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Lithium sulfur battery is one of the most promising applicants for the next generation of energy storage devices whose commercial applications are impeded by the key issue of shuttle effect. To overcome this obstacle, various of two-dimensional (2D) carbon-based metal-free compounds have been proposed to serve as anchoring materials for immobilizing soluble lithium polysulfides (LiPs), which however suffered from low electronic conductivity implying unsatisfactory performance for catalyzing sulfur redox. Therefore, we predicted metallic C5N monolayers, possessing hexagonal (H) and orthorhombic (O) phases, which exhibit excellent performances for suppressing the shuttle effect. First principles simulations demonstrate that O-C5N could serve as bifunctional anchoring material due to its strong adsorption capability to LiPs and excellent catalytic performance for sulfur redox with active sites from both basal plane and zigzag edges. Furthermore, the rate of Li2S oxidation over O-C5N is fast due to low energy barrier of 0.93eV for Li2S decomposition. While for H-C5N only N atoms locating at the armchair edges can efficiently trap LiPs and boost the formation and dissociation of Li2S during discharge and charge processes, respectively. The current work opens an avenue of designing 2D metallic carbon-based anchoring materials for Lithium sulfur battery, which deserves further experimental research efforts.

Responsive Pickering emulsions exhibit promising application in industry owing to the integration of the high storage stability with on-demand demulsification. In this study, stimuli-responsive Pickering emulsions stabilized by poly[oligo(ethylene glycol) methyl ether methacrylate]15-b-poly(diacetone acrylamide)120 (E15D120) worms were indicated, in which E15D120 worms were prepared via reversible addition-fragmentation chain transfer-based aqueous dispersion polymerization using thermo-sensitive POEGMA15 as both the stabilizer block and macro-chain transfer agent. The factors influencing the morphologies of copolymers during polymerization-induced self assembly have been investigated. A series of different morphological polymer nanoparticles including spheres, worms, and vesicles could be produced through rational synthesis. E15D120 worms demonstrated excellent emulsifying performances and could be used as emulsifiers to form n-dodecane-in-water Pickering emulsions at a low content. The formed n-dodecane-in-water Pickering emulsions revealed a slow demulsification at pH 10 or 70 °C or pH 10/70 °C combinations, and several hours were needed for the demulsification of Pickering emulsions. However, n-dodecane-in-water Pickering emulsions displayed a rapid demulsification (∼10 min) at an elevated temperature, such as 90 °C. The different demulsification rates were attributed to different sensitivities of E15D120 worms to external stimuli. Pickering emulsions integrating a rapid responsive demulsification with a slow one would be well satisfactory on different occasions.

A strategy for catalyst-free domino reaction of 4-aminopyridin-2(1H)-ones, arylglyoxal hydrates and different 1,3-dicarbonyl compounds in water has been established. The mild and efficient procedure afforded pyrrolo[3,2-c]pyridine derivatives with 76–94% yields after simple crystallization. The present procedure shows promising characteristics, such as readily available starting materials, the use of water as reaction media, simple and efficient one-pot operation, and avoiding the need for any hazardous or expensive catalysts.

Catalytic combustion is an efficient and economical technique to deal with the air pollution of diluted volatile organic compounds (VOCs). In this work, oxygen-rich CeO2-Nb2O5 mixed oxides (CexNb1-xO4+δ) with varied Ce/Nb molar ratios in the bulk synthesized by modified sol–gel method were investigated for complete catalytic combustion of VOCs as exemplified by monochlorobenzene and toluene. To reveal the structure–function relationship of these materials, comprehensive catalytic performance evaluation and characterizations were performed, which showed that the 4Ce1Nb catalyst (CeO2-Nb2O5 with Ce/Nb molar ratio of 4:1) displayed superb apparent catalytic activity. Complete oxidation could be accomplished below 300 °C, which was significantly lower than that of single-component CeO2 or Nb2O5, as well as some other types of V and Cr based mixed oxide catalysts. Moreover, the apparent catalytic activity of 4Ce1Nb could be maintained for at least 100 h at 280 °C with high selectivity to the formation of HCl and CO2. The improved catalytic performance of 4Ce1Nb could be ascribed to the formation of oxygen-rich CexNb1-xO4+δ mixed oxides with high dispersion of Ce and Nb species into each other, the strong interaction of Ce–O-Nb, an abundance of active oxygen species, high specific surface area and mesoporous structure.

A facile and eco-friendly protocol for the synthesis of sulfonylhydrazones from sulfonyl chlorides, hydrazine hydrate and vinyl azides was developed. The unique advantage of this approach is that desired products can be obtained efficiently in water, which meets the requirements of green chemistry and provides good perspectives for the sustainable production of new drug candidate. Also, this reaction proceeded in moderate to good yields with a wide tolerance of functional groups.

Electrocatalysts are vulnerable to be influenced during the oxygen reduction reaction (ORR) process on the cathodes of direct methanol fuel cells, mainly by the reaction products and air-containing traces of acidic gas carbon dioxide (CO₂), leading to low activity and durability. Herein, an ORR catalyst was derived from furfural, nitrogen carbide (g-C₃N₄), and calcium chloride (CaCl₂) via a dual-template method, resulting in two-dimensional graphene-like carbon nanosheets with a micro–mesoporous architecture, large Brunauer–Emmett–Teller surface areas (748 m²/g), an ultrahigh pyridinic nitrogen-doping level (13.6 wt %), and high degree of graphitization. The as-synthesized sample shows high ORR performance and robust durability in both alkaline and acidic electrolytes undergoing a gas mixture of O₂ and CO₂ (95:5), demonstrating a strong tolerance of CO₂ during the ORR process. Besides, the as-prepared material also exhibits competitive properties in the selective capture of CO₂ gas versus N₂. Thus, this work provides a facile route of preparing high-performance bifunctional carbonaceous materials in both ORR and CO₂ gas capture.

A nontoxic multicarboxylic acid (critic acid) was incorporated into the chitosan/poly(ethylene oxide) composite nanofibers by electrospinning. Critic acid was used to crosslink the chitosan molecules inside the composite nanofibers at elevated temperature, which were characterized by FT-IR and XPS analyses. By increasing the critic acid loading and annealing temperature, the solvent resistance and mechanical properties of these composite nanofibers could be significantly improved. Aspirin, a model drug, has been incorporated into the composite nanofibers and the corresponding drug release performances in PBS solution were evaluated. With the increasing of annealing temperature, the drug release rate of the composite nanofibers was decreasing, which could be ascribed to the reduced swelling ratio and concentration of free volume holes in composite nanofibers. Moreover, the cumulative released aspirin amount in certain release time could be finely tuned by adjusting the initial aspirin loading in the composite nanofibers.

Biopolymer of chitosan (CS) and titanium pillared clays (Ti-PILCs) have been combined in a hybrid as advanced supports for immobilization of PdOx=0,1 species to prepare novel PdOx=0,1@Ti-PILC/CS nano-composite catalysts. The Ti-PILC materials showed high specific surface areas and abundant meso-porous structure with many irregular pore channels caused by collapses of layered structure of clay during Ti pillaring process. Both CS chains and sub-nano sized PdOx particles were successfully incorporated into the pore channels of Ti-PILC, resulting in a decrease in both the specific surface areas and uniform distribution of pore size. Besides conventional methods characterizations, the strong interactions between PdOx species and Ti-PILC/CS support were further evidenced with positron annihilation lifetime spectroscopy studies. The resultant PdOx@Ti-PILC/CS catalyst was highly active for the coupling reactions of aryl halides with phenyl acetylenes. It was recyclable and gave excellent yield up to 13 runs with low leaching of Pd species.

A flexible and efficient three-component reaction has been established for the synthesis of bioactive 1,6-naphthyridine-2,5-diones by using low-cost and readily accessible aminopyridinones, aromatic aldehydes, and Meldrum’s acid as starting materials. The main advantage of this synthetic method is that the yields of the resulting 1,6-naphthyridine-2,5-dione derivatives under ultrasound irradiation in water with acetic acid as catalyst are higher than those from the classical-heating method. The probable reaction mechanism indicates that the process involves a Knoevenagel condensation, Michael addition, and cyclization sequence.

An efficient and eco-friendly approach for highly diastereoselective synthesis of spirocycloalkane fused pyrazolo[3,4-b]pyridine derivatives has been developed. The one-pot three-component reaction enables multiple bond-forming events including C–C and C–N bonds under mild conditions using easily available starting materials, leading to diastereoselective generation of N-containing spirocycles. The advantages of inexpensive and easily available starting materials, green and mild reaction conditions, recyclable and easily separable heterogeneous catalysts, broad substrate scope and simple one-pot operation make this strategy highly attractive.

A concise total synthesis of (±)-conolidine, a potent nonopioid analgesic, in 19% overall yield is described here. A gold(I)-catalyzed Conia-ene reaction (Toste cyclization) and a Pictet-Spengler reaction served as key transformations for assembling the 1-azabicyclo[4.2.2]decane core and defining the geometry of the exocyclic double bond. The activation energies of formation of the vinyl-gold intermediates were calculated and revealed a silyl enol ether with an unprotected indole moiety as a suitable precursor for the Toste cyclization. This six-step synthesis did not involve any nonstrategic redox manipulations.

The mesoporous phenol-formaldehyde resins (PFR) were synthesized using formaldehyde, phenol, F127 template as raw materials by high temperature hydrothermal method under different temperatures. Nitrogen doped mesoporous PFR were synthesized in the same way with another additional raw material HMTA. Two series of carbon materials PCs and PCNs were obtained after calcinating PFR at 700, 800, 900 °C. N2 adsorption analysis indicates that both the two kind of carbon materials have relatively large specific surface area (325–619 cm2/g for PCs and 431–580 cm2/g for PCNs). TEM and XRD analyses prove highly ordered mesoporous structure of the samples. Both the elemental analysis and IR results suggest a high carbon content and the abundant fused-ring structure of the test materials. The positron annihilation spectra show that the corresponding intensity I3 of the longest lifetime component τ3 is less than 2%, indicating that the π electrons in the fused rings with low ionization energy are capable of trapping positrons and inhibiting the formation of o-Ps.

Colloidosomes have gained intensive attention in the past years due to their substantial applications in wide scopes involving encapsulation, catalysis, and drug delivery, etc. In this study, we depicted the templated fabrication of well-shaped colloidosomes with tunable shell thickness by Pickering emulsion at a mild condition. To this end, toluene-in-water Pickering emulsion stabilized by cetyltrimethylammonium bromide (CTAB)–modified polydopamine (PDA) nanoparticles (PDA@CTAB) was prepared. After the covalent cross-linking of PDA nanoparticles assembled on the surface of an oil droplet through chemical reactions occurring in toluene phase, exclusive intra-colloidosomes were afforded. The shell thickness of colloidsomes could be roughly tuned by the adjustment of the amount of the reactive monomers in the oil phase. Our investigations revealed that CTAB was critical for the successful fabrication of well-shaped colloidosomes. Otherwise, only irregular structures were obtained if pristine PDA–stabilized Pickering emulsion was applied. The current strategy could enable hydrophobic cargo, such as 10-hydroxycamptothecin to be encapsulated while colloidosomes were created. The release behavior of the encapsulated cargoes was also investigated.

A novel Fmoc-SPPS compatible peptide thioester generation method leveraging Knorr pyrazole synthesis was reported recently. C-terminal peptide hydrazides, pentane-2,4-dione and excess arylthiol were added in one-pot to efficiently produce peptide thioesters in acidic aqueous solution at room temperature. To elucidate the detailed mechanism of this reaction and the origin of the effect of solution acidity, a theoretical investigation on the Knorr pyrazole synthesis-thioester generation reaction was carried out. Our computational results suggest that the reaction generally proceeds through three stages: hydrazone formation, pyrazole formation and thioester formation. The rate-determining step is the C O bond cleavage step in the pyrazole formation stage. The formed pyrazole is readily converted to thioester in the presence of excess thiophenol. The effect of solution acidity originates from the need for protonation of oxygen atoms to increase the electrophilicity of carbonyl group or the leaving ability of hydroxyl group.

Cobalt, nickel and iron are efficient catalysts for numerous chemical and biological reactions, but they are hardly immobilized on solid matrixes due to their relatively weak chelation with the surface molecules. We have employed a co-electrospraying coupling with glutaraldehyde cross-linking technique to prepare cobalt (Co2+), nickel (Ni2+) and iron (Fe2+) catalyst embedded chitosan microparticles (M@MicroCS) (M = Co, Ni and Fe). The Co@MicroCS beads exhibited excellent catalytic activity for the Heck cross-coupling reactions of aromatic iodides with alkenes. Moreover, the Co@MicroCS bead catalyst could be even reused at least for five times without significant loss of the catalytic activities. The average diameter of the free volume holes for the porous Co@MicroCS beads was determined to be much larger than the size of the reactant and product molecules, allowing them to freely migrate through the catalytic sites inside the chitosan beads. These results clearly indicate that the Heck reactions catalyzed by the Co@MicroCS beads primarily occurs inside the porous chitosan beads. Taken together, we have demonstrated a straightforward approach to prepare efficient and recyclable heterogeneous catalysts derived from the first-row transition metal catalysts by entrapping them inside the chitosan microparticles.

The Nb2O5-TiO2 catalyst system was synthesized via sol-gel method and investigated for adsorption/catalytic combustion of toxic 1,2-dichloroethane (DCE), which was usually recognized as a representative of various chlorinated and brominated VOCs pollutants. The research results of structure-performance relationship revealed that binary Nb2O5-TiO2 were amorphous and mesoporous materials with pore diameter mainly in the range of 2–10 nm, and Nb and Ti elements were uniformly dispersed. The interaction between Nb2O5 and TiO2 coupled with the molar ratio of Nb/Ti improved the physicochemical properties of Nb2O5-TiO2. Moreover, Nb2O5-TiO2 exhibited higher catalytic activity for DCE combustion than single Nb2O5 or TiO2. Especially, the 2Nb1Ti catalyst (Nb/Ti = 2:1, molar ratio) displayed the highest activity, over which 90% conversion of DCE could be achieved at 295 °C. These results were related to that the interaction effect between Nb2O5 and TiO2 improved acidity and oxidizing properties, and the materials had large surface area, all of which were favorable for adsorbing DCE at relatively low temperatures (below 93 °C) on Nb2O5-TiO2 and then improving catalytic combustion performance at lower reaction temperatures than Nb2O5 or TiO2. Besides, during the long-term continuous reaction, even though partial deactivation was observed for this catalyst, it could be suppressed at elevated temperature.

A series of C2v-symmetric diphenylporphyrin complexes containing a metal ion (Mg, Al, Mn, Fe, Co, Zn) have been synthesized and applied as catalysts for the solvent-free cycloaddition of epoxides and carbon dioxide under atmospheric pressure and mild temperature, in concert with phenyltrimethylammonium tribromide (PTAT) as a co-catalyst. The activity of these catalysts deeply relies on their coordinated metal species. [5,15-Diphenylporphyrin]manganese(III) chloride (DPP-MnCl) has been found to be the most effective catalyst under optimal reaction conditions. It's worth mentioning that the cycloaddition of phenyl glycidyl ether (GPE) and CO2 proceeded successfully by DPP-MnCl/PTAT even at 25 °C and atmospheric pressure. Moreover, preliminary kinetic investigations of this cycloaddition were carried out by using catalysts DPP-MnCl, DPP-CoCl and DPP-Zn, revealing that the (phenoxymethyl)ethylene carbonate (PEC) formation with the lowest activation energy is catalyzed by DPP-MnCl. Furthermore, a Lewis acid-base dual cooperative catalytic mechanism has been carefully proposed in light of the catalyst systems and the experimental results.

2D hybrid solid superacids with extremely high acid strength and outstanding mass transfer properties were prepared and exhibit superior activities for biomass conversion., Solid acids have been widely used as heterogeneous catalysts in developing green and sustainable chemistry. However, it remains a challenge to improve the mass transport properties and acid strength of solid acids simultaneously. Herein, we report a class of two dimensional (2D) layered hybrid solid acids with outstanding mass transfer and extremely high acid strength by incorporating sulfonated polymers in-between montmorillonite layers. The 2D layered structure and broad distribution of pore sizes allow for highly efficient mass transport of substrate molecules into and out of the solid acids. The acid strength of these solid acids was found to be stronger than that of 100% H2SO4, H3PW12O40 and any other reported solid acids to date, as determined by 1H and 31P solid-state NMR. These 2D solid acids show extraordinary catalytic performance in biomass conversion to fuels, superior to that of H3PW12O40, HCl and H2SO4. Theoretical calculations and control experiments reveal that H-bond based interactions between the polymer and montmorillonite facilitate the unusually high acid strengths found in these samples.

Nb2O5 based solid superacids (Nb2O5-MOx, M = Ti, W, Zr, Si, Al and Ca, respectively) were synthesized by sol-gel method using citric acid as the cross-linking agent, and then were investigated for catalytic combustion of 1,2-dichloroethane (abbreviation: DCE), one of the typical examples for chlorinated VOCs pollutants. The research results of the structure-performance relationship show that mesopore and amorphous state structure are formed for Nb2O5-MOx, and the metal elements are highly dispersed, which contribute to enhancing the metal-metal interaction and modifying the physicochemical properties of the catalysts. The order for the inherent catalytic activity is: Nb2O5-WO3＞Nb2O5-ZrO2＞Nb2O5-TiO2＞Nb2O5-SiO2＞Nb2O5-Al2O3＞Nb2O5＞Nb2O5-CaO. There exists synergistic catalytic effect: the mesopore and surface acidity facilitate the adsorption, activation and destruction of the C Cl bond in the reactants to form HCl and byproduct C2H3Cl (or carbocation intermediate), and then the redox sites promote deep oxidation of the byproduct/intermediate to convert to CO2 and H2O. Especially, the Nb2O5-TiO2 catalyst represents the highest apparent catalytic degradation activity. It also represents good thermal stability and durability for DCE destruction as well as good resistance to water vapor.

The microstructure of poly (vinyl alcohol)/ montmorillonite (PVA/MMT) matrices and Pd@PVA/MMT catalytic composite was characterized by positron annihilation spectroscopy (PAS) and other techniques, such as high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), and X-ray photo electron spectroscopy (XPS). XRD and HR-TEM results showed that 20% was the saturation loading percentage of PVA intercalation into MMT. Ortho-positronium (o-Ps) annihilations were mainly distributed in the interlayer spacing of MMT and/or open spaces (free volume) of PVA. Below the saturation loading percentage of PVA (≤ 20%), it was found that the o-Ps annihilation lifetime became shorter after the intercalation of PVA chains into MMT layers. With further addition of PVA, the o-Ps annihilation lifetime became longer after the formation of exfoliated structure. The 20%-PVA/MMT matrix has been selected as the platform to further immobilize Pd specie for preparing novel 0.2%-Pd@20%-PVA/MMT catalytic composite. The effects of Pd immobilization on the microstructure of PVA/MMT matrices were also sensitively detected by PAS. The mean size of the micro-defects (from Tao-Eldrup model) increased from 0.28 nm (20%-PVA/MMT) to 0.29 nm (0.2%-Pd2+@20%-PVA/MMT or 0.2%-Pd0@20%-PVA/MMT), respectively. This increase in the size of the micro-defects of 20%-PVA/MMT matrix after Pd immobilization was mainly due to the replacement of the inter-molecular hydrogen bodings of PVA chains by the interactions formed between the PVA chains and Pd species. The prepared 0.2%-Pd0@20%-PVA/MMT catalytic composite showed excellent catalytic efficiency and recyclability in both Heck-type and Sonogashira-type coupling reactions. The correlations between the microstructure and performance of the 0.2%-Pd0@20%-PVA/MMT composite were thoroughly discussed.

Uniform chitosan composite nanofiber mats (CS/PAAS) containing 4.0 wt% polyacrylic acid sodium loading have been prepared by electrospinning, followed by annealing at elevated temperature to improve solvent resistance and mechanical strength. The CS/PAAS nanofiber mats have been characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and tensile strength analysis. The prepared nanofiber mats have been shown to be much better than the pristine chitosan powder to adsorb the chromium (VI) ion. SEM-Energy dispersive X-ray spectroscopic (SEM-EDS) and positron annihilation lifetime spectroscopic (PALS) analysis show that Cr(VI) ion can freely permeate into the composite nanofiber and coordinate with the internal chitosan chain molecules. The adsorption abilities of these cross-linked CS/PAAS nanofiber mats are dependent on the chitosan contents as well as N-atom basicity of the chitosan chain. The adsorption capacity toward Cr(VI) ion was improved to 78.92 mg/g after modification of the chelating ligands for the cross-linked CS/PAAS composite nanofibers.

The study on ionic liquid (IL)-based emulsions is very interesting due to the "green" quality and potential wide applications of ILs, whereas the emulsifiers for the formation of IL-based emulsions are extremely limited and mainly centered on low molecular weight surfactants. In this work, synthesis of amphiphilic double-brush copolymers (DBCs) and their application as bespoke macromolecular emulsifiers for the formation of IL-containing non-aqueous emulsions are described. DBCs consisted of a polyurethane (PU) backbone and poly(

The Co(ii)-catalyzed selective C-H alkenylation of picolinamides with 1,3-diynes has been developed. This protocol can be applied to a variety of 1,3-diynes. In addition, both symmetrical and unsymmetrical internal alkynes were well tolerated, affording the corresponding alkenyl arenes. Moreover, control experiments indicated that C-H bond cleavage may be involved in the rate-determining step. Furthermore, a deuterium incorporation product was achieved when deuterated alcohol was employed as the solvent, which suggested that alcohol was essential for the final protonolysis.

Uniform chitosan fibers (CS/PEO) with diameter of 398±76 nm were prepared by electrospinning with merely 5 wt.% of poly(ethylene oxide) (PEO) loading, and then annealed at elevated temperature without the use of additional crosslinker to improve the thermostability and solvent resistance. Swelling test shows that the CS/PEO composite fibers annealed at 200 oC were stable in 50 wt.% acetic acid aqueous solution. The mechanical strength test shows that the annealing temperature can affect the tensile strength of CS/PEO composite fiber mat. The cross-linked CS/PEO composite fibers provide a useful platform for the immobilization of palladium catalyst to catalyze the Mizoroki-Heck reactions of aromatic halides with olefins. Moreover, these CS/PEO composite fibers could be post modified with special ligands to chelate palladium species efficiently to further improve the catalytic activity and stability.

A Pd(II)-catalyzed denitrogenative and desulfinative addition of arylsulfonyl hydrazides with nitriles has been successfully achieved under mild conditions. This transformation is a new method for the addition reaction to nitriles with arylsulfonyl hydrazides as arylating agent, thus providing an alternative synthesis of aryl ketones. The reported addition reaction is tolerant to many common functional groups, and works well in the presence of electron-donating and electron-withdrawing substituents. Notably, the reported denitrogenative and desulfinative addition was also appropriate for alkyl nitriles, making this newly developed transformation attractive.

Chitosan composite superfine fibers with a diameter of 321 ± 99 nm were prepared by electrospinning with PEO as the co-spinning polymer and itaconic acid as the in situ cross-linking agent. Itaconic acid was homogeneously dispersed in chitosan fibers and the in situ cross-linking endowed the prepared chitosan composite fibers with improved solvent resistance, thermostability and mechanical strength. Palladium species immobilized on these annealed chitosan fibers can efficiently catalyze the reduction reaction of 4-nitrophenol as well as the Mizoroki–Heck reaction of aromatic iodides with n-butyl acrylate in an aqueous medium. Furthermore, the larger fiber structure can facilitate the recovery and reuse of the palladium catalyst. The remarkable catalytic performance and easy recovery make this novel fiber-supported palladium catalyst hold great potential applications in green chemistry.

Room temperature ionic liquids (RTILs)-containing Pickering emulsions exhibit promising application potentials because of the integration of the “green” quality and the tunable applications of RTILs with the advantages of Pickering emulsions, such as the high stability and adjustable droplet size. In the present study, sterically-stabilized polymer nanoparticles (SSPNs) were first prepared via the reversible addition-fragmentation chain transfer (RAFT)-mediated non-aqueous dispersion polymerization, in which poly(lauryl methacrylate) (PLMA) and poly(4-vinyl pyridine) (P4VP) acted as the stabilizer block and the core-forming block, respectively. Kinetically-trapped PLMA-b-P4VP spheres and mixed spherical/worm-like morphologies could be achieved at a target copolymer composition. Subsequently, core cross-linked SSPNs (CSSPNs) were obtained by means of chemical cross-linking of P4VP cores of SSPNs with 1,4-dibromobutane in a diluted solution of SSPNs in toluene (0.4 mg/mL). Stable 1-butyl-3-methylimidazolium tetrafluoroborate-in-toluene ([Bmim][BF4]-in-toluene) non-aqueous Pickering emulsions could be formed at a low emulsifier content of 0.005 wt% adopting CSSPNs with mixed spherical/worm-like morphologies as Pickering emulsifiers. Benefiting from large surface areas of Pickering emulsions and unique chemical/physical properties of RTILs, [Bmim][BF4]-in-toluene Pickering emulsions provided readily available platforms for many organic reactions. As a proof of the concept, proline catalyzed Knoevenagel reaction of 4-nitrobenzaldehyde with malononitrile was chosen as a model here. Both high reaction efficiency and good recyclability were observed.

Chemical fixation of carbon dioxide into commodity chemicals is an appealing approach for CO2 transformations and utilizations. The challenge is to develop highly efficient and reusable heterogeneous catalysts. Herein, a cobalt-porphyrin modified graphene oxide (GOPCoCl) has been prepared with chemical functionalization by the acylation and amidation process on the graphene oxide support, and applied as a heterogeneous catalyst for the solvent-free cycloaddition of carbon dioxide and epoxides. The as-received GOPCoCl has been characterized by different methods, demonstrating that the metalloporphyrin is covalently linked to the graphene oxide (GO) surface. Owing to the uniform active sites and support effects, the catalyst behaved efficient catalytic performance, excellent recyclability, and good substrate expansibility for this solvent-free cycloaddition. Moreover, a synergetic catalytic mechanism has been prudently proposed based on the catalytic system and experimental results.

Metal-Salen (M = Fe, Co, Ni, Cu, Zn) complexes were synthesized to catalyze the oxidation of benzoin to benzil with air as the “green” oxidizing reagent. The effects of temperature, base and solvent on M-Salen catalyzed oxidation of benzoin had been examined and optimized. The catalysis results showed that Co-Salen and Fe-Salen complexes were efficient to catalyze the oxidation reaction with yields over 80% while the catalytic activities of other three M-Salen complexes were poor. Moreover, the Co-Salen catalysis system could be reused three times with satisfied yield.

Well-defined chlorinated polyvinylchloride (CPVC) nanofiber mats were fabricated by electrospinning, and then chemically modified with 1,3-propanediamine (CPVC–NH) and glutaraldehyde (CPVC–NOH) to immobilize palladium active species. The chemical modification could significantly improve the tensile strengths of the CPVC nanofiber mats. Adsorption of Pd(II) ions showed that the treatment of fiber mats with glutaraldehyde decreases it schelating ability. Transmission electron microscopy and X-ray diffraction analysis indicated that palladium species were dispersed more homogeneously on the CPVC–NH fibers than on the CPVC–NOH fibers. Results of Mizoroki–Heck reaction showed that the catalytic activity of Pd catalyst supported on CPVC–NOH fibers was superior to that of the Pd catalyst supported on CPVC–NH fibers. Thus, chemical modification of supporting materials with suitable chelating groups is an efficient way to control the catalytic performance of supported Pd catalysts.

A series of rare earth elements (REE)-modified Pt/MCM-41 catalysts were prepared. The effects of REE-doped MCM-41 on the performance of 0.2%Pt/MCM-41 and on benzene combustion were evaluated. XRD spectra and N 2 adsorption show MCM-41 with high specific surface area and large pore volume has a highly ordered hexagonal mesostructure. The UV–vis DRS show that size of Pt particles changes in the trend of small size after adding Nd, and this result is in excellent agreement with the data obtained from HRTEM-EDS. The highest catalytic activity and durability of 0.2%Pt/6%Nd/MCM-41 is attributed to an optimized Nd content, Pt particles with smaller size and high Pt dispersion on MCM-41.

The Pd(TFA)2-catalyzed denitrogenative addition proceeded with selective C–N bond cleavage of arylhydrazines with nitriles in the presence of DABCO and HFBA under air at room temperature. Aryl ketones could be easily synthesized via the hydrolysis of the ketimine moiety generated in situ without the need for additional water.

Chitosan microspheres-supported palladium catalysts (Pd@CM) for Mizoroki–Heck reaction have been successfully prepared by electrospraying PdCl2/chitosan mixture in a trifluoroacetic acid (TFA) aqueous solution. Swelling capacity measurement and thermal analysis demonstrated that the palladium species in the chitosan microspheres could cross-link the chitosan efficiently. FT-IR spectra demonstrated that the chitosan in the microspheres could be cross-linked by glutaraldehyde, and the formed Schiff bond could chelate the palladium species efficiently. High resolution transmission electron microscopy (HR-TEM) indicated that the entrapment of palladium species in chitosan microspheres could enhance its dispersion. Mizoroki–Heck reaction catalysis results demonstrated that the catalytic activity of Pd@CM was associated with the size of chitosan microspheres. The Pd@CM with a suitable size was even more active than the catalyst with palladium species adsorbed on the surface of chitosan microspheres (Pd-CM). Moreover, the entrapment of palladium species in chitosan microspheres could reduce its aggregation and leaching in the catalysis procedure, which in turn increased the reusability of Pd@CM catalyst. The high catalytic activity and stability of Pd@CM have been attributed to the entrapment of palladium species within the cross-linked chitosan microspheres and the chelation of palladium species with the abundant amine and hydroxyl groups on chitosan chain.

It is significant to explore multiresponsive Pickering emulsions because of their flexibility in terms of demulsification in comparison with the single stimuli-responsive systems. In this study, we described a triple-responsive oil-in-water Pickering emulsion that was stabilized by amphiphilic core cross-linked supramolecular polymer particles (CCSPs). For this purpose, β-cyclodextrin-terminated poly(N-isopropylacrylamide) (PNIPAM-β-CD) and azobenzene-capped poly(4-vinylpyridine) (P4VP-azo) were separately synthesized by reversible addition-fragmentation chain transfer polymerization. By virtue of the inclusion interaction between the β-CD host and the azobenzene guest in dimethyl sulfoxide, the amphiphilic supramolecular block copolymer, poly(4-vinylpyridine)-b-poly(N-isopropylacrylamide) (P4VP-b-PNIPAM), was formed. CCSPs were prepared through the combination of the self-assembly of P4VP-b-PNIPAM in the selective solvent, water, and the cross-linking of the P4VP core with 1,4-dibromobutane. Due to thermoresponsiveness of PNIPAM shells and the supramolecular linkages between the cross-linked hydrophobic P4VP core and hydrophilic PNIPAM shells, the as-prepared CCSPs exhibited temperature-, light-, and amantadine hydrochloride guest-triggered morphological transitions. Such triple-responsive morphological transitions gifted CCSPs stabilized oil-in-water Pickering emulsion with flexible demulsification in response to various factors, such as thermo, light, and amantadine hydrochloride or their combinations. Such triple-responsive oil-in-water Pickering emulsion also provided an ideal platform for heterogeneous reactions conducted at the oil-water interface. A large interfacial area and responsive demulsification allowed the reaction to be performed with an efficient and sustainable pattern.

Injectable multi-responsive hydrogels are very important and exhibit many potential applications in biologically relevant fields. In this work, the preparation of injectable multi-responsive hydrogels at near-physiological conditions and their applications as durg carriers were demonstrated. Diol-capped poly(N, N-dimethylacrylamide)-b-poly(N-isopropylacrylamide) ((OH)2-PDMA-b-PNIPAM) diblock copolymers containing a disulfide linkage on the backbone and N, N-dimethylacrylamide-stat-(2-acrylamidophenylboronic acid) (DMA-stat-2APBA) copolymers were separatedly synthesized. Hydrogels were then prepared by a solution-based mixing of DMA-stat-2APBA with (OH)2-PDMA-b-PNIPAM diblock copolymers in PBS (pH 7.4) solution at a given temperature, i.e. 37 °C. Above the lower critical solution temperature (LCST) of diblock copolymers at around 32 °C, (OH)2-PDMA-b-PNIPAM copolymers self-assembled into core-shell structured macromolecular micelles with numerous diol groups on hydrophilic cornoas. Subsequent complexiation of diols with lateral PBA groups of DMA-stat-2APBA copolymers led to the formation of hydrogels. Due to the integration of a library of responsive units including boronate ester and disulfide DCBs together with thermal responsive PNIPAM blocks within the same system, the as-prepared hydrogels indicated multiple stimuli-responsiveness to pH, temperature, glucose and redox reaction as well as the mechanical field. Such multi-responsive hydrogels could be applied as potential drug carriers. The encapsulation and the stimuli-responsive release of a model drug of Rh B were demonstrated.

Palladium chloride and chlorinated poly (vinyl chloride) (CPVC) mixture were prepared into homogeneous solution, followed by electrospinning to make uniform nanofibers with average diameter of ~460 nm. Then, these composite nanofibers were treated in ethylenediamine solution to functionalize and crosslink the CPVC molecules inside the nanofibers to improve their chelating ability and solvent resistance. The functionalization and crosslinking of CPVC molecules inside composite nanofibers were confirmed by SEM, FT-IR, EA and PALS characterizations. The catalytic performance of these palladium encapsulated CPVC nanofibers (Pd@ACPVC) have been evaluated by the Heck and Sonogashira reactions. The catalysis results demonstrate that this Pd@ACPVC catalyst was very effective and stable to catalyze the coupling reaction of aromatic iodides with alkenes (Heck reaction) or phenyl acetylene (Sonogashira reaction) to afford the coupling products in moderate to excellent yields. Due to the regular fibrous structure, the Pd@ACPVC could be readily separated and recovered from reaction mixture. In addition, the Pd@ACPVC could be separately reused for 10 times for Heck reaction and 8 times for Sonogashira reaction without significant decrement of coupling yields. After careful investigation, the palladium leaching from Pd@ACPVC in the reuse procedure could be ascribed to the loss of chelating groups (amino groups) and expansion of free volume holes in the composite nanofibers. The excellent catalytic activity and stability of Pd@ACPVC could be attributed to the strong chelating ability of amino groups, encapsulation of palladium nanoparticles and ultrafine fiber.

Nonwoven chitosan (CS) nanofiber mats were successfully prepared by the electrospinning of the mixture of CS and poly(ethylene oxide) (PEO) in acetic acid aqueous solution. The CS/PEO fiber mats were treated with glutaraldehyde aqueous solution to stabilize fibers in solution. The concentration of glutaraldehyde is important for incorporating swelling properties in the cross-linked CS/PEO fiber mats. The cross-linked CS/PEO fibers (CCS/PEO fibers) were then used as supports for palladium catalysts in the Mizoroki–Heck reaction. The results of the study demonstrated that the catalytic activities of Pd catalyst supported on CCS/PEO fiber (Pd-CCS/PEO fiber) were highly dependent on the concentration of glutaraldehyde in the cross-linking process. Density functional theory (DFT) calculations indicated that the Schiff bond formed between CS and glutaraldehyde could reduce the energy needed to form a chelate complex between the CCS/PEO fibers and palladium active species. This in turn could decrease the activation energy of the Mizoroki–Heck reactions which occur in the presence of the Pd-CCS/PEO fiber catalysts. The optimized Pd-CCS/PEO fiber catalyst was very efficient and stable in the Mizoroki–Heck reaction of aromatic iodides with olefins.

Micro–meso–macroporous polymers (MOPs) grafted with versatile functional groups, such as sulfonate, amine, triazole, pyridine, strong acidic ionic liquids and triphenylphosphine, were synthesized by in situ cross-linking of different functional molecules with 1,4-bis(chloromethyl)benzene in the presence of Lewis acid catalysts without using additional templates. The resultant hyper-cross-linked nanoporous polymers show unique characteristics such as large BET surface areas (up to 1523 m2 g−1), abundant micro–meso–macropores (4.5–131 nm), and tunable and versatile active sites (acid, base and palladium). These functional polymers exhibit excellent activities and good reusability in biomass conversions, cross-coupling reactions and condensation. The catalytic activities are much better than those of various conventional catalysts such as H3PW12O40, SBA-15-SO3H, Amberlyst 15, and mesoporous H-ZSM-5 Pd/C and even as comparable as those of homogeneous H2SO4 and HCl in the depolymerization of crystalline cellulose into fine chemicals and towards transesterification to biodiesel. This work highlights a low cost route to the synthesis of solid catalysts based on functional nanoporous polymers for catalyzing the production of clean biofuels and fine chemicals.

N rich porous carbon based solid acids (NPC-[CxN][X]) have been successfully synthesized by treatment of N rich porous carbon (NPC) with various quaternary ammoniation reagents such as iodomethane, 1,3-propane sultone, and 1,4-butanesultone, and ion exchange with various strong acids such as HSO3CF3, H2SO4, H3PW12O40, HBF4etc. The NPC support was synthesized by carbonization of KOH-activated polypyrrole without using additional templates. Various characterizations showed that NPC-[CxN][X] possesses abundant nanopores, large Brunauer–Emmett–Teller surface areas, good stability, and strong and controllable acid sites with Bronsted characteristics. The immobilized acidic groups were homogeneously dispersed into NPC-[CxN][X]. Notably, NPC-[CxN][X] acted as efficient, reusable and generalized solid acids, which showed excellent activity in various acid-catalyzed reactions such as esterification and transesterification in the synthesis of biodiesel, dehydration of fructose into 5-hydroxymethylfurfural, depolymerization of crystalline cellulose into sugars, and condensation of phenol with acetone in the synthesis of bisphenol A, much higher than that of various solid acids such as Amberlyst 15, H-ZSM-5, H-USY, and sulfonic group functionalized ordered mesoporous silicas. The preparation of NPC-[CxN][X] leads to the development of porous carbon based solid acids with controllable structural characteristics and excellent catalytic activity.

A novel, facile and efficient strategy for the one-pot synthesis of β-ketosulfones from readily available sulfonyl chloride, hydrazine hydrate and vinyl azides is described. The reaction proceeded very smoothly affording diverse β-ketosulfones in moderate to good yields. This new procedure has the advantages of environmental benign, easy and simple operation, low cost and wide tolerance of functional groups, which provides a highly fascinating protocol to access β-ketosulfones.

An efficient and highly eco-friendly approach to poly-substituted 1,6-naphthyridine derivatives with good to excellent yield has been reported using simple and readily available 4-aminopyridinone, aromatic aldehyde or isatin, and 1,3-cyclohexanedione as substrates. The method features low-cost and readily accessible starting materials, green ultrasonic irradiation in water, recycle heterogeneous solid acid catalyst, broad substrate scope as well as simple one-pot operation make this strategy highly attractive. Mechanistic studies indicate that this transformation involves Knoevenagel condensation, Michael addition, and cyclization sequence.

The mechanism of serine/threonine ligation was investigated by density functional theory. The reaction sequentially proceeds through imine capture, 5-endo-trig cyclization and [1,5] O-to-N acyl transfer steps, all of which occur with the assistance of pyridinium. The imine capture and 5-endo-trig cyclization steps are reversible whereas the [1,5] O-to-N acyl transfer step is irreversible. The [1,5] O-to-N acyl transfer step proceeds through a stepwise addition-elimination mechanism with the C–O bond cleavage as the rate-determining step of the overall reaction. The diastereoselectivity for the exclusive formation of the S-configured N,O-benzylidene acetal-linked peptide originates from the disfavored steric repulsion between the leaving phenolic oxygen and the side chain of the C-terminal peptide in the R-configured C–O bond cleavage transition state in the acyl transfer step. A suitable ring size as well as a good leaving group in acyl transfer are responsible for the high efficiency of the serine/threonine ligation reaction.

The cobalt-catalyzed regioselective C H alkoxylation of 1-naphthylamide with diols through a bidentate-chelation assistance has been developed. In this transformation, not only linear diols, but also branched diols and oligoethylene glycols were tolerated under current reaction conditions, affording the corresponding hydroxyalkyl aryl ethers. In addition, control experiments suggested that picolinoyl was the key directing group, and furthermore, this C8-H alkoxylation reaction might proceed through a single-electron-transfer (SET) process.