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As a result of the increase in industrial activities and the extensive use of automobiles, air pollutants, especially carbon monoxide, reach the alarm level. The removal of carbon monoxide through oxidation is still one of the best tactics so far. Therefore, looking for an active and durable catalyst is considered the key factor for improving the oxidation process. In this work, Pd nanoparticles (1.0, 3.0 and 5.0 wt.%) were supported onto reduced graphene oxide / copper metal organic framework nanocomposite (rGO@Cu-BTC) through one pot solvothermal synthesis method. The catalysts were thoroughly characterized by state-of-the-art techniques such as XPS, SEM, TEM, XRD, N2 physisorption, and FT-IR. The results revealed that the Pd nanoparticles were exceptionally dispersed on rGO@Cu-BTC nanocomposite surface and the Cu-BTC crystals showed excellent octahedral structure with smooth edges as indicated SEM images. The results revealed that 3.0 wt. % Pd/rGO@Cu-BTC acts as an excellent catalyst in the CO oxidation as indicated by T50 and T100 values of 71 and 82 °C, respectively. Additionally, the results showed that rGO has a vital role in the dispersion of Pd NPs on the catalyst surface as well as the presence of surface oxygen groups, which yields higher catalytic activity compared with the catalyst without rGO.

In this paper, through the instrument of the well-known Chebyshev polynomials and subordination, we defined a family of functions, consisting of Bazilević functions of type α, involving the Ruscheweyh derivative operator. Also, we investigate coefficient bounds and Fekete-Szegö inequalities for this class.

Successful monometallic and bimetallic metal–organic frameworks with different Co/Mn ratios have been synthesized under solvothermal conditions. The as-synthesized MOFs followed by deposition of Pd nanoparticles with 0.5 to 7 wt%. The XRD, BET, SEM, TEM, EDAX and FT-IR characterization results reveal that bimetallic MOFs and Pd nanoparticles were finely dispersed on the prepared MOFs surfaces. XRD results confirm the formation of the desire MOFs and show the high degree of dispersion of Pd nanoparticles. TEM images show that Pd nanoparticles are nano-sized with almost uniform shape. EDAX shows that Pd nanoparticles successfully loaded on Co0.5–Mn0.5-MOF-74 catalyst. CO oxidation as a model reaction was then used to assess the catalytic performance of the prepared catalysts. The catalytic activity results show enhancement in the catalytic activities of monometallic MOFs after introducing another metal in the same framework and show an excellent improvement in CO conversion after loading with Pd nanoparticles. Furthermore, the samples that contain Pd nanoparticles exhibits higher catalytic activities which raised with increasing the content of Pd nanoparticles.

In the present work, Mn3O4 was prepared by various methods and successfully loaded with metallic Au nanoparticles reduced by hydrazine hydrate using microwave irradiation (MWI) method. The surface ...

Research has shown that alkali-activated concrete (AAC) is comparable to ordinary Portland cement concrete (OPCC) in terms of mechanical properties and may offer ecological benefits compared to OPCC. This study evaluates the energy and emission of AAC and OPCC across different classifications of concrete compressive strength (40, 60, and 100 ​MPa). Analysis indicates that the selection of constituent materials can substantially affect the energy and emission of AAC and OPCC. Ordinary Portland cement (OPC) is the principal contributor to the energy and emission of OPCC, accounting for 80% of energy and 91% of emissions of OPCC. The activating solution, meanwhile, is the main contributor to the energy and CO2 emission of AAC. Normal strength AAC (40 ​MPa) shows 46% less energy and 73% less CO2 emission than OPCC. However, high-strength AAC (60 ​MPa), using metakaolin as a base material, experiences higher energy (8%) than OPCC yet the emission is 40% less than OPCC. A substitution of fly ash for metakaolin results in superior efficiency of AAC compared to OPCC. Two mixtures of ultra-high-strength AAC (100 ​MPa) result in contradictory findings. One mixture with a sodium hydroxide and silica fume activating solution shows 5% and 30% less energy and CO2 emission, while the other mixture with a sodium hydroxide and sodium silicate activating mixture is less efficient than OPCC.

Topography and geographical conditions in Indonesia are very supportive in the effort to use solar energy as a producer of electrical energy. In this research, Dye Sensitized Solar Cell (DSSC) was fabricated using the doctor blading deposition method for coating TiO2 onto the substrate. The research focused on the effect of varying TiO2 thickness. TiO2 as an electron jumping pathway and binders for dye molecules, dye to absorb photons which will help generate electricity. the iodide / triiodide redox pair as electrolyte, and carbon as the counter electrode on the DSSC. TiO2, organic dyes, electrolytes, and counter electrodes are arranged and combined with a layered structure as a donor-acceptor layer. In testing the output power measurement using the Internet of Things, where testing cells at a thickness of 292 micrometers using a 7 watt LED lamp produces the maximum power reaches 4429.8 x 10-9 W.

Two-dimensional silicon allotrodes– also called Sinicene– have recently experienced intensive scientific research interest due to their unique electrical, mechanical, and sensing characteristics. A novel silicene based nano-material has been enticed great amenities, partially because of its uniformity with graphene. Silicene is a highly sensitive for numerous sensors based on molecular sensing as pH sensor, gas sensor, ion sensor and biosensing are Deoxyribonucleic acid (DNA) nucleobase sensor, photonic sensor, cell-based biosensor, glucose sensor, and bioelectric nose sensor. Nowadays genetic research based on DNA hybridization, which is a vital tools for sensing material and it has various detection methods. Among of them, the detection method is frequency readout used to a label-free detection of DNA hybridization. In this paper we have compared the graphene and silicene quantum capacitance that has been proposed for a DNA hybridization detection method on wireless readout. These method shows, the strands of mismatched and complementary DNA have in different range of frequency to identify output efficiency. With respect to DNA concentration the output of silicene is almost sharply linear than graphene. In addition of field effect transistor, silicene opens a new opportunities due to its band gap whereas graphene indicates zero band gap. It can be stated that silicene is much more reliable as well as much stronger than multi-layered graphene.

Rosiglitazone is an effective insulin-sensitizer, however associated with bone loss mainly due to increased bone resorption and bone marrow adiposity. We investigated the effect of the co-administration of fish oil on rosiglitazone-induced bone loss in C57BL/6 mice and the mechanisms underlying potential preventive effect. Mice fed iso-caloric diet supplemented with fish oil exhibited significantly higher levels of bone density in different regions compared to the other groups. In the same cohort of mice, reduced activity of COX-2, enhanced activity of alkaline phosphatase, lower levels of cathepsin k, PPAR-γ and pro-inflammatory cytokines, and higher level of anti-inflammatory cytokines were observed.Moreover, fish oil restored rosiglitazone-induced reduction of osteoblast differentiation and up-regulation of adipocyte differentiation in C3H10T1/2 cells and inhibited the up-regulation of osteoclast differentiation of RANKL-treated RAW264.7 cells. We finally tested our hypothesis on human Mesenchymal Stromal Cells differentiated in osteocytes and adipocytes confirming the beneficial effect of docosahexaenoic acid during treatment with rosiglitazone, through the downregulation of adipogenic genes, such as adipsin and FABP4 along the PPARg/FABP4 axis, and reducing the capability of osteocytes to switch toward adipogenesis.Fish oil may prevent rosiglitazone-induced bone loss by inhibiting inflammation, osteoclastogenesis and adipogenesis and by enhancing osteogenesis in the bone microenvironment.

The drug resistance of bacteria is a significant threat to human civilization while the action of antibiotics against drug-resistant bacteria is severely limited owing to the hydrophobic nature of drug molecules, which unquestionably inhibit its permanency for clinical applications. The antibacterial action of nanomaterials offers major modalities to combat drug resistance of bacteria. The current work reports the use of nano–metal-organic frameworks encapsulating drug molecules to enhance its antibacterial activity against model drug-resistant bacteria and biofilm of the bacteria. We have attached rifampicin (RF), a well-documented antituberculosis drug with tremendous pharmacological significance, into the pore surface of zeolitic imidazolate framework 8 (ZIF8) by a simple synthetic procedure. The synthesized ZIF8 has been characterized using the X-ray diffraction (XRD) method before and after drug encapsulation. The electron microscopic strategies such as scanning electron microscope and transmission electron microscope methods were performed to characterize the binding between ZIF8 and RF. We have also performed picosecond-resolved fluorescence spectroscopy to validate the formation of the ZIF8-RF nanohybrids (NHs). The drug release profile experiment demonstrates that ZIF8-RF depicts pH-responsive drug delivery and is ideal for targeting bacterial disease corresponding to its inherent acidic nature. Most remarkably, ZIF8-RF gives enhanced antibacterial activity against methicillin-resistant Staphylococcus aureus bacteria and also prompts entire damage of structurally robust bacterial biofilms. Overall, the present study depicts a detailed physical insight for manufactured antibiotic-encapsulated NHs presenting tremendous antimicrobial activity that can be beneficial for manifold practical applications.

This report, for the first time, demonstrated the low-temperature oxidation of carbon monoxide (CO) using nano-catalysts consisting of noble metal nanoparticles incorporated in TUD-1 mesoporous silica nano-structures synthesized via a one-pot surfactant-free sol&ndash, gel synthesis methodology. Herein, we investigated a nano-catalyst, represented as M-TUD-1 (M = Rh, Pd, Pt and Au), which was prepared using a constant Si/M ratio of 100. The outcome of the analytical studies confirmed the formation of a nano-catalyst ranging from 5 to 10 nm wherein noble metal nanoparticles were distributed uniformly onto the mesopores of TUD-1. The catalytic performance of M-TUD-1 catalysts was examined in the environmentally impacted CO oxidation reaction to CO2. The catalytic performance of Au-TUD-1 benchmarked other M-TUD-1 catalysts and a total conversion of CO was obtained at 303 K. The activity of the other nano-catalysts was obtained as Pt-TUD-1 &gt, Pd-TUD-1 &gt, Rh-TUD-1, with a total CO conversion at temperatures of 308, 328 and 348 K, respectively. The Au-TUD-1 exhibited a high stability and reusability as indicated by the observed high activity after ten continuous runs without any treatment. The outcomes of this research suggested that M-TUD-1 are promising nano-catalysts for the removal of the toxic CO gas and can also potentially be useful to protect the environment where a long-life time, cost-effectiveness and industrial scaling-up are the key approaches.

In this contribution, a facile and efficient one-step method for the preparation of mesoporous zirconium and tin tungstate with different Zr or Sn:W molar ratios. The prepared catalysts were characterized by different textural and spectroscopic techniques such as XRD, Raman spectra, SEM, EDX, TEM and N2 adsorption–desorption at − 196 °C. The surface acidity was measured by nonaqueous potentiometric titration of n-butylamine and FTIR spectra of chemisorbed pyridine. XRD results showed that all the prepared samples calcined at 400 °C are amorphous, no evidence for formation of big aggregates of WOx species on the catalyst surfaces, but all WOx species are homogeneously dispersed as small particles on the surfaces. At higher ratio of W (ZrW3 and SnW3) the excess WOx species are distributed inside the pores or block the pores by covering the necks of the pores, which leads to decrease in the specific area as evident from N2 adsorption- desorption study. Raman spectra showed that the tungstate species has WO4 distorted tetrahedral structure. The surface acidity measurement showed that the catalysts contain mixture of Lewis and Bronsted acid sites with different ratios, the maximum B/L ratio reach maximum value at molar ratio 1:2 (ZrW2 and SnW2). The results showed that zirconium tungstate samples have higher surface acidities than tin tungstate samples. The prepared catalysts showed high catalytic activities for the synthesis of 7-hydroxy-4-methyl coumarin via the Pechmann condensation reaction of resorcinol with ethyl acetoacetate. High yield (~ 94%) with 100% selectivity of 7-hydroxy-4-methyl coumarin was obtained under solvent free conditions.

Highly ordered mesoporous MCM-41 and SBA-15 have been synthesized and functionalized with different amounts of propyl sulfonic acid groups using 3-mercaptopropyltrimethoxysilane as sulfur source. The synthesized catalysts have been well-characterized by different techniques such as XRD, FTIR and BET surface area and pore size distribution by BJH method. FTIR spectra of chemisorbed pyridine and temperature programmed desorption of NH3 techniques have been successfully used to characterize the acidic sites. The results showed that, both surface area, mean pore diameter and pore volume decrease as the extent of sulfonation increase. XRD results and TEM images confirm the stability of mesoporous long range order even after sulfonation process done. In addition, the study also showed that, sulfonation enhances the surface acidity and new moderate and strong acid sites were created. All the sulfonated catalysts under investigations have been found to be highly active and selective for the Pechmann condensation reaction of resorcinol with ethyl acetoacetate. More than 98% yield of 7-hydroxy-4-methyl coumarin was obtained with 100% selectivity. Presence of high number of moderate and strong Bronsted acid sites in sulfonated catalysts help in achieving high yields. Furthermore, the MCM-41 sulfonated catalysts showed higher catalytic performance due to their higher surface acidities.

In this work, Pd nanoparticles was precipitated over iron oxide that prepared through two basic approaches to look for better dispersion of Pd nanoparticles and robust catalyst for carbon monoxide oxidation. The first involves direct precipitation of iron oxide using sodium hydroxide, and the second involves hydrothermal treatment after precipitation. The catalysts were characterized by many techniques such as, FTIR, XRD, N2 adsorption-desorption, H2-TPR and TEM images. The catalytic activity of the prepared catalysts was tested in CO oxidation reaction. The XRD showed that, α-FeOOH crystalline structure is formed. While, TEM images showed that, α-FeOOH has nanorods structure with different dimensions. The TPR experiment indicated that the reducibility of Pd/FeOOH catalyst was much more enhanced. The results also demonstrate that, as compared with the direct precipitation approach, the hydrothermal treatment after precipitation approach of iron oxide enable better dispersion of Pd nanoparticles as well as hinder the growth of large Pd crystallites which are important to produce outstanding catalysts for carbon monoxide oxidation.

Isomorphic substitution or post-synthesis incorporation of hafnium into KIT-6 mesoporous material has been fabricated for the first time in highly acidic media using triethylamine hafnium pentachloride ionic liquid (TEA-HfCl5) as a novel hafnium precursor ionic liquid (Si/Hf molar ratio of 90). The prepared catalysts were characterized by X-ray diffraction, Fourier transfer infrared (FT-IR), pyridine-FT-IR, N2-adsorption, transmission electron microscopy and the surface acidity was tested by temperature programmed desorption (NH3-TPD) of ammonia. The effect of the nature of hafnium source in the KIT-6 synthesis has been investigated using different hafnium source, viz., triethylamine hafnium pentachloride ionic and hafnium chloride. Triethylamine hafnium pentachloride ionic was found to be the better hafnium source for HfKIT-6 material synthesis and enhanced the amount of hafnium incorporation in the KIT-6 silica walls. ICP-AES studies evidenced that the proportion of Hf4+ increases using triethylamine hafnium pentachloride ionic. The catalytic performance of SO4 2−/HfKIT-6 was investigated by cracking of 1,3,5-triisopropylbenzene, esterification of acetic acid with n-butanol, while Pd/SO4 2−/HfKIT-6 was examined by n-C7 isomerization reaction. Our findings indicated that HfKIT-6 prepared by ionic liquid approach offered distinct structural and surface features, particularly in terms of Bronsted and Lewis acid site contents. As compared with SO4 2−/HfKIT-6 (direct ionic liquid) and SO4 2−/HfKIT-6 (direct), SO4 2−/HfKIT-6 prepared by post ionic liquid exhibited higher yield percentage of 1,3,5-triisopropylbenzene cracking and n-butyl acetate yield. Furthermore, Pd/SO4 2−/HfKIT-6 catalyst prepared by post ionic liquid shows high isomerization activities compared with Pd/SO4 2−/HfKIT-6 prepared by direct method using TEA-HfCl5 ionic liquid or HfCl4 materials.

In this paper, trifluoromethanesulfonic acid was successfully loaded over calcined crystalline zirconia. Zirconia was calcined at 200, 350, 500, 700 and 900 °C before trifluoromethanesulfonic acid was loaded. The catalysts were characterized by various sophisticated techniques such as FTIR, SEM, TEM, XRD and N 2 adsorption–desorption measurements. The acidic behavior of the catalysts has been studied by nonaqueous potentiometric titration and FTIR spectra of adsorbed pyridine. The results showed that the catalysts are highly acidic and exhibited high catalytic activity in the esterification of acetic acid with benzyl alcohol (95%) with very high selectivity to benzyl ester (96%). Furthermore, the tetragonal phase of zirconia was the only phase up to 500 °C, and completely vanished at 900 °C. These changes in crystalline structure was also found to be related to the number and strength of acid sites. Our results showed that, the number and strength of acid sites were optimum at 350 °C, at which only tetragonal phase is the metastable one. Moreover, the catalysts were capable of recycling for five times without appreciable deactivation at 100 °C.

In this work, a facile and efficient one-step method for the synthesis of highly active mesoporous zirconium and tin(IV) phosphate that exhibit excellent catalytic activity for the synthesis of photochromic bis-naphthopyran via the Claisen rearrangement has been established. The synthesized catalysts were characterized by different textural and spectroscopic techniques such as XRD, FTIR spectra, SEM, TEM and N2 adsorption–desorption at −196 °C. The surface acidity of the prepared catalysts were determined by nonaqueous potentiometric titration with n-butylamine and FTIR of chemisorbed pyridine. XRD and N2 adsorption–desorption measurements showed that, the samples have some mesoporous structure. The surface acidity measurement showed that the samples contain mixture of Lewis and Bronsted acid sites. The results showed that zirconium phosphate samples have higher surface acidities than tin phosphate samples, and the samples with Zr:P ratio 1:3 and Sn:P ratio 1:2 showed the highest surface and Bronsted acidities. The prepared catalysts showed excellent catalytic activity for the synthesis of photochromic bis-naphthopyran via the Claisen rearrangement. High yield (~99 %) with 100 % selectivity of photochromic bis-naphthopyran was obtained in shorter reaction time at room temperature. These acid catalysts may solve the problematic low yield and purification difficulties of the photochromic chromenes reported previously.

High loadings of 12-tungstophosphoric acid (H3PW12O40) were incorporated within highly porous metal-organic framework MIL-101. The samples have been characterized using different techniques such as XRD, TEM, FT-IR, TGA, N2 adsorption and Raman spectroscopy. XRD and TEM did not show any aggregation of the H3PW12O40 nanocrystals on the surface of MIL-101 crystals up to 70 wt%. Similarly, N2 sorption–desorption measurements reveal that samples with H3PW12O40 loading up to 70 wt% retain their mesoporosity. The incorporation of H3PW12O40 crystals gradually increases both the surface acidity and the acid strength of the H3PW12O40/MIL-101 catalysts up to 70 wt% loading. The catalytic performances of the H3PW12O40/MIL-101 solid catalysts were tested in three acid-catalyzed organic transformations, namely, the Pechmann, Esterification and Friedel–Crafts acylation reactions. In the three reactions, the catalytic activity attains the maximum value at 70 wt% of H3PW12O40 loading, thus demonstrating direct correlation with dispersion, mesoporosity and acid strength. The unique attributes of MIL-101 and a well-dispersed level of H3PW12O40 prohibit the conglomeration and deactivation of H3PW12O40, which leads to the enhancement of the catalytic properties. The H3PW12O40 catalysts supported on MIL-101 are potentially promising heterogeneous catalysts for acid-catalyzed organic transformations in environmental friendly processes, to supersede the use of conventional homogeneous H3PW12O40 catalysts.

12-molybdophosphoric acid (PMA) was supported on mesoporous molecular sieves MCM-41 by impregnation of 12-molybdophosphoric acid followed by calcination. The nanochannels of MCM-41 provide a large surface area for the solid state dispersion of 12-molybdophosphoric acid. The samples have been characterized by N 2 adsorption–desorption at −196 °C, transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and FT-IR measurements. The acidity and catalytic activity have been, respectively, examined by nonaqueous titration of n-butylamine in acetonitrile and synthesis of hydroquinone diacetate. The results showed that ordered hexagonal pore structure was observed in the synthesized MCM-41. Also the results indicate that PMA are highly dispersed on mesoporous silica MCM-41 spherical nanoparticles while PMA retains its Keggin structure. On the other hand, with increasing the introduced PMA amount, the specific surface area decreases, and the mesoporous ordering of the samples become poor. Both the surface acidity and the catalytic activity sharply increase with the modification of MCM-41 by PMA but decrease by increasing the calcination temperature. The sample with 55 wt% PMA/MCM-41 calcined at 350 °C shows the highest acidity and catalytic activity.

Nanocrystalline sulfated tin oxide with different sulfate contents (5–30 wt%) were prepared from hydroxylated tin oxide obtained by the precipitation method, followed by wet impregnation with SO 4 2− species using a sulfuric acid solution. In samples calcined at 400, 500 and 600 °C the characterization of the solids was made by DTA, XRD and nitrogen adsorption. The strength and number of acid sites were determined by nonaqueous titration of n-butylamine in acetonitrile. Both Bronsted and Lewis acid sites were determined by FTIR spectra of pyridine adsorbed. Sulfated tin oxides were tested in the synthesis of 7-hydroxy-4-methyl coumarin via solvent free Pechmann reaction of resorcinol:ethylacetoacetate (molar ratio 1:2), at 120 °C. DTA measurements showed that SO 4 2− addition tends to slow down the formation of SnO 2 crystallites. XRD profiles showed that the sulfating inhibits the SnO 2 crystal growth. The SO 4 species remained strongly bonded at the SnO 2 surface stabilizing its crystallite size against sintering and it acts as a structure porogen director mediating nanoparticle growth and assembly yielding a mesostructured form of SnO 2 with wormhole morphology and high thermal stability. The surface areas of the investigated samples were influenced with the sulphate content and calcination temperature. The acidity measurements showed that the total acidity increases with the rise of sulfate content up to 25 wt%. FTIR spectra of pyridine adsorbed on the catalysts showed the presence of both Bronsted and Lewis acid sites. The formation of 7-hydroxy-4-methyl coumarin increases with the increase of surface acidity showing a maximum when the sulfate content and calcination temperature were 25 wt% and 400 °C, respectively.

In this work, solid acid catalysts of the Keggin-type 12-tungstophosphoric acid (H3PW12O40, HPW) incorporated within the mesochannels of MCM-41 are prepared through a simple and effective impregnation method. The catalysts are characterized by various techniques such as XRD, FTIR, TEM, N2 adsorption and thermal analysis. The surface acidities are measured by non-aqueous titration of n-butyl amine in acetonitrile and FTIR spectra of chemisorbed pyridine. The acidity and the textural parameters of the nanocomposites can be controlled simply by changing the loading of HPW on the MCM-41. The results indicate that the surface saturation coverage of MCM-41 is reached with 60 wt% HPW. The high saturation coverage is indicative of the well-dispersion of HPW within the mesochannels of MCM-41. The catalytic activities of the HPW/MCM-41 catalysts for the Pechmann, esterification reaction and Friedel–Crafts acylation reactions are studied in detail. Both the surface acidity and the catalytic activity sharply increase with the modification of MCM-41 by HPW. The sample with 60 wt% HPW shows the highest acidity and catalytic activity. The reusability tests of the catalysts show that the catalysts can be used several times without significant loss in activity. The HPW/MCM-41 catalysts have great potential for applications as commercial catalysts in promoting acid-catalyzed organic transformations under environmental friendly conditions and processes.

During the development of multicellular organisms, many events occur with precise timing. In Drosophila melanogaster, pupation occurs about 12 hours after puparium formation, and its timing is believed to be determined by the release of a steroid hormone, ecdysone (E), from the prothoracic gland. Here, we demonstrate that the ecdysone-20-monooxygenase, Shade, determines the pupation timing by converting E to 20-hydroxyecdysone (20E) in the fat body, which is the organ that senses nutritional status. The timing of shade expression is determined by its transcriptional activator βFTZ-F1. The βFTZ-F1 gene is activated after a decline in the expression of its transcriptional repressor Blimp-1, which is temporally expressed around puparium formation in response to a high titer of 20E. The expression level and stability of Blimp-1 is critical for the precise timing of pupation. Thus, we propose that Blimp-1 molecules function as sands in an hourglass for this precise developmental timer system. Furthermore, our data suggest a biological advantage results from both the use of a transcriptional repressor for the time determination, and association of developmental timing with nutritional status of the organism.

Nanostructured zinc oxide (ZnO) nanobelts and aluminum oxide (Al2O3) nanoribbons have been grown successfully from the vapor phase. XRD results confirmed the purity and the high quality of the formed crystalline materials. TEM images showed that ZnO nanostructures grew in the commonly known tetrapod structure with nanobelts separated from the tetrapods with an average width range of 10–30 nm and a length of about 500 nm. Al2O3 nanostructures grew in the form of nanoribbons with an average width range of 20–30 nm and a length of up to 1 μm. The catalytic oxidation of CO gas into CO2 gas over the synthesized nanostructures is also reported. Higher catalytic activity was observed for Pd nanoparticles loaded on the ZnO nanobelts (100% conversion at 270 °C) and Al2O3 nanoribbons (100% conversion at 250 °C). The catalytic activity increased in the order Cu

We have developed an efficient method to generate highly active Pd nanoparticles supported on graphene (Pd/G) by microwave-assisted chemical reduction of the corresponding aqueous mixture of a palladium salt and dispersed graphite oxide (GO) sheets. The Pd/G demonstrated excellent catalytic activity for the carbon–carbon cross-coupling reactions (Suzuki, and Heck) with a broad range of utility under ligand-free ambient conditions in an environmentally friendly solvent system. It also offers a remarkable turnover frequency (108,000 h−1) observed in the microwave-assisted Suzuki cross-coupling reactions with easy removal from the reaction mixture, recyclability with no loss of activity, and significantly better performance than the well-known commercial Pd/C catalyst. The catalyst was fully characterized by a variety of spectroscopic techniques including X-ray diffraction (XRD), Raman, TGA, electron microscopy (SEM, TEM), and X-ray photoelectron spectroscopy (XPS). The remarkable reactivity of the Pd/G catalyst toward Suzuki cross-coupling reactions is attributed to the high degree of the dispersion and concentration of Pd(0) nanoparticles supported on graphene sheets with small particle size of 7–9 nm due to an efficient microwave-assisted reduction method.

The effects of superficial gas velocity on heat transfer coefficient and its time-averaged radial profiles along the bed height have been investigated in a pilot-plant scale bubble column of 0.44 m diameter using air–water system. Notable differences were observed in heat transfer coefficients along the bed axial locations particularly between the sparger (Z/D = 0.28) and the fully developed flow (Z/D = 4.8) regions. In the fully developed flow region larger heat transfer coefficient values were obtained compared to those in the sparger region. About 14–22% increase in heat transfer coefficients measured in the fully developed flow region has been observed compared to those measured in the distributor region when the superficial gas velocity increases from 0.05 to 0.45 m/s. The heat transfer coefficients in the column center for all the conditions studied are about 9–13% larger than those near the wall region. It has been noted that in the fully developed flow region, the axial variation of the heat transfer coefficients was not significant.

WO3 loaded on nano-crystalline sulfated tin oxide solid acid catalyst has been synthesized and studied for selective nitration of phenol. The catalysts were characterized by various analytical and spectroscopic techniques including thermal analysis, powder X-ray diffraction (XRD), N2 adsorption and FTIR spectra. The surface acidity was measured by no aqueous potentiometric titration and FTIR spectra of chemically adsorbed pyridine. The acidity measurements showed that the samples contain both Lewis and Bronsted acid sites; moreover, the total acidity increases with the rise of WO3 content up to 30 wt.% (monolayer coverage) and decreases thereafter. The results also showed the possibilities of interaction of WO3 with sulfate and/or SnO2 surface that led to some changes in the surface structure of the catalyst. The catalytic activity well correlates with Bronsted acid sites of these catalysts. The effect of the reaction parameters, i.e. reactants molar ratio, reaction temperature and time was also investigated. The catalyst was reused for five times with excellent percentage conversion and high selectivity towards ortho isomer. The possible reaction mechanism for the formation of ortho and para isomers was also discussed.

A series of solid acid catalysts were synthesized by incipient wetness impregnation method by varying the wt% of 12-tungstophosphoric acid (TPA) on tin oxide. The prepared catalysts were characterized by thermal analysis, XRD, FT-IR and BET surface area. The acidity of the catalyst was measured by different techniques. The suitability of the materials was studied for acid-catalyzed esterification reaction using acetic acid and amyl alcohol. The acidity measurements showed that the total acidity increases with the rise of TPA content up to 20 wt% (monolayer coverage) and decreases thereafter. FT-IR spectra of pyridine adsorbed on the catalysts showed the presence of both Bronsted and Lewis acidities. Material with 20 wt% TPA on tin oxide having high surface area and acid sites acts as the better catalyst for esterification reaction. For the material that exhibits the optimum catalytic activity, selective poisoning of the potential catalytic centers revealed that Bronsted sites play the major role in carrying out the reaction. The straight-line plots of −ln(1-ester formed) versus catalyst weights support that the esterification reaction obeys first-order kinetics. The reusability study justifies that the catalyst is stable and active.

The effect of the incorporation of SO 4 2− in ZrO 2 was studied. Materials were prepared by wet impregnation method with varying SO 4 2− content (5, 10, 15, 20, 25 and 30 wt%). The structural properties of these catalytic materials were studied by thermal analysis, X-ray diffraction, nitrogen adsorption at −196 °C, potentiometric titration with n -butylamine and adsorption of pyridine at room temperature. DTA measurements showed that SO 4 2− addition tends to slow down the formation of ZrO 2 crystallites. XRD shows that the samples contain mixture of tetragonal and monoclinic zirconia phases. The percentage of tetragonal zirconia phase was found to depend on sulfate content and calcination temperature. After calcination at temperature as high as 600 °C, the amount of tetragonal phase is reduced. The surface areas of the investigated samples were influenced with the sulphate content and calcination temperature. The acidity studies demonstrate the presence of mixture of Bronsted and Lewis acid sites. SO 4 2− /ZrO 2 containing 15 wt.% SO 4 2− and calcined at 500 °C exhibited maximum catalytic activity for ethanol dehydration. The catalytic activity was strongly influenced with the structural properties and surface acidities of the catalysts investigated.

The effect of sulfate content and calcination temperature on the structure, acidity and catalytic activity of tin oxide was investigated. Sulfated tin oxide samples were characterized by thermal analysis (DTA and TGA), powder X-ray diffraction (XRD) and N 2 adsorption at −196 °C. The surface acidity was measured by Potentiometric titration, DSC-TGA and FT-IR techniques. The catalytic performance was evaluated on the esterification of acetic acid with amyl alcohol in the vapor phase between 150 and 250 °C. XRD measurements show that the sulfating of SnO 2 tends to hinder the crystallization of SnO 2 and inhibits crystal growth. It was found that the surface acidity increases with the increase of thermal treatment up to 550 °C, while the further increase of calcination temperature beyond 750 °C leads to a decrease of acid sites and acid sites strength. The addition of sulfate to SnO 2 brings about an increase of the specific surface area, whereas the calcination temperature exhibits a reverse trend. The formation of amyl acetate increases with increase of surface acidities. Lewis and Bronsted acid sites appears to be needed for catalytic activity in amyl acetate formation, both are maximum when the sulfate content and calcination temperature are 30 wt.% and 550 °C, respectively.

A series of MoO 3 /ZrO 2 catalysts with different molybdenum content of 5–30 wt.% MoO 3 were prepared by impregnation method. The prepared catalysts were calcined at 400, 550, 700, 800, and 1000 °C. The structural characteristics were investigated by means of thermal analysis (DTA and TGA), powder X-ray diffraction (XRD) while the textural properties was determined from low temperatures adsorption of N 2 at −196 °C. The surface acidity was measured with nonaqueous titration of n -butylamine in acetonitrile. The catalytic activity was tested by cumene dealkylation and ethanol conversion using the microcatalytic pulse technique. XRD reveals that the samples contain mixture of tetragonal and monoclinic zirconia phases. At low MoO 3 loading, i.e. 3, MoO 3 was not detected. When the loading of MoO 3 exceeds 15 wt.%, crystalline MoO 3 and Zr(MoO 4 ) 2 were formed, particularly for the higher calcination temperature products. The incorporation of MoO 3 into ZrO 2 enhanced the surface acidity of the catalysts. It was found that the surface acidity gradually increased as the temperature of thermal treatment was increased from 400 to 550 °C and also with the molybdenum oxide content. This increase in the surface acidity was correlated with the degrees of crystallinity of the samples. The surface area was found to increase with increasing of MoO 3 up to 15 wt.%. Further increase of MoO 3 beyond 15 wt.% led to a decrease of N 2 - S BET . The catalytic activity was strongly influenced with the textural, structural properties and surface acidities of the catalysts investigated.

This review article discusses the reaction of nitrilimines and nitrile oxides with hydrazines, hydrazones, and oximes. Three reaction modes were observed. The article mainly covers our work published over the last fifteen years, in which interesting heterocyles such as oxadiazoles, triazoles, and tetrazines were synthesized and fully characterized. View Full-Text Keywords

Cycloaddition of the reactive intermediates 4 with 1-(cyanomethyl)benzotriazole (5) and its N-2 isomer 9 furnished, after spontaneous rearrangements, the 1,2,4-triazole derivatives 8 and 10. Analogously, reaction of 4 with ethyl cyanoacetate lead to the 1,3,5-trisubstituted 1,2,4-triazoles 12, which gave on treatment with hydrazine the corresponding hydrazides 13. Treatment of 13d with galactose or phenyl isothiocayanate gave the 1-D-galactose-acylhydrazone 14 and the 1,2,4-triazole derivative 15, respectively. Compounds 8c; 10b,c; 13a,c and 14 were selected for the antitumor screening, whereby 8c, 13a, and 13c showed remarkable activity against leukemia, ovarian, renal and lung cancers (8c with Gl(50) of 0.70 microM, 0.07 microM against leukemia (CCRF-CEM and RPMI-8226), 0.02 microM against ovarian (OVCAR-3) and 0.60 microM against renal (CARKI-1) and lung cancers, respectively).

C-Acetyl-N-arylnitrilimines (2) react with acetaldehyde, alkanone, and cycloalkanone benzoylhydrazones (3) to give the cycloaddition products 4-benzoylamino-4,5-dihydro-1,2,4-triazoles (4–15) rather than the tetrazine cyclocondensation products (16).

The reaction of nitrilimines (2) with 1-substituted-1-methylhydrazines (3–6) led to the formation of the respective amidrazones (7) when R = CH3, Ph, and to the acyclic adducts (8,9) when R = CHO and COCH3. The acyclic adducts underwent thermal oxidative cyclization at CH3 to give the unexpected 1,2,4,5-tetrazines (10,11). Dihydro-l,2,4,5-tetrazines (12) were also seperated when R = CHO.

Hydrazonoyl halides (1a–e) react with cycloalkanone oximes (2–6) to give substituted heterocyclic spiro compounds (8–11a–e). Reaction of triazaspiro[4.5]dec-2-ene (9b) with acetic anhydride gave the ring transformation product triazole (17b) instead of the N-acetyl derivative (16b).

A series of Ni/Al2O3–AlPO4 catalysts has been prepared, thereby allowing the effect of nickel content and calcination temperature on the structural and catalytic activity of such solids to be inves...

Nitrilimines 2 are found to react with alkoxycarbonylhydrazines 3–5 to afford the acyclic adducts 6–8. 6c is oxidized upon heating with charcoal in refluxing toluene to the corresponding formazan 9c. Compounds 8 cyclize upon heating with charcoal in refluxing toluene to the corresponding 6-acetyl-4-aryl-2-ethoxycarbonyl-1,2,3,4-tetrahydro-s-tetrazines (10) rather than to the expected corresponding tetrazinones 11. NMR study of compounds 10 showed that these compounds exist in a tautomeric equilibrium.

Oximic 1,2,4-triazole ligands 2a – e were prepared from the reaction of 3-acetyl-4,5-dihydro-1H-1,2,4-triazoles 1a – e with hydroxylamine hydrochloride at room temperature. At higher temperatures, the reaction afforded, however, the novel ring transformation product 4-amino-2-(4-chlorophenyl)-5-methyl-2H-1,2,3,6-oxatriazine 3 . The reaction of the ligands 2a – e with nickel (II) and palladium (II) acetates in ethanol at room temperature yielded the respective square planar complexes 5a – e , 6a , e . X-ray structure determination of one of these complexes ( 5a ) revealed that metallation led to unexpected ring transformation of the triazole ligand. It is probable that such ring transformation generated the imidazole- N -oxide intermediate 4a which coordinated to Ni(II) ion, and the 4N-donor set comprises both imidazole nitrogen and arylhydrazone nitrogen. The whole process is associated with loss of one hydrogen molecule and formation of one new π-bond. The new compounds were characterized by elemental analysis, IR, 1 H NMR, 13 C NMR and HRMS.

3-Acetyl-1,2,4-triazole hydrazones (3b,c) and methylhydrazone (4d) were prepared by reacting triazoles (1b–d) with an excess of hydrazines at room temperature. Square planar nickel(II) complexes (8b,c) of (3b,c) were obtained from their reaction with Ni(OAc)2 in a 2:1 mol ratio in EtOH at room temperature. The spectral data suggest structures (8b,c) for the obtained complexes, which result from ring opening of the triazole ring followed by recyclization to give the 5-arylhydrazono-2,3-dihydro-4H-1,2,4-triazine ligand (7b,c). The reaction of triazole methylhydrazone (4d) with Ni(OAc)2 in EtOH resulted, however, in the formation of the starting triazole (1d). All new compounds were characterized by elemental analysis, i.r., 1H-n.m.r. 13C-n.m.r. and hrms.

C-Acetyl-N-arylnitrilimines (2) react with acetaldehyde, alkanone, and cycloalkanone benzoylhydrazones (3) to give the cycloaddition products 4-benzoylamino-4,5-dihydro-1,2,4-triazoles (4–15) rather than the tetrazine cyclocondensation products (16).

Pentaerythritol, (1,1,1-trishydroxymethyl)methyl methane and (1,1,1-trishydroxymethyl)nitromethane are converted into 2-aryl-5,5-bis(hydroxymethyl), 2-aryl-5-hydroxymethyl-5-methyl- or 2-aryl-5-hydroxymethyl-5-nitro-1,3-dioxanes and a range of derivatives. X-Ray and NMR analysis establishes that the latter is obtained as a single diastereomer whose structure is unambiguously determined. These materials can be elaborated to chiral derivatives of the starting (1,1,1-trishydroxymethyl) methanes.