Green Synthetic Route Research Articles

Imidazolate-mediated assembled structures of Co-LDH sheets for efficient electrocatalytic oxygen evolution

To fully achieve an eco-friendly means of storing electricity in the form of chemical fuels, the development of a green synthetic route towards highly active oxygen evolution reaction (OER) electrocatalysts is required.

Ambient stable naphthalenediimide radical ions: synthesis by solvent-free, sonication, mechanical grinding or milling protocols

Green synthetic routes to a library of twenty four diphosphonium substituted naphthalenediimide (NDI) radical ions [NDI(PR3)2]˙+ Br− (R = alkyl/aryl) with excellent yields and stability are reported.

Single step green synthesis of stable nickel and nickel oxide nanoparticles from Calotropis gigantea: Catalytic and antimicrobial potentials

Nickel (Ni) and nickel oxide (NiO) nanoparticles (NPs) were successfully synthesized by using a simple, novel and green synthetic route using metal salt and leaves extract of a wild plant “Calotropis gigantea” which act as reducing as well as stabilizing agent due to extra availability of phenolic contents and antioxidants in it. Optimization was carried out by varying different parameters controlling the reaction and the best yield was obtained at 80°C temperature, 90min incubation time, pH 12, 1mM precursor concentration and 20% extract concentration. Characterization was made by using various characterizing techniques. UV/VIS absorption peak was at 400nm for synthesized Ni NPs and at 415 for NiO NPs. The average size of the particles was 20–40nm, in the case of NiO NPs and <60nm for Ni NPs confirmed by X-ray diffraction analysis and Scanning electron microscope (SEM). Functional groups indication was made by using Fourier transform Infrared (FT-IR) spectroscopic analysis of materials. Catalytic efficiency was investigated against methylene blue dye, the maximum degradation efficiency was 98.8%, followed by first order reaction kinetics. Synthesized NPs were highly stable i.e. till 3 months. Biological test results exposed that synthesized Ni and NiO nanoparticles have broad spectrum antibiotic abilities against E. coli and Bacillus subtilus.

A green synthetic route to phenolics fabricated magnetite nanoparticles from coconut husk extract: Implications to treat metal contaminated water and heavy metal stress in Oryza sativa L.

Iron oxide nanoparticles are biocompatible. Therefore these particles are in demand for environmental cleanup. In the present study, semicrystalline magnetite nanoparticles synthesized by mixing equal volume of 10.0 mM ferric chloride solution and coconut husk extract (10.0 g L−1) at room temperature. Phenolics in the husk extract fabricated onto nanoparticles. These particles found to efficiently adsorb Ca and Cd from aqueous media. Kinetic studies indicated metal adsorption was a combined effect of both physical and chemical processes. Equilibrium studies showed maximum adsorption capacity of particles for Ca (13.7 mg g−1) and Cd (9.6 mg g−1). Calcium and Cd adsorption fitted well to Langmuir and Freundlich isotherm respectively. Both Ca and Cd had maximum adsorption at pH 6.0 and temperature 30.0 °C. Amendment of the nanoparticles (0.5 mg g−1 sand) enhanced Fe accumulation in rice plants and enabled Ca as well as Cd tolerance. Plant growth promoting effects of the nanoparticles reflected as an increase of biomass, the quantum yield of photochemistry, and chlorophyll content. Thus it is concluded that nanoparticle produced in the study is an eco-friendly material for environmental remediation.

Green synthetic route for perfumery compound (2-methoxyethyl) benzene using Li/MgO catalyst

Ethers are one of the most prominent compounds among perfumery chemicals. (2-Methoxyethyl) benzene commonly known as phenyl ethyl methyl ether (PEME) is widely used in flavour and fragrance industries. Conventionally, synthesis of PEME involves the use of hazardous and polluting chemicals, which in turn affects the purity of perfumery compound. Thus, developing a green route to synthesise PEME without any hazardous chemicals is desirable. In the current work, a new process is developed for the synthesis of PEME using solid base catalysts including MgO and Li/MgO (with different loadings of lithium) and dimethyl carbonate (DMC) as a methylating agent as well as a solvent. Different kinetic parameters were studied to achieve the optimum yield of the desired product. At optimum reaction conditions i.e., 1000 rpm of speed, $$1.33 \times 10^{-2}\,\hbox {g/cm}^{3}$$ of catalyst loading, 1:10.5 mole ratio (2-Phenyl ethanol: DMC), $$180\,^{\circ }\hbox {C}$$ , 95% conversion of 2-phenyl ethanol with 98% selectivity of PEME was achieved. A detailed kinetic model was also developed and apparent activation energy for the reaction was calculated as 11.93 kcal/mol. SYNOPSIS:2-Methoxyethyl benzene commonly known as phenyl ethyl methyl ether (PEME) was selectively synthesised in high yields from 2-phenyl ethanol (2-PE) and dimethyl carbonate (DMC) as a methylating agent with carbon dioxide and methanol as co-products. Li/ MgO with different loadings of Li was studied and 0.1% Li/MgO was found to be the best catalyst among the screened catalysts. PEME has wide applications as perfumery compound.

Eco-friendly biosynthesis, anticancer drug loading and cytotoxic effect of capped Ag-nanoparticles against breast cancer

The work aimed to prepare silver nanoparticles (Ag-NPs) from silver nitrate and various concentrations of the seed extract (Setaria verticillata) by a green synthetic route. The chemical and physical properties of the resulting Ag-NPs were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometry and ultraviolet–visible (UV–Vis) spectrophotometry. Anticancer activity of Ag-NPs (5–20 nm) had dose-dependent cytotoxic effect against breast cancer (MCF7-FLV) cells. The in vitro toxicity was studied on adult earthworms (Lumbricina) resulting in statistically significant (P < 0.05) inhibition. The prepared NPs were loaded with hydrophilic anticancer drugs (ACD), doxorubicin (DOX) and daunorubicin (DNR), for developing a novel drug delivery carrier having significant adsorption capacity and efficiency to remove the side effects of the medicines effective for leukemia chemotherapy.

Facile and Green Synthesis of Saturated Cyclic Amines

Single-nitrogen containing saturated cyclic amines are an important part of both natural and synthetic bioactive compounds. A number of methodologies have been developed for the synthesis of aziridines, azetidines, pyrrolidines, piperidines, azepanes and azocanes. This review highlights some facile and green synthetic routes for the synthesis of unsubstituted, multisubstituted and highly functionalized saturated cyclic amines including one-pot, microwave assisted, metal-free, solvent-free and in aqueous media.

Exploration of Wedelia chinensis leaf-assisted silver nanoparticles for antioxidant, antibacterial and in vitro cytotoxic applications

Green synthetic route of silver nanoparticles (AgNPs) has already been proved to be an advantageous over other physico-chemical approaches due to its simplicity, cost effectiveness, ecofriendly and nontoxicity. In this finding, aqueous Wedelia chinensis leaf extract (WLE) mediated synthesis of AgNPs was approached. Surface plasmon resonance (SPR) band at 408 nm preliminary indicated the formation of AgNPs, while TEM and XRD characterization confirmed the formation of spherically shaped and crystalline AgNPs with an average size of 31.68 nm, respectively. The plausible biomolecules in the aqueous leaf extract responsible for the reduction and stabilization of AgNPs were identified by FTIR analysis and found to be polyphenolic groups in flavonoid. Further, synthesized AgNPs was explored for different biological applications. Biosynthesized AgNPs showed significant free radical scavenging activity as compared to Wedelia leaf extract and antibacterial activity against clinically isolated test pathogens where Gram-negative bacteria were found more susceptible to AgNPs than Gram-positive one. In addition, in vitro cytotoxic response was also evaluated on hepatocellular carcinoma Hep G2 cell lines and showed a dose-dependent cytotoxic response with an IC50 value of 25 μg/mL.

Strong UV Emission from Colloidal Eu2+‐Doped BaSO4 Nanoparticles: A Material for Enhancing the Photocatalytic Activity of Carbon Dots

AbstractIn this article, we report a facile microwave‐assisted green synthetic route for the preparation of highly luminescent water dispersible polyacrylic acid‐coated europium (Eu2+)‐doped BaSO4 nanoparticles at low temperature for the first time. Polyacrylic acid coating over nanoparticles renders them water dispersible. Upon ultraviolet (UV) (250 nm) excitation, europium‐doped BaSO4 nanoparticles exhibit a strong and broad UV luminescence near at 368 nm. This emission peak is quite strong and has a relative luminescence quantum yield (QY) of 53 %. The high QY of the UV emission from the nanoparticles is explored for the enhancement of the visible photocatalytic properties of the carbon dots (Cdots). In fact, faster degradation of the Rhodamine B is noted for the mixture containing both Eu2+‐doped BaSO4 nanoparticles and cetyl trimethylamonium bromide capped carbon dots. This is attributed to the strong overlap of the UV emission of Eu2+ with the absorption spectrum of Cdots leading to high energy transfer efficiency (∼64 %). The energy transfer process is supported by the observation of lower dye degradation for the diluted colloidal mixtures where the average distance between Eu2+ in BaSO4 to Cdots nanoparticles is increased.

A Facile Green Synthetic Route for the Preparation of Highly Active \u03b3-Al2O3 from Aluminum Foil Waste

A novel green preparation route to prepare nano-mesoporous γ-Al2O3 from AlCl3.6H2O derived from aluminum foil waste and designated as ACFL550 is demonstrated, which showed higher surface area, larger pore volume, stronger acidity and higher surface area compared to γ-Al2O3 that is produced from the commercial AlCl3 precursor, AC550. The produced crystalline AlCl3.6H2O and Al(NO3)3.9H2O in the first stage of the preparation method were characterized by single-crystal XRD, giving two crystal structures, a trigonal (R-3c) and monoclinic (P21/c) structure, respectively. EDX analysis showed that ACFL550 had half the chlorine content (Cl%) relative to AC550, which makes ACFL550 a promising catalyst in acid-catalysed reactions. Pure and modified ACFL550 and AC550 were applied in acid-catalysed reactions, the dehydration of methanol to dimethyl ether and the total methane oxidation reactions, respectively. It was found that ACFL550 showed higher catalytic activity than AC550. This work opens doors for the preparation of highly active and well-structured nano-mesoporous alumina catalysts/supports from aluminum foil waste and demonstrates its application in acid-catalysed reactions.

Sustainable Catalytic Process with a High Eco‐Scale Score for the Synthesis of Five‐, Six‐, and Seven‐Membered Heterocyclic Compounds Using Nanocrystalline Zeolites

AbstractNanocrystalline ZSM‐5 and Beta zeolites were evaluated as catalysts for the one‐pot synthesis of a wide range of five‐, six‐, and seven‐membered heterocyclic compounds. Seven‐membered compounds were prepared by the reaction of o‐phenylenediamine and ketones, whereas five‐membered compounds were obtained when o‐aminothiophenol was reacted with ketones under the same reaction condition. Several other seven‐membered compounds were prepared by the reaction of (E)‐chalcone with o‐phenylenediamine/o‐aminothiophenol, whereas the six‐membered compounds described in this study were prepared by the reaction of o‐phenylenediamine with 2‐bromoacetophenone/2‐hydroxy acetophenone. Two other five‐membered compounds were prepared by the reaction of aniline with benzaldehyde and thioglycolic acid, and the reaction of glycerol with acetone. The mechanisms responsible for the formation of the different products were elucidated based on the results of time‐dependent 1H NMR experiments. To the best of our knowledge, this work represents the first reported systematic assessment of the catalytic activity of nanocrystalline zeolites for the synthesis of heterocyclic compounds. Notably, the catalysts were readily recovered and reused without any considerable decrease in their catalytic activity. The high eco‐scale score and low E‐factor value of this process clearly demonstrate that it represents a green and sustainable synthetic route for the preparation of a wide range of heterocyclic compounds of significant industrial importance.

Gram-scale, cost-effective and eco-friendly synthesis, structural and optical properties of Fe:CdS colloidal nanocrystals

The synthesis of luminescent nanocrystals via easily handled methods has received tremendous attention in recent years, especially toward scaling-up fabrication. In this work, we present a gram-scale, cost-effective and eco-friendly strategy for synthesis of water-soluble and emissive Fe:CdS nanocrystals with highly tunable properties. The structural and optical properties of the as-synthesized nanocrystals were systematically explored. The obtained Fe:CdS nanocrystals possess cubic zinc blende structure, and the Fe:CdS nanocrystals are nearly spherical and show narrow size distribution. Utilizing thioglycollic acid as the capping agent finally facilitates the water solubility of Fe:CdS nanocrystals, which makes them very useful for biomedical applications. The influence of reaction temperature on the optical properties of the as-prepared nanocrystals was investigated in detail. The particle size and optical properties of the resulting Fe:CdS nanocrystals are found to be easily tailored by simply adjusting the reaction temperature, in which the emission peaks of the Fe:CdS nanocrystals red-shift with an increase in the particle sizes of the nanocrystals. Compared to bulk CdS, the remarkable blue shift of absorption peaks induced by reaction temperature indicates strong quantum confinement effect. More interestingly, the band gap of the as-formed nanocrystals can be tailored in a broad range of 3.40 to 3.10eV by altering the reaction temperature. The synthetic strategy displayed here is preponderant in that the precursors are nontoxic and easily available, and the particle size and optical properties of the resulting nanocrystals are readily tailored. This work offers a reliable and green synthetic route toward water-soluble and highly luminescent nanocrystals with tunable optical properties.

Green Synthetic Routes to Pharmaceutical Drugs

Green Synthetic Routes to Pharmaceutical Drugs

Sonochemical synthesis and stabilization of concentrated antimicrobial silver‐chitosan nanoparticle dispersions

ABSTRACTThis work reports on a green synthetic route to produce concentrated aqueous dispersions of silver nanoparticles (AgNP) employing high‐intensity ultrasound (US) and chitosan (CS) as a nontoxic reducing agent for Ag+ salts and AgNP stabilizer. The sonication simultaneously boosted the synthesis and improved the stability of the AgNP, capping them with CS. Hybrid AgNP‐CS antimicrobial dispersions, stable for at least 6 months, were synthesized in a simple single step process. The use of US allowed for applying relatively mild processing temperatures (60 °C) and reaction time between 30 min and 3 h to obtain concentrated dispersions of AgNP that otherwise could not be obtained even after 72 h under mechanical stirring at the same reaction conditions. Upon sonication spherical AgNP‐CS with a size between 60 and 100 nm were generated, in contrast to the average diameter of ∼200 nm of the particles obtained by stirring. The antibacterial efficiency of the AgNP‐CS hybrids was evaluated against the medically relevant pathogens Staphylococcus aureus and Escherichia coli. The US‐synthesized AgNP‐CS showed more than three fold higher antibacterial activity compared to the particles obtained under stirring, due to their higher concentration and smaller size. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45136.

Silver nanoparticle and lysozyme/tannic acid layer-by-layer assembly antimicrobial multilayer on magnetic nanoparticle by an eco-friendly route

A facile, economical and green synthetic route was developed to fabricate magnetic nanocomposite arming with silver nanoparticles (AgNPs) for antibacterial application. In this synthesis, two natural compounds, positively charged lysozyme (Lys) and negatively charged tannic acid (TA), were alternately deposited on Fe3O4 nanoparticles (IONPs) surface by layer-by-layer (LbL) self-assembly technique. And then AgNPs were embedded by an in situ reduction of Ag+ so as to achieve complementary antibacterial functions to act against Gram-positive and Gram-negative bacteria. In which, the deposition of AgNPs can be facilely achieved without any external reducing agent. The systematic antibacterial assays showed that synthesized nanocomposites had high antibacterial efficiency against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Investigation of antimicrobial mechanism suggested that these nanocomposites could lead to the disorganization of bacterial cytomembrane and leakage of cytoplasmic contents. Moreover, the permeable alteration of cytoplasmic membrane may facilitate the Ag+ released from nanocomposite entering into cells, and further cause the bacterial death. Due to the excellent magnetic responsive performance of IONPs, the nanocomposites can be easy recovery by external magnetic field from application environment after disinfection. By taking advantages of such properties, the developed nanocomposite could be an ideal candidate with promising antibacterial applications.

Facile Green Synthetic Route to the Zinc Oxide (ZnONPs) Nanoparticles: Effect on Green Peach Aphid and Antibacterial Activity

In this study, zinc oxide nanoparticles (ZnONPs) were synthesized using Punica granatum peel extract in one–step reaction at room temperature. Zinc oxide nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), ultraviolet visible spectroscopy (UV-vis) and scanning electron microscopy (SEM). The UV-vis absorption spectrum shows an absorption band at 278 nm due to ZnO nanoparticles. XRD characterized the final product as highly crystalline ZnO with sizes in the range 10-40 nm. The SEM results reveal a presence of network of randomly oriented ZnO nanoplatelets with an average size of 40 nm and thicknesses of about 8 nm. This study determined the effect of zinc oxide nanoparticles on green peach aphid and antibacterial activity.

Facile synthesis of water soluble fluorescent metal (Pt, Au, Ag and Cu) quantum clusters for the selective detection of Fe3+ions as both fluorescent and colorimetric probes

A facile and green synthetic route is developed to prepare water soluble, green-fluorescent Pt, Au, Ag and Cu quantum clusters (QCs), employing innoxious L-histidine as a capping agent. These metal QCs give out emissions at 455–495 nm, with maximum excitation wavelengths ranging between 350 and 401 nm. Interestingly, these histidine-stabilized metal quantum clusters also possess non-linear optical properties like two-photon luminescence, which is detected when they are exposed to a femtosecond laser at 812 nm. Luminescence quantum yields of Pt (2.93%), Au (13.10%), Ag (6.97%) and Cu (8.29%) clusters are found to be distinctly different, and lifetime measurement results suggest that the emissions of metal clusters (4.59–7.39 ns) stem from singlet transitions among different electron energy levels rather than metal–ligand electron transfer behaviors. The Pt, Au, Ag and Cu quantum clusters have average sizes of 1.3–1.9 nm, and are mainly composed of 11, 9, 4 and 7 metal atoms, respectively, according to the electrospray ionization mass spectrometry results. Moreover, the as-prepared metal clusters are sensitive to aqueous ferric ions, both as highly selective fluorescent and colorimetric probes in a low and wide concentration range, and are promising in many biological applications.

Environmentally friendly and facile synthesis of Rh nanoparticles at room temperature by alkaline ethanol solution and their application for ethanol electrooxidation

A facile, fact and green synthetic route was developed to prepare Rh nanoparticles at room temperature.

In vitro Antibacterial and Anticancer Potential of CeO2 Nanoparticles Prepared by Co-precipitation and Green Synthesis Method

Cerium oxide nanoparticles (CeO2 NPs) were synthesized through chemical (co-precipitation method) (C-CeO2 NPs) and green synthetic route (A. indica leaf extract) (G-CeO2 NPs) and comparative studies were also carried out in the first time. From the XRD Pattern of C-CeO2 and G-CeO2 NPs revealed that both were in cubic phase. The morphological and elemental compositions were identified by FESEM, TEM and EDAX spectra. The optical characterizations were carried out using UV-Visible and Photoluminescence spectral analysis. Further the FT-IR and FT-Raman analysis were also confirmed to formation of CeO2 nanoparticles. The oxidation states of the elements Ce (3d), C (1s) and O (1s) were confirmed by XPS studies. The green synthesized CeO2 NPs possessed a higher antibacterial activity than chemical CeO2 NPs. The cytotoxic effect of C-CeO2 and G-CeO2 NPs were analyzed in cultured (A549) human lung cancer cell line.

Synthesis and characterization of calcium-induced peanut protein isolate nanoparticles

A convenient and green synthetic route using calcium ion induction was first used to prepare peanut protein isolate (PPI) nanoparticles.