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There is a growing interest in the design and construction of artificial photosythetic materials for solar energy utilization and conversion. Inspired by the structure of thylakoid membrane, we present here a hybrid construct for light-harvesting and oxygen releasing. Our design conjugates chlorophyll to TiO2 in a native-like membrane environment. The natural bilayer structure of lipids is utilized to localize the amphiphilic chlorophyll a and hydrophobic tetrabutyl titanate TBOT in the liposomal membrane during hydration process. The coassembled structure, which mimics the essential organization of the thylakoid membrane, is characterized using a combination of field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometer (EDS), Ramam spectra, pressure (π)-area (Α) isotherms, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) analysis. Our results demonstrate successful insertation of chlorophyll a in the membrane and confirm the in situ formation of TiO2 nanoshell confined at the lipid bilayer/water interface. We further show that the hybrid liposomes exhibit unambiguous photoactivity in visible light-harvesting and oxygen release, likely resulting from a larger specific surface area of the TiO2 shell, an efficient interfacial conjugation of the chlorophyll molecules with the thin TiO2 layer. The density functional theory (DFT) calculations were in accordance with the eletron injection processes.We expect that the present work will open a new insight into interfacial recombination between light-harvesting pigments and their sensitized photocatalysis, and develop a new kind of artificial photosynthetic materials with zero-cost of environmental degradation and high efficiency for the photocatalytic O2 production.

Dehydrogenation of propane in the presence of CO2 (CO2-ODHP) is an important route for the synthesis of propylene and utilization of the waste CO2. In the present work, diverse GaN supported on NaZ...

Hydrogenolysis of biomass-derived lignin sources is highly important for the conversion of renewable biomass resources to biofuels. However, lots of developed catalysts suffer from the drawbacks of expensive precious metal catalysts and/or operation under harsh conditions. In the present work, Co–Ni bimetallic catalysts were prepared and applied in catalyzing hydrogenolysis of Caryl–O aromatic ethers with high activities under the promotion of Nb2C MXene additive. Especially, the hydrogenolysis of diphenyl ether (DPE), a 4–O–5 model compound, to cyclohexane (cy) and cyclohexyl alcohol (cy-ol) could be achieved over the Co2Ni1Ox–Nb2C MXene catalytic system at 120 °C and under 5 bar of H2, which are mild conditions in comparison with those for the developed heterogeneous precious-metal-free catalysts. The excellent catalytic performances stemmed from the strong interaction between Co and Ni species and the promotion of Lewis acidic sites offered by Nb2C MXene. The proposed reaction pathway involved the direct hydrogenolysis of DPE route, in which DPE was initially hydrogenolyzed to benzene and phenol. They were further hydrogenated to cy and cy-ol. The present work not only develops a noble-metal-free bimetallic catalyst for utilization of biomass-derived lignin sources, but also provides a novel strategy for using the Nb2C MXene material.

Deoxynivalenol (DON) or “vomitoxin” is a mycotoxin produced by Fusarium species. Few food poisoning cases caused by DON have been reported since the 1990s in China. However, on May 16, 2019, the Zh...

In the present study, an overall decomposition mechanism of ammonium dinitramide (ADN) in the gas phase via density functional theory (DFT) calculations was studied. Thermogravimetry-Fourier transform infrared (TG-FTIR) and thermogravimetry-mass spectrometer (TG-MS) techniques were used to verify the calculation results. In the thermal decomposition of gaseous ADN (ADN(g)), ADN(g) first decomposed into dinitraminic acid (HDN) and NH3, followed by HDN decomposition into other products with small molecules. HDN is found to isomerize into five isomers (HDN-1–5) in the gas phase. For the initial decomposition of HDN, the favorable decomposition pathway of HDN-4 (a structure of HON(O)NNO2) is more likely to form HNO3 and N2O with a huge release of energy (approximately 45 kcal mol−1). Moreover, product HNO3 and NH3 can first combine to form NH4NO3. Both calculated and experimental results indicate that the product N2O is first formed in the thermal decomposition of ADN(g). Moreover, the formation mechanism and kinetics of other products (NH3, H2O, NO, N2O, NO2, HONO, HNO3, etc.) were also studied and proposed in the thermal decomposition of gaseous ADN. Overall, the systematic mechanistic investigations have provided new and detailed insights on the mechanism and kinetics of the thermal decomposition of gaseous ADN as well as informative factors to further improve the experimental performances, which can surely be beneficial to other energetic material syntheses.

Deep eutectic solvents (DESs) have attracted considerable attention due to their unique properties. In recent years, novel deep eutectic solvents based on polyethylene glycol (PEG) have been proposed, which are called PEGylated DESs. Owing to their excellent properties, PEGylated DESs have been applied in many fields, such as extraction, biomass dissolution and material preparation. For better application of PEGylated DESs in various fields, the solid understanding of their fundamental properties is indispensable. In this work, nine PEGylated DESs based on carboxylic acids, amides and ammonium salts were prepared and characterized by FTIR, 1H NMR and DSC analysis. The physicochemical properties including pH values, polarity, density, viscosity, conductivity, and thermal stability were investigated. Walden plot analysis was also conducted in order to evaluate the ionicity of the PEGylated DESs. The nature of the components plays a vital role in the properties of the PEG based DESs. There is a negative correlation between the pH values and polarity of the PEGylated DESs, which can be applied to infer the polarity via pH measurement. The density and viscosity gradually decrease with increasing temperature due to thermal expansion. Except for the ammonium salt based DESs, the PEGylated DESs exhibit a “poor ionic” nature and have a negligible conductivity owing to the lack of ionic species. According to the above research, PEGylated DESs with specific properties could be elaborately designed via choosing appropriate components, thus facilitating their application.

The intrinsic effect of the support microstructure on the catalytic function of VOx/Al2O3 in the oxidative dehydrogenation of propane (ODHP) was studied. The results of characterization indicate that similar vanadia species are supported on Al2O3 with different microstructures, but that the interactions between VOx and alumina are slightly modified. In this case, the microstructure-dependent catalytic function in the ODHP reaction is rigorously revealed. The flower-like morphology with non-compact and non-monolithic particles assembled as nanoribbons exhibits inter-particle stacking pores, which contribute to a severe extra-granular diffusion limitation (EGDL). The sphere-like morphology with compact and monolithic particles assembled as nanosheets possesses both inter-particle and intra-particle pores, which lead to a moderate EGDL. However, neither catalyst exhibits an intra-granular diffusion limitation (IGDL). Conversely, the bulk-like morphology with monolithic particles and without the assembly of secondary granules only exhibits intra-particle pores, which results in a slight EGDL and IGDL. Moreover, these two disturbances of diffusion can be excluded by means of controlling the reaction parameters. A comparison of the apparent and intrinsic kinetics, together with the structure–function relationship, determines that the EGDL might play an important role in influencing the ODHP efficiency. An in situ FT-IR study shows that the adsorption-activation of propane and that of propylene proceed via different initial intermediates and transformation processes. The former initially involves surface propoxide species that will be transformed into aldehydic and ketonic intermediates at the reaction temperature. The latter directly involves π-allyl alkoxidic and σ-allyl aldehydic species, as well as vanadia-carboxylate species with a quasi-anhydride structure at ambient temperatures, at which these intermediates are prone to catalytic combustion.

Increasing concerns about the potentially negative impacts of chemical production on sustainable development of the overall environment have spurred numerous attempts to seek greener reaction mediums, recyclable catalysts, and high-efficiency procedures. Herein, a cyclometalated Ir complex with a pyrene tag was successfully immobilized onto multiwalled carbon nanotubes via π–π stacking interactions, through which an easily reusable Ir catalyst was constructed. The immobilization process was effectively monitored by using a fluorescence spectroscopy technique, and the immobilized Ir catalyst was well characterized and evaluated. It is found that the immobilized Ir catalyst exerts activity comparable to that of the corresponding homogeneous Ir catalyst for the dehydrogenation of indolines in an aqueous solution. More importantly, the catalyst could be recycled seven times without obvious loss of the Ir-active center and noticeable decrease in the yield of the targeted product. Additionally, the observed sli...

We report a hybrid bioactive system inspired by the biosilicification of diatoms. Monodisperse chloroplast/silica hybrid microspheres with core–shell structure were designed and prepared. Natural fresh chloroplasts, the photosynthetic plant organelle, were surfacely covered with silica shell by mild sol–gel process. The charge of chloroplast surface attracts negatively charged silica particles in the sol generated from subsequent hydrolysis and condensation of the tetraethyl orthosilicate (TEOS), which benefits single-chloroplast encapsulation. SEM images confirm the closed topologies, sizes, and dispersions of hybrid microspheres comparable to those of parent chloroplasts. The elemental analysis using EDX, the particle size distribution analyses using DLS, the thermochemical analyses using TGA measurements and structural characterization using XRD provide evidence for the formation of silica coating. Monitoring declines in the visible light absorption production yields information regarding the declines in the light-harvesting ability of chlorophyll, which confirmed that the silica shell in the present work extends the photochemical vitality of chloroplasts. Results from oxygen production measurements also demonstrate the existence of silica shell confers real protection on the bioactivity of chloroplasts. We envisage that the stand-alone chloroplast encapsulation enables preparation of living-cell-templated microspheres exhibiting capacity for photosynthetic bioreactors, sensors, green coatings, catalysts, more generally opening a window for construction of stable, environment friendly, functional hybrid materials.

The intercalation of guest molecules into layered materials is an important strategy to develop multifunctional hybrid nanocomposites and porous materials. The unique mesoporous structure and the intrinsic acidity of metal oxide intercalated porous clay heterostructure (PCH) make it a promising catalytic material. In contrast to the current synthesis methods of PCH that have complex procedures and structure-controlling difficulties, a novel one-step approach with supercritical CO2 (scCO2) as medium was invented using montmorillonite (Mt) as the host matrix and cetyltrimethylammonium bromide as the structure-directing agent (SDA). In this simple and efficient approach, the high diffusivity of scCO2 ensures the facile transportation of cationic SDA into the interlayer space of Mt via ion exchange, which eliminates a requirement for the high solubility of a SDA in scCO2. As a result, the co-assembly of the SDA and the oxide precursor controlled in the interlayer space of Mt leads to the highly ordered PCH. Furthermore, this unique approach provides a general technique to synthesize multi-functional intercalation compounds.

By using N,N-dimethylformamide (DMF) as a methylenating reagent, the copper-catalyzed CH activation of indole was demonstrated as an efficient and facile protocol for synthesizing 3,3′-diindolylmethane (DIM) and its derivatives. The results indicate that copper chloride was the best catalyst among the investigated transition metal salts, which affords an excellent regioselectivity and good yield when tert-butyl hydroperoxide (TBHP) was used as an oxidant.

The strong desire for developing promising candidates of insensitive nitro energetic materials has spurred numerous attempts to discern the nitration details. The nitration mechanism of 2-methyl-4,6-dihydroxypyrimidine (MDP) with nitronium (NO2+) to form 2-dinitromethylene-5,5-dinitropyrimidine-4,6-dione is studied via DFT-B3LYP/6-311G(d,p) method. The possible nitration pathways are excavated and illustrated. Herein, a unique/incredible induction/enhancement of the co-existing acidic group of HSO4− to the targeted nitration is definitively proposed. The impact of the introduction order of four nitro groups (–NO2) on the title nitration is systematically demonstrated. It is suggested that the proposed induction of HSO4− may effectively promote/catalyze not only the NO2+ attack, but the H-transfer and H-abstraction as well, and thus dramatically decreases the activation free energy of the nitration system. Moreover, the NO2+ attack may be dynamically affected by the pre-introduced –NO2 and the resulted fluctuation of charge distribution in the pre-intermediates, which has been primarily supported via the calculated atomic charge, Coulomb attraction and Fukui function. It is indicated that the preferential dinitration on –CH3 with the induction of HSO4− (path A) is the most likely pathway. It is optimistically expected that the present study may provide a theoretical basis to the research and engineering tests of the title nitration, and promote the exploration of related insensitive energetic materials.

Cost-effective adsorbents for volatile organic compounds elimination were synthesized at room temperature. New kinds of external cross-linkers were developed and used in the one-step Friedel–Crafts reaction. The synthesized polymers exhibit a high surface area (BET surface area up to 1345 m2 g−1), large pore volume, superhydrophobic nature and excellent adsorption capacity for benzene, which is one of the highest to date among the reported adsorbents. It also possesses super preferential selectivity towards benzene in a high humid gas stream. Therefore, this kind of material is a promising adsorbent for air purification and environmental protection.

A new kind of hydrophobic hyper-cross-linked polymers (HCPs) with high surface area, large pore volume, and controllable average pore size was prepared. The synthesized HCP-0.5 sample, having the biggest BET specific surface area (1394 m(2)/g), pore volume (1.55 m(3)/g) and micro-mesopore structure (average pore diameter of 4.4 nm), was used as a novel adsorbent for removing benzene. The results of the static adsorption/desorption experiment at 298,308 and 318 K showed that HCP-0.5 has a very large adsorption capability of 19.16 mmol g(-1) at 298 K for benzene. Dynamic adsorption experiments of benzene on HCP-0.5 under dry and humid condition (RH = 80%) revealed that the existence of water vapor had little effect on dynamic adsorption capacity of benzene on HCP-0.5 and almost did not change the breakthrough time. Therefore, these synthesized polymers can be used as efficient and competitive adsorbents for removing VOCs, especially under humid conditions. (C) 2015 Elsevier B.V. All rights reserved.

The sorption thermodynamics and kinetics of disperse dyes on polylactic acid (PLA) fibers were investigated. PLA is crucial for a sustainable textile industry. However, the low dye exhaustion limits the textile application of PLA fibers. The basic dyeing parameters have been determined to provide an in-depth understanding of dyeing behavior. The weak sorption affinities were attributed to the weak dye-fiber interaction and favorable chemical potential of dyes in solvent. Enthalpy–entropy compensation effect also played a role in weak sorption. The interplay of dye structure and enthalpy, entropy changes was rationalized using molecular surface area and rotatable bonds. The conformation constraint strategy was proposed to overcome weak sorption affinity problem by lowering the entropy penalty. Temperature dependence of diffusion coefficients was well reproduced using molecular collision based diffusion model. The activation energies of diffusion have been correlated with molecular volumes of dyes.

Reactive dyeing of wool fabrics in non-aqueous green solvents was investigated with the aim to cut effluent discharge via dyebath reuse. Hydrolysis of reactive dyes is the major obstacle for recycle and reuse of the spent dye bath. In the current work, 10 non-nucleophilic solvents were screened based on their Environmental, health, and safety (EHS) profile to be used as the dyeing media. Dimethyl sulfoxide (DMSO) and dimethyl carbonate were chosen for their favorable EHS score. ATR-IR, SEM and XRD analysis had revealed DMSO pretreatment induced appreciable morphological and structural changes wool fabrics, leading to enhanced dyeability. DMC was used in combination with DMSO to facilitate dye adsorption as a poor solvent for the dyes. The effect of dyeing temperatures, dyeing time, and DMC content on final depth of shade was investigated. Covalent fixation and ionic fixation were determined for the solvent-dyed wool fabric using a pyridine-stripping procedure and compared to that of an aqueously-dyed control. The results showed that about 30% higher covalent fixation was achieved in non-aqueous system, which leads to higher depth of shade (ΔK/S = 1.3-4.9), enhanced color build up properties and better colorfastness (0.5-1 grade). A multi-cycle repeated dyeing sequence involving the recovered solvents and dyes was demonstrated to give consistently high shade buildup and colorfastness. The recyclable dyeing procedure developed in the current study provides an alternative to effluent treatment in reduction of pollutant discharge for a more sustainable textile industry.

Sustainable reactive dyeing of cotton in green non-nucleophilic solvents was investigated. Dye fixation in the new medium was modeled using DFT calculations with the aim of understanding the role of organic bases. The novel procedure uses non-nucleophilic green solvents instead of water to eliminate the dye hydrolysis. All residuals in the spent dye bath could be conveniently recycled and reused. The three major stages in cotton reactive dyeing, cellulose swelling, dye adsorption and dye fixation were optimized respectively. Two organic bases and potassium carbonate were studied for dye fixation. The mechanisms of the amine-promoted dye fixation were modeled using density function theory (DFT) calculations. The formation of the amine-dye intermediate was elucidated and analyzed using high performance liquid chromatography (HPLC) analysis. The quaternary ammonium catalysis effect on intermediates forming was observed. A 10-cycle repeated dyeing sequence was demonstrated using Reactive orange 5 to give consistently high shade buildup, excellent colorfastness and dramatic reduction in resource consumption. The results have implications for better understanding the new hydrolysis-free and recyclable solvent dyeing process.

A novel fluorinated reversible addition-fragmentation chain transfer agent, S,S-di-pentaflourobenzyl trithiocarbonate (DPFBTTC), was designed and synthesized. DPFBTTC and dibenzyl trithiocarbonate (DBTTC) were applied in the polymerization of dodecafluoroheptyl methacrylate (DFHMA), hexafluorobutyl methacrylate (HFBMA), and trifluoroethyl methacrylate (TFEMA) in scCO2. The polymerization processes were monitored using a high-pressure in-situ NIR, through which the polymerization kinetics was investigated and the controllability of DPFBTTC was evaluated. It is found that the controllability of DPFBTTC presented in the order of DFHMA > HFBMA > TFEMA, indicating that DPFBTTC may fit for the controlled polymerization of the highly fluorinated methacrylates. Moreover, the controllability of DPFBTTC is verified to be better than that of DBTTC, possibly resulting from the enhanced accessibility/miscibility of DPFBTTC to the fluorinated monomer used. We believe that the employment of DPFBTTC and the resulted introduction of stable pentafluorobenzyl end groups to the polymer are expected to distinctly improve performances of the polymer, and thus will meet the special application requirements. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015

Ammonium perfluorooctanoate (APFO) is an additive used in synthesis of fluoropolymer and subsequently existed in the final product. However, the residues of APFO in fluoropolymer caused serious environmental problems. An enhancement in solubility of APFO in supercritical carbon dioxide (scCO2) is definitively accomplished via intermolecular interaction. Based on intermolecular interaction, the solvation mechanism of APFO in gaseous and supercritical CO2 was systematically demonstrated by introducing the concepts of transition pressure (PT). Considering the intermolecular interactions between APFO and CO2 are complicated, perfluorooctanoic acid (PFOA) was used instead of APFO. When the pressure reached PT, the intermolecular interactions between PFOA and CO2 reached the maximum, and the binary phase changed from heterogeneous to homogeneous phase. PT of PFOA + CO2 increased from 12.0 ± 0.26 to 20.2 ± 0.43 MPa when temperature changed from 333 to 373 K. Under different conditions, the effects of pressure and temperature on the extraction efficiency of APFO were investigated, and the optimized conditions was 12 MPa, and 333 K. An extraction efficiency of 92.3 ± 0.755% is obtained.

High pressure in situ Fourier transfer infrared/near infrared technology (HP FTIR/NIR) along with theoretical calculation of density functional theory (DFT) method was employed. The solvation behaviors and the free radical homopolymerization of methyl methacrylate (MMA), methacrylate acid (MAA), trifluoromethyl methacrylate (MTFMA) and trifluoromethyl methacrylate acid (TFMAA) in scCO2 were systematically investigated. Interestingly, the previously proposed mechanism of intermolecular-interaction dynamically-induced solvation effect (IDISE) of monomer in scCO2 is expected to be well verified/corroborated in view that the predicted solubility order of the monomers in scCO2 via DFT calculation is ideally consistent with that observed via HP FTIR/NIR. It is shown that MMA and MAA can be easily polymerized, while the free radical polymerizability of MTFMA is considerably poor and TFMAA cannot be polymerized via the free radical initiators. The &alpha, trifluoromethyl group (&ndash, CF3) may effectively enhance the intermolecular hydrogen bonding and restrain the diffusion of the monomer in scCO2. More importantly, the strong electron-withdrawing inductive effect of &ndash, CF3 to C=C may distinctly decrease the atomic charge of the carbon atom in the methylene (=CH2). These two factors are believed to be predominantly responsible for the significant decline of the free radical polymerizability of MTFMA and the other alkyl 2-trifluoromethacrylates in scCO2.

Nano-platinum granules were affixed to MWCNTs via a liquid-reduction method. Different methods were utilized to introduce Fe(III) into the Pt/MWCNT catalyst. The influence of Fe(III) on the performance of a selective citral hydrogenation over the Pt/MWCNTs in isopropanol was investigated. Characterization techniques such as XRD, TEM, TPR, XPS and N 2 physisorptions were used. Changes in the absorbance and wavenumber for the C O bond in the citral were monitored with a high-pressure in situ infrared spectrometer. When 0.25 wt.% Fe(III) was added, the citral conversion remained unchanged, but the selectivity toward the unsaturated alcohols increased from 33.7 to 90.7%.

Vanadium-containing titanosilicates and V-containing SBA-15 catalysts for oxidative dehydrogenation (ODH) of n-butane at lower temperatures and with lower vanadia contents were contrastively studied. The catalysts were investigated by various techniques, namely, N2 adsorption–desorption, SAXS, TEM, FT-IR, XRD, XRF, H2-TPR, O2-TPD, and XPS, in relation to their performance for the ODH of n-butane. Results reveal that titanosilicate materials synthesized exhibit mesoporous structure, high BET specific surface area, and high total pore volume. H2-TPR, O2-TPD, and XPS results show that lattice oxygen exists in the surface of the V-containing titanosilicate catalysts and enhances the reducibility of vanadia-based catalysts with increasing TiO2 loadings. The V-containing titanosilicate catalysts exhibit much higher catalytic activity for the ODH of n-butane than that of V-containing SBA-15 at a significantly lower temperature of 460 °C, which indicates that lattice oxygen in the catalyst plays an important role...

The nitration mechanism as well as the kinetics of triazol-3-one (TO) with nitronium (NO2+) in both a concentrated nitric acid and a nitric–sulfuric acid system was theoretically studied. Firstly, the density functional theory (DFT) with a B3LYP functional was employed to investigate the mechanism of the mentioned reactants towards the targeted product, 5-nitro-2,4-dihydro-1,2,4-triazol-3-one (NTO). An unexpected induction effect, which derived from the coexisting acid group (NO3− and/or HSO4−), was proclaimed. The impact of the induction effect on the nitration of TO was systematically demonstrated. It is found that unlike the nitration of most aromatics, the nitration of TO with NO2+ to form NTO does not follow the typical electrophilic substitution mechanism. Based on the results calculated in each acid system, the nitration mechanisms, including the NO2+ direct nitration (path A), NO3−-induced nitration (paths Bn–Dn) and HSO4−-induced nitration (paths Bs–Ds), were proposed. It is indicated that path A is unlikely or unfavorable due to the high activation barrier in the rate-determining step, whereas paths Bn–Dn and Bs–Ds are favorable, mainly attributed to the significant decrease of the activation energy induced by NO3− and HSO4− during the nitration process, especially for the NTO-oriented path Bn and Bs. Secondly, the canonical variational transition (CVT) state theory with small curvature tunneling (SCT) correction was used and the rate constants of the rate-determining steps for all paths at different temperatures were calculated. It is shown that the nitration rate in either path Bn or path Bs outdistances that in path A, indicating that NO3− and HSO4− accelerate the nitration of TO with NO2+, and ultimately favour the formation of NTO due to the proposed induction effect of each acid group. An enhanced catalytic effect of the nitric acid or/and sulfuric acid is thought to be embodied in not only the acceleration to the formation of NO2+, but also the induction effects of NO3− and HSO4− during the nitration processes. Meanwhile, it is suggested that the concentration of nitric acid and sulfuric acid in each nitration system should be well controlled since the favourable condition to produce NO2+ and NO3−/HSO4− differs in the concentrations of the corresponding acids.

A prominent enhancement in solubility of epoxide oligomers in supercritical CO2 (scCO2) was definitively accomplished via fluorination. The fluorinated epoxide oligomers (FEO) exhibited incredibly low transition pressure (PT) as compared with a library of other epoxide oligomers. For determining the nature of the observed special affinity of the FEO to CO2, the detailed solvation behaviors of 14 epoxide oligomers in gaseous and supercritical CO2 were investigated using a high-pressure in situ ATR FTIR system as the pressure increased from 0.1 to 40.0 MPa. The key role of the intermolecular interactions on the enhanced solubility of the FEO in scCO2 was established and the major factors impacting the molecular interplay between the epoxide oligomers and CO2 were systematically evaluated. We attribute the uniquely enhanced solubility of the FEO in scCO2 to the synergistic effects of the increased special attraction between the FEO and CO2, the decreased self-interaction among the FEO and the excellent accessibility of the FEO to CO2. Since the FEO are suggested to be the most soluble species in scCO2, we optimistically believe that the FEO may act as the ideal solubilizing chain after being transplanted or grafted into other targeted molecules and thus can be employed in developing a series of novel fluorinated monomers, ligands/complexes/catalysts and surfactants in a scCO2 system.

A series of Ni–SiO2 catalysts was synthesized by the complex-decomposition method using different amino acids as complexing agents and fuels and nickel nitrate and tetraethoxysilane as precursors of Ni and SiO2, respectively. For comparison, ammonium hydroxide and acetic acid were also used as complexing agents and fuels. Characterization by XRD, TEM, and N2 adsorption–desorption at low temperature indicated that the structural and textural properties of the Ni–SiO2 catalysts were strongly dependent on the complexing agent used. The dispersion of metallic Ni was increased by optimizing the complexing agent used. As revealed from H2-TPR patterns, Ni–SiO2 exhibited significantly different interactions between Ni and SiO2, the extent of which was influenced by the complexing agent used. The Ni–SiO2 catalysts were comparatively evaluated for carbon dioxide reforming of methane (CDR) under the following conditions: CH4/CO2 = 1.0, T = 750 °C, GHSV = 53200 mL·g–1·h–1, and P = 1.0 atm. The results indicate that t...

A novel, high-efficiency and high-selectivity construction of β-trifluoromethyl enol ether via base-induced/promoted C–O coupling of trifluoromethylated vinyl chloride and phenols is presented with a broad substrate scope. The reaction mechanism, especially the significantly high selectivity, was excavated and understood via DFT calculation and is well supported by the experimental observation.

Schiff-cobalt (salenCo) and Schiff-chromate (salenCr) were synthesized and used as catalysts for copolymerizing of propylene oxide (PO) and CO2. The alternating copolymer of polycarbonate was successfully obtained under mild conditions in the presence of 4-(dimethylamino)-pyridine (DMAP) cocatalyst. The influences of DMAP amount, polymerization time, temperature, and CO2 pressure on the copolymerization efficiency and selectivity to polycarbonate were investigated in the presence of catalysts. Under the optimized conditions, salenCo/DMAP exhibited an excellent catalytic efficiency with perfectly alternating copolymerization products (99% carbonate and more than 99% polycarbonate with head-to-tail linkage) and high selectivity to polycarbonate over cyclic carbonate (more than 99% polymeric product) without byproduct (polyether). While only 76% selectivity to polymer, 95% carbonate linkage, and 80% head-to-tail connection unit were obtained over salenCr/DMAP catalyst. Furthermore, the catalytic activity of ...

Montmorillonite (Mt) was modified via cation-exchange using silver nitrate (AgNO3) as a precursor to exchange the Na+ in the Mt interlayer space and produce (Ag+Mt). The twice dipping and twice rolling method was subsequently used to further strengthen sutures (Ag+Mt/sutures). When the blood and tissue compatibility of the Ag+Mt/sutures prepared by different processes was assessed, the Ag+Mt/sutures were discovered to exhibit good blood and tissue biocompatibilities. Subsequently, when the antibacterial properties were examined, the Ag+Mt/sutures were found to inhibit bacterial growth by 99 ± 0.9% for both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus.

A triple-sensitive polymer of poly(ethylene glycol)-iminoboronate nitrobenzyl ethanediol chelate (PEG-INEC) is efficiently fabricated via the convenient aqueous iminoboronate multi-component reaction (MCR) of methoxypolyethylene glycol amine (mPEG-NH2 ), 2-formylphenylboronic acid (FPBA), and bis(2-nitrophenyl) ethanediol (BNPE, a photo-cleavable nitrobenzyl alcohol derivate). The aqueous MCR synthetic procedure is followed using 1 H NMR and turbidity analysis. It is shown that polymer nano-aggregates of PEG-INEC in aqueous solution can be dissociated through the stimuli responsive reactions of the hydrophobic iminoboronate nitrobenzyl ethanediol chelates (INECs) when exposed to UV light, acid, and H2 O2 , respectively. Furthermore, upon the stimulation of combined triggers, the dissociation of polymer nano-aggregates can be accelerated to different extents, resulting in the synergistic release of encapsulated hydrophobic molecules in water. The proposed facile and general method is quite desirable and of great importance in practical applications like drug and gene delivery.

A one-step, continuous flow-phase, highly catalytic hydrogenation–isomerization of dicyclopentadiene (DCPD) directly into exo-tetrahydrodicyclopentadiene (exo-THDCPD) has been successfully performed over a fixed-bed reactor. This method is a greener and more cost-effective single-step route than the use of AlCl3 and noble metals (Pd, Pt, and Au) and, instead, employs a combination of Ni/γ-Al2O3 for hydrogenation and Ni/Hβ for isomerization. The bifunctional catalysts provided 100% DCPD conversion and 70% selectivity for exo-THDCPD and displayed a high stability without obvious deactivation over 200 h of testing. The synergistic effect of Ni hydrogenation activity and the isomerization activity of the supports is a key factor for the catalytic hydrogenation–isomerization of DCPD. A series of supports (ReY, USY, USReY, HY, HReY, Hβ, MCM-41, γ-Al2O3, SiO2, and NaY) were initially investigated as the Ni-supported catalysts. Surprisingly, we found that Hβ had a high activity for the isomerization of endo-THDCP...

TiO2 was prepared by a hydrothermal method. It was chemically combined with carboxymethyl cellulose prepared from biodegradable ramie fiber to obtain the TiO2/ramie fiber composite. The TiO2/ramie fiber composites were characterized by an X-ray diffractometer, an environmental scanning electron microscope, and a Fourier-transform infrared spectra. The results indicate that TiO2 is chemically combined with ramie fiber, and it can be reused more than five times without obvious TiO2 loss. The photocatalytic performances of TiO2 and TiO2/ramie fiber composite used to degrade both a methyl orange (MO) anionic dye and a rhodamine B (RB) cationic dye solution indicate that the photocatalytic activities of TiO2 for the degradation of the above described solutions are greatly improved when the TiO2 is dispersed on ramie fiber. When 0.5 g of the TiO2/ramie fiber composite is added to a dye solution for 3 h, the degradation rates for the initial concentrations (20 mg/L of MO and 12 mg/L of RB) are greater than 90 %. The photocatalytic degradation of MO can be described as a zeroth order reaction.

By using N,N-dimethylformamide (DMF) as a methylenating reagent, the copper-catalyzed CH activation of indole was demonstrated as an efficient and facile protocol for synthesizing 3,3′-diindolylmethane (DIM) and its derivatives. The results indicate that copper chloride was the best catalyst among the investigated transition metal salts, which affords an excellent regioselectivity and good yield when tert-butyl hydroperoxide (TBHP) was used as an oxidant.

Pt/MWCNT and Pd/MWCNT nanocatalysts were prepared via a liquid reduction method. The selective hydrogenation of cinnamaldehyde (CAL) was investigated over 5.0 wt.% Pt/MWCNT and 5.0 wt.% Pd/MWCNT catalysts in a CO2-expanded alcoholic medium at different reaction conditions. The hydrogenation selectivities over these two catalyst types were shown to be entirely different. It was found that the Pt/MWCNT catalysts are highly selective for C=O bonds, giving the unsaturated alcohol a selectivity for cinnamyl alcohol (COL) of 97.3% and a conversion rate for cinnamaldehyde of 99.3%. Conversely, the Pd/MWCNT catalyst is highly selective for C=C bonds, producing a saturated aldehyde with a selectivity for hydrocinnamaldehyde (HCAL) of 91.3% and a conversion rate for cinnamaldehyde of 98.6%. The small diameter of the Pt or Pd granules over the multiwalled carbon nanotubes (MWCNTs) leads to a high catalyst activity, and an increase of CO2 pressure results in a better hydrogenation performance for C=O bonds than that for C=C bonds.

The strong desire for the extensive application of supercritical carbon dioxide (scCO2) as an environmentally benign solvent in polymers synthesis and processing has spurred numerous attempts to discern and improve its solvability toward monomers as well as polymers. The detailed solvation processes along with the phase behaviors of a fluorinated liquid monomer (LM) of 2,2,2-trifluoroethyl methacrylate (TFEMA), as well as another 13 non-fluorinated LMs in gaseous and supercritical CO2, were respectively investigated by using a newly built high-pressure ATR-FTIR in situ monitoring system as CO2 pressure stepwise increased from 0 to 38.0 MPa. Interestingly, an unexpected vibrational absorption variation, especially a distinct blue-shift in the in situ FTIR spectra of the functional groups in each LM + CO2 binary system, was generally observed during the solvation process as CO2 pressure increased. A similar variation trend of the vibrational absorption of the C–F bond in the TFEMA + CO2 system was also obta...

The influence of ethylenediamine (en)/Co molar ratio on the preparation of Co/SiO2catalysts was studied. The decomposition of these Co-en species resulted in the formation of small cobalt nanoparticles. The highly dispersed catalysts led to lower FT activity due to an increase of cobalt-silica interaction except Co(en)2/SiO2catalyst. Meanwhile, higher selectivity for light hydrocarbons was observed, which was ascribed that smaller cobalt particles containing active sites depressed the chain growth.

Fluorescent photolabile groups undergoing convenient synthesis and fast cleavage are being explored because of their increasing utility in both synthetic and biological chemistry. Herein, a model photosensitive poly(ethylene glycol)-lipid of NP-B-PEG with a 2-nitrobenzyl 2-pyridinylmethyl borate hydrophobic tail is synthesized. The (1) H-NMR and absorption spectra analysis of NP-B-PEG upon 365 nm irradiation in water supports a rapid photocleavage of nitrobenzyl borate with the concomitant hydrolysis of 2-pyridinylmethyl borate. It is also shown that the borate tail hydrolyzes slowly in water. Fortunately, when the polymer aqueous solution is loaded with the hydrophobic doxorubicin (DOX), the borate hydrolysis can be much retarded. The phototriggered experiment shows a two-stage DOX release: first, the slow leakage as a result of the photocleavage of 2-nitrobenzyl borate before the vesicle disintegration; second, the quick DOX precipitation from the disintegrated vesicles induced by the speeding up hydrolysis of 2-pyridinylmethyl borate.

The typical polymerization process in supercritical fluids (SCFs) was improved through modifying the reaction system and designing and using sampling tubes. The efficacy of the newly developed procedure was demonstrated by the free radical homopolymerization of 2,2,2-trifluoroethyl methacrylate (TFEMA) and coplymerization of TFEMA and N-vinylpyrrolidone (NVP) in supercritical carbon dioxide (scCO2). Results indicate that the newly developed procedure has the characteristics of minimum loss of reactants and polymerization starting at the desired temperature and pressure. Furthermore, the polymerization process can be well tracked by analyzing the reaction mixtures online sampled from the reactor at certain reaction times by FT-IR, 1H NMR, and GPC. The reaction time and the product properties can be optimized based on the tracking results. For the first time, block copolymers by free radical polymerization in scCO2 was successfully synthesized by sequential addition of TFEMA and methyl methacrylate (MMA) in...

The first examples of a Pd-catalyzed carbonylation of aryl boronic acids with sp3 carbon partners are presented. Various boronic acids were shown to react with 1,3-diesters and 1,3-diketones to afford structurally unique carbonyl compounds. By employing 2-substituted 1,3-diesters, synthetically-challenging quaternary carbon centres were accessed. In total, 42 examples of aryl carbonyl compounds were prepared in moderate to good yields. The catalytic system features the use of a bidentated phosphine ligand and a relatively low CO pressure (5 atm), providing an easy, alternative method for the preparation of triketones.

The intermolecular and intramolecular coupling reaction of carboxylic derivaties with aromatic ketones induced by titanium tetrachloride and zinc powder was studied.

To study the effect of fluoride on oxidative stress, DNA damage and apoptosis as well as cell cycle of rat oral mucosal cells and hepatocytes.Ten male SD rats weighing 80-120 g were randomly divided into control group and fluoride group, 5 animals each group. The animals in fluoride group had free access to deionized water containing 150 mg/L sodium fluoride (NaF). The animals in control group were given distilled water. Four weeks later, the animals were killed. Reactive oxygen species (ROS) in oral mucosa and liver were measured by Fenton reaction, lipid peroxidation product, malondialdehyde (MDA), was detected by thiobarbituric acid (TBA) reaction, reduced glutathione (GSH) was assayed by dithionitrobenzoic acid (DTNB) reaction. DNA damage in oral mucosal cells and hepatocytes was determined by single cell gel (SCG) electrophoresis or comet assay. Apoptosis and cell cycle in oral mucosal cells and hepatocytes were detected by flow cytometry.The contents of ROS and MDA in oral mucosa and liver tissue of fluoride group were significantly higher than those of control group (P0.01), but the level of GSH was markedly decreased (P0.01). The contents of ROS, MDA and GSH were (134.73 +/- 12.63) U/mg protein, (1.48 +/- 0.13) mmol/mg protein and (76.38 +/- 6.71) mmol/mg protein in oral mucosa respectively, and (143.45 +/- 11.76) U/mg protein, (1.44 +/- 0.12) mmol/mg protein and (78.83 +/- 7.72) mmol/mg protein in liver tissue respectively. The DNA damage rate in fluoride group was 50.20% in oral mucosal cells and 44.80% in hepatocytes, higher than those in the control group (P0.01). The apoptosis rate in oral mucosal cells was (13.63 +/- 1.81) % in fluoride group, and (12.76 +/- 1.67)% in hepatocytes, higher than those in control group. Excess fluoride could differently lower the number of oral mucosal cells and hepatocytes at G0/G1 and S G2/M phases (P0.05).Excess fluoride can induce oxidative stress and DNA damage and lead to apoptosis and cell cycle change in rat oral mucosal cells and hepatocytes.

The first examples of a Pd-catalyzed carbonylation of aryl boronic acids with sp(3) carbon partners are presented. Various boronic acids were shown to react with 1,3-diesters and 1,3-diketones to afford structurally unique carbonyl compounds. By employing 2-substituted 1,3-diesters, synthetically-challenging quaternary carbon centres were accessed. In total, 42 examples of aryl carbonyl compounds were prepared in moderate to good yields. The catalytic system features the use of a bidentated phosphine ligand and a relatively low CO pressure (5 atm), providing an easy, alternative method for the preparation of triketones.

The intermolecular and intramolecular coupling reaction of carboxylic derivaties with aromatic ketones induced by titanium tetrachloride and zinc powder was studied.