- Molecular photoconductor with simultaneously photocontrollable localized spins
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UV irradiation reversibly switches a new insulating and nonmagnetic molecular crystal, BPY[Ni(dmit)2]2 (BPY = N,N-ethylene-2,2-bipyridinium; Ni(dmit)2 = bis(1,3-dithiole-2-thione- 4,5-dithiolato)nickelate(III)), into a magnetic conductor. This is possible because the bipyridyl derivative cations (BPY2+) trigger a photochemical redox reaction in the crystal to produce a change of ～10% in the filling of the Ni(dmit)2 valence band, leaving localized spins on the BPY themselves. In the dark, almost all of the BPY molecules are closed-shell cations, and most of the Ni(dmit)2 radical anions form spin-singlet pairs; thus, this material is a diamagnetic semiconductor. Under UV irradiation, a photocurrent is observed, which enhances the conductivity by 1 order of magnitude. Electron spin resonance measurements indicate that the UV irradiation reversibly generates carriers and localized spins on the Ni(dmit)2 and the BPY, respectively. This high photoconductivity can be explained by charge transfer (CT) transitions between Ni(dmit)2 and BPY in the UV region. In other words, the photoconduction and "photomagnetism" can be described as reversible optical control of the electronic states between an ionic salt (BPY2+/[Ni(dmit) 2]-, nonmagnetic insulator) and a CT complex (BPY 2(1-δ)+/[Ni(dmit)2](1-δ)- (δ - 0.1), magnetic conductor) in the solid state.
- Naito, Toshio,Karasudani, Tomoaki,Mori, Shigeki,Ohara, Keishi,Konishi, Kensuke,Takano, Takahiro,Takahashi, Yukihiro,Inabe, Tamotsu,Nishihara, Sadafumi,Inoue, Katsuya
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Read Online
- Green Synthesis of Leaning Tower[6]arene-Mediated Gold Nanoparticles for Label-Free Detection
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Here a facile synthesis strategy toward carboxylated leaning tower[6]arene (CLT6)-mediated gold nanoparticles (CLT6-AuNPs) without external energy sources and reducing agents has been developed. Due to the cavity structure of CLT6, CLT6-AuNPs with a controllable particle size show good stability and excellent performance in label-free detection of diquat. Significantly, we reveal the reduction mechanism of AuNP formation, which is the cleavage of some phenyl ether bonds of CLT6 to produce reductive phenols, thus reducing Au3+ to AuNPs.
- Zhang, Hao,Wang, Xin,Huang, Kun-Tao,Liang, Feng,Yang, Ying-Wei
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supporting information
p. 4677 - 4682
(2021/06/28)
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- Bipyridinium and Phenanthrolinium Dications for Metal-Free Hydrodefluorination: Distinctive Carbon-Based Reactivity
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The development of novel Lewis acids derived from bipyridinium and phenanthrolinium dications is reported. Calculations of Hydride Ion Affinity (HIA) values indicate high carbon-based Lewis acidity at the ortho and para positions. This arises in part from extensive LUMO delocalization across the aromatic backbones. Species [C10H6R2N2CH2CH2]2+ (R=H [1 a]2+, Me [1 f]2+, tBu [1 g]2+), and [C12H4R4N2CH2CH2]2+ (R=H [2 a]2+, Me [2 b]2+) were prepared and evaluated for use in the initiation of hydrodefluorination (HDF) catalysis. Compound [2 a]2+ proved highly effective towards generating catalytically active silylium cations via Lewis acid-mediated hydride abstraction from silane. This enabled the HDF of a range of aryl- and alkyl- substituted sp3(C?F) bonds under mild conditions. The protocol was also adapted to effect the deuterodefluorination of cis-2,4,6-(CF3)3C6H9. The dications are shown to act as hydride acceptors with the isolation of neutral species C16H14N2 (3 a) and C16H10Me4N2 (3 b) and monocationic species [C14H13N2]+ ([4 a]+) and [C18H21N2]+ ([4 b]+). Experimental and computational data provide further support that the dications are initiators in the generation of silylium cations.
- Burton, Katherine I.,Elser, Iris,Waked, Alexander E.,Wagener, Tobias,Andrews, Ryan J.,Glorius, Frank,Stephan, Douglas W.
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supporting information
p. 11730 - 11737
(2021/07/16)
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- Covalent Organic Frameworks Enabling Site Isolation of Viologen-Derived Electron-Transfer Mediators for Stable Photocatalytic Hydrogen Evolution
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Electron transfer is the rate-limiting step in photocatalytic water splitting. Viologen and its derivatives are able to act as electron-transfer mediators (ETMs) to facilitate the rapid electron transfer from photosensitizers to active sites. Nevertheless, the electron-transfer ability often suffers from the formation of a stable dipole structure through the coupling between cationic-radical-containing viologen-derived ETMs, by which the electron-transfer process becomes restricted. Herein, cyclic diquats, a kind of viologen-derived ETM, are integrated into a 2,2′-bipyridine-based covalent organic framework (COF) through a post-quaternization reaction. The content and distribution of embedded diquat-ETMs are elaborately controlled, leading to the favorable site-isolated arrangement. The resulting materials integrate the photosensitizing units and ETMs into one system, exhibiting the enhanced hydrogen evolution rate (34600 μmol h?1 g?1) and sustained performances when compared to a single-module COF and a COF/ETM mixture. The integration strategy applied in a 2D COF platform promotes the consecutive electron transfer in photochemical processes through the multi-component cooperation.
- Mi, Zhen,Zhou, Ting,Weng, Weijun,Unruangsri, Junjuda,Hu, Ke,Yang, Wuli,Wang, Changchun,Zhang, Kai A. I.,Guo, Jia
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supporting information
p. 9642 - 9649
(2021/03/16)
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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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supporting information
p. 14433 - 14442
(2019/10/11)
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- Tetrachlorocuprate-bipyridyl quaternary ammonium salt and preparation method and application thereof
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The invention belongs to the technical field of fine chemosynthesis and particularly relates to a tetrachlorocuprate-bipyridyl quaternary ammonium salt with weeding and antibacterial dual functions. Acompound prepared from tetrachlorocuprate anions and 1,1'-ethylene-2,2'-bipyridyl cations has a chemical structure represented by a formula (I), i.e., shortened for [EtBiPy][CuCl4]. A preparation method of the compound comprises the steps of preparing a 1,1'-ethylene-2,2'-bipyridyl dibromo salt, preparing the tetrachlorocuprate anions and preparing the tetrachlorocuprate-bipyridyl quaternary ammonium salt. The tetrachlorocuprate-bipyridyl quaternary ammonium salt provided by the invention has relatively high antibacterial capability to Staphylococcus aureus and Escherichia coli and also has arelatively good contact poisoning effect on weeds.
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Paragraph 0013; 0022-0025
(2019/02/03)
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- Small Crystal ZSM-5, Its Synthesis and Use
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A molecular sieve having the framework structure of ZSM-5 is described comprising crystals having an external surface area in excess of 100 m2/g (as determined by the t-plot method for nitrogen physisorption) and a unique X-ray diffraction pattern.
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- Effect of chemical structure of bipyridinium salts as electron carrier on the visible-light induced conversion of CO2 to formic acid with the system consisting of water-soluble zinc porphyrin and formate dehydrogenase
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Effect of chemical structures of some 2,2′-bipyridinium salts (BP2+) as the electron carrier molecules on the visible-light induced conversion of CO2 to formic acid with the system consisting of water-soluble zinc tetraphneylporphyrin tetrasulfonate (ZnTPPS) and formate dehydrogenase (FDH) in the presence of triethanolamine (TEOA) as an electron donor molecule was investigated. Irradiation of a CO2 saturated solution containing TEOA, ZnTPPS, BP2+ and FDH with visible light resulted in production of formic acid. By using 1,1′-ethylene-2,2′-bipyridinium dibromide (DB2+) as an electron carrier molecule, the effective formic acid production was observed compared with the other 2,2′-bipyridinium salt derivatives.
- Amao, Yutaka,Abe, Ryutaro,Shiotani, Sachina
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p. 149 - 153
(2015/10/28)
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- Conversion of solar energy to chemical energy
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The rate of evolution of hydrogen from water by photochemical process using solar energy has been investigated employing fourteen metal complexes as catalysts, ten electron relays, three electron donors and two co-catalysts in different permutation and combinations. The effect of varying reaction conditions like temperature, concentration and pH have also been investigated for the optimum production of hydrogen by the photochemical cleavage of water molecules.
- Ranganayakulu,Murthy
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scheme or table
p. 309 - 316
(2011/08/09)
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- Revisiting the IspH catalytic system in the deoxyxylulose phosphate pathway: Achieving high activity
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(Chemical Equation Presented) From two C5 isoprene building blocks, isopentenyl diphosphate (IPP) and its isomer dimethylallyl diphosphate (DMAPP), the more than 30000 members of the isoprenoid family are constructed in nature using two biosynthetic pathways, the mevalonate (MVA) pathway and the deoxyxylulose phosphate (DXP) pathway. IspH of the DXP pathway is a protein containing an iron-sulfur cluster and catalyzes a reductive dehydration reaction of the DXP pathway. In the literature, a wide range of Escherichia coli IspH activities have been reported (2.0 nmol min-1 mg-1 to 3.4 μmol min-1 mg-1). For such a broad range of activities, reaction assays were carried out under many different conditions, preventing direct comparison of the activities and determination of the key factor responsible for such a dramatic difference in IspH activities. In this work, we systematically examined the role of redox mediators in IspH catalysis using E. coli IspH as the enzyme and dithionite as the ultimate electron source. Our studies not only suggest the importance of the iron-sulfur cluster but also improve the E. coli IspH activity by nearly 97-fold relative to that from the E. coli NADPH-flavodoxin reductase-flavodoxin system.
- Xiao, Youli,Chu, Lisa,Sanakis, Yiannis,Liu, Pinghua
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supporting information; experimental part
p. 9931 - 9933
(2009/12/08)
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- Free-energy dependence of electron-transfer rate constants at Si/liquid interfaces
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The interfacial energetics and kinetics of n-type Si electrodes in contact with a series of one-electron, outer-sphere redox couples were investigated using the differential capacitance vs potential and current density vs potential measurements, respectively. The differential capacitance vs potential measurements were essentially independent of the ac frequency imposed on the interface, with linear Bode plots between ≈103 and ≈105 Hz. The current density vs potential plots exhibited first-order kinetic dependence on the concentration of electrons at the semiconductor surface and a first-order kinetic dependence on the concentration of acceptors in the solution.
- Fajardo,Lewis
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p. 11136 - 11151
(2007/10/03)
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- Solid, herbicidal bipyridinium quaternary salt compositions
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Bipyridinium quaternary salt compositions are prepared which are dry, free-flowing, wettable powders. The solid compositions are complexes of the bipyridinium salts and algin.
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- Solid, herbicidal complexes
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Low viscosity heteropolysaccharides, e.g., xanthan gum, S-194, and guar gum, are disclosed. These gums are especially useful in preparing herbicidal compositions.
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- 5,6-Dihydro-1,2,4,6-thiatriazin-5-one-1,1-dioxides
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5,6-Dihydro-1,2,4,6-thiatriazin-5-one-1,1-dioxides of the formula STR1 where R1 is hydrogen, a metal atom or an unsubstituted or substituted ammonium radical, R2 is a saturated or unsaturated straight-chain aliphatic radical of up to 10 carbon atoms, a cycloaliphatic radical or 3 to 7 carbon atoms, a branched saturated or unsaturated aliphatic radical of 3 to 10 carbon atoms, a halogen-, alkoxy- or alkylmercapto-substituted aliphatic radical of 2 to 10 carbon atoms tetrahydrofuryl substituted methyl, a cycloalkoxy-substituted aliphatic radical of 4 to 10 carbon atoms, unsubstituted or halogen-substituted benzyl or phenyl, halophenyl, or alkylphenyl of a total of up to 10 carbon atoms, R3 is hydrogen, a straight-chain aliphatic radical of up to 10 carbon atoms, a cycloaliphatic radical of 3 to 7 carbon atoms, a branched aliphatic radical of 3 to 10 carbon atoms, haloalkyl, or alkoxyalkyl of 2 to 10 carbon atoms and X is oxygen and may also be sulfur if R2 is unsubstituted or halogen-substituted benzyl, processes for their preparation, and herbicides containing the above compounds.
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- Herbicidal compositions
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A solid complex of a herbicidal bipyridylium salt in combination with urea or thiourea having the formula: Wherein X represents the bipyridylium salt, A represents urea or thiourea, n is 1, 2 or 4, and m is 0 to 4, its preparation and use are disclosed.
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