Green preparation of argentum tungstate and characterization as nanorod with catalytic evaluation for synthesizing tetracyclic xanthenes and validation as anti-TB

1-Methylimidazolium tricyanomethanide {[HMIM]C(CN)3} as a novel, green and nano molten salt catalyst was designed and fully identified by IR, 1H NMR, 13C NMR, mass, thermal gravimetric (TG), derivative thermal gravimetric (DTG), X-ray diffraction (XRD) pattern, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses. The catalytic application of {[HMIM]C(CN)3} for the one-pot three-component condensation reaction of various aromatic aldehydes, amides and β-naphthol was studied through the preparation of 1-amidoalkyl-2-naphthols at room temperature under solvent-free conditions in comparison with nano SnO2. In the presented investigations, some products were produced and reported for the first time.

Magnetic nanoparticle-supported molybdate sulfuric acid (MNPs-MSA) was synthesized and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM). The catalytic activity of MNPs-MSA was investigated as a recoverable catalyst for the one-pot synthesis of novel 2-substituted aryl (amino) and aryl (indolyl) kojic acid derivatives from the reaction of aldehydes with aniline or indole and kojic acid in high yield at room temperature under solvent-free conditions Abstract should briefly state the purpose of the research, the principal results, and the major conclusions of the study.

Background: Thiazolidinone-4-ones belong to an important heterocyclic compounds because of their broad spectrum of biological activities. Several methods for the synthesis of 4-thiazolidinones were reported in the literature. The main synthetic routes to synthesize 1,3-thiazolidin-4-ones is the three component reaction between amine, a carbonyl compound and a mercapto-acid. Objective: Dapsone-Cu supported on silica coated Fe3O4 (Fe3O4@SiO2-pr@dapsone-Cu) as a new heterogeneous nanoparticle catalyst was synthesized and the structure and morphology of this catalyst were characterized by Fourier transform infrared spectroscopy (FT-IR), Xray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), zeta potential, vibrating sample magnetometry (VSM) and thermal gravimetric analysis (TGA). The new synthesized catalyst was applied as an effective nanocatalyst for the synthesis of new derivatives of azo-linked thiazolidinones through one-pot multi-component reaction of various aromatic aldehydes, thioglycolic acid and 4-aminoazobenzene under solvent-free condition. Methods: A mixture of aldehyde, thioglycolic acid, 4-aminoazobenzene (1 mmol) and 0.05 g Fe3O4@SiO2@dapsone-Cu MNPs were stirred at room temperature under solvent-free condition. Results: We report a facile, green, new and efficient method for the synthesis of thiazolidine-4-ones through three component reaction of various aldehydes, thioglycolic acid and 4-aminoazobenzene in the presence of Fe3O4@SiO2-propyl@dapsone-Cu complex under solvent-free reaction. Conclusion: This new procedure has the notable advantages such as excellent yields, short reaction time, operational simplicity, easy work-up, eco-friendly and using a non-toxic catalyst. Also, the catalyst is easily recoverable in the presence of an enourmous magnet and reused for six consecutive reaction cycles without significant loss of activity.

In this work, silver nitrate complexes of sulfanilamide-5-methyl-2-thiophene carboxaldehyde (SMTCA) ligand intercalated Zn/Al-layered double hydroxide [Ag-SMTCA-LDH] were synthesized for the potential application as an antimicrobial system. The SMTCA ligand was synthesized by reacting sulfanilamide and 5-methyl-2-thiophene carboxaldehyde in methanol and further complexation with silver nitrate metal ions [Ag-SMTCA]. The structural analyses of synthesized compounds confirmed an intercalation of Ag-SMTCA into Zn/Al-NO3-LDH by flake/restacking method. SMTCA, Ag-SMTCA and Ag-SMTCA-LDH were characterized by 1H nuclear magnetic resonance (1H NMR) spectroscopy, Fourier-transform infrared (FTIR), ultraviolet-visible (UV-Vis) spectrophotometer, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). It was found that Ag-SMTCA-LDH exhibited good antimicrobial activity against both gram-positive (Bacillus subtilis, [B. subtilis], Staphylococcus aures, [S. aureus]) and gram-negative (Escherichia coli, [E. coli], Pseudomonas aeruginosa [P. aeroginosa]) bacteria as well as excellent antioxidant activity.

An efficient green method has been developed for the cascade multi-component Hantzsch reaction of acridinediones and biscoumarins using Fe3O4@SiO2@Ni–Zn–Fe layered double hydroxide (LDH). Nano Ni–Zn–Fe LDH immobilized on silica-layered magnetite was synthesized via a simple co-precipitation procedure, and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The nanocatalyst has the usual features of Fe3O4@SiO2 and Ni–Zn–Fe LDH. Moreover, it contains magnetism properties which is related to the presence of magnetite in the nanocatalyst and can be easily separated from the reaction mixture with an external magnetic field. Subsequently, the nanomagnetic-LDH was used to evaluate catalytic activity with the tandem synthesis of acridinedione and biscoumarin derivatives. The mesoporous catalyst showed excellent performance for multi-component reactions between aromatic aldehydes, 4-hydroxycoumarin, and dimedone and ammonium acetate. Acridinediones were provided within 15–35 min in 80–96% yields under solvent-free conditions in 70–80 °C and also, biscoumarins were obtained within 1–40 min in 87–95% yields under reflux conditions in water. The present study includes noteworthy advantages of mild reaction conditions, short times of reaction, absence of hazardous and expensive organic solvents and reagents, presence of water as an eco-friendly solvent, using green nanomagnetic-LDH and the ability to recycle the nanocatalyst.

Promising hydrothermal technique for efficient CO2 methanation over Ni/SBA-15

A magnetically recoverable nanocatalyst based on 1-methylimidazolium hydrogen sulfate ionic liquid has been synthesized by reaction of 1-methylimidazole with 3-(trimethoxysilyl)propyl chloride group, leading to formation of 1-methyl-3-(triethoxysilyl)propyl imidazolium chloride ([pmim]Cl). The ionic liquid was anchored onto silica-coated magnetic Fe3O4 particles, and Cl− anion exchange by treatment with H2SO4 afforded the corresponding immobilized ionic liquid MNP-[pmim]HSO4. The synthesized catalyst was characterized by various techniques such as Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), (differential) thermogravimetry (TG/DTG), CHN analysis, and vibrating-sample magnetometry (VSM), revealing the superparamagnetic nature of the particles. From electron microscopy (SEM and TEM) studies it can be inferred that the particles were mostly spherical in shape with average size of 20 nm. The loading amount of ionic liquid supported on the magnetic particles was indicated to be 0.98 mmol/g by the results of elemental and thermogravimetric analyses (CHN and TG). The catalytic activity of the supported ionic liquid was examined in synthesis of 1,8-dioxodecahydroacridines by condensation reaction of cyclic diketones with aromatic aldehydes and ammonium acetate or primary amines under solvent-free conditions. The catalyst could be easily recovered by applying an external magnetic field and reused for at least nine runs without deterioration in catalytic activity.

CHAPTER 1 Seed-Mediated Growth of Silver Nanocubes and Their Morphological Transformation Silver nanoparticles are often synthesized in organic solvents with the use of high reaction temperatures. If nanoparticles can be synthesized in aqueous solution, the method would be energy-saving and environmentally friendly. In the literature, long reaction time and high temperatures are still need to synthesize silver nanocubes. Here we present a facile and low temperature approach to prepare silver nanocubes in aqueous solution and investigat how the reaction rate controls the final product morphology. In this study, we have developed a seed-mediated growth method to synthesize Ag nanocrystals in aqueous solution. The method involves the addition of a small volume of a seed solution to an aqueous solution of silver nitrate (AgNO3), cetyltrimethylammonium chloriode (CTAC), and ascorbic acid (AA). We utilized AgNO3 as silver source, CTAC as surfactant, and AA as reducing agent. Silver nanocubes were generated in 2 hours at 60 oC. Transmission electron microscopy (TEM), powder X–ray diffraction (PXRD) pattern, and scanning electron microscopy (SEM) have been employed to characterize the nanocubes enclosed by {100} facets. The edge length of cubes can also be tuned from 46 to 55 nm. Here, we also present the effects of NH3 solution on morphological transformation. The acceleration of the reaction rate by introducing NH3 solution promotes the formation of the {111} facets. The solution color at different time points during synthesis also proved that the reaction rate controlled the final particle morphology. CHAPTER 2 Synthesis of Au–Ag Core–Shell Heterostructures with Systematic Shape Evolution and Their Optical Properties In this study, we have utilized rhombic dodecahedral gold nanocrystals as the structure-directing cores for the growth of Ag shells in aqueous solution. Au–Ag core–shell heterostructures with different morphologies can be directly synthesized. The reagents we used are silver nitrate (AgNO3), cetyltrimethylammonium chloriode (CTAC), ascorbic acid (AA), and sodium hydroxide (NaOH). By simply varying the concentration of reducing agent or silver source, shape evolution from cubes, truncated cubes, cuboctahedra, truncated octahedra and octahedra were obtained. The reaction was finished within 50 minutes at 30 oC. This is a time- and energy saving method. These monodisperse nanocrystals can readily form self-assembled structures. By monitoring the solution color at different time points during synthesis or changing the temperature, particle growth rates was found to be fastest for octahedra covered by {111} facets. On the other hand, a slower reaction rate favors the generation of cubes enclosed by {100} facets. The nanocube and nanooctahedra size can also be tuned within a range. UV–vis spectra were used to investigate their unique optical property and suggested that their optical responses are closely related to silver shell thickness and gold core size. Both spectral blue-shifts and red-shifts of the Au–Ag nanocrytals compared to Au cores have been observed. With very thin shell thickness, spectral blue-shift was recorded. As particle size increases, red-shift occur.

The hydrothermal-calcination technique was used to modify raw sand with silver (Ag) at different weight percentages: 2%, 5%, and 10% using silver nitrate. The raw and sand-coated Ag nanoparticle samples were analyzed using various techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) analysis. The antibacterial properties of the raw and modified sand samples were evaluated using the zone of inhibition test and the minimum inhibitory concentration (MIC) method. This study aims to determine the efficiency of sand-coated Ag nanoparticles in removing iron ions and bacteria, specifically Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), compared to raw sand. The results showed that the Ag content in the modified sand increased proportionally with the silver nitrate concentration. The modification of raw sand with 2% Ag nanoparticles resulted in a significant increase in surface area (85.78%), adsorption pore diameter (138%), and micropore volume (65.65%). The sand modified with 2% Ag exhibited a 31.29% higher removal efficiency and 14.6 mg/g greater adsorption capacity for iron ions than raw sand. A feed pH level between 4 and 10 was found to be optimal for iron removal efficiency (99.95%) using a 1.5 g/L sand-coated with 2% Ag. The maximum adsorption capacity of iron ions obtained in this study was 64 mg/g using sand-coated 2%Ag (dose = 0.2 g/L) at 24 °C in 4 h. Studies utilizing zone of inhibition and MIC methods revealed that the modified sand exhibits strong antibacterial properties against both Gram-positive and Gram-negative strains. In contrast, the raw sand shows no antibacterial activity. All sand-coated Ag nanoparticle samples achieved 100% growth inhibition at 72 µg/mL.

Biologically synthesized nanoparticles are rapidly evolving because it is cost effective and eco-friendly, this also contributes to its preference over nanoparticles from other sources. In this study, silver nanoparticles were synthesized from Albuca setosa aqueous bulb (ASB) extracts and the biological activities evaluated. The silver nanoparticles were synthesized from ASB extracts using silver nitrate and characterized using UV–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The antioxidant activity was determined by evaluating the effect on 2,2-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, 2,2[Formula: see text]-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid diammonium salt (ABTS). The antibacterial potential was investigated on selected Gram positive and Gram negative bacteria while the cytotoxicity was evaluated on MDA-MB-231 breast cancer cells (ATCC HTB-26). Albuca setosa silver nanoparticles (AS-AgNPs) was formed within 60 min reaction time of UV–Vis absorption. The FTIR showed that acid anhydride, alkene, amine, aldehyde, ester, ketone and carbonyl groups contributed to the synthesis of the AS-AgNPs, while SEM and TEM showed stable irregular shaped monodispersed silver nanoparticles with average size of 7 nm. The XRD patterns revealed diffraction peaks at [Formula: see text] and 92.37∘ that was indexed to (1 1 0), (1 1 0), (1 0 0), (1 0 0) and (1 0 0) planes of face-centered cubic (fcc) crystalline structure respectively. The synthesized nanoparticles possess good antioxidant activity with IC50 of [Formula: see text] and [Formula: see text][Formula: see text][Formula: see text]g/ml for DPPH and ABTS, respectively, and inhibit the growth of Staphylococcus faecalis and Bacillus cereus with MIC of 25 and 15[Formula: see text][Formula: see text]g/ml respectively. AS-AgNPs also revealed higher cytotoxic efficacy against MDA-MB-231 breast cancer cells with IC50 of [Formula: see text][Formula: see text][Formula: see text]g/ml. AS-AgNPs showed acceptable size and shape of nanoparticles and could therefore be a potential source of antimicrobial and anticancer agents. It can be concluded that the synthesized AS-AgNPs is a good source of anticancer agent with broad spectrum of antibiotic activity.

Abstract Cu 2+ @MSNs‐(CO 2 − ) 2 has been prepared and characterized by using small angle powder X‐ray diffraction (XRD), Nitrogen adsorption–desorption analysis, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy dispersive X‐ray (EDX), Thermal analyses (TGA‐DTA) and FT‐IR studies. A facile one‐pot, four‐component condensation reaction of ethyl acetoacetate, hydrazine hydrate, aromatic aldehydes, and barbituric acid for synthesis of pyrazolopyranopyrimidines is efficiently catalyzed over Cu 2+ @MSNs‐(CO 2 − ) 2 in water. This catalyst is easily recovered from the reaction mixture and reused several times without any loss in catalytic activity.

Silver(I) oxide (Ag2O) is a p-type semiconductor with a reported band gap of 1.46 eV. Ag2O has the same cubic cuprite crystal structure as that of Cu2O. In the first project, we have successfully developed a facile procedure for the synthesis of Ag2O nanocrystals with systematic shape evolution from cubic to octahedral and hexapod structures by adjusting the amounts of NH4NO3, AgNO3, and NaOH solutions added to make the reaction mixture, while keeping their molar ratios constant. The crystals are mostly sub-micrometer-sized. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy characterization have been used to determine their crystalline facets. This work represents one of the first reports to achieve synthesis of Ag2O nanocrystals with systematic shape evolution. In the next study, we used Ag2O nanocubes, rhombicuboctahedra, octahedra, and extended hexapods to examine the relative stability of different crystal faces of Ag2O by selectively etching the least stable faces. NH3 was used as the etchant. By carefully controlling the volume of NH3 solution injected, only a specific face was etched, resulting in the formation of new Ag2O nanostructures. Ag(NH3)2+ formed from dissolved silver ions should drive the etching process while NaOH tunes the reaction equilibrium to control morphology of the etched nanocrystals. The order of facet stability in this reaction was found to be {111} > {110} > {100}. The {100} faces are most easily etched. In the third work, the use of these Ag2O heterostructures as templates for the formation of Ag2O–Ag2S core–shell structures and Ag2S cages with morphology control via nanoscale Kirkendall effect was considered. Cubic and hexapod-shaped Ag2S nanocages were produced from Ag2O nanocrystals of corresponding shapes. Cyclic voltammetry curves and scanning electron microscopy images were taken on cubic Ag2O crystals and cubic Ag2O–Ag2S core–shell structures to examine the effects of electrochemical redox processes on the morphology and composition integrity of the initial particles for the first time.

Bisferrocene-containing ionic liquid supported on silica coated Fe3O4: A novel nanomagnetic catalyst for the synthesis of dihydropyrano[2,3-c]coumarin derivatives

Nanotechnology and nanoparticles (NPs) researches have attracted a lot of interest in recent decades, and there is growing attention to find more effective ways for their synthesis. The use of biological approach, (using various microorganisms), as bio-nanofactories provides a clean and promising alternative process for the fabrication of silver nanoparticles. This study confirmed the production of silver nanoparticles (AgNPs) by a cost effective, safe and environment-friendly technique using silver nitrate and supernatants of the bacterium Bacillus subtilis ssp spizizenii MT5 as a bio reducing agent. Supernatants of the tested microbe growing on nutrient broth (NB) were used for fabrication of AgNPs. Some parameters of optimization i.e., incubation time, silver nitrate concentration, mixing ratio of culture supernatant and silver nitrate, media type, temperature degree and pH level were studied. The biosynthesis of AgNPs in the cell extract filtrate was confirmed and characterized by biophysical methods using the advanced available instruments. The determined conditions for the bioinspired synthesis of AgNPs revealed that incubation time was 40 h, silver nitrate concentration was 3mM, supernatant and silver nitrate ratio was 1:4, medium type was nutrient broth (NB), agitation speed was 160 rpm, temperature degree was 35°C and pH level was 7. Characterizations of the produced bio silver nanoparticles were done using the advanced available methods. The ultraviolet-visible spectrum showed an absorption peak at 420 nm. Transmis­sion electron microscopy (TEM) showed that the mean diameter of the formed AgNPs was 38 to 49 nm. Powder X-ray diffraction (XRD) showed that the particles are crystalline in nature, with a face-centered spherical structure. Dynamic light scattering (DLS) and Zeta potential analysis showed that the average AgNPs size was 31.42 nm and the zeta potential was -20.8mV, Fourier Transform Infrared Spectroscopy analysis (FT - IR) confirmed the presence of elemental silver and the dual function of biomolecule responsible for the bio reduction and stabilization of AgNPs in the reaction mixtures. The scanning electron microscopy (SEM) micrograph indicated that produced AgNPs are spherical in shape. However, it also showed an indeterminate morphology. Energy-dispersive X-ray spectroscopy (EDX) exhibited strong signal in the silver region which confirms the formation of AgNPs.

The preparation of N-propylpiperazine sulfonic acid-functionalized Fe3O4-magnetic core–shell silica nanoparticles (Fe3O4/SiO2-Propyl-Pip-SO3H) as a new recoverable and heterogeneous nanocatalyst is described. The size, morphology and other properties of this catalyst were characterized using various techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, elemental analysis, vibrating sample magnetometery and acid–base titration. Moreover, we have examined the catalytic activity of these nano-sized particles for one-pot, efficient and facile synthesis of biologically active 9H-xanthene or methylenediphenol derivatives via three-component condensation reaction of xylenol and aldehydes under solvent-free conditions at 120 °C. This method provides many advantages such as high yields of products, short reaction times, waste free and mild reaction conditions. Also, this nanocatalyst can be easily recovered by an external magnetic field and can be reused for this condensation five times in succession without considerable loss of its catalytic activity.