A novel metal-free porous covalent organic polymer for efficient room-temperature photocatalytic CO_(2) reduction via dry-reforming of methane

At room temperature,the conversion of greenhouse gases into valuable chemicals using metal-free catalysts for dry reforming of methane(DRM) is quite promising and challenging.Herein,we developed a novel covalent organic porous polymer (TPE-COP) with rapid charge separation of the electron–hole pairs for DRM driven by visible light at room temperature,which can efficiently generate syngas (CO and H_(2)).Both electron donor (tris(4-aminophenyl)amine,TAPA) and acceptor (4,4',4'',4'''-((1 E,1'E,1''E,1'''E)-(ethene-1,1,2,2-tetrayltetrakis (benzene-4,1-diyl))tetrakis (ethene-2,1-diyl))tetrakis (1-(4-formylbenzyl)quinolin-1-ium),TPE-CHO) were existed in TPE-COP,in which the push–pull effect between them promoted the separation of photogenerated electron–hole,thus greatly improving the photocatalytic activity.Density functional theory (DFT) simulation results show that TPE-COP can form charge-separating species under light irradiation,leading to electrons accumulation in TPE-CHO unit and holes in TAPA,and thus efficiently initiating DRM.After 20 h illumination,the photocatalytic results show that the yields reach 1123.6 and 30.8μmol g^(-1)for CO and H_(2),respectively,which are significantly higher than those of TPE-CHO small molecules.This excellent result is mainly due to the increase of specific surface area,the enhancement of light absorption capacity,and the improvement of photoelectron-generating efficiency after the formation of COP.Overall,this work contributes to understanding the advantages of COP materials for photocatalysis and fundamentally pushes metal-free catalysts into the door of DRM field.

Bis(trifluoromethylsulfonyl)phenylamines as Internal Donors for Ziegler-Natta Polymerization Catalysts

Several bis（trifluoromethylsulfonyl）phenylamines have been synthesized and used as internal donors for the preparation of heterogeneous Ziegler-Natta catalysts for propylene polymerization. These new cata- lysts are highly active and stereospecific in combination with an external donor for the polymerization of propylene. The activity of these catalysts is dramatically influenced by the electronic capability of the phenyl substituents on the sulfonyl phenylamines. Therefore, the performances of the catalysts can be modified by adjusting the electronic property of the phenyl substituents of the sulfonyl phenylamines.

Synthesis of Novel Electron Donors and Their Application to Propylene Polymerization

A series of electron donors,including 1,1-cyclopentanecarboxylic acid diethyl ester (CPCADEE),1,1cyclopentanedimethanol acetic diester (CPDMAD),1,1-biethoxymethyl pentane (BEMP),2,2-diethyl diethylmalonate (DEDEM)and 2,2-diethyl-1,3-propanediol acetic diester (DEPDADE),were synthesized by diethyl malonate (DEM).The purities and structures of the above products were characterized by gas chromatography (GC) and gas chromatography-mass spectrometer (GC-MS),respectively.Furthermore,the possible optimal three-dimensional structures of these donors were simulated by means of Gaussian 03 and Chem 3D.Then these electron donors were coordinated with tetrachloro titanium (TiCl 4) and chloride magnesium (MgCl 2)to obtain the catalysts for the polymerization of propylene.The catalytic activities and properties of polypropylene are greatly improved by adding external donor(ED) when CPCADEE or DEPDADE is used as internal donor(ID).However,when BEMP was used as ID,the highest catalytic activity is obtained without adding ED,which can reduce production costs and simplify catalytic synthesis.The experiments indicate that BEMP has the shortest distance of oxygen atoms and the highest electronegativity.

Anaerobic Degradation of Tetrachloroethylene Using Different Co-substrates as Electron Donors

Objective To investigate the biodegradation of tetrachloroethylene （PCE） by acclimated anaerobic sludge using different co-substrates, i.e., glucose, acetate, and lactate as electron donors. Methods HP-6890 gas chromatograph （GC） in combination with auto-sampler was used to analyze the concentration of PCE and its intermediates, Results PCE could be degraded by reductive dechlorlnation and the degradation reaction conformed to the first-order kinetic equation. The rate constants are klaetate〉kglucose〉kacetate. The PCE degradation rate was the highest in the presence of lactate as an electron donor. Conclusion Lactate is the most suitable electron donor for PCE degradation and the electron donors supplied by co-metabolic substrates are not the limiting factors for PCE degradation,

Effect of C/N Ratio,Temperature,pH on Autotrophic Denitrification Rate with Hydrogen Gas,Iron(Ⅱ) and Sodium Sulfide as Electron Donors

Nitrate is considered to be one of the most widely present pollutants leading to eutrophication of environment. The purpose of this work was to isolate and identify new anaerobic denitrifying bacteria from reservoir sediments and utilize different electron donors for isolates to improve nitrate removal efficiency. Using traditional enrichment approach,one purified anaerobic bacterium( Y12) capable of NO-3-N removal from sediments was obtained. The species identity of Y12 was determined via 16 S rRNA gene sequence analysis to be Acinetobacter. In this work,the fastest denitrification rates were observed with ferrous iron as electron donor.And,slightly slower rates were observed with hydrogen and sodium sulfide as electron donors. However,when used hydrogen gas, ferrous iron and sodium sulfide as electron donors, C / N ratios had little effect on autotrophic denitrification rate at the initial C / N ratio from 1.5 to 9.0. Meanwhile,when made use of hydrogen gas,ferrous iron and sodium sulfide as electron donors,a maximum nitrate removal ratio of 100.00%,91.43%and 87.99% at the temperature of 30 ℃,respectively. Moreover,maximum denitrification activity was observed at p H 6.0-7.0.

Propylene Polymerization Catalysts with Sulfonyl Amines as Internal Electron Donors

Three sulfonyl aliphatic amines [（R2SO2）2NR1, viz.： compound 1, in which RI=Me, and R2=Ph; compound 2, in which R1=n-Bu, and R2=CF3; and compound 3, in which RI=C8H17, and R2=CF3], have been synthesized and employed as internal electron donors （IED） for the preparation of Ziegler-Natta catalysts for the polymerization of propylene. The contents of Ti, H and C in these catalysts have been determined by elemental analysis and UV-vis spectrophotometry. The effect of the structure and dosage of the electron donor, the A1/Ti ratio and the polymerization temperature on the catalyst performance has been studied. Under optimized conditions, the catalyst with a highest activity yielded polypropylene with high isotacticity in the absence of external electron donors.

EFFECT OF ELECTRON DONORS ON THE SELECTIVE HYDROGENATION OF DIENE TO MONOENE OVER HETEROGENIZED Pd CATALYST

In the selective hydrogenation of diene (or alkyne) using heterogenized homogeneous catalyst, the high selectivity of monoene formation only appears in a very short time interval. The addition of suitable electron donors can decrease or even cease the monoene hydrogenation and thereby keep the high monoene selectivity after reaching its maximum.

CATIONIC POLYMERIZATION OF ISOBUTYLENE COINITIATED BY AICI_3 IN THE PRESENCE OF ETHYL BENZOATE

The cationic polymerizations of isobutylene （IB） coinitiated by AlCl3 were carried out in solvent mixture of nhexane/methylene dichloride （n-hex/CH2Cl2） of 60/40 V/V in the presence of ethyl benzoate （EB） at various temperatures range from -80℃ to -30℃. The effects of EB concentration （[EB]） and polymerization temperature on monomer conversion, weight-average molecular weight （Mw） and molecular weight distribution （MWD, Mw/Mn） of polyisobutylene （PIB） products were investigated. The rate of polymerization decreased while Mw of PIB products increased with increasing [EB]. The polymers with high molecular weight could be prepared in the presence of a suitable amount of EB. Significantly, the polymers with high Mw of 80.2 × 10^4 and 65.4 × 10^4 could be produced at -80℃ and -70℃ at [EB] = 0.24 × 10^3 mol/L respectively, which were much higher than that （Mw = 57.9 × 10^4） of PIB prepared at -100℃ in the absence ofEB. A simple but effective method for preparing the high molecular weight polyisobutylenes was developed in this work. It has been also found that the activation energy for propagation （Ep） depended on the polymerization temperature range in the presence of EB. An obvious inflection of the linear plots of lnXn versus 1/Tp occurred at the temperature range from -60℃ to -50℃ at four different concentrations of EB from 0.19 × 10^3 mol/L to 0.33× 10^3 tool/L, and thus the inflection temperature （Tinf） was in the range of -60℃ to -50℃. When [EB] was in the range of 0.24 × 10^3 mol/L to 0.33× 10^3 mol/L, Ep was determined to be around -12 kJ/mol when the polymerization was carried out at temperatures from -80℃ to Tinf and to be around -28 kJ/mol at temperatures from Tinf to -15℃ respectively.

A new D–D–π–A dye for efficient dye-sensitized solar cells

New metal-free organic dye sensitizers containing mono-triphenylamine or bis-triphenylamine as the electron donor, a thiophene as the π-conjugated system, and a cyanoacrylic acid moiety as the electron acceptor were synthesized. The optical and electrochemical properties of the dyes were investigated,and their performance as sensitizers in solar cells was evaluated. Dye-sensitized solar cells based on dye containing bis-triphenylamine as the electron donor produced a photon-to-current conversion efficiency of 6.06%（Jsc = 14.21 m A/cm;, Voc = 0.62 V, ff = 0.69） under 100 m W/cm;simulated AM 1.5 G solar irradiation（100 m W/cm;）.

Preparation of Ultra-High Molecular Weight Polypropylene Using Ziegler-Natta Catalyst via Combining Internal Electron Donor and Cocatalyst Loading

Due to the development of the new energy industry,polypropylene with ultra-high molecular weight plays a crucial role for battery isolation membrane.This work investigated the effect of internal electron donor of Ziegler-Natta catalyst system on the molecular weight of the obtained polypropylene.The scanning electron microscope(SEM)and Canon camera were used to characterize the surface morphologies of catalyst particles and polymer particles,respectively.Compared with the polypropylene particles featuring a spherical shape,these study results confirmed that the morphology duplication theory from the catalyst particle to the morphology of polymer particle was exhibited.The gel permeation chromatography(GPC)results revealed that the obtained polypropylene has a much higher average molecular weight than those prepared by conventional method.The Fourier transform infrared spectrometry(FT-IR)and X-ray photoelectron spectroscopy(XPS)revealed that the carbonyl oxygen atom on ester group was preferentially bound to Mg and Ti,as compared to the ether oxygen atom.The XPS results showed that the ratio of Ti^(3+)/Ti^(4+)could be changed by internal electron donors.When Ti3+content was nearly 99%in the Ziegler-Natta catalyst system,isotactic polypropylene with an ultra-high molecular weight of up to 1.42×10^(6)g/mol was obtained by Cat.3.This result implied that internal electron donor ID3 could reduce theβ-hydride elimination reaction to further increase the molecular weight of the obtained polymer.

SUPPORTED CATALYST WITHOUT EXTERNAL ELECTRON DONOR FOR PROPYLENE POLYMERIZATION Ⅱ. TACTICITY DISTRIBUTION AND MICROSTRUCTURE OF POLYPROPYLENE

Propylene was polymerized with a novel supported Ziegler-Natta catalystcontaining 2,2-di-iso-butyl-1,3-dimethoxy-propane (DIBDMP) as internal donor and in theabsence of external donor. The tacticity distribution of polypropylene was obtained by usingtemperature rising elution fractionation (TREF) technique and microstructure of fractionswas studied with ^(13)C-NMR. Compared with the catalyst without electron donor, this cat-alyst gives a considerably narrower tacticity distribution. Fractionation data demonstratethat DIBDMP shows better performance than aromatic diester DNBP (di-n-butyl phtha-late). Chemically inverted propylene units and less stereoblockiness are found in the firstfraction. Possible reasons for these were presented.

Synthesis and Electrochemical Studies on BEDT-TTF Derivatives with Hydroxyl Groups

New electron donors with hydroxyl groups were synthesized and characterized spectroscopically. Their redox potentials were determined with cyclic voltammetry, and the comparison with BEDT-TTF [Bis(ethylenedithio)tetrathiafulvalene] in this aspect was made. These results indicated that the new electron donors had similar electron-donating capabilities as BEDT-TTF.

Acid-base and Electron Donor Properties of Pr_6O_(11)and Its Mixtures with Alumina

The electron donor properties of Pr6O11 activated at 300, 500 and 800℃ are reported from the studies on adsorption of electron acceptors of various electron affinity (7, 7, 8, 8-tetracyanoquinodimethane , 2. 3. 5. 6-tetrachloro-1, 4-benzoquin one, p-dinitrobenzene, and m-dinitrobenzcne) in three solvents (acetonitrile, 1,4-dioxan and ethyl acetate). The extent of electron transfer during adsorption is understood from magnetic measurements and ESR spectral data. The corresponding data on mixed oxides of Pr and Al are reported for various compositions. The acid / base properties of these oxides are determined using a set of Hammett indicators.

Theoretical Studies on the Intramolecular Electron Transfer in Some Aromatic Systems

In this work, the excited states of the title compounds are calculated by using time-dependent density functional theory (TDDFT). Firstly, the variation of the sequences of intramolecular charge local excitation (LE) and intramolecular charge transfer (CT) in the gas phase is studied by changing electron donors or acceptors. Then, the effects of Polarized Continuum Model (PCM) and Self-consistent Isodensity Polarized Continuum Model (SCI-PCM) in solvents on the calculated results are discussed. It is shown that the calculated results obtained by the PCM are in more agreement with the experimental data. Finally, the excited states of compounds in different solvents were calculated by PCM. Compared with the results obtained in gas phase, the absorption spectra of the CT state in the solvents have a larger red shift; however, the spectra for the LE state are hardly changed.

Synthesis of PE with Broad MWD Catalyzed by Supported Ziegler-Natta Catalyst Consisting of Cycloalkoxy Silane as IED

Two kinds of cycloalkoxy silane compounds were synthesized and used as the internal electron donors （IEDs） of supported Ziegler-Natta catalyst for ethylene polymerization to produce polyethylene with broader molecular weight distribution （MWD）, The effect of the structure and the amount of these IEDs on the polymerization performance was in- vestigated. The results implied that the molecular weight distribution of the obtained polyethylene could be adjusted by the incorporation of IEDs. SEM result showed that the morphology of catalyst particle was spherical and uniform in size distribution. The titanium content of these catalysts was higher, the active TiCl4 species were easily anchored on the support than that without adding IED, which was determined by ICE The GPC result confirmed that the polyethylene with broader molecular weight distribution in the range of from 23.4 to 25.6 was obtained using triethoxy-（-cyclopentyloxy）-silane （ED1） and triethoxy-（-cyclohexyloxyl）- silane （ED2） as the internal electron donors.

Bioinspired Noncyclic Transfer Pathway Electron Donors for Unprecedented Hydrogen Production

Electron donors are widely exploited in visible-light photocatalytic hydrogen production.As a typical electron donor pair and often the first choice for hydrogen production,the sodium sulfide-sodium sulfite pair has been extensively used.However,the resultant thiosulfate ions consume the photogenerated electrons to form an undesirable pseudocyclic electron transfer pathway during the photocatalytic process,strongly limiting the solar energy conversion efficiency.Here,we report novel and bioinspired electron donor pairs offering a noncyclic electron transfer pathway that provides more electrons without the consumption of the photogenerated electrons.Compared to the state-of-the-art electron donor pair Na_(2)S-Na_(2)SO_(3),these novel Na_(2)S-NaH_(2)PO_(2)and Na_(2)S-NaNO_(2)electron donor pairs enable an unprecedented enhancement of up to 370%and 140%for average photocatalytic H_(2)production over commercial CdS nanoparticles,and they are versatile for a large series of photocatalysts for visible-light water splitting.The discovery of these novel electron donor pairs can lead to a revolution in photocatalysis and is of great significance for industrial visible-light-driven H_(2)production.

Universally improving effect of mixed electron donors on the CO_2 fixing efficiency of non-photosynthetic microbial communities from marine environments

The universality of improved CO2 fixing upon the addition of mixed electron donors（MEDs）composed of Na2 S,NO2-,and S2O32-to non-photosynthetic microbial communities（NPMCs）obtained from 12 locations in four oceans of the world was validated. The CO2 fixing efficiencies of NPMCs were universally enhanced by MED compared with those obtained using H2 alone as electron donor,with average increase of about 276%. An increase in microbial inoculation concentration could increase the net amount of CO2 fixing to853.34 mg/L in the presence of MED. NO2-and S2O32-may play the roles of both electron acceptor and electron donor under aerobic conditions,which may improve the energy utilization efficiency of NPMC and enhance the CO2 fixation efficiency. The sequence determination of 16 S ribosomal deoxyribonucleic acid（rDNA） from 150 bacteria of NPMC showed that more than 50% of the bacteria were symbiotic and there were many heterotrophic bacteria such as Vibrio natriegens. These results indicate that NPMC acts as a symbiotic CO2 fixing system. The interaction between autotrophic and heterotrophic bacteria may be a crucial factor supporting ladder utilization and recycling of energy/carbon source.

Synthesis of a novel diether–ester conjugated model compound for electron donors of the polypropylene catalysts

A novel diether-ester conjugated electron donor model compound, 1,3-dimethoxypropan-2-yl benzoate, was synthesized via a reaction of 1,3-dimethoxypropan-2-ol and benzoyl chloride in the presence of triethyl amine and 4-dimethylaminopryidine. Compared to the known routes of preparing diethers, which usually employ the reactions to O-alkylate the corresponding diols with O-alkylating reagents, the presented method here provides a new way to prepare the diether electron donor compounds. It avoids employing the traditional O-alkylation reactions, so that highly toxic O-alkylating chemicals, such as iodomethane, and very strong basic deprotonating reagents, such as alkoxides or metal hydrides, are not required. The product can be obtained in high yields without complicated purification processes. Catalyst component containing the electron donor compound was prepared and used to catalyze propylene polymerization.

Rongalite as a Versatile Reagent in Organic Synthesis

This review provides a comprehensive summary of progress to date in the utilization of rongalite as a versatile reagent in organic synthesis,with a focus on recent researches.The contents have been organized according to the functions exhibited by rongalite.Reaction mechanisms are provided,demonstrating the multifaceted roles of this compound in various transformations,including as a sulfone,C1 or masked proton source and as a single electron donor or reducing agent.

Elemental Doping Boosts Charge-Transfer Excitonic States in Polymeric Photocatalysts for Selective Oxidation Reaction

Energy-transfer-mediated synthetic reactions play vital roles in the production of high-value-added organics,where the longlived exciton harvesting is an essential precondition for the process.However,for semiconductors with strong excitonic effects like conjugated polymers,their predominant Frenkel exciton with a short lifetime in the unified framework gives rise to low efficiency photocatalysis.Herein,we propose the boosting of the charge-transfer exciton with a long-lived state by introducing spatially separated electron and hole regions.By taking polymeric carbon nitride(PCN)as a prototype,we demonstrate that sulfur doping leads to the formation of electron donor and acceptor motifs in the tri-s-triazinebased backbone,which would accommodate long-lived excitonic states with remarkable charge-transfer characteristics.The extraordinary long-lived charge-transfer exciton harvesting endows sulfur-doped PCN with high-efficiency photocatalytic performance in 1O2 generation and selective oxidation of organic sulfides.This work provides a brand new perspective for designing advanced photocatalysts for energy-transfer-mediated sunlight utilization.