Hydrazine Hydrate In Presence Research Articles

Silver Nanoparticles: Synthesis in Newly Formed Ternary Deep Eutectic Solvent Media, Characterization and their Antifungal Activity

Background: When halide salts and hydrogen bond donors are combined, they produce Deep Eutectic Solvents, which have a lower freezing/melting point than the individual components. At room temperature, they have emerged as viable alternatives to ionic liquids. The wonderful features of deep eutectic solvents such as humidity tolerance, high-temperature stability, low cost, non-hazardous, reusable, and recyclable nature, allow them to replace ionic liquids. Objective: To prepare two newer Ternary Deep Eutectic Solvents using Malonic acid - Glucose – Glutamine and Malonic acid - Fructose – Glutamine. Using the prepared ternary deep eutectic solvents, to synthesize silver nanoparticles and study the antifungal behavior. Methods: The ternary deep eutectic solvents were prepared by the evaporation method in water and subjected to measure the properties such as density, pH, conductivity, viscosity, and absorption frequencies of Fourier Transform Infrared Spectroscopy. The prepared deep eutectic solvents are used for the synthesis of Silver Nanoparticles by the chemical reduction method in presence of Hydrazine Hydrate as a reducing agent and sodium hydroxide as a stabilizing agent. The synthesized nanoparticles are characterized by UV-Visible Spectroscopy, Fourier Transform Infrared Spectroscopy, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analysis techniques. Results: The characteristic absorption peak of UV-Visible Spectroscopy shows that silver nanoparticles were formed. FTIR exposes the metallic and other bonding of the nanoparticles and the caping materials. From the XRD pattern, we found the crystalline and the images formed in the SEM are in the nanoscale. The average particle size of silver nanoparticles is 116.87nm and 26.61 nm. Conclusion: In our study, two types of novel ternary deep eutectic solvents were developed. They act as a better solvent media for the synthesis of silver nanoparticles and the synthesized nanoparticles show antifungal behaviors against some fungi.

Mechanosensitive non-equilibrium supramolecular polymerization in closed chemical systems

Chemical fuel-driven supramolecular systems have been developed showing out-of-equilibrium functions such as transient gelation and oscillations. However, these systems suffer from undesired waste accumulation and they function only in open systems. Herein, we report non-equilibrium supramolecular polymerizations in a closed system, which is built by viologens and pyranine in the presence of hydrazine hydrate. On shaking, the viologens are quickly oxidated by air followed by self-assembly of pyranine into micrometer-sized nanotubes. The self-assembled nanotubes disassemble spontaneously over time by the reduced agent, with nitrogen as the only waste product. Our mechanosensitive dissipative system can be extended to fabricate a chiral transient supramolecular helix by introducing chiral-charged small molecules. Moreover, we show that shaking induces transient fluorescence enhancement or quenching depending on substitution of viologens. Ultrasound is introduced as a specific shaking way to generate template-free reproducible patterns. Additionally, the shake-driven transient polymerization of amphiphilic naphthalenetetracarboxylic diimide serves as further evidence of the versatility of our mechanosensitive non-equilibrium system.

Bis(NHC)-Pd(II) and Pd(0) complexes supported on magnetic SBA-15 for the selective aerobic oxidation of benzyl alcohols to benzaldehydes and reduction of nitroarenes

The present study describes the synthesis, characterization, and use of two new supported magnetic Pd-NHC catalysts based on Pd(II) and Pd(0). A composite of magnetite-silica core shells and SBA-15 was successively treated with (3-aminopropyl) triethoxysilane (APTES), cyanuric chloride (CC), imidazole, 2-bromopyridine, and trans-[Pd(Cl)2(SMe2)2] complex. The obtained supported bis(NHC)-Pd(II) complex, Fe3O4@SiO2@SBA-AP-CC-bis(NHC)-Pd(II), was characterized by Fourier transform infrared spectroscopy (FT-IR), X‐ray diffraction spectroscopy (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), energy‐dispersive X‐ray analysis (EDX), and Brunauer-Emmett-Teller surface area measurement (BET). The catalytic potential of the supported bis(NHC)-Pd(II) complex was explored for the selective preparation of benzaldehydes from the corresponding benzyl alcohols. The Pd(0) catalyst, Fe3O4@ SiO2@SBA-AP-CC-bis(NHC)-Pd(0), was obtained via reduction of the Pd(II)-catalyst with NaBH4. The obtained Pd(0)-catalyst efficiently reduced nitroarenes to anilines in the presence of hydrazine hydrate. The Pd contents of the Pd(II)-catalyst (2.83%wt.; 0.266 mmol/g) and Pd(0)-catalyst (2.26%wt., 0.212 mmol/g) were measured by atomic absorption spectroscopy. Both reactions are conducted under optimal reaction conditions of the solvent, the base, and the catalyst dosage. The catalysts enjoy easy magnetic separation, recyclability over eight runs without significant loss activity, and noticeable stability. They showed negligible palladium leaching (0.83% in the oxidation of benzyl alcohol and 0.1% in the reduction of nitroarenes).

TFE assisted mechanochemical synthesis of new pyrazolones from Meldrum acid carbothioamides-Experimental and theoretical studies

Facile synthesis of Meldrum acid carbothioamides 3 from condensation of Meldrum acid and aryl isothiocyanates under ultrasonication is reported. The structure of carbothioamides was investigated in solid and solution state from X-ray diffraction and spectroscopic studies, respectively. Studies on photo-tautomerism emanating from proton switching between O and S under UV irradiation have been reported. S-methyl derivatives 4 of carbothioamides 3 were also prepared and solid state structure of the representative compound was described. Novel synthetic mechanochemical route to synthesis of functionalized pyrazolones 5 from reaction of carbothioamides 3 or their S-methyl derivatives and hydrazine hydrate in presence of 2,2,2-trifluoroethanol has been developed. The structure and proton tautomerism of pyrazolones has been assigned on spectroscopic grounds and authenticated by single crystal X-ray diffraction (SCXRD) studies. The tautomeric equilibrium between different forms of pyrazolone 5a has been studied by ab initio calculations. Experimental studies are in congruous with theoretical results. Further, synthesis of new thiazole derivatives 6 and thiazolidin-5-one derivatives 7 linked with Meldrum's acid (MA) moiety was achieved from reaction of 3 with 3-chloro-2,4-pentanedione and chloroacetyl chloride, respectively. Spectroscopic studies confirmed the structure of new developed products.

Synthesis of some new 2-mercaptobenzoxazol and study their biological activity against some plant pathogenic fungi

The research included synthesis of 2-mercapto benzoxazole (MBO) (1) ) from the reaction of ortho hydroxyl aniline with carbon disulfide in ethanolic potassium hydroxide. The hydrazine benzoxazole HMBA2 (2) was synthesized from the reaction of compound MBO (1) with hydrazine hydrate in presence of alcohol. Compounds (3(a- e)) were synthesized by condensate on of substituted Benzaldehydes with 2-Hydrazino benzoxazole HMBA2. The Ethyl2-(benzoxazolylthio) acetate EMBA1 (4) obtained from the reaction of compound MBO (1) with solution of ethyl chloro acetate using KOH alcoholic .Finally the compound hydrazide HMBA(5 (a- e)) was synthesized from the reaction of compound (4) with hydrazine hydrate in presence of alcohol .All these synthesized compounds were characterized on the basis of their 1H-NMR ,IR, The study is Showed biological activity for chemical compounds, at three concentration 100, 200, 300 ppm in toxic potato Dextrose Agar (PDA) medium method against phytopathogenic fungi three species Fusariumgraminarium, Sclerotiniasclerotium and Rhizoctoniasolani, its isolation on nutritious PDA medium from root plants wheat ,eggplant and cotton continually, diameter measure of fungi growth colony result showed all compound growth inhibition barring MMBA compound non effective inhibition its, appear MBO moral superiority after bring HMBA2 both induce inhibition amount 49.69 and 34.22% continually. Compound concentration its average effect result reveal third significant superior on first and second concentration, interference effect concentration and species chemical compound notice higher inhibition amount 100%with third concentration MBO compound all test its fungi .

Development of Thermal Camouflage Polyester-Cotton Blended Fabric for Defense Security Personnel via Coating with Graphene Oxide and Reduced Graphene Oxide

ABSTRACT In this study, graphene oxide (GO) was prepared with modified Hummer’s method while reduce graphene oxide (rGO) was prepared in the presence of hydrazine hydrate and then coated on polyester cotton (PC) blend camouflage pattern print fabric using the pad-dry-cure method. The as-synthesized GO and rGO were characterized by dynamic light scattering (DLS) analysis, X-ray diffraction (xRD), and UV-visible spectrophotometry. The surface morphology and the thermal camouflage property of the coated fabric were investigated by scanning electron microscopy (SEM) and infrared thermal imaging test, respectively. The average particle size of GO and rGO were 99.8 nm and 0.4 nm, respectively. The fabrics treated with GO and rGO apparently reduced the emitting temperature of the human body and made it similar to the surrounding environment. The increase in the concentration of coating materials (GO and rGO) resulted in the enhancement of camouflage property. Interestingly, the camouflage property of the coated fabric was very good even after several washing cycles. Based on these scientific outcomes, the coating of PC fabric with GO and rGO is a novel and successful approach in the development of thermal camouflage technical textiles which can be potentially applied on pilot-scale experiments to establish its industrial-scale feasibility.

Hollow CoO Nanoparticles Embedded in N‐doped Mesoporous Graphene for Efficient Oxygen Reduction Reaction

AbstractDevelopment of reactive and stable non‐preciously metallic catalysts toward oxygen reduction reaction is a fascinating research field for fuel cells. Herein, a hybrid electrocatalyst consisted of hollow CoO nanoparticles embedded in N‐doped mesoporous graphene (CoO@N−G) has been successfully prepared via carbonizing the precursor which is prepared from graphene oxide and N, N′‐Bis(salicylidene) ethylenediamine cobalt salt in the presence of hydrazine hydrate. The formation of hollow CoO nanoparticles is generally attributed to the nanoscale Kirkendall effect. The effective synergistic effect of hollow CoO nanoparticles and N‐doped mesoporous graphene is helpful to obtain excellent electrocatalytic activity with four‐electron selectivity, long‐term stability and good anti‐methanol.

Assessment of Physicochemical, Anticancer, Antimicrobial, and Biofilm Activities of N-Doped Graphene

Nanomedicine has been used as a precise treatment for many diseases. The advantage of using nanodrugs is that they have more permeability and less toxicity to cells, which enhances the drug delivery system. Graphene is well known for its potential biological applications in drug, food, and pharma industries. This study aimed to assess the productivity and potentiality of nitrogen-doped graphene (NDG) and to evaluate their anticancer, antimicrobial, and biofilm inhibition activity. Nitrogen-doped graphene was synthesized by using a one-pot facile synthesis of NDG, wherein the NDG was prepared by the reduction of graphene oxide (GO) in the presence of hydrazine hydrate as a reducing agent, while ammonium hydroxide was used as a source of nitrogen on the surface of graphene. As-synthesized NDG was characterized by various characterization techniques such as UV-Vis, FT-IR, XRD, XPS, TEM, and N2 sorption studies analysis. Antimicrobial, anticancer, and biofilm inhibition assays were performed by standard protocols. N-doped graphene (NDG) showed better activity against Gram-positive bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), Bacillus subtillis, Streptococcus pneumoniae, and Streptococcus mutans (p ≤ 0.05), whereas there was no activity against Gram-negative strains in Klebsiella pneumoniae and Pseudomonas aeruginosa. Biofilm inhibition was also improved with NDG compared to the standard ampicillin. NDG showed better results in both MCF-7 and Hela cell lines with IC50 of 27.15 µg/mL and 30.85 µg/mL, respectively. In conclusion, NDG has the best ability for use as a biomolecule, and research studies focusing on proteomics, metabolomics, and in vivo studies are needed to increase the impact of NDG in the drug and pharma industry.

Sustainable Coordination Polymer-Based Catalyst and Its Application in the Nitroaromatic Hydrogenation under Mild Conditions.

Nitroarene reduction has played a crucial role in the environment remediation and public health. However, few research studies have been undertaken regarding the use of infinite coordination polymer-based catalysts in this process. Herein, we are looking for a way to catalyze the reduction of nitroarenes using a new and well-designed coordination polymer-based palladium catalyst. The Co-BDC-NH2 coordination polymer was prepared through a co-precipitation reaction between 2-amino-1,4-benzenedicarboxylic acid as a linker and the cobalt cation as a node. Functionalization of the prepared Co-BDC-NH2 with 2-pyridinecarboxaldehyde and subsequent metallation with a Pd cation led to the formation of the final catalyst, i.e., Co-BDC-NH2-py-Pd. It has been specified that palladium species substantially contribute to the reduction of nitroarenes in the presence of hydrazine hydrate (N2H4·H2O). The highest conversion (100%) of nitroarenes to the corresponding amines was achieved under relatively mild conditions. This heterogeneous catalyst was able to catalyze the reduction of nitroarenes to desired products without changing other substituents. The reusability and stability of the catalyst were confirmed through four consecutive reduction tests without a major decrease in catalytic activity.

Facile One-Pot Multi-Component Synthesis, Characterization, Molecular Docking Studies, Biological Evaluation of 1,2,4-Triazolo Isoindoline-1,3-Diones and Their DFT Calculations

Alkyl/aralkyl/phenacyl thiotriazolyl isoindoline-1,3-diones were synthesized by the reaction of dipotassium cyanodithioimidocarbonate salt with hydrazine hydrate, phthalic anhydride and alkyl/aralkyl/phenacyl bromides using acetic acid and sodium acetate via a one-pot four-component synthesis. Alternatively, the same final products were also synthesized by the reaction of dipotassium cyanodithioimidocarbonate salt with hydrazine hydrate in presence of acetic acid to give intermediate 5-amino-4H-1,2,4-triazole-3-thiol [I]. This compound was further reacted with phthalic anhydride, followed by a reaction with alkyl/aralkyl/phenacyl bromides to give the title compounds in a two-step process. In this method, the yields are less compared to one-pot four-component synthesis. All the newly synthesized compounds were characterized by their spectral studies (FTIR, 1H-NMR, 13C-NMR, Mass). Further, the synthesized compounds were screened for their in-vitro anticancer activity. Compounds 5 m, 5p, 5r showed good cytotoxic assay against Hela cancer cell lines. Furthermore, compounds 5(a-t) were subjected to their docking analysis and DFT calculations.

Synthesis and characterization of Graphene Oxide and its reduction with different reducing agents

-The present work reports the simplistic formation of graphene oxide (GO) and reduced graphene oxide (rGO) by oxidizing graphite powder with the 9:1 volume combination of concentrated sulfuric acid/and ortho-phosphoric acid (H2SO4/H3PO4) in the company of KMnO4 as an oxidant. The acid combination solution of H2SO4/H3PO4 produces the improved oxidized hydrophilic GO without any evolution of hazardous gases instead of only H2SO4, which differentiates this procedure from the Hummers’ method. Then, the synthesized GO is diminished to rGO by employing various reducers namely hydrazine hydrate, sodium borohydride and, ascorbic acid through the chemical route. The properties of synthesized materials have been investigated by diverse investigative systems that are X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Raman spectroscopy and, Energy Dispersive X-ray spectroscopy (EDS) which approved its high crystallinity and reduction of GO into rGO. EDS analysis confirms that the carbon to oxygen ratio is higher in rGO prepared by using hydrazine hydrate in comparison to rGO made by using sodium borohydride and ascorbic acid which reveals the good reducing capability of hydrazine hydrate. Hence, it may be concluded that the rGO synthesized by the reduction of GO in the presence of hydrazine hydrate is better as compared to others and it is expected that the synthesized material may be used for various applications.

Thermal Degradation of Natural Rubber Vulcanizates Reinforced with Organomodified Kaolin Intercalates

In this study, Natural Rubber Vulcanizates (NRV) reinforced with organomodified kaolin was developed. The NRV were subjected to thermal degradation to ascertain its suitability for high-temperature automotive applications. Kaolin intercalation was achieved using derivatives of Rubber seed oil (Hevea brasiliensis) and Tea seed oil (Camellia sinensis) in the presence of hydrazine hydrate as co-intercalate. The developed Natural Rubber Vulcanizates were characterised using Thermogravimetric Analysis (TGA), Fourier Transform Infrared (FTIR) Spectroscopy and Scanning Electron Microscopy (SEM). FTIR spectra obtained for the organomodified natural rubber vulcanizates revealed the presence of carbonyl groups at bands 1564cm-1 and 1553cm-1 which is an indication of organomodified kaolin intercalation within the Natural Rubber matrix for kaolin intercalates of Rubber seed oil and Tea seed oil respectively while no value was reported for the Natural Rubber vulcanizates obtained from the pristine kaolin filler. TGA results indicated that NRV developed from kaolin intercalates of Rubber seed oil (RSO) with onset degradation and final degradation temperatures of 354.2°C and 601.3°C were found to be the most thermally stable of the Natural Rubber Vulcanizates investigated. The SEM micrograph revealed that the kaolin nanofillers in Rubber Seed Oil modified Natural Rubber Vulcanizates were well dispersed as compared to that of Tea Seed Oil modified Natural Rubber Vulcanizates.

Pyrazoline analogs as potential anticancer agents and their apoptosis, molecular docking, MD simulation, DNA binding and antioxidant studies

N-formyl pyrazoline derivatives (3a–3l) were designed and synthesized via Michael addition reaction through cyclization of chalcones with hydrazine hydrate in presence of formic acid. The structural elucidation of N-formyl pyrazoline derivatives was carried out by various spectroscopic techniques such as 1H, 13C NMR, FT-IR, UV–visible spectroscopy, mass spectrometry and elemental analysis. Anticancer activity of the pyrazoline derivatives (3a–3l) was evaluated against human lung cancer (A549), fibrosarcoma cell lines (HT1080) and human primary normal lung cells (HFL-1) by MTT assay. The results of anticancer activity showed that potent analogs 3b and 3d exhibited promising activity against A549 (IC50 = 12.47 ± 1.08 and 14.46 ± 2.76 µM) and HT1080 (IC50 = 11.40 ± 0.66 and 23.74 ± 13.30 µM) but low toxic against the HFL-1 (IC50 = 116.47 ± 43.38 and 152.36 ± 22.18 µM). The anticancer activity of potent derivatives (3b and 3d) against A549 cancer cell line was further confirmed by flow cytometry based approach. DNA binding interactions of the pyrazoline derivatives 3b and 3d have been carried out with calf thymus DNA (Ct-DNA) using absorption, fluorescence and viscosity measurements, circular dichroism and cyclic voltammetry. Antioxidant potential of N-formyl pyrazoline derivatives (3a–3l) has been also estimated through DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical and H2O2. Results revealed that all the compounds exhibited significant antioxidant activity. In silico molecular modelling and ADMET properties of pyrazoline derivatives were also studied using PyRx software against topoisomerase II receptor with PDB ID: 1ZXM to explore their best hits. MD simulation of 3b and 3d was also carried out with topoisomerase II for structure–function correlation in a protein. HuTopoII inhibitory activity of the analogs (3a–3l) was examined by relaxation assay at varying concentrations 100–1000 µM.

Preparation and characterization of 6-O-caffeic acid chitosan

The modified chitosan retains the excellent properties of chitosan and can broaden its application. In this paper, an approach of protection-deprotection was used to synthesize 6-O-caffeic acid chitosan with chitosan as the raw material. Firstly, the free amino group on the 2-position carbon of chitosan was protected by phthaloylation, and then the -OH of 6-position carbon of chitosan reacted with caffeic acid by ester condensation. Finally, in the presence of hydrazine hydrate, the amino group was deprotected to form 6-O-caffeic acid chitosan. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) characterized the structures of the intermediates and products. The results showed that 6-O-caffeic acid chitosan was successfully obtained. Thermogravimetric analysis indicated that 6-O-caffeic acid chitosan had better thermo-stability than chitosan in nitrogen. This will expand the application of chitosan in vaious fields.

Influence of TiO2’s (101) crystal facet exposure on the photoelectroactivity of TiO2 nanooctahedra/BiVO4 nanocomposite

This work studies a research regarding the effect of exposing (101) crystal facet of anatase TiO2 to photoelectroactivity of photoanode composed of TiO2 nanooctahedra/BiVO4 nanocomposite film. Here, the photoanode was fabricated by depositing the nanocomposite on the surface of FTO via doctor blade technique. In this study, anatase TiO2 nanooctahedra were synthesized via solvothermal method in the presence of hydrazine hydrate as a directing agent. Furthermore, the as-prepared TiO2 nanooctahedra was characterized using X-Ray Diffractometer (XRD), Transmission Electron Microscopy (TEM), Brunauer-Emmelt-Tellers (BET) and UV-Vis diffuse reflectance spectra (DRS). Based on the result, the diffraction peaks revealed characteristic for the pure anatase phase with exposure (101) crystal facet. Additionally, photoelectrochemical response of the photoanode was also evaluated using a three-electrode system and exhibited a significantly high current density value of 0.26 mA/cm2.

Preparation of Ag/reduced graphene oxide reinforced copper matrix composites through spark plasma sintering: An investigation of microstructure and mechanical properties

The reduced graphene oxide (rGO) decorated with Ag nanoparticles was synthesized by the chemical reduction of graphene oxide in an aqueous solution containing AgNO3, in the presence of hydrazine hydrate as a reducing agent. The reduction of graphene oxide was confirmed by FT-IR and raman spectroscopy analyses. The x-ray diffraction pattern and UV–visible investigations demonstrated the formation of Ag particles on the surface of rGO sheets. After successful decoration, the Ag/rGO nano-composite was used as the reinforcement in the copper matrix composite. Cu–Ag/rGO composites with different percentages of Ag/rGO (0.4, 0.8, 1.6 and 3.2 vol%.) were prepared by mechanical milling and spark plasma sintering (SPS). The effects of the Ag/rGO content on the consolidation process, micro-hardness, bending strength and also, fracture surface of the prepared samples were then investigated. The three-point bending strength of the sintered samples was increased from 285 to 472 MPa by the addition 0.8 vol%. of Ag/rGO, as compared to the pure Cu. Moreover, increasing the reinforcement content to the 3.2 vol%. Ag/rGO led to decreasing the bending strength to 433 MPa. The highest micro-hardness (81 Hv) was obtained for the composite sample containing the 1.6 vol%. Ag/rGO. By increasing Ag/r-GO as the reinforcement (3.2 vol%.), the Vickers hardness was decreased to 69 Hv. Also, investigation of the fracture surface morphology showed transformation of fracture mechanism from plastic changes to brittle ones by raising the Ag/rGO content volume from 0.8 to 1.6 vol %.

Chemoselective Reduction of Nitroarenes with Hydrazine over a Highly Active Alumina-Supported Cobalt Nanocatalyst

A green and efficient procedure is reported for the chemoselective reduction of nitroarenes catalyzed by a highly active alumina-supported cobalt nanocatalyst in the presence of hydrazine hydrate. The nanocatalyst can be applied under mild reflux conditions for the synthesis of arlyamines in high yields. Moreover, the catalyst can be easily recovered by simple filtration and reused several times without obvious loss in its catalytic activity.

Nanoheterostructures of ZnO Nanorods Decorated with ZnFe2O4 Nanoparticles by a Simple Solution Process

Background: Nanoheterostructures of ZnFe2O4–ZnO is a potential functional material synthesized by various complicated synthesis processes. However, most of the processes are not at all cost effective because these generally require high-temperature treatment as well as long reaction time and complicated experimental procedure. Thus, a simple, low cost and highly efficient synthesis process is still highly required. Objective: The aim of the present study is to synthesize ZnFe2O4–ZnO nanoheterostructures by a simple solution process vis-à-vis to characterize the structural and optical properties of the sample. Methods: Nanoheterostructures of ZnFe2O4 decorated on ZnO nanorods (ZFZO) have been synthesized by two-step low-temperature solution process in the presence of hydrazine hydrate. Results: X-ray diffraction study showed the presence of hexagonal ZnO and cubic ZnFe2O4 spinel. Transmission electron microscopic analysis confirmed the formation of nanoheterostructures of ZnFe2O4 decorated on ZnO nanorods. The optical property of the sample was characterized by UVVisible spectroscopy. Moreover, the oxidation states of the elements were examined by X-ray photoelectron spectral studies. A probable formation mechanism of the nanoheterostructures was drawn. Conclusion: This simple solution based synthesis process is found to be an easy and cost- effective synthesis strategy as realized from the characterizations of structural and functional properties of the synthesized samples of ZnFe2O4–ZnO nanoheterostructures.

Biosynthesized gold nanoparticles supported on magnetic chitosan matrix as catalyst for reduction of 4-nitrophenol

The design and environmentally-safe synthesis of magnetically recoverable solid-supported metal nanoparticles with remarkable stability and catalytic performance has significant industrial importance. In the present study, we have developed an inexpensive bioinspired approach for assembling gold nanoparticles (AuNPs) in magnetic chitosan network under green, mild and scalable condition. AuNPs were well loaded on the surface of the magnetic support due to the presence of hydroxyl (-OH) and amino (-NH2) groups in chitosan molecules that provided the driving force for the complexation reaction with the Au(III) ions. Reduction of the Au(III) to Au(0) is achieved by using Melicope ptelefolia aqueous leaf extract. The synthesized magnetic chitosan supported biosynthesized Au nanocatalyst was characterized using Fourier Transform Infrared (FT-IR), Carbon, Hydrogen and Nitrogen (CHN), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and Atomic Absorption Spectroscopy (AAS) analyses. FTIR spectrum of magnetic chitosan shows peaks at 1570 cm-1 indicative of N-H bending vibration and at 577 cm-1 which designates the Fe-O bond. CHN analytical data further supported the coating of chitosan onto the magnetite. TEM analysis shows an amorphous layer around the magnetite core which supported the coating of chitosan on the magnetite surface and the average particle size of AuNPs calculated was 7.34 ± 2.19 nm. XRD analysis shows six characteristics peaks for magnetite corresponding to lattice planes (220), (311), (400), (422), (511) and (440) in both the magnetite and magnetic chitosan samples (JCPDS file, PDF No. 65-3107). Meanwhile, XRD analysis of catalyst shows characteristic peaks of AuNPs at 2q (38.21°, 44.38°, 62.2°, 77.32° and 80.76°) are corresponding to (111), (200), (220), (311) and (222) lattice plane (JCPDS file, PDF No.04-0784). AAS analysis shows the loading of AuNPs as 5.4%. The rate constant achieved for the reduction of 4-nitrophenol to 4-aminophenol in the presence of hydrazine hydrate using 10 mg of catalyst is 0.0046 s-1. The magnetic chitosan supported AuNPs is effective as catalyst for the reduction of 4-nitrophenol.

One-Pot Synthesized Pd@N-Doped Graphene: An Efficient Catalyst for Suzuki–Miyaura Couplings

Nitrogen-doped graphene (NDG)-palladium (Pd)-based nanocatalysts (NDG@Pd) can be potentially applied as an efficient catalyst for the preparation of biaryls in a Suzuki–Miyaura coupling reaction. Herein, we report the one-pot facile synthesis of an NDG@Pd nanocatalyst, wherein the nanocatalyst was prepared by the simultaneous reduction of graphene oxide (GRO) and PdCl2 in the presence of hydrazine hydrate as a reducing agent, while ammonium hydroxide was used as a source of “N’’ on the surface of graphene. The as-synthesized NDG@Pd nanocatalyst, consisting of smaller-sized, spherical-shaped palladium nanoparticles (Pd-NPs) on the surface of NDG, was characterized by several spectroscopic and microscopic techniques, including high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET). The nanocatalyst displayed outstanding catalytic activity in the Suzuki–Miyaura cross-coupling reactions of phenyl halides with phenyl boronic acids under facile conditions in water. The catalytic activity of NDG@Pd was found to be a more efficient catalyst when compared to pristine highly reduced graphene oxide (HRG) based Pd nanocatalyst (HRG@Pd). Furthermore, the reusability of the catalyst was also tested by repeatedly performing the same reaction using the recovered catalyst. The N-doped catalyst displayed excellent reusability even after several reactions.