO behaviors. Complexes 2 and 4 show a completely gradual and steep SCO, respectively. Such different SCO behaviors can be attributed to an electronic substituent effect in the bipyridyl ligand conformation and a crystal packing effect. Importantly, the electronic substituent effect of the isopropyl acetate group and C-H···O supramolecular interactions in 4 contribute to a highly cooperative behavior, which leads to an abrupt thermally induced spin transition.
- Xue, Shufang,Guo, Yunnan,Rotaru, Aurelian,Müller-Bunz, Helge,Morgan, Grace G.,Trzop, Elzbieta,Collet, Eric,Oláh, Julianna,Garcia, Yann
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- Bolaamphiphiles bearing bipyridine as mesogenic core: Rational exploitation of molecular architectures for controlled self-assembly
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A bolaamphiphile (5,5-B2NBr8) bearing a functional bipyridine moiety as the mesogenic core is reported for the first time. 5,5-B2NBr8 was found to self-assemble into uniform fibrous structure in aqueous solution, when the concentration was higher than cmc. Analogues of 5,5-B2NBr8 with structural differences in chain length, headgroup, mesogenic core, and substituted position were synthesized, elucidating that small variances of the molecular structure could lead to dramatic changes of the resulting assemblies. For example, compound 4,4-B2NBr8 showed only spherical colloidal aggregates rather than fibers as 5,5-B2NBr8 did, while the only difference between them was the position at which the alkyl chains were attached onto bipyridine. A probable model for the fibrous structure of 5,5-B2NBr8 was proposed. Moreover, exploiting the coordination capacity of bipyridine, assembly and disassembly of 5,5-B2NBr8 could be reversibly controlled through the addition of EDTA and Cu(II), respectively.
- Wu, Guanglu,Verwilst, Peter,Xu, Jun,Xu, Huaping,Wang, Ruji,Smet, Mario,Dehaen, Wim,Faul, Charl F. J.,Wang, Zhiqiang,Zhang, Xi
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- INHIBITORS OF COLLAGEN PROLYL 4-HYDROXYLASE
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Biheteroaryl dicarboxylates and esters, and salts thereof which are useful as modulators of CP4H activity and more particularly as inhibitors of CP4H. Compounds of formula: and salts thereof where: X is S, O, NH, or NR, where R is an alkyl group having 1-3 carbon atoms; R1 and R2 independently are —OR7, or —NHSO2R8, where R7 is selected from: hydrogen, alkyl, alkenyl, alkoxyalkyl, —R′—CO—R″, —R′—CO—O—R″, —CO—R″, —R′—O—CO—R″, —R′—CO—NR″, —CO—NR″, or —R′—O—CO—NR″, and R8 is selected from hydrogen, alkyl, aryl, arylalkyl; R3, R4 and R6 independently are hydrogen, alkyl, alkoxy, alkenyl, alkenoxy, halo alkyl, haloalkenyl, halogen, hydroxyl, hydroxyalkyl, hydroxyalkenyl, aryl, aryloxy, arylalkyl or arylalkyloxy; R5 is hydrogen, halogen, alkyl having 1-3 carbon atoms, or alkoxy having 1-3 carbon atoms; —R′— is a divalent straight chain or branched alkylene, and —R″ is an alkyl, alkenyl, arylalkyl, or aryl group. Methods for inhibition of CP4H in vivo and in vitro.
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Paragraph 0297; 0298; 0299
(2016/10/17)
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- Primary coloured electrochromism of aromatic oxygen and sulfur diesters
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Eleven aromatic diesters and thioic S,S′-diesters were synthesized and investigated using electrochemical (cyclic voltammetry and controlled potential electrolysis) and UV-vis spectroscopic techniques over a range of temperatures. Nine of the compounds exhibited vibrant colour changes from a colourless state in their neutral forms to brightly coloured upon one-electron electrochemical reduction in acetonitrile. The compounds were found to display either red, green or blue colours in their one-electron reduced states. The electrochromic properties of 3 of the compounds that displayed the most vibrant colour changes were examined in solution using a gold micro-mesh electrode laminated inside a polymer film.
- Xu, Xiuhui,Webster, Richard D.
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p. 18100 - 18107
(2014/05/20)
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- A molecular Pd(ii) complex incorporated into a MOF as a highly active single-site heterogeneous catalyst for C-Cl bond activation
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The organic palladium complex Pd(H2bpydc)Cl2 (H 2bpydc = 2,2′-bipyridine-5,5′-dicarboxylic acid) was immobilized on a porous metal-organic framework UiO-67 (Zr6O 4(OH)4(bpdc)6, bpdc = para- biphenyldicarboxylate) using a direct incorporation strategy. The use of a large amount of the H2bpdc ligand (90 mol% of the mixed ligands) that can't chelate the Pd complex allowed the formation of isolated Pd single active sites uniformly distributed in the MOF network. Pd(ii) doped UiO-67 is isostructural to the parent UiO-67 framework, with a high surface area and pore volume of ca. 2000 m2 g-1 and 0.79 cm3 g -1, respectively. The material was highly efficient in the catalytic conversion of aryl chlorides, showing remarkably higher activity than the homogeneous Pd counterparts. High yields were achieved in Heck and Suzuki-Miyaura coupling reactions of chloroarenes bearing a wide range of substituents. Moreover, the catalyst was recoverable and reusable, giving essentially identical activity after at least 5 cycles. The combination of the advantages of both homogeneous molecular Pd catalysts and solid MOF structures in this system may bring new opportunity in the development of highly active heterogeneous palladium catalysts for a variety of Pd-catalyzed transformations. This journal is the Partner Organisations 2014.
- Chen, Liyu,Rangan, Sylvie,Li, Jing,Jiang, Huanfeng,Li, Yingwei
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p. 3978 - 3985
(2014/08/05)
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- Reductive couplings of 2-halopyridines without external ligand: Phosphine-free nickel-catalyzed synthesis of symmetrical and unsymmetrical 2,2'-bipyridines
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An unexpectedly facile synthetic approach for symmetrical and unsymmetrical 2,2'-bipyridines through the Ni-catalyzed reductive couplings of 2-halopyridines was developed. The couplings were efficiently catalyzed by 5 mol % of NiCl2.6H2O without the use of external ligands. A variety of 2,2'-bipyridines including caerulomycin F have been efficiently synthesized.
- Liao, Lian-Yan,Kong, Xing-Rui,Duan, Xin-Fang
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p. 777 - 782
(2014/04/03)
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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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experimental part
p. 117 - 124
(2011/01/07)
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- Unusual chemoselective addition of diisopropylzinc to 2,2′-bipyridine-5,5′-dicarbonyl compounds in the 2-position and autoxidative reconversion with carbon-carbon bond cleavage
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The chemoselective addition of diisopropylzinc to 2,2′-bipyridine-5,5′-dicarbonyl compounds in the 2-position and autoxidative reconversion with carbon-carbon bond cleavage was presented. It was shown that i-Pr2Zn do not add to the aldehyde moiety but to the 2-position of the bipyridine to afford possessing a quaternary carbon atom in a yield of 69%. It was found that the i-Pr2Zn does not add to the aldehyde but to the 2-position of the bipyridine ring by destroying the aromaticity of the pyridine ring.
- Tanji, Shigehisa,Shibata, Takanori,Sato, Itaru,Soai, Kenso
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p. 217 - 218
(2007/10/03)
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