Showing papers in "Research on Chemical Intermediates in 2019"

Design and tailoring of one-dimensional ZnO nanomaterials for photocatalytic degradation of organic dyes: a review

Abstract: Photocatalysis using semiconductors has emerged as a promising wastewater treatment process to overcome the major challenges faced by conventional technologies. The advantages of ZnO nanomaterials over other semiconductors, and their structure-dependent properties, make them important building blocks in nanotechnology as multifunctional materials. Moreover, it has been confirmed that ZnO nanomaterials can exhibit high performance in photodegradation of organic dyes for treatment of industrial effluent. The wurtzite structure of ZnO contains polar and nonpolar planes; the low surface energy and thermodynamic stability of the nonpolar planes enable formation of one-dimensional (1D) ZnO structures, which are desirable compared with zero-dimensional (0D) and two-dimensional (2D) nanoarchitectures. Also, relative to other forms, the superiority of 1D ZnO nanostructures in dye photodegradation makes them promising as a future research direction and for commercial use. Therefore, understanding the design and synthesis of 1D ZnO nanomaterials is of critical importance for the development of novel and high-performance photocatalysts. Rational design of 1D ZnO nanophotocatalysts is thus required to enhance their photodegradation activity via efficient separation of charge carriers, increased surface-to-volume ratio, enhanced light absorption capacity, and improved stability/reusability. We briefly describe herein the most widely applied synthesis methods, including vapor-phase and solution-based strategies, to understand different methods for tailoring 1D ZnO nanophotocatalysts. Moreover, to elucidate the effect of their physical/chemical properties on the photodegradation efficiency, all the modification methods are categorized into four different approaches, viz. (1) morphology control, (2) induction of defects, (3) modulation by doping, and (4) formation of hybrids and heterojunctions. An overview of all aspects of charge generation, separation, and transfer during dye photodegradation by engineered 1D ZnO nanomaterials is also provided.

Graphene based emergent nanolights: a short review on the synthesis, properties and application

Abstract: Graphene oxide (or graphene) derived graphene quantum dots (GQDs) are the primary building blocks for nano-devices because of their superior electronic, thermal, optical and toughening (in matrix) characteristics. There are various methods to prepare GQDs where “top-down” method has been practiced widely. This is a size reduction technique from micrometer sized graphene sheets to nanometer sized (< 10 nm) quantum particles with well-confined shape and quantum confinement effect. GQDs are emerging as promising optical materials for biological applications. This review will project the detailed “top-down” method; rather such as molecular scissoring of graphene sheets to quantum dots, optical characteristics and applications.

Synthesis and characterization of spinel FeAl2O4 (hercynite) magnetic nanoparticles and their application in multicomponent reactions

Abstract: The spinel ferrite FeAl2O4 (hercynite) MNPs (magnetic nanoparticles) were applied as a reusable catalytic system for the one-pot synthesis of benzo[a]pyrano[2,3-c] phenazine and polyhydroquinoline derivatives via a multicomponent reaction under green reaction conditions. The structure of the prepared nanocatalyst has been characterized by XRD, FTIR, SEM, EDS, BET, and VSM techniques. The FeAl2O4 MNPs act as Lewis acids and offer several advantages such as high yields of products, short reaction times, and easy workup procedure. Moreover, the recycled nanocatalyst was used at least four times without significant loss of its activity.

Preparation of NPK nanofertilizer based on chitosan nanoparticles and its effect on biophysical characteristics and growth of coffee in green house

Abstract: NPK nanofertilizer was prepared by loading nitrogen (N), phosphorous (P) and potassium (K) into chitosan nanoparticles. The chitosan nanoparticles were prepared via ionic gelation of tripolyphosphate and chitosan solution. The chitosan nanoparticles were characterized by SEM, TEM, zeta potential and size distribution. The results showed that size distribution was from 300 to 750 nm and zeta potential of around 50 mV. The released kinetics of nitrogen, phosphorous and potassium in nanofertilizer were also investigated for 240 h. The nanofertilizer was applied to coffee seedlings in a greenhouse condition. The results showed that the nanofertilizer enhanced uptake of nutrients, photosynthesis and growth of coffee plants. Application of the nanofertilizer improved 17.04% nitrogen, 16.31% phosphorous and 67.50% potassium content in the leaves of treated plots compared to the control; total chlorophyll content increased up to 30.68% and 71.7% of photosynthesis net rate. Application of nanofertilizer also enhanced leaf number, plant height and leaf area of the coffee seedlings. Using the nanofertilizer may be a potential way to enhance use efficiency of fertilizers for coffee.

Facile synthesis of monodispersed Pd nanocatalysts decorated on graphene oxide for reduction of nitroaromatics in aqueous solution

Abstract: We synthesized the reproducible heterogeneous catalyst of graphene oxide (GO)-supported palladium nanoparticles (NPs) via a simple and green process. The structure, morphology and physicochemical properties of the synthesized heterogeneous catalyst were characterized by the latest techniques such as high-resolution transmission electron microscopy (TEM), scanning TEM, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. The GO-supported Pd NPs (Pd/GO nanocatalyst) exhibited excellent catalytic activity for the reduction of nitroaromatics to aminoaromatics in aqueous sodium borohydride. The nitroaromatics were converted to corresponding aminoaromatics with high yields (up to 99%) using Pd/GO nanocatalyst in aqueous solution. The hybrid heterogeneous catalyst showed 83% of conversion after six cycles in the reduction of nitrobenzene to aminobenzene. These features ensured the high catalytic activity of the introduced graphene oxide supported Pd nanocatalysts.

Surfactant for better tomorrow: applied aspect of surfactant aggregates from laboratory to industry

Abstract: Surfactant is a special kind of amphiphilic compound composed of water-loving and hating parts. The remarkable physical properties like interfacial tension, wettability, emulsifying and dispersing ability make the surfactant accessible for numerous applications from laboratory to commercial products. In recent years, the commercial applications of surfactant have led to greater relevance on account of the environmental concerns and market pressures of this compound. The utility of surfactants in global market increases steadily since its formulation with several beneficial aspects in pharmaceutical, detergent, cosmetic, paint, food science, gas hydrate, nanotechnology, petroleum recovery, bioremediation, chemical transformation and drug delivery. This review briefly discusses the applied aspect of surfactants in diverse area as well as catalytic effect of micelle in organic reactions from the recent literature survey. The trend of increasing use of bioderived surfactants in the modern field of research is also considered in this report. The recent advancement of surfactant-based organic transformations has been emphasized with the role of surfactant aggregates in course of different organic reactions.

Synthesis of zinc oxide nanoparticles (ZnO NPs) using pure bioflavonoid rutin and their biomedical applications: antibacterial, antioxidant and cytotoxic activities

Abstract: The present study reports an eco-friendly green synthesis of zinc oxide nanoparticles (ZnO NPs) using the bioflavonoid rutin. The synthesized ZnO NPs were characterized by UV–visible spectroscopy, XRD, FE-SEM, EDX, FTIR and zeta potential analyses. FE-SEM image showed that the synthesized ZnO NPs were rod shaped. FTIR spectral studies confirmed the role of bioflavonoid rutin for the reduction, capping and synthesis of ZnO NPs. The green synthesized ZnO NPs showed significant antibacterial activity against both Gram-positive (B. subtilis and S. aureus) and Gram-negative (K. pneumoniae and E. coli) bacterial pathogens. However, the synthesized ZnO NPs were more effective against Gram-negative bacteria compared to Gram-positive bacteria. The in vitro antioxidant ability of ZnO NPs was investigated spectrophotometrically using DPPH and H2O2 assay. The percentage of antioxidant activity increased with increasing concentration of ZnO NPs. Furthermore, synthesized ZnO NPs showed effectiveness in inhibiting the human MCF-7 breast cancer cells. In conclusion, the synthesized ZnO NPs using bioflavonoid rutin might be used as a strong biocidal and antioxidant agent in biomedical and pharmaceutical industries.

Green synthesis of silver nanoparticles using Piper longum catkin extract irradiated by sunlight: antibacterial and catalytic activity

Abstract: In this study, rapid and cost-effective biosynthesis of silver nanoparticles (AgNPs) was synthesized by using Piper longum (P. longum) catkin extract. The bioreduction of AgNPs was initially confirmed by using UV–visible spectroscopy which exhibits characteristic absorption peak at 450 nm in 120 s when exposed to sunlight. The phytoconstituents responsible for the reduction of AgNO3 to Ag NPs were examined using Fourier transform infrared spectroscopy. The crystalline nature of Ag NPs was confirmed using the X-ray diffraction pattern. Morphological studies confirmed the synthesized Ag NPs were monodispersed and spherical in shape with the size ranging from 15 to 40 nm. The zeta potential analysis of the synthesized AgNPs exhibit negative value (− 24.3 mV), which indicates higher stability. Further, the proficiency of the synthesized AgNPs was evaluated against mastitis-causing bacteria. Hence, the Ag NPs showed the maximum zone of inhibition against Staphylococcus aureus (12.45 mm), Pseudomonas aeruginosa (12.34 mm), and Bacillus subtilis (9.75 mm). In addition, the catalytic efficiency of Ag NPs was investigated for the conversion of methyl orange to hydrazine derivatives, methylene blue to leuco methylene blue, and o-nitrophenol to o-aminophenol in 4, 5 and 3 min, respectively. Hence, this study explores the doctrine of green chemistry for the rapid production of AgNPs that act as a potential candidate to alleviate mastitis-causing bacteria and clear up diverse environmental problems.

Characterization of the structural changes of human serum albumin upon interaction with single-walled and multi-walled carbon nanotubes: spectroscopic and molecular modeling approaches

Abstract: Through the incorporation of spectorescopic and molecular methods of modeling, the researchers investigated the interaction between Carbon Nanotubes (CNTs) and Human Serum Albumin (HSA). Fluorescence spectroscopy revealed the ability in both single-wall and multi-wall CNTs to quench the spectrum through a static quenching procedure obtained from the Stern–Volmer quenching constant (Ksv) at three different temperatures. The Ksv values of HSA–CNTs complexes were 1.96 × 105 M−1 and 2.44 × 105 M−1 that showed two different behaviors of interaction between HSA and CNTs. The Van’t Hoff equation was used to calculate thermodynamic parameters of Gibbs free energy (ΔG°), entropy (ΔS°) and enthalpy changes (ΔH°). The binding distances (r) between the donor (Trp residue of HSA) and acceptor (CNTs) was measured through the Forster theory of non-radiative energy transfer, and it was found to be less than 7 nm. The conformational changes of protein in the presence of CNTs were revealed through synchronous fluorescence spectra and three-dimensional fluorescence spectra analysis. The experimental results were confirmed through molecular modeling technique. Circular dichroism technique showed the secondary structure changes of HSA upon interaction with CNTs. The complex formation of HSA and CNTs was determined by the measurement of the electric conductivity. The molecular modeling technique determined the binding site of CNTs that were embedded in the subdomain IIIB of HSA. These analyses play a major role in drug delivery and pharmacodynamics studies for better understanding of nanotechnology levels.

Graphene oxide-based zirconium oxide nanocomposite for enhanced visible light-driven photocatalytic activity

Abstract: In the present investigation, an efficient visible light-active, graphene oxide-based zirconium oxide nanocomposite (GO–ZrO2) has been synthesized by co-precipitation method. The synthesized photocatalyst was characterized by XRD, FTIR, FE-SEM, EDS, TEM, TGA, PL, UV-DRS and BET surface area analysis. The characterization results illustrate the homogeneous dispersion of ZrO2 nanoparticles in the GO–ZrO2 nanocomposite with excellent harmony between GO and ZrO2 nanoparticles. The photocatalytic efficiency of the synthesized GO–ZrO2 nanocomposite was evaluated by photodegradation of hazardous, water-soluble rhodamine B and methylene blue dyes under visible light irradiation. The 90% photocatalytic degradation of rhodamine B dye (with initial conc. 30 mg/L) was observed in 105 min of visible light irradiation, while 99.23% of methylene blue (with initial conc. 100 mg/L) dyes degradation was observed in just 60 min using 25 mg/100 ml dose of GO–ZrO2 nanocomposite as a photocatalyst. The mechanistic investigation using scavengers suggest that the superoxide (O 2 ·− ) is the most reactive species involved in the photodegradation of organic dyes. The synthesized photocatalyst GO–ZrO2 nanocomposite also exhibits excellent thermal stability and reusability.

Synthesis of Mn-doped TiO2 by novel route and photocatalytic mineralization/intermediate studies of organic pollutants

Abstract: The doping of TiO2 particles with various manganese (Mn) concentrations (0.25–1.0%) were synthesized using simple sol–gel and modified sol–gel technique. The characteristics of synthesized particles were found employing standard analytical techniques such as X-ray diffraction, scanning electron microscopy and UV–Vis spectroscopy. The photocatalytic activity of the synthesized particles was compared by investigating the mineralization of two selected organic pollutants like ketoprofen and chlorothalonil. The photocatalysts which were produced by improved sol–gel technique show the lower value of band gap energy and small size crystallite and, hence, exhibit better photocatalytic activity. The outcomes also designate that the concentration of dopant Mn 0.75% indicated the highest photocatalytic activity than other concentrations of dopant in the mineralization of both the compounds. The mineralization kinetics of both compounds was studied under various situations like reaction pH and catalyst dosage. The mineralization rates were highly affected by all the above parameters. An effort has also been performed to highlight the intermediates produced during the photooxidation of both the compounds using the GC–MS analysis method. Both compounds show the production of several intermediates. A possible pathway for the production of different products has been suggested.

Biological synthesis of silver nanoparticles in Tribulus terrestris L. extract and evaluation of their photocatalyst, antibacterial, and cytotoxicity effects

Abstract: In recent years, progress of biological synthesis of nanoparticles is inevitable due to its important applications. In this research, a new and simple method for the synthesis of AgNPs from plant extracts is presented. The extract from shoots of the plant Tribulus terrestris L. was mixed with AgNO3 with the aim of biologically synthesizing AgNPs. The biomolecules existing in the extract were accountable for the fast reduction of silver ions (Ag+) to AgNPs. Characterization of biosynthesized AgNPs was performed by UV–Vis, TEM, DLS, and XRD. The AgNPs exhibit a strong peak at 434 nm, and sphere-shaped AgNPs were found to be ~ 25 nm. The biosynthesized silver nanoparticles have demonstrated high antibacterial effect against pathogenic bacteria (i.e., Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa). In addition, the in vitro cytotoxicity effect of biosynthesized silver nanoparticles was also investigated and was detected to be up to 15.62 μg/mL in the treated Neuro2A cells. The plant-mediated biosynthesis of AgNPs has comparatively rapid, eco-friendly, inexpensive and wide-ranging application in modern medicine and the food industry.

Magnetic Fe3O4-supported sulfonic acid-functionalized graphene oxide (Fe3O4@GO-naphthalene-SO3H): a novel and recyclable nanocatalyst for green one-pot synthesis of 5-oxo-dihydropyrano[3,2-c]chromenes and 2-amino-3-cyano-1,4,5,6-tetrahydropyrano[3,2-c]quinolin-5-ones

Abstract: Synthesis of a novel magnetic 1-naphthalenesulfonic acid-grafted graphene oxide (Fe3O4-GO-naphthalene-SO3H) via a three-step procedure has been described. The structure of this newly synthesized nanographene oxide was fully characterized by X-ray diffraction, energy dispersive X‐ray, vibrating sample magnetometer, scanning electron microscopy, Fourier-transform infrared, Raman spectroscopy, and thermo-gravimetric analytical techniques. The catalytic efficiency of these nanoparticles as recyclable nanocatalyst was explored in one-pot three-component reaction between aldehydes, malononitrile, and 4-hydroxyquinolin-2(1H)-one or 4-hydroxycoumarin under green conditions in water for the synthesis of 2-amino-3-cyano-1,4,5,6-tetrahydropyrano[3,2-c]quinolin-5-ones and 5-oxo-dihydropyrano[3,2-c]chromenes (coumarins) respectively. High yields of the products, low reaction times, easy preparation of the catalyst, and use of water as green solvent are the main advantages of this protocol. In addition, the catalyst can be easily separated simply by using a magnet and reused for six fresh runs without significant loss of activity.

Green and convenient protocols for the efficient reduction of nitriles and nitro compounds to corresponding amines with NaBH4 in water catalyzed by magnetically retrievable CuFe2O4 nanoparticles

Abstract: In this study, firstly, CuFe2O4 nanoparticles were prepared by a simple operation. The structure of the mentioned nanoparticles was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, inductively coupled plasma-optical emission spectrometry, vibrating sample magnetometer and also Brunauer–Emmett–Teller and Barrett–Joyner–Halenda analyses. The prepared magnetically copper ferrite nanocomposite was successfully applied as a simple, cost-effective, practicable, and recoverable catalyst on the green, highly efficient, fast, base-free, and ligand-free reduction of nitriles and also on the affordable and eco-friendly reduction of nitro compounds with the broad substrate scope to the corresponding amines with NaBH4 in water at reflux in high to excellent yields.

Phyto-synthesis of silver nanoparticles using aerial extract of Salvia leriifolia Benth and evaluation of their antibacterial and photo-catalytic properties

Abstract: We have synthesized silver nanoparticles (Ag-NPs) via a simple and eco-friendly method through the utilization of aqueous aerial parts of Salvia leriifolia Benth. The formation of Ag-NPs was indicated by varying the observed colors towards dark red. The biosynthesized Ag-NPs were characterized with diverse instrumental tools, e.g., UV–Vis, XRD, FESEM, EDX, TEM, and FTIR. As for the results, Ag-NPs formation using silver nitrate (1.0 mM) led to the development of EMly shaped nanoparticles with a mean diameter of about 12.7 nm. Moreover, the green synthesized Ag-NPs seemed to demonstrate a higher antibacterial activity in opposition to pathogenic bacteria (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa). Maximum inhibition zone belonged to E. coli with 10.5 mm. Also, biosynthesized Ag-NPs seem to contain satisfying photocatalytic activity against stable organic compound (i.e., Methylene Blue). This process may be extended for the vast scale preparation of metal nanoparticles for various industrial applications.

The isolation of chitinase from Streptomyces thermocarboxydus and its application in the preparation of chitin oligomers

Abstract: Microbial chitinase has received great attention due to its medical, biological, and agricultural applications. In this study, over 50 bacterial strains were isolated from Taiwanese soils using medium containing squid pen powder (SPP) as the sole source of carbon/nitrogen. Based on chitinolytic activity, Streptomyces thermocarboxydus TKU045 was selected for further study. Optimized culture conditions revealed that S. thermocarboxydus TKU045 could produce the highest chitinase activity (52.985 U/mL) when cultured in a medium containing 1% (w/v) SPP at 45 °C for 36 h. Characterized TKU045 chitinase showed novel properties with a smallest molecular weight (12.8 kDa by sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis) and more acidic optimal pH (pH 4) than those of other Streptomyces chitinases. A combination of high-performance liquid chromatography and matrix-assisted laser desorption ionization time of flight mass spectrometer data revealed that chitin oligomers (COS) obtained from the hydrolysis of colloidal chitin by TKU045 chitinase comprise oligomers with multiple degrees of polymerization (DP) varying from 1 to 7. The COS with low DP exhibited enhanced 2,2-diphenyl-1-picrylhydrazyl radical scavenging capability and promoted the growth of Lactobacillus lactis. Taken together, the COS obtained by hydrolyzing colloidal chitin with TKU045 chitinase could have the potential to be used in medicine or nutraceuticals due to its active anti-oxidant and prebiotic contents.

Synthesis, characterization and environmental applications of bismuth vanadate

Abstract: Pollution and the scarcity of water resources are considered major issues of concern in recent years. Treatment technology is important for reuse of water and wastewater, especially industrial wastewater. The photocatalytic process using semiconductors has emerged as a promising method in removing aqueous pollutants. Among the semiconductor photocatalysts, bismuth vanadate (BiVO4) is an effective visible light driven photocatalyst with various excellent properties such as narrow bandgap, resistance to corrosion, and low toxicity. In the past, much research was focused on synthesizing BiVO4 and enhancing its photocatalytic activity. A comprehensive discussion on synthesis and characterization (including morphology and structure) are presented in this review. Furthermore, the application of BiVO4 photocatalytic activity in water treatment is also discussed; the degradation of dye molecules and actual organic pollutants in the photocatalytic system under visible light irradiation is explained. This review is beneficial for further related research such as material development and pollution prevention.

Three-component solvent-free synthesis of 5-substituted-1H-tetrazoles catalyzed by unmodified nanomagnetite with microwave irradiation or conventional heating

Abstract: A convenient, rapid, and highly efficient procedure for synthesis of 5-substituted-1H-tetrazoles was developed via multicomponent domino Knoevenagel condensation/1,3-dipolar cycloaddition reaction between aromatic aldehydes, malononitrile, and sodium azide in presence of Fe3O4 magnetic nanoparticles, using microwave irradiation and conventional heating, under solvent-free conditions. The procedure is efficient due to the low cost and nontoxicity of the catalyst, elimination of volatile and toxic solvents, very short reaction time, excellent product yield, easy methodology, and simple workup. The magnetite catalyst was recycled using an external magnet and could be reused in at least five consecutive runs, delivering high product yield. We illustrate that green, efficient, and recoverable Fe3O4 magnetic nanoparticles can catalyze Knoevenagel condensation/1,3-dipolar cycloaddition of aromatic aldehydes, malononitrile, and NaN3 to synthesize 5-substituted-1H-tetrazoles using microwave irradiation and conventional heating.

Catalytic comparison of various polar Zn(II)-Schiff base complexes and VO(II)-Schiff base complexes in (ep)oxidation processes of 1,2-cyclohexene and cyclohexane

Abstract: The reactivity of Zn2+ and VO2+ ions towards pyridinyl Schiff bases, in the absence or presence of a p-sodium sulfonate group (HPSNa and HPS, respectively), provided polar and less polar catalyst complexes, which were characterized by various measurements. Stability constants of Zn-complexes [Zn(PS)2 and Zn(PSNa)2], and VO-complexes [VO(PS)2 and VO(PSNa)2] were measured spectrophotometrically. A typical (ep)oxidation processes of 1,2-cyclohexene or cyclohexane using 30% aqueous H2O2 catalyzed by our synthesized catalyst system, were tested. VO-complexes were found to be more effective catalysts than Zn-chelates. The polarity of Zn- and VO-complexes, i.e. the presence of p-SO3Na, displayed an observable influence on their catalytic performance chemoselectively. The polar catalyst system, Zn(PSNa)2 and VO(PSNa)2, in polar solvents such as H2O, MeOH, acetonitrile and acetone exhibited higher catalytic activity towards the (ep)oxidation processes than the less polar catalysts, Zn(PS)2 and VO(PS)2. In a less polar solvent such as CHCl3, polar catalysts showed higher conversion, but low chemoselectively, whereas the less polar catalysts showed relatively higher conversion and chemoselectivity. Under solvent-free conditions, less polar complexes were found to be more efficient catalysts than the polar chelates.

Visible light-induced conversion of biomass-derived chemicals integrated with hydrogen evolution over 2D Ni 2 P–graphene–TiO 2

Abstract: Highly selective photocatalytic conversion of biomass-derived chemicals into value-added chemicals and clean hydrogen energy under mild conditions by simultaneously utilizing photogenerated holes and electrons is in line with the theme of sustainable development of green chemistry. Herein, a two-dimensional (2D) heterostructure of ternary Ni2P–graphene–lepidocrocite TiO2 (NPG–TiO2) with intimately interfacial contact has been successfully fabricated, which exhibits significantly elevated photocatalytic performance toward coevolution of benzaldehyde (2.17 mmol/h/g) and hydrogen (1.97 mmol/h/g) from biomass-derived benzyl alcohol in aqueous solution under the visible light irradiation. Mechanistic studies reveal that in this ternary heterostructure, graphene serves as an electron relay mediator to facilitate the flow of electrons from TiO2 to Ni2P due to its inherent electrical conductivity, and the Ni2P provides the active sites for photocatalytic proton reduction to hydrogen. It is anticipated that this work would make a contribution to rational design of 2D flat-structured multi-component photocatalysts for selective conversion of biomass-derived chemicals coupled with hydrogen evolution.

Anti-cancer, anti-oxidant and molecular docking studies of thiosemicarbazone indole-based derivatives

Abstract: Based on the structural elements of bioactive 3-substituted indoles, a new series of indole–thiosemicarbazone hybrid derivatives were designed, synthesized, and well-characterized using different spectral techniques. The intended scaffolds were screened for their in vitro anti-proliferative activities against breast cancer (MCF-7), lung cancer (A-549), and liver cancer (Hep-G2) cell lines, as well as their anti-oxidant properties. Cytotoxicity studies revealed that compound 6n was the most potent, at least threefold more potent than the commercially available reference drug etoposide, against A-549. In addition, morphological analysis by the acridine orange/ethidium bromide double staining test and flow cytometry analysis confirmed induction of apoptosis in the A-549 cells by compound 6n. In order to validate the experimental results, molecular studies were performed to achieve the possible binding interactions of the most potent compound (6n) and colchicine with tubulin as well as ANP with ATPase domain of topoisomerase IIα active sites. Moreover, the radical scavenging potential of the final derivatives was found to be excellent with the range of 0.015–0.630 µM, comparable to the standard ascorbic acid (0.655 µM).

Microwave-assisted and thermal synthesis of nanosized thiazolyl-phenothiazine derivatives and their biological activities

Abstract: Efficient synthesis of a series of nanosized phenothiazine derivatives incorporating thiazole moiety was achieved using microwave irradiation as well as thermal conditions. Reaction of 2-(1-(10H-phenothiazin-2-yl)ethylidene)hydrazine-1-carbothioamide with various types of hydrazonoyl halide or α-haloketone afforded corresponding thiazolyl phenothiazines in good to excellent yield. Mass, 1H and 13C nuclear magnetic resonance (NMR), ultraviolet–visible (UV–Vis), X-ray diffraction (XRD), and elemental analyses confirmed the structure of all the new derivatives. The reaction progressed under microwave irradiation in shorter reaction time with higher yield compared with the conventional method. The antimicrobial and antitumor activities of selected derivatives were investigated, revealing that some of them showed high potency compared with standard references.

The magnetic nanostructured natural hydroxyapatite (HAP/Fe3O4 NPs): an efficient, green and recyclable nanocatalyst for the synthesis of biscoumarin derivatives under solvent-free conditions

Abstract: The magnetic nanostructured natural hydroxyapatite (HAP/Fe3O4 NPs) as a novel magnetic nanocatalyst was synthesized and fully characterized. The excellent catalytic activity of HAP/Fe3O4 NPs was investigated in the synthesis of biscoumarin derivatives under mild, green and solvent-free conditions. A series of aromatic (bearing different functional groups), heteroaromatic and aliphatic aldehydes have been converted to biscoumarins with good to excellent isolated yields. The significant advantages offered by the present method in close agreement with green chemistry principles are: catalyst is inexpensive, non-toxic, easy handling and reusable up to six recycle runs, magnetic separation of nanostructured catalyst, simple work-up procedure, short reaction time, high yields of products and using solvent-free conditions.

Preparation of Ag/UiO-66-NH2 and its application in photocatalytic reduction of Cr(VI) under visible light

Abstract: Herein, UiO-66-NH2 as a kind of metal organic framework materials (MOFs) is first prepared via a facile solvothermal method and then loaded with Ag nanoparticles to form an Ag/UiO-66-NH2 composite, which is applied as the photocatalyst for the visible-light driven reduction of Cr(VI). The UV–Vis diffuse reflectance spectroscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and photocurrent response analyses are performed to systematically characterize the composite. Ag nanoparticles with an average size of ca. 11.5 nm are distributed on the surface of UiO-66-NH2. The composite shows improved visible-light absorption ability and enhanced separation efficiency of photo-generated charge carriers. As a result, better photocatalytic Cr(VI) reduction is achieved on Ag/UiO-66-NH2 under the visible-light irradiation compared with UiO-66-NH2.

Fe3O4-supported N-pyridin-4-amine-grafted graphene oxide as efficient and magnetically separable novel nanocatalyst for green synthesis of 4H-chromenes and dihydropyrano[2,3-c]pyrazole derivatives in water

Abstract: Fe3O4-magnetized N-pyridin-4-amine-functionalized graphene oxide [Fe3O4@GO-N-(pyridin-4-amine)] was readily prepared via a three-step procedure. The synthesized nanofilms were characterized by scanning electron microscopy, powder X-ray diffraction analysis, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, vibrating-sample magnetometry, and elemental analysis. The prepared magnetic amine-functionalized graphene oxide exhibited high catalytic activity for one-pot three-component synthesis of dihydropyrano[2,3-c]pyrazole and tetrahydrobenzo[b]pyran (4H-chromene) derivatives. Excellent product yield, short reaction time, use of water as green solvent, and easy workup procedure are the main advantages of the present protocol. In addition, the catalyst could be easily separated by magnetic decantation and reused for six cycles without significant loss of catalytic activity.

Metal ion adsorption from wastewater by g-C3N4 modified with hydroxyapatite: a case study from Sarcheshmeh Acid Mine Drainage

Abstract: Hydroxyapatite (Hap) modified graphitic carbon nitride (g-C3N4) powders (Hap/g-C3N4) were prepared and characterized. The sorption activities of g-C3N4 and Hap/g-C3N4 were evaluated for the removal of Cu2+, Mn2+, Zn2+, Pb2+, Fe3+ and Cd2+ metal ions from simulated wastewater (synthetic solutions containing metal ions) and acid mine drainage from the sSarcheshmeh Copper Mine. The results indicated that the sorption capacities (SC) of g-C3N4 remarkably increased after the modification by Hap. Hap/g-C3N4 possessed higher SC than unmodified g-C3N4. So, the sorption mechanisms appear mainly attributable to the chemical interactions between the metal ions and functional groups on the Hap/g-C3N4 surface. More adsorption sites were formed on Hap/g-C3N4, which possessed abundant surface hydroxyl, phosphate and –NH2/–NH–/=N groups causing the higher efficiency of metal ion uptakes. Divalent metal cations are first adsorbed on the Hap/g-C3N4 surface and then substitution with Ca2+ ion can occur. Effect of pH evaluations confirmed that SC increased steeply with the pH increasing on both g-C3N4 and Hap/g-C3N4 adsorbents. The kinetic study demonstrated that the adsorption data were correlated well with the Langmuir isotherm model, and the adsorption process successfully followed the pseudo-second-order model.

Ionic polyacrylamide hydrogel improved by graphene oxide for efficient adsorption of methylene blue

Abstract: The ionic polyacrylamide/graphene oxide (PAM/GO) hydrogel as an excellent methylene blue (MB) adsorbent was prepared by an improved one-step radical polymerization method using graphene oxide, acrylamide, and polar second monomers. The hydrogel was characterized by Fourier transform infrared spectroscopy, Raman spectra, X-ray diffraction, scanning electron microscopy, and 13C nuclear magnetic resonance spectrum. The effects of pH, contact time, initial concentration of MB, and temperature on the adsorption capacity for MB of the prepared hydrogel were investigated. The Langmuir isotherm was a suitable model for describing the adsorption process. The adsorption system fitted with the pseudo-second-order kinetic model in the adsorption process. Compared with the ionic PAM/GO, the anionic PAM/GO significantly improved the adsorption capacity for MB with an increase from 128.23 to 255.48 mg g−1 at 20 °C.

Enhanced photocatalytic decolorization of methyl orange dye and its mineralization pathway by immobilized TiO2/polyaniline

Abstract: An immobilized TiO2/polyaniline (TiO2/PANI) bilayer photocatalyst was fabricated to decolorize methyl orange (MO) dye in aqueous solution. The synergistic decolorization of MO occurred via photocatalysis by TiO2 top layer and adsorption by PANI sub-layer. The fabrication of the photocatalyst was pertaining to the loading of TiO2 (0.32–2.24 mg cm−2) and PANI (0.32–1.92 mg cm−2). Increasing the loading would increase the thickness of the layer whereas an increment in the adsorption rate constant would essentially increase the synergistic photocatalytic–adsorption in the decolorization of MO. The TiO2 and PANI layer loading was optimized at 1.27 and 0.63 mg cm−2, respectively. The optimized TiO2/PANI photocatalyst removed MO dye by four and three times more effectively than the TiO2 and PANI single layer, respectively. The aeration, which supplied the dissolved oxygen, was optimized at 40 mL min−1 of flow rate. The photocatalytic degradation mechanism of MO was initiated by the demethylation followed by the aromatic ring opening and ended with a complete oxidation of the aliphatic chain to become CO2 and H2O. The TOC and IC analyses confirmed the mineralization of MO.

Application of Fe-MOFs in advanced oxidation processes

Abstract: Metal organic frameworks (MOFs) are novel porous materials formed by the link-up of transition metal ions through organic bridges. Fe-based metal organic frameworks (Fe-MOFs), an important branch of MOFs, not only have the characteristics of porous channels, exceptionally high specific surface area and multiple active sites like most MOFs, but are more environmentally friendly than other MOFs. Therefore, Fe-MOFs are more suitable for environmental restoration. This paper focuses on the application of Fe-MOFs in advanced oxidation processes (AOPs). The heterogeneous catalysts used in conventional AOPs are generally less efficient due to the difficulty in balancing specific surface area and stability. Therefore, MOFs, a novel multifunctional material with exceptionally high surface area, multiple active sites, acid-base stability and thermal stability, are expected to be heterogeneous catalysts for next-generation AOPs. By surveying the application of MOFs in different AOPs (Fenton-like, photocatalysis and sulfate radical (SO4·−)-mediated oxidation), it was found that MOFs not only exhibited excellent catalytic performance in various AOPs, but also improved the pH range for AOPs. The non-specificity of MOFs and the wide adaptability to pH (3.0–6.5) have contributed to the tremendous development of heterogeneous catalysts, while the mechanism of MOFs synthesis, how to convert sulfate ions in natural water into sulfate radicals, and how to reduce the cost of synthesis remain to be further studied. AOPs with Fe-MOFs are similar to Santa Claus with reindeer, in that Fe-MOFs help AOPs do their job (i.e., treat water pollution) more efficiently.

Fe3O4@SiO2-BenzIm-Fc[Cl]/ZnCl2: a novel and efficient nano-catalyst for the one-pot three-component synthesis of pyran annulated bis-heterocyclic scaffolds under ultrasound irradiation

Abstract: In this study, a novel magnetically recoverable Fe3O4@SiO2-BenzIm-Fc[Cl]/ZnCl2 nano-particle was synthesized using a simple chemical coprecipitation approach. In the FT-IR spectroscopy of nano-particles, related absorption peaks appeared which confirmed the successful synthesis of nano-catalyst. In the EDX spectrum of the nano-catalyst, the expected elements on their regions appeared. The XRD diffusion patterns of nano-catalysts showed the crystalline dispersions of Fe3O4 magnetic nano-particles. According to the FE-SEM and TEM images, the nano-particles have relative mono-dispersity and the average size of nano-particles is around 35 nm. The catalytic activities of the novel magnetic nano-particle were evaluated in the one-pot three-component synthesis of a wide variety of pyran annulated bis-heterocyclic derivatives (38 compounds) under ultrasonic irradiation. A simple, facial and highly efficient ultrasound-assisted method has been introduced for the synthesis of fused bis-heterocyclic pyran derivatives by one-pot, three-component reactions at room temperature. A series of pyrano[3,2-c]chromene derivatives were synthesized using a novel nano-catalyst via the condensation reaction of different aldehydes, malononitrile and 4-hydroxycoumarin. Kojic acid was also used in the three-component reaction for the synthesis of pyrano[3,2-b]pyran derivatives. The method was successful in the synthesis of various pyrano[2,3-d]pyrimidine derivatives. Additionally, new ultrasound-assisted synthesis protocol was used for the synthesis of novel chromeno[2,3-d]pyrimidine derivatives via three-component condensation of aromatic aldehydes, orcinol and barbituric acid. The new catalytic method exhibits some notable advantages such as short reaction times, operational simplicity, green reaction conditions, high yields and easy work-up and purification steps. In addition, the novel magnetic nano-particle could be easily separated by an external magnet and reused for six times without significant loss of its catalytic activity in the reaction.