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The two-step strategy screening based high throughput calculation is an effective method to search for highly active single atom catalysts (SACs) for efficient nitrogen reduction reaction (NRR), sharing a common feature of active metal centers MN4. However, this method faces the lack of descriptor for designing SACs due to limited data. Herein we proposed a robust empirical rule to estimate 312 credible limiting potentials for NRR over 104 C3N-supported SACs. It is found that the limiting potential scales clearly with the adsorption free energies of two key reaction intermediates (∗N2H and ∗NH2), which are significantly dependent on the structure relating descriptor φ, and the activity of SACs with and without N coordination exhibits similar catalytic efficiency. We identified four high-performance SACs having moieties of CrC2N2, CrC4, MnC4 and OsC4 with high selectivity towards NRR and competitive limiting potentials of −0.40, −0.45, −0.53 and −0.54 V, respectively. The φ values for these four SACs are around 19–25 which fall within its optimal ranges of 20–25 validating its prediction fidelity. This work broadens the discovery of two-dimensional carbon-nitrides supported SACs free of N coordination towards efficient N2 reduction and opens a new route of descriptor-guided design of efficient SACs for electrocatalysis process.

Photoelectrochemical oxygen reduction reaction (ORR) toward H2O2 is highly desirable because only sunlight, O2 and water are required in the process. However, the corresponding studies are still at its infancy because of the lack of suitable photocathodes, especially inorganic semiconductor photocathodes. In this work, we report CuBi2O4/CuO (CBO/CuO) heterojunction submicrocrystalline film photocathodes with efficient ORR activity for H2O2 production. The heterojunction film photocathodes were prepared through thermal evaporation of Cu and Bi metals under vacuum and subsequent annealing treatment. Furthermore, the doping of Gd3+ ions into CBO/CuO could significantly enhance the yield of H2O2. As a result, the concentration of H2O2 could reach 1.3 mM within 30 min, which is 6 times higher than that obtained on the pristine CBO/CuO photocathode. The theoretical calculations suggested that the introduction of Gd could adjust the electronic structure of CBO surface and promote 2e ORR pathway for selective production of H2O2. Our work not only provides a new strategy for designing highly efficient photocathode for H2O2 production but also will evoke more interest in photoelectrocatalytic ORR through inorganic semiconductor photocathode.

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.

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.

The exploration of Pickering emulsions is very significant owing to their versatile and important applications in many scopes. In this study, synthesis of a novel kind of single-chain polymer nanoparticle (SCPN) and its stabilized Pickering emulsions were demonstrated. To this end, linear-dendritic diblock copolymers consisting of poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA) blocks and four-generation dendritic aliphatic polyester blocks (G

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.

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.

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.

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 multicomponent two-step strategy for the synthesis of polysubstituted pyrrolo[3,2-c]pyridin-4-one derivatives has been described. The reactions can be readily performed by mixing inexpensive starting materials using two-step methods under mild conditions, and the products can be easily obtained from the mother liquid without any further treatment. Moreover, the solid acid catalyst can be circulated at least 6 times without obvious deactivation. Furthermore, a mechanism for the reaction process has been proposed. Overall the bond forming efficiency, the use of green solvent as the reaction medium, recyclability of the solid acid catalyst, easy work-up/purification, and a wide substrate scope make this method highly attractive to assemble heterocyclic scaffolds.

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.

A novel one-pot multi-step domino strategy for the synthesis of functionalized 2-substituted acetic acids, 2-substituted (1,2,5-triarylpyrrolo[3,2-c]pyridin-3-yl)acetates and 2-substituted-(1,2,5-triarylpyrrolo[3,2-c]pyridin-3-yl)-N-arylacetamides has been established from inexpensive and readily available starting materials. The reaction can be easily performed by employing different substrates via a one-pot multi-step domino reaction. The target products can be easily obtained with satisfactory yields by only simple recrystallization from a mixture of hot 95% ethanol and N,N-dimethylformamide. The reaction features of readily available starting materials, broad substrate scope, bond-forming efficiency, simple one-pot multi-step synthesis as well as green reaction media, make the procedure highly useful for the construction of potential pharmacological heterocyclic molecules.

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(

An efficient strategy was developed for the synthesis of indenopyrrolopyridinone derivatives from 4-hydroxy-6-methyl-2H-pyran-2-one, an amine, and 2,2-dihydroxy-1H-indene-1,3(2H)-dione by a one-pot, two-step, four-component process. The one-pot reaction gives various substituted indenopyrrolopyridinones in good yields and uses a solid acid as a recyclable catalyst in water. This procedure has the advantages of inexpensive substrates, a reusable solid-supported catalyst, and a convenient one-pot operation.

We report here a high temperature directed, self-assembly to the synthesis of ordered mesoporous organic polymers (OMPs) with different nanopore sizes and BET surface areas. The synthesized OMPs have large BET surface areas (219–512 m2/g), ordered mesopores, and adjustable pore volumes (0.20–0.48 cm3/g). Their rules of sub-nano level structures such as free volumes, unopened nanopores and electronic environment in the synthesized OMP materials were systematically investigated by using positron annihilation lifetime spectroscopy, which acts as an important technique for investigating microstructures of ordered mesoporous organic polymers and optimization of synthetic conditions of porous organic polymers.

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.

In this study, an efficient heterogeneous catalyst including palladium (Pd) and zinc (Zn) nanoparticles supported on chitosan/silica (CS/SiO2) composite membrane is synthesized using partially etching of SiO2 technique. N2 sorption isotherm results shows that the prepared Pd-Zn@CS/SiO2 (1/1) porous membrane had a BET surface area of 26.50m2/g. High-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS), characterization of the catalyst shows that the Pd0 nanoparticles (below 5nm), and Zn0 aggregates (about 10-15nm) dispersed well in the CS/SiO2 matrix. Zinc crystal was also detected by X-ray diffraction study and HR-TEM observation. The prepared Pd-Zn@CS/SiO2 membrane catalyst is highly active for Ullmann reductive homocoupling reactions of aryl iodides and aryl bromides, and can be recycled 5 times without significant loss of activities. This work supplies a successful approach to realize Pd catalysts and Zn reducing reagent co-immobilized in the same carrier material with excellent catalytic performances.

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.

Described herein is a convenient and highly selective synthesis of alkynylated isoquinolines and biisoquinolines from various aryl ketone O-pivaloyloxime derivatives and 1,3-diynes via rhodium-catalyzed C-H bond activation. In this transformations, alkynylated isoquinolines, 3,4'- and 3,3'-biisoquinolines could be obtained respectively through changing the reaction conditions. Mechanistic investigation revealed that the C-H activation of aryl ketone O-pivaloyloxime was the key step to this reaction.

An efficient domino approach for the synthesis of new pyrano[4,3-b]pyrazolo[4,3-e]pyridin-5(1H)-one derivatives has been developed using reusable sulfonic organic resin as catalyst in water. The unique feature of sulfonic organic resin makes the formation of pyrano[4,3-b]pyrazolo[4,3-e] pyridin-5(1H)-ones be possible, and avoids generating ring opening products. The plausible mechanism for this domino reaction is proposed.

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.

Pd and transition metal oxides functionalized ZSM-5 single crystals with b-axis aligned mesopores (ZSM-5-OM-PdO x -MO x ) were prepared. ZSM-5-OM support was obtained from crystallization of aluminosilicate gels in the presence of cationic polymers. Characterizations indicate abundant nanopores and highly crystalline degree of ZSM-5-OM-PdO x -MO x , and active species of Pd and transition metals were homogeneously dispersed into ZSM-5-OM, which showed unique interactions and enhanced ability for activating oxygen. Catalytic tests showed that ZSM-5-OM-PdO x -MO x were highly active and reusable catalysts for selective oxidation of alcohols under aerobic and solvent free condition, which were much better than those of Pd/transition metal oxides functionalized ZSM-5, mesoporous silica of SBA-15, and activated carbon catalysts.

Amino group-functionalized, ordered mesoporous polymers (OMP-NH2 ) were prepared using a solvent-free synthesis by grinding mixtures of solid raw precursors (aminophenol, terephthaldehyde), using block copolymer templates, and curing at 140-180 °C. OMP-NH2 was functionalized with acidic sites and incorporated with palladium, giving multifunctional solid catalysts with large Brunauer-Emmett-Teller (BET) surface areas, abundant and ordered mesopores, good thermal stabilities, controllable concentrations, and good dispersion of active centers. The resultant solid catalysts showed excellent catalytic activities and good reusability in biomass conversions and cross-coupling reactions-much superior to those of various reported solid catalysts such as Amberlyst 15, SBA-15-SO3 H, and Pd/C and comparable to those of homogeneous catalysts such as heteropoly acid, HCl, and palladium acetate. A facile green approach was developed for the synthesis of ordered mesoporous polymeric solid catalysts with excellent activities for conversion of low-cost feedstocks into useful chemicals and clean biofuels.

Density functional theory calculations have been carried out to study the mechanism of the gold-catalyzed highly selective hydroamination of alkylidenecyclopropanes. Two main mechanisms (i.e., double-bond activation-first and three-membered-ring activation-first mechanisms) have been examined. The double-bond activation-first mechanism results in the alkene hydroamination product, and it mainly consists of three steps: C-N bond formation, C-C bond rotation, and protodeauration (rate-determining step). Meanwhile, the three-membered-ring activation-first mechanism finally produces allylic amines, and it occurs via the ring-opening (rate-determining step), C-N bond formation, and protodeauration steps. The calculation results show good agreement with the experimental outcomes on the chemo-, regio-, and diastereoselectivity. On this basis, we found that the regioselectivity is caused by the C-C bond rotation step, while the diastereoselectivity is determined by both the C-C bond rotation and the protodeauration steps in the double-bond activation-first mechanism.

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.

Magnetically active, ordered and stable mesoporous carbons with partially graphitized networks and controllable surface wettability (PR-Fe-P123-800 and PR-Ni-P123-800) have been synthesized through direct carbonization of Fe or Ni functionalized, and ordered mesoporous polymers at 800°C, which could be synthesized from self assembly of resol (phenol/formaldehyde) with block copolymer template (P123) in presence of Fe3+ or Ni2+, and hydrothermal treatment at 200°C. PR-Fe-P123-800 and PR-Ni-P123-800 possess ordered and uniform mesopores, large BET surface areas, good stabilities, controllable surface wettability and partially graphitized framework. The above structural characteristics result in their enhanced selective adsorption property and good reusability for organic pollutants such as RhB, p-nitrophenol and n-heptane in water, which could be easily regenerated through separation under constant magnetic fields and washing with ethanol solvent. The unique magnetically active and adsorptive property found in PR-Fe-P123-800 and PR-Ni-P123-800 will be very important for them to be used as efficient absorbents for removal of various organic pollutants in water.

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.