Green Synthetic Approach Research Articles

Microwave-Accelerated Facile Synthesis of 1H-Pyrazolo[1,2-b]Phthalazine-5,10-Dione Derivatives Catalyzed by WEMPA

An efficient and rapid one-pot multicomponent synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones through condensation of aldehyde, malononitrile and phthalhydrazide catalyzed by agro-waste solvent catalyst-derived water extract of mango peel ash (WEMPA) under microwave irradiation is described. Further, the catalyst is prepared from agricultural waste and characterized for elemental composition by different techniques such as SEM-EDX, XRD and flame photometry. This green synthetic approach offers various advantages such as inexpensive, abundantly available source, shorter reaction time (6–8 min), good-to-excellent yield (83%–89%), simple workup and a sustainable alternative method to the existing protocols. All the synthesized compounds (4a–l) was confirmed by FT-IR, 1H-NMR, 13C-NMR and LC-MS.

Calcium Carbide: Versatile Synthetic Applications, Green Methodology and Sustainability

Acetylene is a key building block for organic chemistry and potentially can be involved in a diverse range of synthetic transformations. However, critical analysis of practical considerations showed that application of gaseous acetylene in regular synthetic labs encounters a number of difficulties. Safety limitations due to flammable and explosive nature of gaseous acetylene and requirements for specialized high‐pressure equipment impose serious drawbacks. Typical reaction conditions involve excess of gaseous reactant, which is simply released to the atmosphere at the end of the reaction, thus generating waste and causing contamination. Calcium carbide brings a new green and sustainable wave into powerful alkyne transformations and significantly expands the repertoire of traditional acetylene chemistry. The novel trend of using calcium carbide instead of gaseous acetylene is synthetically beneficial and opens a novel reactivity for the C≡C unit. This review highlights recent advances in carbide chemistry, demonstrates its advantages and prospects in term of green synthetic approach.

Optical characterization and concentration-dependent antibacterial activity of silver nanoparticles (AgNPs) using aqueous Melastoma malabathricum extract against Staphylococcus aureus

The approach towards green synthetic methods has been enormously encouraged to synthesise nanoparticles for various uses. In this study, the one-pot synthetic method was adapted to synthesise silver nanoparticles (AgNPs) using Melastoma malabathricum (M. malabathricum) aqueous extract. The formation of AgNPs was confirmed by observing the results obtained by optical characterisation methods. The plasma resonance band along with shoulder at 375 nm and 595 nm, respectively, in Uv-Visible spectra supported the conversion of silver (Ag) to AgNPs reduced by functional groups present in the plant extract. The size of AgNPs was 31 nm and cubic in shape as confirmed by X-ray diffractometry (XRD) using Scherer equation. X-Ray Fluorescence (XRF) results also confirmed the presence of silver. The FTIR characterisation confirmed the presence of reducing functional groups. The antibacterial activity of AgNPs against Staphylococcus aureus (S. aureus) was carried out by disc diffusion method with increasing concentration of AgNPs, and enhanced inhibition zone was observed. The AgNPs obtained can be further explored against different bacterial strains and can a potential candidate as an antibacterial agent using the green synthetic approach.

Novel bio-mediated Ag/Co3O4 nanocomposites of different weight ratios using aqueous neem leaf extract: Catalytic and microbial behaviour

An environmentally safe, economically, fast, and green synthetic approach was presented in this work for the fabrication of Ag-NP, Co3O4-NP and different weight ratio of Ag/Co3O4-NC. The synthesized samples were characterized by Fourier-transform infrared spectroscopy (FT-IR) and UV–visible spectrophotometry, Transmission Electron Microscopy (TEM), Scanning electron microscopy (SEM) along with X-ray energy dispersive spectroscopy (EDAX), and X-ray diffraction (XRD). The catalytic behaviour of the synthesized samples toward the reduction reaction of 4-nitrophenol in the presence of NaBH4 was studied. It is indicated that the synthesized nanocomposites show a satisfactory catalytic activity. The catalytic reduction of p-NP to p-AP obeys first-order kinetics with rate constant in the following order (Ag-NP> (Ag/Co3O4-NC) −1:1 > 1:3 > 3:1> Co3O4). This may be attributed to the high dispersion of Ag-NP compared to cobalt oxide nanoparticles. The microbial activity of the samples was analyzed using seven species of pathogenic microorganisms; 1) two species belongs to Gram negative bacteria; Escherichia coli (E.coli), and Salmonella, 2)four species belongs to Gram positive bacteria Marsa, Listeria, Staphylococcus aureus (S. aureus), bacillus subtilis (B.subtilis), and 3) one pathogenic fungal species Candidia. The data show that all samples exhibited an excellent range of inhibition toward all tested pathogenic microorganisms.

Synthesis and characterization of thermo/pH-sensitive pectin-graft-poly(dimethylaminoethyl methacrylate) coated magnetic nanoparticles

Herein, thermo- and pH-sensitive pectin-graft-poly(dimethylaminoethyl methacrylate) copolymer-coated magnetic nanoparticles were synthesized via a green and rapid synthetic approach based on microwave irradiation. Firstly, a novel thermo- and pH-sensitive pectin-graft-poly(dimethylaminoethyl methacrylate) copolymer (Pec-g-PolyDMAEMA) was synthesized and then, Pec-g-PolyDMAEMA based magnetic nanoparticles (Pec-g-PolyDMAEMA@Fe3O4) were produced via microwave-assisted co-precipitation method. The thermo/pH/magnetic field multi-sensitive hybrid nanoparticle was characterized by techniques like TEM, VSM, FT-IR, and TGA/DSC. In vitro release studies of 5-Fluorouracil (FL) were carried out by altering the temperature (37 and 44°C), pH (5.5 and 7.4) and presence of an AMF. The FL release of Pec-g-PolyDMAEMA@Fe3O4@FL exhibited pH-sensitive behavior. They showed thermo/pH-sensitive FL release features with the greatest release of FL at 37°C (56%) than at 44°C (40%) and at pH of 7.4 (63%) than at pH of 5.5 (45%) within 48h. The FL release was also significantly increased (100%) with the presence of a 50 mT magnetic field. These results indicate that the developed Pec-g-PolyDMAEMA@Fe3O4 nanoparticles are promising in the application of multi-stimuli-sensitive delivery of drugs.

Recent Advances on Copper Complexes as Visible Light Photoinitiators and (Photo) Redox Initiators of Polymerization

Metal complexes are used in numerous chemical and photochemical processes in organic chemistry. Metal complexes have not been excluded from the interest of polymerists to convert liquid resins into solid materials. If iridium complexes have demonstrated their remarkable photochemical reactivity in polymerization, their high costs and their attested toxicities have rapidly discarded these complexes for further developments. Conversely, copper complexes are a blooming field of research in (photo) polymerization due to their low cost, easy syntheses, long-living excited state lifetimes, and their remarkable chemical and photochemical stabilities. Copper complexes can also be synthesized in solution and by mechanochemistry, paving the way towards the synthesis of photoinitiators by Green synthetic approaches. In this review, an overview of the different copper complexes reported to date is presented. Copper complexes are versatile candidates for polymerization, as these complexes are now widely used not only in photopolymerization, but also in redox and photoassisted redox polymerization processes.

Synthesis and characterization of TiO2-based nanostructures via fluorine-free solvothermal method for enhancing visible light photocatalytic activity: Experimental and theoretical approach

Surface-fluorinated anatase TiO2 nanosheets have been widely prepared using hydrofluoric acid (HF) as morphology controlling agent with several titanium alkoxides. However, hazardous and other scientific problems associated with HF are major obstacles towards its global commercialization. Therefore, this study introduces a facile, green and fluorine-free solvothermal synthetic approach to prepare anatase TiO2 nanosheets (TNSs), involving commercial TiO2 nanoparticles as titanium source and N, N dimethylformamide (DMF) as morphology controlling agent under alkaline environment. A Box-Behnken-Design 3-level experimental design was applied to optimize the major key synthesis parameters for tuneable TNSs performance by manipulating the reaction temperature (120−180 °C), reaction time (3−48 hr) and dose of DMF (5−40 mL). The proposed model was verified through the analysis of variance and performing experiments at predicated optimal conditions (temperature =165.35 °C, time = 25.50 h and DMF dose =22.50 mL). The quadratic model was found to be best-fitted with the maximum correlation coefficients (R2 = 0.989 and adjusted R2 = 0.975) between predicted and actual results. The crystal growth mechanism of TNSs was also proposed. The formation of tetragonal TNSs (10 nm) containing the highest surface area with least bandgap upto 2.62 eV, confirmed through XRD, TEM, BET, DRS, FTIR and XPS measurements. The excellent photocatalytic performance was exhibited by as-developed TNSs for phenol degradation upto 95.33 % under visible-light. The photoactivity of TNSs was found to be strongly associated with synthesis parameters including hydrothermal temperature, reaction time and DMF dose. The phenol degradation data was well explained via pseudo-first-order kinetics and Langmuir isotherm models. Thermodynamic parameters were suggested the nature of phenol degradation process. This enhanced degradation activity of TNSs was attributed to the well-defined morphology, larger surface area, improved energy harvesting aptitude and abated recombination rate of photogenerated electron hole-pairs resulting an enhancement in the photogenerated charge carrier.

Reusable fibrous adsorbent prepared via Co-radiation induced graft polymerization for iodine adsorption

Volatile iodine released from nuclear power plant reactors is radiological hazard to environment and human's health because of their high fission yield and environmental mobility. The complexity of nuclear waste management motivated the development of solid-phase adsorbents. Herein, co-radiation induced graft polymerization (CRIGP) was employed in the graft polymerization of N-vinyl-2-pyrrolidone (NVP) onto polyethylene-coated polypropylene skin–core (PE/PP) fibers using electron beam (EB) irradiation. This work provides a one-step green synthetic approach to prepare iodine fibrous adsorbents without any chemical initiators or large amount of organic solvent. The original and modified PE/PP fibers were characterized by fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG) and scanning electron microscopy (SEM) to demonstrate the grafting of NVP onto the PE/PP fibers. The capacity of iodine absorbed by the PE/PP-g-PNVP fibers was 1237.8 mg/g after 180 min. Meanwhile, absorbents can be regenerated efficiently by two different means of ethanol elution and heating at 120 °C, respectively. Within 10 min, 94.17% and 90.12% of the iodine can be released from the PE/PP-g-PNVP fibers with these two methods, respectively. The adsorbent exhibited a long service life of at least ten adsorption–desorption cycles, suggesting that PE/PP-g-PNVP fibers might be a promising adsorbent for volatile iodine adsorption from fission products in nuclear power plant reactors.

Green Synthesis of 1-Aryl-2,3,4,9-Tetrahydro-1H-B-Carbolines using Fe(Iii)-Montmorillonite and Study of their Antimicrobial Activity

A series of 1-aryl-2,3,4,9-tetrahydro-1H-_-carbolines were synthesized using green ultrasonic synthetic approach in aqueous medium via the Pictet-Spengler reaction. The condensation reaction of tryptamine and various aromatic aldehydes at 80oC in aqueous medium produced the corresponding 1-aryl-2,3,4,9-tetrahydro-1H-β-carbolines by means of heterogeneous catalysis with Fe(III)-montmorillonite catalyst. The driving force for reaction feasibility in terms of the condensation of β-arylethylamine with the corresponding aldehyde followed by the ring closure reaction is the acidic nature of the Fe(III)-montmorillonite catalyst. The advantage of this methodology is high product yield and short reaction time compared to the conventional heating and microwave irradiation methods. The structures of synthesized compounds were confirmed by IR, 1H and 13C NMR spectroscopy, mass spectrometry, and elemental analysis. All products were screened for their antimicrobial activity, and some compounds exhibited significant activity against selected bacteria and fungi.

Inhibition effect of rhodanines containing benzene moieties on pentose phosphate pathway enzymes and molecular docking

Recently, inhibition studies of pentose phosphate pathway (PPP) enzymes have come out as an encouraging approach for pharmacological intervention in a variety of disorders. For this purpose, the rhodanines (Ph-Rhs) containing different benzene moiety were obtained via a green synthetic approach over a one pot reaction. We tested their inhibition effect on PPP enzymes glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD). As a result of these studies, inhibition constant (Ki) of Ph-Rhs on PPP enzymes were found in the range of 6.57 ± 2.03 to 91.60 ± 9.25 μM for G6PD and 11.17 ± 3.01 to 64.51 ± 4.26 μM for 6PGD. Moreover, binding energies were calculated with docking studies as −5.234 and −5.071 kcal/mol for G6PD and 6PGD, respectively.

Green synthesis of Ag-ZnO nanocomposites using Trigonella foenum-graecum leaf extract and their antibacterial, antifungal, antioxidant and photocatalytic properties.

In the present study, biological synthesis of Ag-ZnO nanocomposites was performed using hydroalcoholic extract of fenugreek leaves. Metal/semiconductor oxide nanocomposites are excellent owing to their optical, electrical, magnetic, and chemical properties that are not detected in single individual constituents. The synthesized Ag-ZnO nanocomposites were investigated through the use of methods such as FTIR, UV vis DRS, SEM-EDX, TEM, XRD, zeta potential analysis, and DLS. The synthesized Ag-ZnO nanocomposites had an average particle size of about 75nm and a zeta potential of -37.5mV. The XRD results confirmed that Ag was successfully introduced into the Ag-ZnO nanocomposites via a hydrothermal method. The antimicrobial and antifungal activities of Ag-ZnO nanocomposites were evaluated by agar well diffusion method against three microbial and fungal strains; it was found that the Ag-ZnO nanocomposites were toxic against all the tested microbial and fungal strains. Ag-ZnO nanocomposites was observed to have significant antioxidant activity against DPPH (2,2-diphenyl-1-picrylhydrazyl) free radicals. The Ag-ZnO nanocomposites exhibited excellent photocatalytic activity and stability against the degradation of malachite green under visible light irradiation. The study successfully applied a simple and eco-friendly method for synthesizing efficient multifunctional Ag-ZnO nanocomposites using green synthetic approach.

Synthesis of Co3O4 Nanomaterial with Cetyltrimethylammonium Bromide Using Sol–Gel Method in Environmentally Benevolent Aqueous Media

A new green synthetic approach of cobalt oxide (Co3O4) nanomaterial with cetyltrimethylammonium bromide (CTAB) using the sol–gel method was investigated. In this preparation, water is considered as a core solvent, and the synthetic approach is environmentally advantageous because of its low cost, easy preparation, and industrial viability due to this solvent. Investigation of nanomaterial have been done by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet visible spectroscopy (UV-Visible), energy dispersive X-ray spectroscopy (EDX), and fourier transform Infrared spectroscopy (FTIR). Highly dispersed characterization results were shown by synthesized nanomaterial. This green approach proves an effective, eco-friendly, simple and valuable approach for the synthesis of Co3O4 nanomaterial.

One-pot synthesis of nitrogen doped graphene-thionine-gold nanoparticles composite for electrochemical sensing of diethylstilbestrol and H2O2

In this work, a facile, one-pot, and green synthetic approach was proposed to prepare a novel nanocomposite of nitrogen doped graphene-thionine-gold nanoparticles (NG-Thi-AuNPs), which was then modified on electrode to fabricate an electrochemical sensor for diethylstilbestrol (DES) accurate and reliable detection based on ratiometric strategy. The synthesized NG-Thi-AuNPswas characterized by transmission electron microscope, scanning electron microscope, Fourier transform infrared spectrum, and X-ray diffraction. Due to the merits of good conductivity and high electroactive surface of NG and AuNPs, as well as the synergistic interaction toward DES, the nanocomposite showed high sensitivity for DES detection. Moreover, the modified Thi exhibited a constant current response regardless how the DES concentration changed, which made Thi to be a good inner reference to improve the accuracy and reliability of the sensor. Thus, a ratiometric signal (ΔiDES/ΔiThi) was measured and calculated for DES detection with a wide linear range and a low limit of detection of 5.0 × 10−8 - 8.0 × 10−5 mol/L and 9.6 × 10−9 mol/L, respectively. Due to the excellent conductivity and high electrocatalytical activity of the nanocomposite, the sensor was employed for the sensitive detection of H2O2 with the linear range of 5.0 × 10−7- 1.0 × 10−2 mol/L. With the good anti-interference, reproducibility, and stability, the prepared sensor was successfully used for real samples determination.

Green Synthetic Approaches in Organic Synthesis: A Short Review

Green Synthetic Approaches in Organic Synthesis: A Short Review

Identification and development of thiazole leads as COX-2/5-LOX inhibitors through in-vitro and in-vivo biological evaluation for anti-inflammatory activity.

Treatment of inflammation using NSAIDs is coupled with a risk of severe gastric adverse events. Development of dual COX-2/5-LOX inhibitors turns out to be an imperative area devoted to safer NSAIDs. A series of thiourea, thiazole, and thiazolidene derivatives were synthesized by green synthetic approach and COX-1, COX-2 and 5-LOX inhibition screening resulted in the identification of a potent compound 6l with IC50 of 5.55µM, 0.09µM, and 0.38µM respectively. Compound 6l made significant decrease (60.82%) in the carrageenan-induced edema in male Wistar rats. qRT-PCR analysis and determination of PGE2 and LTB4 in the rat paw tissues indicated that this thiazole based dual inhibitor significantly reduced the expression of COX-2 and 5-LOX genes besides the marked reduction in both PGE2 and LTB4 levels. The gastric safety profiling revealed an enhanced gastrointestinal safety of the compound 6l on histopathological examination. Molecular docking studies at COX-2 and 5-LOX active sites were consistent with biological studies by significant protein-ligand interaction. Besides, results of in-vitro PGE2 and LTB4 studies on RAW 264.7 cells as well as antioxidant studies were parallel to the dual inhibitory activity. The present investigations identify a promising lead having anti-inflammatory potential with an improved gastric safety profile.

Facile and green synthesis of reduced graphene oxide for remediation of Hg(II)-contaminated water

Mercury contamination of freshwater supplies poses a significant challenge to fresh water supplies, particularly in regions with historical or current gold mining. Nanomaterials are increasingly explored for the remediation of mercury-contaminated water due to their unique properties. Here, we report on the application of reduced graphene oxide (rGO) obtained via a facile, one-pot, green synthetic approach for treatment of Hg(II) contaminated water. In this approach, graphene oxide (GO) nanosheets prepared by a modified Hummer’s method were reacted with L-cysteine under mild conditions, resulting in nanosheets that were both reduced, and thiol functionalized. After characterization, the rGO nanosheets were used in batch studies to test the effect of time, solution pH, adsorbate and adsorbent concentrations on Hg removal. The reduction and functionalization of GO to rGO was confirmed by FTIR, XRD and elemental analysis. TEM images revealed a tendency for nanosheets stacking, particularly after functionalization. The adsorption of Hg(II) from solution was found to be optimal at pH 4 and reduction and functionalisation by cysteine increased Hg(II) removal by >15%. These data show that (i) L-cysteine affords an efficient, green, and relatively cheap means to produce rGO that can be applied for the treatment of Hg-contaminated water, (ii) Treatment with rGO yields a high efficiency for removal of Hg(II) ions by exploiting the affinity of Hg(II) ions for thiol groups contained in cysteine.

A Practical Green Synthesis of bis(Pyrazolyl)methanes Using Mohr’s Salt

In recent decades, safe green synthetic approaches have attracted much interest from chemists.1–3 Running chemical reactions in safe and non-toxic media, such as water, is one of these approaches, ...

Green Chemistry Approaches to the Synthesis of Coumarin Derivatives

This review is a compilation of the green synthetic methods used in the synthesis of coumarin derivatives. Coumarins are a class of compounds with a pronounced wide range of biological activities, which have found their application in medicine, pharmacology, cosmetics and food industry. Their biological activity and potential application are highly dependent on their structure. Therefore, many researchers have been performing the synthesis of coumarin derivatives on a daily basis. High demands for their synthesis often result in an increased generation of different waste chemicals. In order to minimize the utilization and generation of toxic organic substances, green synthetic methods are applied in this manner. These methods are getting more attention in the last few decades. Green chemistry methods cover a wide range of methods, including the application of ultrasound and microwaves, ionic liquids and deep eutectic solvents, solvent-free synthesis, mechanosynthesis and multicomponent reactions. All typical condensation reactions for coumarin synthesis like Knoevenagel, Perkin, Kostanecki-Robinson, Pechmann and Reformansky reactions, have been successfully performed using these green synthetic methods. According to the authors mentioned in this review, not only these methods reduce the utilization and generation of toxic chemicals, but they can also enhance the reaction performance in terms of product yields, purity, energy consumption and post-synthetic procedures when compared to the conventional methods. Due to the significance of coumarins as biologically active systems and the recent demands of reducing toxic solvents, catalysts and energy consumption, this review provides a first full literature overview on the application of green synthetic methods in the coumarin synthesis. It covers a literature search over the period from 1995-2019. The importance of this work is its comprehensive literature survey on a specific class of heterocyclic compounds, and those researchers working on the coumarin synthesis can find very useful information on the green synthetic approaches to their synthesis. There are some reviews on the coumarin synthesis, but most of them cover only specific reactions on coumarin synthesis and none of them the whole range of green chemistry methods.

Green Synthetic Approach for Photo-Cross-Linkable Methacryloyl Hyaluronic Acid with a Tailored Substitution Degree.

The conventional synthesis of methacryloyl hyaluronic acid (HA-MA) requires an extremely high amount of modification reagents, the organic solvents, and strenuous purification steps. Herein, a new green synthetic approach for the methacryloyl hyaluronic acid preparation with a tailorable substitution degree (SD) is reported, in which methacryloyl hydrazide is used as a more reactive reagent and only water is used as the solvent. The new method significantly reduces the amount of functionalization reagents (as low as only 0.3 equiv) and avoids the use of any organic solvents. The substitution degree can be tailored from 26% to 86% in a facile controllable manner. The new HA-MA (termed as HA-MA-H) can be UV-cross-linked to form a biocompatible hydrogel.

A perspective on environmentally benign protocols of thiazole synthesis

Thiazole has widespread importance in materials and medicines. Several reviews are reported which cover essential properties of thiazoles such as pharmacological activities, structure-activity relationship studies, and various synthetic routes. However, synthesis based on a greener approaches, particularly metal-free reactions, usage of mild, nontoxic, recyclable catalysts, eco-sustainable protocols, efficient solvents have not been exclusively reviewed. Current review emphasizes green synthetic approaches for substituted thiazoles that have been performed within the last decade.