- Colorimetric detection of in situ metal acetates and fluorides by a bipyridyl-linked Schiff base
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A new bipyridyl moiety linked Schiff base (bipy-1) was developed and showed selective recognition of dimethyl sulphoxide solution of tetrabutyl ammonium salt of F- ion with absorbance at 529 nm and interesting binding of aqueous Co, Ni, and Cu acetates/fluorides, as confirmed by distinct color changes from fluorescent green to pink or orange with absorbance at 480-510 nm. However, in situ formation of Co, Ni, and Cu acetates/fluorides also was found to be able to respond to similar color and absorption changes.
- Suganya, Sivalingam,Zo, Hye Jin,Park, Jong S.,Velmathi, Sivan
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- Functionalized chitosan adsorbents allow recovery of palladium and platinum from acidic aqueous solutions
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Platinum (Pt) and palladium (Pd) are precious metals considered critical in our society and are needed in a variety of sustainable technologies. Their scarcity urges the increase of recycling from secondary waste streams through new and efficient recovery techniques. Adsorption is an established recovery method for liquid streams, where chitosan shows promising results as a low-cost adsorbent, derived from biomass. This biopolymer is able to capture metals, but suffers from a low stability under acidic conditions and poor adsorbing properties. In this study, three new chitosan derivatives were synthesized and employed for Pd(ii) and Pt(iv) recovery from acidic solutions. Specific and simple modifications were selected based on their known affinities for these metal ions and taking into account the principles of green chemistry. The prepared derivatives consist of 1,10-phenanthroline-2,9-dicarbaldehyde cross-linked chitosan (Ch-PDC), [2,2′-bipyridine]-5,5′-dicarbaldehyde cross-linked chitosan (Ch-BPDC) and glutaraldehyde cross-linked chitosan grafted with 8-hydroxyquinoline-2-carbaldehyde (Ch-GA-HQC). For all derivatives, the adsorption occurred fast and equilibrium reached within 30 min. The Langmuir isotherms revealed a maximum adsorption capacity for Pd(ii) and Pt(iv) of respectively 262.6 mg g-1 and 119.5 mg g-1 for Ch-PDC, 154.7 mg g-1 and 98.3 mg g-1 for Ch-BPDC and 340.3 mg g-1 and 203.9 mg g-1 for Ch-GA-HQC. Such adsorption capacities are considerably higher compared to the biosorbents reported in the literature. Excellent physical properties in homo- and heterogeneous systems and high regeneration performances demonstrate that chitosan-based adsorbents are very promising for Pd(ii) and Pt(iv) recovery from acidic solutions.
- Mincke, Stein,Asere, Tsegaye Grima,Verheye, Ivar,Folens, Karel,Vanden Bussche, Flore,Lapeire, Linsey,Verbeken, Kim,Van Der Voort, Pascal,Tessema, Dejene A.,Fufa, Fekadu,Du Laing, Gijs,Stevens, Christian V.
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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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- New synthetic path to 2,2′-bipyridine-5,5′-dicarbaldehyde and its use in the [3+3] cyclocondensation with trans-1,2-diaminocyclohexane
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2,2′-Bipyridine-5,5′-dicarbaldehyde has been prepared in two steps by enamination of 5,5′-dimethyl-2,2′-bipyridine with Bredereck's reagent, and subsequent oxidative cleavage of the enamine groups with sodium periodate. On condensation of this dialdehyde with enantiomerically pure trans-1,2-diaminocyclohexane, the macrocyclic [3+3] hexa Schiff base has been obtained in excellent yield. Its reduction has given large macrocyclic hexaamine having three bipyridine units incorporated into the macrocycle structure.
- Hodacova, Jana,Budesinsky, Milos
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- Photocurrent response of bipyridine containing poly(p-phenylene-vinylene) derivatives
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The photoinduced charge separation and subsequent transport under an external electric field is studied in the family of poly[bipyridine/(p-phenylene-vinylene)n] derivatives having n = 0, 1, and 3, respectively, p-phenylene-vinylene subunits separating the bipyridylene vinylene skeleton. Steady-state photocurrent of the polymers is studied in sandwich and surface configurations and correlated with transient photocurrent measurements. The results reveal the facile electric-field-induced separation of the electron-hole pair for n = 1 samples relative to n = 3 samples. We also estimate the energy barriers involved in the process of carrier generation and transport in these systems.
- Narayan,Geetha,Nakmanovich,Ehrenfreund,Eichen
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- Stable Radical Cation-Containing Covalent Organic Frameworks Exhibiting Remarkable Structure-Enhanced Photothermal Conversion
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The production of a radical cation-containing covalent organic framework (COF) has been accomplished by sequential in situ reactions, quaternization, and one-electron reduction of the 2,2′-bipyridine-based COFs. The acid-catalyzed COF formation enables the cis configuration of 2,2′-bipyridyl moieties in the structure, of which the stability arises from the eclipsed stacking of the two-dimensional layered structure. The postfunctionalization generates cyclic alkylated diquats as the sole products from the controlled quaternization. The reduction of diquat cations on the COF skeletons results in a large number of radical cations, which delocalize and uniaxially stack on top of one another by virtue of interlayered ?-electronic couplings. The absorption of the near-infrared (NIR) region exhibited by the cationic radical COF is remarkably high owing to the intercharge transfer across the ?-coupling interlayers. Also, the long-range array of extended and planar frameworks in such a COF leads to the extra stability of the radical cations against external stresses. The structure-enhanced performance of the COF material is witnessed with photothermal conversion efficiencies of as high as 63.8 and 55.2% when exposed to 808 and 1064 nm lasers, respectively. Further PEG modification on such a COF allows photoacoustic imaging and photothermal therapy in vivo under NIR light illumination to be manifested.
- Mi, Zhen,Yang, Peng,Wang, Rong,Unruangsri, Junjuda,Yang, Wuli,Wang, Changchun,Guo, Jia
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- Designed synthesis of porphyrin-based two-dimensional covalent organic frameworks with highly ordered structures
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Porphyrins are representative functional π-systems; synthesizing their highly ordered structures is an established goal in chemistry. Here, we report the designed synthesis of a series of porphyrin-based covalent organic frameworks with highly ordered structures through polycondensation. The porphyrinbased frameworks exhibited high crystallinity, high porosity, and extended π-conjugation over the polyporphyrin sheets.
- Chen, Xiong,Gao, Jia,Jiang, Donglin
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- Covalent Organic Frameworks toward Diverse Photocatalytic Aerobic Oxidations
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Photoactive two-dimensional covalent organic frameworks (2D-COFs) have become promising heterogenous photocatalysts in visible-light-driven organic transformations. Herein, a visible-light-driven selective aerobic oxidation of various small organic molecules by using 2D-COFs as the photocatalyst was developed. In this protocol, due to the remarkable photocatalytic capability of hydrazone-based 2D-COF-1 on molecular oxygen activation, a wide range of amides, quinolones, heterocyclic compounds, and sulfoxides were obtained with high efficiency and excellent functional group tolerance under very mild reaction conditions. Furthermore, benefiting from the inherent advantage of heterogenous photocatalysis, prominent sustainability and easy photocatalyst recyclability, a drug molecule (modafinil) and an oxidized mustard gas simulant (2-chloroethyl ethyl sulfoxide) were selectively and easily obtained in scale-up reactions. Mechanistic investigations were conducted using radical quenching experiments and in situ ESR spectroscopy, all corroborating the proposed role of 2D-COF-1 in photocatalytic cycle.
- Liu, Shuyang,Tian, Miao,Bu, Xiubin,Tian, Hua,Yang, Xiaobo
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supporting information
p. 7738 - 7744
(2021/05/07)
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- Phosphonate-Mediated Immobilization of Rhodium/Bipyridine Hydrogenation Catalysts
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RhL2 complexes of phosphonate-derivatized 2,2′-bipyridine (bpy) ligands L were immobilized on titanium oxide particles generated in situ. Depending on the structure of the bipy ligand—number of tethers (1 or 2) to which the phosphonate end groups are attached and their location on the 2,2′-bipyridine backbone (4,4′-, 5,5′-, or 6,6′-positions)—the resulting supported catalysts showed comparable chemoselectivity but different kinetics for the hydrogenation of 6-methyl-5-hepten-2-one under hydrogen pressure. Characterization of the six supported catalysts suggested that the intrinsic geometry of each of the phosphonate-derivatized 2,2′-bipyridines leads to supported catalysts with different microstructures and different arrangements of the RhL2 species at the surface of the solid, which thereby affect their reactivity.
- Forato, Florian,Belhboub, Anouar,Monot, Julien,Petit, Marc,Benoit, Roland,Sarou-Kanian, Vincent,Fayon, Franck,Jacquemin, Denis,Queffelec, Clémence,Bujoli, Bruno
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p. 2457 - 2465
(2018/02/06)
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- Spin-dimer networks: Engineering tools to adjust the magnetic interactions in biradicals
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Magneto-structural correlations in stable organic biradicals have been studied on the example of weakly exchange coupled models with nitronyl nitroxide and imino nitroxide spin-carrying entities. Here, heteroatom substituted 2,2′-diaza- and 3,3′-diaza-tolane bridged biradicals were compared with the hydrocarbon analogue, while a biphenyl model with its 2,2′-bipyridine counterpart. For a 3,3′-diazatolane bridge the torsional angle between the nitronyl nitroxides and the pyridyl rings increased heavily (~52-54°) leading to a smaller theoretical intra-dimer exchange coupling value. However, a very large antiferromagnetic coupling was obtained experimentally. This could be appropriately explained by the presence of dominating inter-dimer exchange between the molecules. For the bis(imino nitroxide) with tolane bridge a field induced ordered state between 1.8 to 4.3 T in AC-susceptibility measurements was observed. In terms of a Bose Einstein condensate (BEC) of triplons this phenomenon could be described as a magnetic field induced ordered phase with 3D character.
- Borozdina, Yulia B.,Mostovich, Evgeny A.,Cong, Pham Thanh,Postulka, Lars,Wolf, Bernd,Lang, Michael,Baumgarten, Martin
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p. 9053 - 9065
(2017/09/22)
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- NITROGEN-CONTAINING HETEROCYCLIC ALKENYL COMPOUND, ORGANIC SEMICONDUCTOR MATERIAL AND ORGANIC SEMICONDUCTOR DEVICE
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PROBLEM TO BE SOLVED: To provide a compound that is high in charge transfer and atmosphere stability and is suitable for an organic semiconductor material, provide an organic semiconductor material comprising the compound, and provide an organic semiconductor element comprising the organic semiconductor material. SOLUTION: The present invention provides a compound represented by formula (1), specifically a compound represented by formula (2) (Ar1 is an unsaturated cyclic hydrocarbon group or the like; Ar2 is an unsaturated heterocyclic group containing nitrogen with an unshared electron pair, or the like; B is -CH=CH- or -C≡C-; X11-X13 independently represent C-R or N; at least one of X12 and X13 is N). SELECTED DRAWING: Figure 1 COPYRIGHT: (C)2018,JPOandINPIT
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Paragraph 0130; 0131
(2017/12/27)
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- Towards covalent organic frameworks with predesignable and aligned open docking sites
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A strategy for the synthesis of covalent organic frameworks with open docking sites is developed. The docking sites are ordered on the channel walls and structurally predesignable for meeting various types of noncovalent interactions, thus opening a way towards designing supramolecular materials based on crystalline porous organic frameworks. This journal is the Partner Organisations 2014.
- Chen, Xiong,Huang, Ning,Gao, Jia,Xu, Hong,Xu, Fei,Jiang, Donglin
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supporting information
p. 6161 - 6163
(2014/06/09)
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