Showing papers in "Research on Chemical Intermediates in 2017"

Synthesis and pharmacological properties of chalcones: a review

Abstract: Chalcones and their analogs have been an area of great interest in recent years. Numerous research papers have been published, and chalcones continue to show promise for new drug investigations. Researchers have explored new approaches for the synthesis of chalcone derivatives, which have revealed an array of pharmacological and biological effects. These chalcone derivatives have shown important antimicrobial, antifungal, anti-mycobacterial, antimalarial, antiviral, anti-inflammatory, antioxidant, antileishmanial anti-tumor, and anticancer properties. This review highlights the synthesis and pharmacological properties of chalcone derivatives.

The preparation, and applications of g-C3N4/TiO2 heterojunction catalysts-a review

Abstract: In recent years, more and more attention has been paid in the research of heterojunction catalysts, due to their better catalytic ability than that of single component catalysts Up to now, many kinds of heterojunction catalysts have been reported, such as Bi2O3/Bi2WO6, WO3/BiVO4, SnO2/TiO2, CdS/TiO2, Ta3N5/Pt/IrO2 and so on, among which the heterojunction catalyst composed of g-C3N4 and TiO2 has been studied tremendously recently, due to the high activity, high thermal and chemical stability, and well matched energy structure of them Up to now, many methods have been explored for the synthesis of g-C3N4/TiO2 heterojunction catalysts, such as ball milling of g-C3N4 and TiO2, hydrothermal growth of TiO2 on g-C3N4 and so on In this review, the recent researches on the synthesis of g-C3N4/TiO2 catalysts were summarized Moreover, the applications of g-C3N4/TiO2 catalysts in the field of photocatalysis were detailedly introduced

Iron-based metal–organic frameworks (MOFs) for visible-light-induced photocatalysis

Abstract: Photocatalysis is one of the best solutions to solve the problems of global energy shortage and environmental deterioration since it can utilize the abundant and ubiquitous solar light for chemical transformations. In addition to traditional semiconductor-based photocatalysts, metal–organic frameworks (MOFs), a class of micro–mesoporous hybrid materials, are recently emerging as a new type of photocatalytic materials due to their unique structural characteristics. Among all the MOFs, Fe-containing MOFs are extremely appealing in photocatalysis since most of the Fe-based MOFs are visible light responsive due to the existence of extensive iron–oxo (Fe–O) clusters. In addition, Fe is an earth-abundant metal and Fe-containing complexes are commonly used in catalysis and photocatalysis. In this short review, we summarized the recent progress in using Fe-based MOFs for several photocatalytic applications, including pollutants degradation, water oxidation/reduction, CO2 reduction and organic transformations, with a focus on their different light-harvesting properties as compared with that of Ti- and Zr-containing MOFs as well as the structural influence on photocatalysis due to the existence of the diversified Fe-based MOFs. We hope that such a review can stimulate intensive research for rational design of Fe-based MOFs, one of the most promising MOF-based systems, for photocatalysis.

Reduced graphene oxide/ZnFe2O4 nanocomposite as an efficient catalyst for the photocatalytic degradation of methylene blue dye

Abstract: This research effort reports the design and development of reduced graphene oxide/zinc ferrite (rGO/ZnFe2O4) nanocomposites for the photo-oxidative degradation of methylene blue (MB) dye. The composite formation of rGO sheets with ZnFe2O4 nanostructures was achieved by a simple process of one- step solvothermal strategy, in which the simultaneous reduction of GO and Zn2+ and Fe3+ ions was achieved. The morphological studies revealed that the surfaces of rGO sheets were densely covered by the 280-nm-sized spherical ZnFe2O4 nanostructures and the average size of nanoparticles that constitutes the sphere was found to be 10 nm. The cubic spinel structure of prepared ZnFe2O4 nanomaterials was confirmed from the diffraction patterns and the nucleation sites exploited for the composite formation of ZnFe2O4 nanostructures with rGO sheets was explored by using FT-IR spectroscopy. The catalytic efficiency of prepared nanostructures toward MB dye degradation in the presence of H2O2 was evaluated in detail, in which rGO/ZnFe2O4 composite exhibited the remarkable catalytic activity toward MB degradation. The complete MB degradation observed at rGO/ZnFe2O4 composite is attributed to the π–π interaction, hydrogen bonding and electrostatic interaction exerted between the rGO/ZnFe2O4 and MB dye and the involved degradation reaction followed a pseudo-first-order kinetics. Thus, the proposed effort has not only provided a simple approach to synthesize the ZnFe2O4-based composites but has also provided a feasible solution for the effective and economically viable approach for the complete degradation of hazardous organic dye.

Preparation of chitosan nanoparticles by TPP ionic gelation combined with spray drying, and the antibacterial activity of chitosan nanoparticles and a chitosan nanoparticle–amoxicillin complex

Abstract: Chitosan nanoparticles were prepared from chitosan with various molecular weights by tripolyphosphate (TPP) ionic gelation combined with a spray drying method. The morphologies and characteristics of chitosan nanoparticles were determined by TEM, FE-SEM and from their mean sizes and zeta potentials. The effect of chitosan molecular weight (130, 276, 760 and 1200 cPs) and size of spray dryer nozzle (4.0, 5.5 and 7.0 µm) on mean size, size distribution and zeta potential values of chitosan nanoparticles was investigated. The results showed that the mean size of chitosan nanoparticles was in the range of 166–1230 nm and the zeta potential value ranged from 34.9 to 59 mV, depending on the molecular weight of chitosan and size of the spray dryer nozzles. The lower the molecular weight of chitosan, the smaller the size of the chitosan nanoparticles and the higher the zeta potential. A test for the antibacterial activity of chitosan nanoparticles (only) and a chitosan nanoparticle–amoxicillin complex against Streptococcus pneumoniae was also conducted. The results indicated that a smaller chitosan nanoparticle and higher zeta potential showed higher antibacterial activity. The chitosan nanoparticle–amoxicillin complex resulted in improved antibacterial activity as compared to amoxicillin and chitosan nanopaticles alone. Using a chitosan nanoparticle–amoxicillin complex could reduce by three times the dosage of amoxicillin while still completely inhibiting S. pneumoniae.

Activated carbon obtained from sapelli wood sawdust by microwave heating for o -cresol adsorption

Abstract: Activated carbon (AC) was prepared from sapelli wood sawdust using a microwave heating process. The biomass was mixed with inorganic components (lime + ZnCl2 and FeCl3) to form a homogeneous paste. The AC samples are denoted as AC-1A (100 g sapelli wood sawdust + 20 g lime + 80 g ZnCl2), AC-2A (150 g sapelli wood sawdust + 20 g lime + 80 g ZnCl2), AC-1B (100 g sapelli wood sawdust + 20 g lime + 40 g ZnCl2 + 40 g FeCl3), and AC-2B (150 g sapelli wood sawdust + 20 g lime + 40 g ZnCl2 + 40 g FeCl3). The samples were placed in a microwave oven and pyrolyzed under nitrogen flow. To increase their porosity, the pyrolyzed samples were subjected to a leaching process (with 6 mol L−1 HCl) under reflux to eliminate inorganic components. Several analytical techniques such as Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and N2 isotherm and vapor adsorption analyses were performed to characterize the AC materials. The samples presented high Brunauer–Emmett–Teller (BET) surface areas, up to 941.08 m2 g−1 for AC-1A. The AC materials were tested for their o-cresol removal ability by determining the best fits to equilibrium and kinetic data using the Sips isotherm and fractional-order model, respectively. The maximum adsorption capacity of the AC samples as obtained from the Sips model was correlated with the surface area. The proposed adsorption mechanism suggests that hydrogen bonding, donor–acceptor complexation, and π–π interactions play key roles. The adsorbents were also tested for treatment of simulated industrial effluents, showing very good efficiency. Almost complete regeneration of the AC adsorbents was achieved using 10 % EtOH + 5 mol L−1 NaOH as eluent. These results demonstrate that sapelli wood sawdust is a promising precursor for preparation of AC to remove o-cresol from aqueous solution.

Synthesis and characterization of Zinc Oxide nanoparticles using marine Streptomyces sp. with its investigations on anticancer and antibacterial activity

Abstract: Synthesis of zinc oxide nanoparticles (ZnONPs) by an ecological approach using Streptomyces sp. as reducing agent is reported. ZnONPs were synthesized from aqueous zinc chloride solution by cell-free supernatant of a novel isolate. Hyperchromic shift was observed at 364 nm using UV–visible spectroscopy and also by the naked eye as a color change from dark green to milk white. Evidence for proteins acting as reducing and capping agent was obtained by Fourier-transform infrared spectroscopy. From the X-Ray diffraction studies, the lattice planes and obtained peak positions confirmed the hexagonal close-packed crystalline structure of ZnONPs. Surface topographical studies revealed that the biosynthesized ZnONPs had spherical shape with mean diameter of about 20–50 nm. Transmission electron microscopy revealed that the nanoparticles had spherical structure with uniform distribution along the surface. The anticancer activity of the synthesized nanoparticles was evaluated against A549 lung cancer cells, and their antibacterial activity against Escherichia coli and Bacillus subtilis was analyzed and reported.

Recent developments in chemistry, coordination, structure and biological aspects of 1-(acyl/aroyl)-3-(substituted) thioureas

Abstract: 1-(Acyl/aroyl)-3-(substituted)thioureas are privileged architectures that have received remarkable attention of researchers in view of their variable topological aspects, binding modes and broad spectrum promising pharmacological properties. Reactivity of acyl thiourea derivatives has presented various organic transformations into other demanding scaffolds and this is an attractive strategy for synthetic chemists to access heterocyclic cores. Multiple binding sites make them flexible ligands for complexation with transition metals thus occupying a distinct position in coordination chemistry. 1-(Acyl/aroyl)-3-(substituted)thioureas have also emerged as attractive candidates in various fields such as ion sensors, corrosion inhibitors, molecular electronics, in metal extraction and in pharmaceuticals. The medicinal chemistry of this organo-sulfur framework and the derived metal complexes has witnessed fantastic progress in the current era. In continuation of our efforts to compile data on the structural aspects and numerous applications of 1-(acyl/aroyl)-3-(substituted)thiourea analogs, continuous advances have prompted us to present an overview of the last 2 years literature on this exciting family of compounds through this review article.

New advances strategies for surface functionalization of iron oxide magnetic nano particles (IONPs)

Abstract: Over the past two of decades, iron oxide nanoparticles (IONPs) have attracted significant attention for a wide range of biomedical applications. For the successful use of IONPs in nano-biotechnology, surface coating and specific functionalization is critical. Many types of materials can be used in the surface coating of IONPs for nano-bio applications, including organic compounds and inorganic materials. This review focuses on recent developments and various strategies for surface coating of IONPs. In addition, the different materials used for the functionalization of IONPs are classified and discussed in detail. The design of IONPs with multifunctional coatings for bio-applications is an area of considerable interest. Surface functionalization of IONPs allows them to attach to various biomolecules, making them a promising candidate for bio-applications.

A novel magnetically recyclable silver-loaded cellulose-based bionanocomposite catalyst for green synthesis of tetrazolo[1,5-a]pyrimidines

Abstract: 5-Methyl-7-aryl-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylic ester derivatives were efficiently synthesized by reaction of methyl or ethyl acetoacetate, 5-aminotetrazole (produced from 2-cyanoguanidine and sodium azide), and various aromatic aldehydes in presence of a new cellulose-based Ag-loaded magnetic bionanostructure. This protocol offers many advantages such as short reaction time, high yield, the remarkable magnetic property of the nanocomposite, and easy separation of the nanocatalyst from the reaction mixture without considerable loss of catalytic activity. Furthermore, X-ray diffraction analysis, field-emission scanning electron microscopy, and energy-dispersive X-ray (EDX) analysis were used to characterize the prepared nanocatalyst.

Five-component domino synthesis of tetrahydropyridines using hexagonal PbCr x Fe 12− x O 19 as efficient magnetic nanocatalyst

Abstract: Hexagonal PbCr x Fe12−x O19 nanostructures were prepared through a sol–gel autocombustion (SGAC) method using malonic acid as fuel Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, and vibrating-sample magnetometry were used as tools to study the structure, morphology, and composition of the nanostructures The optimal product was further evaluated as a reusable magnetic catalyst in a five-component reaction for synthesis of highly functionalized tetrahydropyridines (HF-THP) All reactions completed in short time and all products were obtained in good yield in presence of the magnetic nanocatalyst Besides, it was found that PbCr x Fe12−x O19 could be recovered five times, without any noticeable loss in catalytic activity

Heteropolyacid supported on amine-functionalized halloysite nano clay as an efficient catalyst for the synthesis of pyrazolopyranopyrimidines via four-component domino reaction

Abstract: An efficient heterogeneous hybrid catalyst was developed by functionalization of halloysite clay nanotubes by γ-aminopropyltriethoxysilane and then immobilization of a Keggin type heteropolyacid, phosphotungstic acid. This hybrid catalyst was characterized by SEM/EDX, FTIR and XRD and its catalytic activity for the synthesis of pyrazolopyranopyrimidine derivatives via four-component domino reaction of barbituric acid, hydrazine hydrate, ethyl acetoacetate and benzaldehyde was investigated. The results indicated that the hybrid system can promote the reaction to afford the desired products in high yields and short reaction times. The superior catalytic activity of this system was confirmed when compared with those reported, previously. Moreover, this novel heterogeneous catalyst was found to be easily separable and recyclable. It was re-used at least three times with negligible loss of activity. Significantly, this protocol can be extended to nonconventional green heating sources such as microwave and ultrasonic irradiations.

Evaluation of photocatalytic activity, antibacterial and cytotoxic effects of green synthesized ZnO nanoparticles by Sechium edule leaf extract

Abstract: Recently, green synthesized nanoparticles have been appearing as a most effective activity in antibacterial and anticancer studies probably because of their faster synthesis rate, remarkable biocompatibility and non-toxicity to healthy cells. In the present study, temperature-dependent eco-friendly synthesis of zinc oxide nanoparticles (ZnO NPs) using Sechium edule leaf extract was performed, characterized by spectroscopic techniques, and electron microscopy studies confirm that 400 °C was favorable for the formation of ZnO NPs. The optical absorption spectra (UV–visible spectroscopy) of ZnO NPs appeared as an intense band at 362 nm and transmission electron microscopy results revealed that the spherical-shaped nanoparticles average range was found to be 36.2 nm and the zeta potential was −19.5 mV. Furthermore, compared with chemically synthesized ZnO NPs, the biosynthesized ZnO NPs were significant owing to their photocatalytic activity towards the degradation of reactive blue 160, and they also showed significant cytotoxicity to MCF-7 breast cancer cells (IC50 ~3.5 µg/mL). Finally, biosynthesized ZnO NPs can be used as prospective antibacterial agents on Bacillus subtilis and Klebsiella pneumoniae. Thus, biosynthesized ZnO NPs could potentially be used as an excellent therapeutic agent in the medical field.

Synthesis and therapeutic potential of quinoline derivatives

Abstract: Quinolines are nitrogen-containing bicyclic compounds that are widely found throughout Nature in various forms. Quinoline derivatives are utilized in the areas of medicine, food, catalysts, dyes, materials, refineries, electronics, etc. The quinoline nucleus is present in numerous biological compounds, e.g., antimalarial, antimicrobial, antimycobacterial, antidepressant, anticonvulsant, antiviral, anticancer, antihypertensive, platelet-derived growth factor (PDGF) receptor tyrosine kinase (RTK) inhibitory, antiinflammatory, antioxidant, and anti-human immunodeficiency virus (HIV) agents. However, owing to the swift development of new molecules containing this nucleus, many research reports have been generated in a brief span of time. There therefore seems to be a requirement to collect recent information in order to understand the current status of the quinoline nucleus in medicinal chemistry research, focusing in particular on the numerous attempts to synthesize and investigate new structural prototypes with more effective antimalarial, antimicrobial, and anticancer activity.

Evaluation of poly ε-caprolactone electrospun nanofibers loaded with Hypericum perforatum extract as a wound dressing

Abstract: In this study, for the first time, a biocompatible and non-toxic herbal wound dressing was made by encapsulation of Hypericum perforatum alcoholic extract at different concentrations (10, 30 and 50 % v/v) into poly e-caprolactone electrospun nanofibers to achieve an effective wound dressing. The electrospinning processing parameters such as needle tip to collector distance, applied voltage and flow rate of feed solution were changed until accumulated nano-scale fibers without bead structures were obtained. Then, the morphology of the nanofibrous structures was investigated by scanning electron microscopy. After synthesis of the nanofibers in optimal conditions, the antibacterial activity of the optimized bandages was investigated by the disc diffusion method against strains of Staphylococcus aureus and Escherichia coli. The release content of the herbal drug was tested by the total immersion method in phosphate buffer saline and displayed a constant drug liberation with time. Water vapor transmission rate for the wound dressing was evaluated by pseudo-extra cellular fluid for optimal samples. The crystallinity and thermal behavior of the mats with and without H. perforatum alcoholic extract were studied by X-ray diffraction and differential scanning calorimetry. The results of antibacterial activity, cell culture and In vitro methyl thiazolyl tetrazolium assays demonstrated these unique structures as being very useful as burn and ulcer dressings.

Visible light-induced degradation of phenolic compounds by Sudan black dye sensitized TiO2 nanoparticles as an advanced photocatalytic material

Abstract: Using a simple impregnation process, the present study has introduced a novel route for the photosensitization of TiO2 nanoparticles using Sudan black B dye as a sensitizer. DRS, XRD, FE-SEM, BET, UV–Vis, FT-IR and TGA–DSC analyses were considered for characterization of the synthesized purple powder as a visible light photocatalyst for removal of the phenolic pollutant. The band gap of the dye-sensitized TiO2 and corresponding BET surface area were 2.9 eV and 50.0 m2 g−1, respectively. Based on the results, Sudan Black sensitized TiO2 photocatalyst outperforms the pure commercial TiO2 (Degussa P25) in terms of phenol degradation under visible light. Under a 100-min photo-catalytic experiment, dye-sensitized TiO2 removed 96 % of the phenol content. The Sudan black B dye-sensitized TiO2 is expected to show further interesting physical characteristics related to potential uses.

Magnetic materials and water treatments for a sustainable future

Abstract: After a brief historical classification of the main discoveries related to magnetism, magnetic materials have been rationally ordered in a simple (and hopefully clear) organization. A great effort was realized in the description of the different synthetic approaches for the preparation of magnet-sensitive materials (in particular, focusing on iron oxides). The principal useful techniques for evaluating the magnetic properties in materials (namely, MFM and magnetization hysteresis) have been presented, providing useful examples in order to understand both the potentiality and limits of these characterization methods. Finally, the application of magnet-sensitive materials in water remediation processes has been provided, highlighting both advantages and disadvantages of their use compared to conventional treatments. In this context, the action mechanism and the possible integration of this class of materials into processes involving wastewater treatments are widely discussed, keeping an eye toward the future perspectives.

Green and efficient synthesis of acridine-1,8-diones and hexahydroquinolines via a KH2PO4 catalyzed Hantzsch-type reaction in aqueous ethanol

Abstract: A simple, clean, and economical methodology for the synthesis of acridine-1,8-dione and hexahydroquinoline derivatives via Hantzsch-type condensation has been described. This study highlights the development of a new green pathway for the preparation of substituted 1,4-dihydropyridines derivatives. The mild, cheap, and nontoxic potassium dihydrogen phosphate (KH2PO4) is proved to be an efficient catalyst for the above multi-component reaction to get excellent yields. Widely available and mostly benign catalyst, eco-friendly solvent, and easy purification are among the several attractive features.

Cobalt-doped BiVO 4 (Co-BiVO 4 ) as a visible-light-driven photocatalyst for the degradation of malachite green and inactivation of harmful microorganisms in wastewater

Abstract: Co-doped BiVO4, a visible-light-responsive photocatalytic semiconductor, was synthesized using a microwave hydrothermal method. The doped sample exhibited much higher photocatalytic activity for malachite green degradation under visible light irradiation than undoped BiVO4. Similarly, improved inactivation efficiency toward Escherichia coli and Chlamydomonas pulsatilla (green tide) were observed with Co-doped BiVO4. The degradation of malachite green by Co-doped BiVO4 reaches 99% within 90 min irradiation to visible light. Similarly, the inactivation of Escherichia coli reaches 81.3% in 5 h and Chlamydomonas pulsatilla reaches 65.6% in 1 h irradiation to visible light. The enhanced photoactivity is believed to be due to the increment of the visible light absorption range by narrowing the band gap energy. In addition, the highly exposed reactive (010) facets can efficiently capture the photoinduced electrons, promote charge separation, and reduce recombination probability. Thus, these findings provide mechanistic insight into the effectiveness of Co-doped BiVO4 semiconductors for the treatment of wastewater that contains industrial effluents and microorganisms.

Comparison between preparative methodologies of nanostructured carbon nitride and their use as selective photocatalysts in water suspension

Abstract: Carbon nitride photocatalysts have been prepared by different methodologies, such as chemical ultrasonic irradiation (sonochemical treatment), hydrothermal and ball milling and thermoexfoliation, and have been used for the selective oxidation of 5-hydroxymethyl-2-furaldehyde (HMF) to form 2,5-furandicarboxyaldehyde (FDC) in water suspension both under UV and natural solar irradiation. The physico-chemical features of the photocatalysts have been studied by X-ray diffraction, infrared spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, scanning electron microscopy, and specific surface area measurements. The results indicate that exfoliation of carbon nitrides can increase the conversion of HMF and the selectivity to FDC. In particular, samples exfoliated by both thermal and acidic ultrasonic irradiation treatments showed the best photocatalytic performance.

Degradation kinetics of pollutants present in a simulated wastewater matrix using UV/TiO2 photocatalysis and its microbiological toxicity assessment

Abstract: Water pollution is one of the major concerns over long-term sustainability of the environment. Effective and efficient treatment of polluted wastewater is still a serious challenge for global researchers. In the last 2–3 decades, due to the incessant emergence of micropollutants in surface and ground water bodies, several endeavors have been made to resolve the water pollution issues either through chemical, physical and biological degradation processes or through removal/separation processes using different adsorbents and membranes. It has been found that most of the studies are mainly limited to single or binary pollutant analysis in a pure water matrix. Therefore, in this novel investigation, a mixture of five different pollutants has been studied for UV/TiO2-based photocatalytic degradation. In the present study, a commercially available TiO2, an antibiotic, i.e. Ciprofloxacin and four different synthetic dyes, i.e. Rhodamine B, Methylene Blue, Methyl Orange and Amaranth have been used as a photocatalyst, a pharmaceutical and various industrial dyes, respectively, in a batch photocatalytic reactor system with a stirrer. It is important to note that the commercial TiO2 photocatalyst has also been characterized with the help of several characterization techniques. The present study is mainly focused on the degradation of different micropollutants present in the simulated wastewater matrix and their individual degradation kinetics. It is interesting to observe that MB and RhB have shown the maximum degradation followed by CIP (96.21, 96.15 and 89.62%, respectively). In addition, a microbiological assay has also been performed to check the toxicity variation in the degraded products. It is quite interesting to observe that the simulated wastewater matrix has completely lost its microbial toxicity within 120 min of UV/TiO2-based photocatalytic treatment. Finally, total organic carbon evaluations of various treated samples have also been performed and the obtained results substantiate the theory of assimilable organic carbon.

Synthesis and characterization of tribenzyl ammonium-tribromide supported on magnetic Fe3O4 nanoparticles: a robust magnetically recoverable catalyst for the oxidative coupling of thiols and oxidation of sulfides

Abstract: Taking into account the principles of green chemistry, magnetic nanoparticles, especially Fe3O4 nanoparticles, open up a new chapter in modern organic synthesis to inset a fascinating, stupendous and efficient catalytic strategy for facilitating catalyst recovery in various chemical reactions. Inspired by this topic, tribenzyl ammonium-tribromide immobilized on magnetic nanoparticles (Fe3O4–TBA-Br3) as a bromine source was successfully synthesized and its catalytic activity in the oxidative coupling of thiols and oxidation of sulfides was investigated. It is the first report on the use of the immobilized bromine source on Fe3O4 nanoparticles as a nanomagnetic recyclable catalyst for the oxidative coupling of thiols. The nanosolid catalyst could be easily recovered by a simple magnetic separation and reused for several cycles without significant degradation in catalytic activity.

Cyclodextrin nanosponges: a potential catalyst and catalyst support for synthesis of xanthenes

Abstract: The nanoporous framework of a cyclodextrin nanosponge was used as catalyst for accelerating the one-pot, three-component reaction of dimedone, aldehyde, and phenols for synthesis of xanthene derivatives. Moreover, the nanocavities of cyclodextrin nanosponges were exploited for immobilization of heteropolyacids through the wet impregnation method. This catalyst exhibited superior catalytic performance compared to the bare cyclodextrin nanosponge. Despite the good catalytic activity, the leaching of the catalytic species did not allow efficient recovery and reusability. To circumvent this problem, the cyclodextrin nanosponge was amine-functionalized prior to heteropolyacid immobilization. The results proved that the amine functionalities had an effective role in preserving the catalytic species and improving the reusability through decreasing the leaching time. This catalyst was used for synthesis of a variety of xanthenes in aqueous media. The catalytic amount of catalyst afforded the desired product in excellent yields and with a relatively short reaction time. The results suggested cyclodextrin nanosponge-based catalysts as potential candidates for promoting chemical reactions.

Synthesis of nZVI@reduced graphene oxide: an efficient catalyst for degradation of 1,1,1-trichloroethane (TCA) in percarbonate system

Abstract: Graphene-oxide-supported nano zero-valent iron (nZVI) composite (nZVI–rGO) was synthesized and tested as an efficient percarbonate activator for degradation of 1,1,1-trichloroethane (TCA). Significant dispersion of nZVI on the surface of reduced graphene oxide (rGO) was observed, with good limitation of nanoparticle agglomeration and aggregation. Good TCA degradation efficiency of 90% was achieved in 2.5 h in presence of 0.8 g/l nZVI–rGO catalyst and 30 mM sodium percarbonate (SPC) oxidant; however, excessive catalyst or oxidant concentration reduced the degradation efficiency. Investigation of reactive oxygen species using radical probe compounds as well as radical scavengers confirmed presence of hydroxyl (OH·) and superoxide ( $${\text{O}}_{2}^{\cdot - }$$ ) radicals that are responsible for the TCA degradation. The morphology and surface characteristics of the heterogeneous catalyst were analyzed by transmission electron microscopy and scanning electron microscopy. Brunauer–Emmett–Teller analysis revealed that the synthesized catalyst had large surface area and small particle size of 299.12 m2/g and 20.10 nm, respectively, compared with 5.33 m2/g and 1.12 µm for bare graphene oxide. X-ray diffraction analysis revealed good dispersion of nZVI on the surface of rGO. Fourier-transform infrared characteristic peaks confirmed strong attachment of Fe onto the rGO surface. Energy-dispersive spectroscopy analysis validated the stoichiometric composition of the prepared Fe/rGO material. In conclusion, use of nZVI–rGO-activated SPC could represent an alternative technique for remediation of TCA-contaminated groundwater.

Recent progress in insertion and cyclopropanation reactions of metal carbenoids from α-diazocarbonyl compounds

Abstract: Metal–carbenoids from α-diazocarbonyl compounds are well-known reactive intermediates with a long history of useful applications in synthetic organic chemistry. The carbenoids, generated in situ from the catalytic decomposition of α-diazocarbonyls, react by different pathways such as insertions, cyclopropane formation, and cycloadditions of ylides, etc. in inter- and intramolecular versions of the reactions. These reactions have been employed in the architecture of several complex molecules of natural origin. The present review paper discusses the recent progress in catalytic insertion (X–H: X = C, N, O, S, Si, and B), and cyclopropane-forming reactions of α-diazocarbonyl compounds with a focus on regio-, diastereo-, and enantioselective reactions.

Using magnetized water as a solvent for a green, catalyst-free, and efficient protocol for the synthesis of pyrano[2,3-c]pyrazoles and pyrano[4′,3′:5,6]pyrazolo [2,3-d]pyrimidines

Abstract: A facile, eco-friendly, and highly efficient one-pot four-component protocol is demonstrated for the synthesis of the pyrano[2,3-c]pyrazole and pyrano[4′,3′:5,6]pyrazolo [2,3-d]pyrimidine derivatives using magnetized water as a new green solvent. Simplicity, short reaction time, high yield, easy work-up, and absence of hazardous organic solvents are the main advantages of this method .

Degradation of trichloroethylene in aqueous solution by persulfate activated with Fe(III)–EDDS complex

Abstract: In this study, an environmentally friendly complexing agent, S,S′-ethylenediamine-N,N′-disuccinic acid (EDDS), was applied in Fe(III)-mediated activation of persulfate (PS), and the degradation performance of trichloroethylene (TCE) was investigated. The effects of PS concentration, Fe(III)/EDDS molar ratio, and inorganic anions on TCE degradation were evaluated, and the generated reactive oxygen species responsible for TCE removal were identified. The results showed that nearly complete TCE degradation was achieved with PS of 15.0 mM and a molar ratio of Fe(III)/EDDS of 4:1. An increase in PS concentration or Fe(III)/EDDS molar ratio to a certain value resulted in enhanced TCE degradation. All of the anions (Cl−, HCO3 −, SO4 2−, and NO 3 − ) at tested concentrations had negative effects on TCE removal. In addition, investigations using radical probe compounds and radical scavengers revealed that sulfate radicals (SO 4 ·− ), hydroxyl radicals (·OH), and superoxide radical anions (O 2 ·− ) were all generated in the Fe(III)–EDDS/PS system, and ·OH was the primary radical responsible for TCE degradation. In conclusion, the Fe(III)–EDDS-activated PS process is a promising technique for TCE-contaminated groundwater remediation.

Eco-friendly highly efficient solvent free synthesis of benzimidazole derivatives over sulfonic acid functionalized graphene oxide in ambient condition

Abstract: Sulfonated graphene oxide (GO-HSO3) heterogeneous catalyst was prepared at molecular level and characterized by using various modern analytic and spectroscopic methods. Using prepared heterogeneous catalyst GO-HSO3, benzimidazole synthesis was carried out by means of reacting diamine and aldehyde at room temperature in solvent free condition. The catalyst GO-HSO3 showed tremendous catalytic activity in selective synthesis of benzimidazole, as a result 100 % conversion of reactants and up to 89.0 % yield of respective benzimidazole was achieved using 0.1 mg of catalyst in very short reaction duration. The GO-HSO3 catalyst was separated from the reaction mixture by simple filtration process at the end of reaction and reused for six successive cycles without noteworthy loss of catalytic activity and selectivity. Key advantageous of this protocol is high yield, low cost, and easy work-up procedure as well as short reaction time and solvent free condition. The present method is found eco-friendly, highly efficient, solvent free, high yielding, and clean method for the synthesis benzimidazole derivatives at room temperature.

Electroactive nanostructured scaffold produced by controlled deposition of PPy on electrospun PCL fibres

Abstract: The electrical conductivity of biodegradable polymeric scaffolds has shown promising results in tissue engineering, particularly for electrically excitable tissues such as muscles and nerves. Herein, we demonstrate a novel processing approach to produce electroactive nanofibres. Electrically conducting, robust nanofibres comprising both a biodegradable component using poly(e-caprolactone) (PCL) and a conducting component, polypyrrole (PPy), have been produced by electrospinning and vapour phase polymerization. The PCL/PPy nanofibres were characterised in terms of morphology, electrical conductivity, and dimensional stability. The as-prepared nanofibres were found to be cytocompatible with good electrical conductivity and mechanical properties. It was found that electrical conductivity of the PPy coated PCL nanofibre was 1.9 S/cm, which is much higher than that of PCL mixed with PPy in other studies. Cell viability on the scaffolds were firstly examined by in vitro culturing the L929 fibroblast cells for 24 h, revealing viability of 97.6 ± 2.7 %. Then PC12 cells differentiation observed by neurite outgrowth which occurred after 4 days of culture on the scaffolds. Significantly larger areas of the PPy coated PCL were covered by cells compared to PCL without coating. The obtained results from filament staining suggested the high potentials of the conducting scaffold for use in neural tissue engineering.

The facile synthesis of graphitic carbon nitride from amino acid and urea for photocatalytic H2 production

Abstract: We report on the facile synthesis of g-C3N4 based polymers by co-condensing urea with glycine for photocatalytic hydrogen evolution. The as-prepared photocatalysts were then characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence emission spectrometry, electron paramagnetic resonance spectrometry and transmission electron microscopy. Compared with pristine g-C3N4, obtained from direct pyrolysis of urea, the CNU-G5 photocatalyst showed largely enhanced photocatalytic H2 activities about 75 μmol h−1, which is 5 times higher than of the pristine CNU. The enhanced activities are ascribed to the larger specific area surface, strengthened optical absorption and improved electron transport ability. Our work opens up a new pathway for the synthesis graphitic carbon nitride photocatalysts with glycine modification to enhance photocatalytic activities.