Green Procedure For Synthesis Research Articles

Laccase Immobilized Fe3O4-Graphene Oxide Nanobiocatalyst Improves Stability and Immobilization Efficiency in the Green Preparation of Sulfa Drugs

This paper, reports on the novel and green synthesis procedure for sulfonamides that involved the immobilization of Trametes Versicolor laccase onto the Fe3O4–graphene nanocomposite via glutaraldehyde (GA) crosslinking (Lac/Fe3O4/GO). Various parameters, mainly, activation time, GA, and laccase concentration were investigated and optimized. The results showed that the optimal contact time was 4 h, GA concentration was 5% while laccase concentration was 5 mg·mL−1, at which a high enzyme activity recovery was achieved (86%). In terms of the stability of immobilized laccase to temperature and storage conditions, the performance of the nanobiocatalyst was found to significantly exceed that of free laccase. The results have indicated that nearly 70% of relative activity for immobilized laccase remained after the incubation period of 2 h at 55 °C, but only 48% of free laccase remained within the same time period. Moreover, the immobilized laccase retained 88% of its initial activity after storage for 20 days. In case of the free laccase, the activity retained within the same time period was 32%. In addition, the nanobiocatalyst possessed better recycling performance as evidenced from the observation that after eight cycles of repeated use, it retained 85% of its original activity.

Palladium based heterogeneous catalyst by evaporation‐induced self‐assembly: use of biopolymer as a surface functionalizing and reducing agent

Palladium‐based composites are widely used as a heterogeneous catalyst in carbon–carbon coupling reactions and in catalytic converters used in the car industry. In this work, we demonstrate a simple, green and scalable synthesis procedure to obtain palladium (Pd) based heterogeneous catalyst. Surface functionalized silica microparticles were obtained in one‐step by spray‐drying a colloidal suspension of silica nanoparticles and gum arabic, an environmental‐friendly biopolymer. Subsequently, palladium nanoparticles were reduced and attached to the substrate by gum arabic. The as‐synthesized composite was characterized by field‐emission scanning electron microscopy (FESEM), energy‐dispersive x‐ray spectroscopy (EDS), x‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), small angle x‐ray scattering (SAXS), and high‐resolution transmission electron microscopy (HR‐TEM). The Pd@SiO2 composite was used as a catalyst in the reduction reaction of 4‐nitrophenol by sodium borohydride. The catalyst showed good recycling properties. The present environmental‐friendly approach for fabrication of Pd‐based heterogeneous catalyst circumvents various complex chemical steps involved in conventional chemical methods and could be generalized for the production of ceramic or magnetite‐based Pd composites.

NH3(CH2)5NH3BiCl5 as a new hybrid and efficient catalyst for the synthesis of 1-(benzothiazolylamino)methyl-2-naphthol derivatives under solvent-free conditions

Abstract A simple, efficient and green procedure for synthesis 1-(benzothiazolylamino)methyl-2-naphthol derivatives via one-pot three-component condensation of aromatic aldehydes, β-naphthol and 2-aminobenzothiazole has been studied by using a novel hybrid catalyst NH3(CH2)5NH3BiCl5 under solvent-free conditions at 100 °C. This method has several advantages such as operational simplicity, recyclability of catalyst, easy workup, short reaction time and excellent yields.

Green synthesis of zirconia nanoparticles based on Euclea natalensis plant extract: Optimization of reaction conditions and evaluation of adsorptive properties

The development of nanomaterials has attracted increasing attention recently. The study of new technologies to obtain these materials becomes extremely important since the majority of the nanomaterials synthesized require reagents and solvents. These reagents and solvents are sometimes toxic and may generate harmful residues to the environment and the health of living beings. Therefore, green synthesis is a potential alternative to obtain nanoparticles, sustainably, using ecological sources. This study developed a method of synthesizing the green of zirconia (ZrO2) nanoparticles using Euclea natalensis (Natal gwarri or Natal ebony tree with African origin) plant extract. Moreover, the adsorptive properties against tetracycline were evaluated. A factorial design was applied in the synthesis process, and an optimization of the reaction parameters (plant extract concentration, precursor concentration, and calcination temperature) was also described for the first time in literature. The nanoparticles were characterized using the XRD, FTIR and TEM techniques, and then subjected to batch adsorption tests. The samples presented the zirconia monoclinic and tetragonal phases, according to the XRD analysis, yielding materials with minimum crystallite sizes equal to 5.25 nm. The FTIR spectra confirmed the results obtained by the XRD, presenting band characteristic of the zirconia monoclinic and tetragonal phases. The particles had a rounded morphology with a very low average diameter ranging from 5.90 to 8.54 nm. Moreover, the nanoparticles were applied to the adsorption of tetracycline. The samples were synthesized with vegetal extract and precursor concentration equal to 50 g L−1 and 0.03 mol L−1, respectively, and calcination temperature of 550 °C, presented in the best performance (loading of 30.45 mg g−1). The adsorption capacity of the zirconia synthesized in this study was significantly higher than other common materials applied to tetracycline removal. The green synthesis procedure, as well as the application of the zirconia nanoparticles to the adsorption of an emerging pollutant, were promising.

Biogenic synthesis of copper oxide nanoparticles using plant extract and its prodigious potential for photocatalytic degradation of dyes

The development of benign and efficient approaches for treating industrial grade toxic organic dyes is an ongoing challenge. To this end, copper oxide nanoparticles (CuO NPs) were prepared by a simple, environment friendly, and economical green synthesis procedure by using Psidium guajava leaf extract as reducing agent (i.e., for the reduction of metal salt) as well as capping agent and copper acetate monohydrate as metal salt. The formation of mono-dispersed and spherical (average size 2–6 nm with BET surface area 52.6 m2/g) CuO NPs was confirmed by various spectroscopic and microscopic techniques. The CuO NPs exhibited excellent degradation efficiency for the industrial dyes, i.e., Nile blue (NB) (93% removal in 120 min) and reactive yellow 160 (RY160) (81% removal in 120 min) with apparent rate constants of 0.023 and 0.014 min−1, respectively. The CuO catalyst was found to be reusable for photocatalytic dye degradation even after five consecutive cycles. The limit of detection (LOD) values for NB and RY160 were 4 and 9 mg/L, respectively. In light of their high reusability and photocatalytic efficiency along with adaptability to green synthesis, the use of biogenic CuO NPs is a promising option for the purification of water resources contaminated with industrial dye.

Appraisal of the biological aspect of Zinc oxide nanoparticles prepared using extract of Camellia sinensis L.

Green synthesis of nanoparticles by plant extracts is receiving enormous attention due to their abundant availability, providing a broad range of eco-friendly and bioactive metabolites. This study was designed to synthesize biocompatible zinc oxide nanoparticles (ZnO-NPs) using the aqueous leaf extracts of the Camellia sinensis L. at 400 and 550 °C calcination temperatures. The physicochemical properties, as well as nanometric characterization of the ZnO-NPs, were performed by Energy Dispersive x-ray Spectroscopy (EDS), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), and UV−visible spectroscopy. To achieve nanoparticles for being applied in bioactive molecules delivery applications, biological assays such as in vitro cytotoxicity; antibacterial, hemolytic, anti-oxidant (FRAP and DPPH) activities were done for the synthesized NPs. The results were promising and indicated that both of the prepared NPs displayed reliable outcomes for antibacterial activity and blood biocompatibility assays. Whereas, ZnO-NPs prepared at 550 °C had lower cytotoxicity than those prepared at 400 °C calcination in MCF-7 and fibroblast cell lines. Our findings demonstrated that the using aqueous leaf extracts of the Camellia sinensis L. for the preparation of ZnO-NPs is an efficient green synthesis procedure and the obtained NPs have acceptable biocompatibility and bioactivity.

Chitosan-mediated facile green synthesis of size-controllable gold nanostars for effective photothermal therapy and photoacoustic imaging

With the large near-infrared (NIR) absorption and the high NIR photothermal effect, gold nanostar (AuNS) has potential application in the biomedical field. However, the complicated synthesis process with toxic precursors is a serious issue for its practice. Herein, we reported a novel green synthesis procedure using chitosan polymer from marine and vitamin C for the preparation of AuNS. For the first time, chitosan was used as a stabilizer, shape-directing, and size-controllable agents for the preparation of AuNS. The size of the obtained AuNS ranged from 111 to 225 nm with different λmax. The AuNS exhibited near-infrared absorption with the excellent biocompatibility toward non-cancerous cell line (MG63) and cancerous cell line (MDA-MB-231). The in vitro photothermal therapy and photoacoustic imaging with assisting of obtained AuNS were also proved the high efficiency of these nanoparticles.

The effect of biogenic manufactured silver nanoparticles on human endothelial cells and zebrafish model

Human health and environment have been continuously getting exposure to toxic chemicals including nanomaterial; therefore, nontoxicity has recently attracted huge amount of attention. In this study, RU-AgNPs were synthesized by a green synthesis procedure and evaluated for their toxicity in human umbilical vein endothelial cells (HUVECs) as well as on zebrafish embryos via apoptotic pathway. The synthesized RU-AgNPs were average in size (20–25 nm) with a negative surface charge of −13.43 mV. As a result, RU-AgNPs potentiated the formation of reactive oxygen species (ROS) in HUVECs as confirmed by the results of immunoblotting analysis using apoptotic markers, such as Bax, Bcl2, and cytochrome C. Moreover, the induction of apoptosis in HUVECs was also authenticated in a dose-dependent manner after the treatment with RU-AgNPs by the Incucyte analysis. In vivo trials conducted on zebrafish visualized the mortality, malformation, and imbalanced in the heart rate, and cell death of the whole embryo, including severe morphological changes in the yolk sac and the tail of zebrafish. Furthermore, the results of western blot analysis demonstrated the increasing intensity of apoptotic biomarkers such as Bax, Bcl2, and Cyto C, including enhanced production of ROS, validating the cell death in zebrafish larvae. In addition, chemically functionalized silver nanoparticles found to be more cytotoxic than biogenic functionalized silver nanoparticles. Above-mentioned findings clearly demonstrate that Ru-AgNPs cause the toxicity via ROS-induced apoptotic pathway. Therefore, it is necessary to decide RU-AgNPs toxicity levels before being used in any biomedical application.

Caffeine as a naturally green and biodegradable catalyst promoted convenient and expedient synthetic route for the synthesis of polysubstituted dihydro-2-oxypyrroles

A green, convenient, high yielding and one-pot procedure for synthesis of high substituted dihydro-2-oxypyrroles by domino four-component condensation reaction between aromatic/aliphatic amines, dialkyl acetylenedicarboxylate and formaldehyde in the presence of a catalytic amount of caffeine as a green, natural, expedient and biodegradable catalyst under ambient temperature was studied. The salient features of this green approach are simplicity of operation and work-up procedures with no necessity of chromatographic purification steps, use of safe, non-volatile, non-corrosive and green catalyst, the availability and easy to handle of this solid catalyst, one-pot reaction, economical and clean synthesis. KEY WORDS: Caffeine, Green catalyst, Polysubstituted dihydro-2-oxypyrroles, Ambient temperature, Simple work-up Bull. Chem. Soc. Ethiop. 2019, 33(1), 149-158DOI: https://dx.doi.org/10.4314/bcse.v33i1.15

A green procedure for one-pot synthesis of N, N’-alkylidene bisamides under solvent- and catalyst-free conditions

An effective solvent- and catalyst-free method was introduced for synthesis of symmetrical N, N’-alkylidene bisamides as high usage compounds in organic chemistry. In order to show the generality, the synthesis was done with various benzamides and aldehydes to obtain various derivatives in high yields.

Green Procedure for One-Pot Synthesis of Azelaic Acid Derivatives Using Metal Catalysis

Green Procedure for One-Pot Synthesis of Azelaic Acid Derivatives Using Metal Catalysis

Sustainable Generation of Ni(OH)2 Nanoparticles for the Green Synthesis of 5-Substituted 1H-Tetrazoles: A Competent Turn on Fluorescence Sensing of H2O2.

A mutually correlated green protocol has been devised that originates from a sustainable production of β-Ni(OH)2 nanoparticles which is used for an efficient catalytic synthesis of versatile substituted tetrazoles, under mild reaction conditions in water via a simple, one-pot, eco-friendly method. The synthesis is followed by derivatization into a highly fluorescence active compound 9-(4-(5-(quinolin-2-yl)-1H-tetrazol-1-yl)phenyl)-9H-carbazole that can be used at tracer concentrations (0.1 μM) to detect as well as quantify hydrogen peroxide down to 2 μM concentration. The nanocatalyst was synthesized by a simple, proficient, and cost-effective methodology and characterized thoroughly by UV–vis absorption and Fourier transform infrared spectra, N2 adsorption/desorption, high resolution transmission electron microscopy, powder X-ray diffraction pattern, field emission scanning electron microscopy, and thermogravimetric analysis. Broad substrate scope, easy handling, higher efficiency, low cost, and reusability of the catalyst are some of the important features of this heterogeneous catalytic system. The strong analytical performance of the resultant derivative in low-level quantification of potentially hazardous hydrogen peroxide is the key success of the overall green synthesis procedure reported here.

Surface Modification of Silicon Nanoparticles by an "Ink" Layer for Advanced Lithium Ion Batteries.

Owing to its high specific capacity, silicon is considered as a promising anode material for lithium ion batteries (LIBs). However, the synthesis strategies for previous silicon-based anode materials with a delicate hierarchical structure are complicated or hazardous. Here, Prussian blue analogues (PBAs), widely used in ink, are deposited on the silicon nanoparticle surface (PBAs@Si-450) to modify silicon nanoparticles with transition metal atoms and a N-doped carbon layer. A facile and green synthesis procedure of PBAs@Si-450 nanocomposites was carried out in a coprecipitation process, combined with a thermal treatment process at 450 °C. As-prepared PBAs@Si-450 delivers a reversible charge capacity of 725.02 mAh g-1 at 0.42 A g-1 after 200 cycles. Moreover, this PBAs@Si-450 composite exhibits an exceptional rate performance of ∼1203 and 263 mAh g-1 at current densities of 0.42 and 14 A g-1, respectively, and fully recovered to 1136 mAh g-1 with the current density returning to 0.42 A g-1. Such a novel architecture of PBAs@Si-450 via a facile fabrication process represents a promising candidate with a high-performance silicon-based anode for LIBs.

Performance and mechanism of simultaneous removal of Cd(II) and Congo red from aqueous solution by hierarchical vaterite spherulites

Hierarchical vaterite spherulites, synthesized by a simple injection-precipitation method at room temperature, were applied for the simultaneous removal of heavy metal Cd(II) and dye Congo red (CR) from aqueous solution. Batch experiments reveal that the maximum removal capacities of as-prepared vaterite spherulites to Cd(II) and CR are 984.5 and 89.0 mg/g, respectively, showing excellent removal performance for Cd(II) and CR. Furthermore, in the binary Cd(II)-CR system, the removal capacity of vaterite to Cd(II) is significantly enhanced at lower CR concentration (<100 mg/L), but inhibited at higher CR concentration (>100 mg/L). In contrast, the concurrent Cd(II) shows negligible effect on the CR removal. The simultaneous removal mechanism was investigated by FESEM, EDX, XRD, FT-IR and XPS techniques. The simultaneous removal of Cd(II) and CR in the binary system is shown to be a multistep process, involving the preferential adsorption of dye CR, stabilization of CR to vaterite, coordination of the adsorbed CR molecules with Cd(II), and transformation of vaterite into otavite. Given the facile and green synthesis procedure, and effective removal of Cd(II) and CR in the binary system, the obtained vaterite spherulites have considerable practical interest in integrative treatment of wastewater contaminated by heavy metals and dyes.

Facile synthesis of silver nanoparticles using harmala alkaloids and their insecticidal and growth inhibitory activities against the khapra beetle

In order to find new, less toxic and eco-friendly pest control agents, natural products are considered to be alternative options of potentially active compounds. In this context, the aim of the present study was the isolation and structural elucidation of the β-carboline and quinazoline alkaloids of Peganum harmala L. seeds. Silver nanoparticles (AgNPs) were prepared using alkaloids through a green synthesis procedure. Harmala alkaloids and their AgNPs showed considerable insecticidal and growth inhibitory activities against khapra beetle, Trogoderma granarium (Everts) (Coleoptera: Dermestidae). On a toxicity bioassay using treated filter papers, the total harmala alkaloids (THAs) were the most toxic followed by harmaline, harmine and harmalol, where LC50’s ranged between (30.6–61.7 µg/cm2) and (24.4–46.1 µg/cm2) 24 h post-treatment against larvae and adults, respectively. The two quinazolines, vasicine and vasicinone, showed moderate to weak activities. At 48 h post-exposure, efficacy of all alkaloids was increased. When tested as AgNPs (size 22.5–66.2 nm diameter), toxicity of alkaloids, especially the β-carbolines, was strongly increased, where LC50 values ranged between (4.7–11.4 µg/cm2) and (4.1–10.2 µg/cm2) 48 h post-treatment against larvae and adults, respectively. Feeding the 2nd instar larvae AgNPs-treated grains at sublethal concentrations led to significant drawbacks on the normal growth and development of the insect. These effects appeared as a high percentage of malformed larvae and pupae, a prolonged life span and a significant reduction in adult emergence. Results suggest the potential of using harmala alkaloids and their AgNPs as a natural approach for controlling T. granarium.

Glutathione-Directed Green Synthesis of Ag Nanoclusters with Highly Fluorescence

A facile green method to synthesize fluorescent Ag nanoclusters (NCs) has been developed by employing glutathione (GSH) as capping agent as well as reducing agent. The fluorescent nanocomposites powder possesses strong emission and excellent stability. By changing the mole ratios of glutathione to silver precursor, nanoclusters with different emissions are obtained. The as-synthesized GSH-Ag nanocomposite is well characterized by fluorescence spectroscopy, HRTEM, XPS, and IR spectroscopy. The green synthesis procedure has also been used to synthesize fluorescent GSH-Au nanoclusters with good success.

Naked eye and smartphone applicable detection of toxic mercury ions using fluorescent carbon nanodots

Chitosan passivated carbon nanodots (C-Dots$_{CHIT})$ were synthesized from expired molasses via a simple and green thermal synthesis procedure. As-synthesized C-Dots were nitrogen-doped (NC-Dots$_{CHIT})$ by posttreatment with liquid ammonia and used as nanoprobes for fluorometric detection of mercury ions (Hg(II)$_{aq.})$. Fluorescence response of NC-Dots$_{CHIT}$ in the presence of mercury was evaluated and compared with that of the polyethylene glycol passivated C-Dots$_{PEG}$. This sensing strategy using NC-Dots$_{CHIT}$ displayed a wide linear working range from 1.25 $\mu $g/mL to 43.54 $\mu $g/mL with a detection limit of 1.41 $\mu $g/mL. The fluorescence of C-Dots$_{PEG}$ did not show any significant change upon mercury addition. Selectivity of as-synthesized NC-Dots$_{CHIT}$ to Hg(II)$_{aq.}$ was assessed by comparing the level of fluorescence quenching in the presence of four other divalent cations (cadmium(II), zinc(II), nickel(II), and copper(II)). Finally, synthesized nanoprobes were embedded into the cross-linked alginate hydrogels and test strips were formed on the FTO-coated glass. Images captured under a UV light source (λexc: 365 nm) were successfully processed by a smartphone application. Color codes generated by the app showed a close resemblance to the data gathered from fluorescence spectroscopy. The proposed detection system was applied satisfactorily to both a certified calibration standard and real water samples. The methodology developed within this study could be a potential candidate for detection of mercury concentration in water samples with high recovery rates reaching up to 98%. This smartphone applicable detection platform that uses carbon nanodots as cheap yet sensitive nanoprobes could lead to more advanced lab-on-site systems for water or food sample analysis that can be performed by anyone, anywhere, anytime.

ChemInform Abstract: A General, Effcient and Green Procedure for Synthesis of Dihydropyrimidine‐5‐carboxamides in Low Melting Betaine Hydrochloride/Urea Mixture.

AbstractA new, environment‐friendly protocol is described for the synthesis of dihydropyrimidine‐5‐carboxamides in a low‐melting deep eutectic solvent from a mixture of betaine hydrochloride with urea.

Oxidation of benzyl alcohol by K2FeO4 to benzaldehyde over zeolites

A novel and green procedure for benzaldehyde synthesis by potassium ferrate oxidation of benzyl alcohol employing zeolite catalysts was studied. The prepared oxidant was characterized by SEM and XRD. The catalytic activity of various solid catalysts was studied using benzyl alcohol as a model compound. USY was found to be a very efficient catalyst for this particular oxidation process. Benzaldehyde yields up to 96.0% could be obtained at the following optimal conditions: 0.2 mL of benzyl alcohol, 4 mmol of K2FeO4, 0.5 g of USY zeolite; 20 mL of cyclohexene, 0.3 mL of acetic acid (36 wt %), 30°C temperature, 4 h reaction time.

A General, Effcient and Green Procedure for Synthesis of Dihydropyrimidine‐5‐carboxamides in Low Melting Betaine Hydrochloride/Urea Mixture

AbstractA simple, facile and convenient strategy has been developed for the synthesis of dihydropyrimidine‐5‐carboxamides in low melting mixture of betaine hydrochloride/urea. In this procedure, the low melting mixture of betaine hydrochloride/urea plays a triple role: as a catalyst, solvent and reactant. The present green protocol has advantages such as high yield of products, short reaction times, operational simplicity, no chromatographic separation, eco‐friendliness, and applicability for large‐scale synthesis.