Green Synthetic Approach Research Articles

Anatase TiO2 Mesocrystals: Green Synthesis, In Situ Conversion to Porous Single Crystals, and Self-Doping Ti3+ for Enhanced Visible Light Driven Photocatalytic Removal of NO.

Mesocrystals are of great interest for a wide range of applications owing to their unique structural features and properties. The realization of well-defined metal oxide mesocrystals through a facile and green synthetic approach still remains a great challenge. Here, a novel synthesis strategy is reported for the production of spindle-shaped anatase TiO2 mesocrystals with a single-crystal-like structure, which was simply achieved through the one-step hydrolysis reaction of TiCl3 in the green and recyclable media polyethylene glycol (PEG-400) without any additives. Such anatase mesocrystals were constructed from small nanocrystal subunits (≈1.5-4.5 nm in diameter) and formed through oriented aggregation of the nanocrystals pre-formed in the reaction system. Owing to their novel structural characteristics, the as-synthesized anatase mesocrystals could be easily fused in situ into porous single crystals by annealing in air. More significantly, after being annealed in vacuum, Ti3+ sites could be easily induced in the anatase crystal lattice, resulting in the formation of Ti3+ self-doped anatase mesocrystals. The thus-transformed mesocrystals exhibited enhanced visible light activity towards the photocatalytic oxidation of nitric oxide (NO) to NO3- , which could be largely attributed to their intrinsic Ti3+ self-doped nature, as well as high crystallinity and high porosity of the mesocrystalline architecture.

A green synthetic approach toward the synthesis of structurally diverse spirooxindole derivative libraries under catalyst-free conditions

A catalyst-free green methodology for the synthesis of pharmacologically important spirooxindole derivatives has been developed by a three-component domino reaction between isatin, various amino compounds, and 1,3-dicarbonyl or 3-phenylisoxazolone compounds in ethyl L-lactate medium at room temperature. This new efficient synthetic method facilitated the formation of a wide range of biologically significant spirooxindole derivatives (including 17 new spirooxindoles) under very mild conditions. The cytotoxic activity of one of the isoxazole-fused spirooxindoles was evaluated in MDA-MB 468 breast cancer cell line. It was found that cell survivability decreases with increasing concentration of the selected compound in MDA-MB 468 breast cancer cells.

Green synthesis of β-CD-functionalized monodispersed silver nanoparticles with ehanced catalytic activity

Increasing application of noble-metal nanoparticles (MNPs) urges the development of a nontoxic and environmentally friendly synthesis methodology. In this paper,using β-Cyclodextrin (β-CD) as reducer and stablizer, a green synthetic approach of monodispersed silver nanoparticles (AgNPs) with diameter between 10–25nmin aqueous alkaline medium is reported. By varying the molar ration of β-CD/AgNO3, the size of as-prepared silver particles can be readily controlled. Furthermore, the formation mechanism of the AgNPs was discussed. On the basis, the catalytic activity of the as-prepared AgNPs was studied toward reduction of p-nitrophenol by NaBH4. The experimental results shown that surface modified by β-CD can improve the catalytic activity of the silver nanoparticles.

A Decade Update on Benzoxazoles, a Privileged Scaffold in ­Synthetic Organic Chemistry

In 2014, more than 80% of the marketed drugs in the US contained heterocyclic compounds, which play a major role in the drug-discovery process, as one of the primary components. Benzoxazole, consisting of an oxazole ring fused with a benzene ring, has shown profound impact in drug discovery research owing to its important bioactivity. This moiety has also shown important properties in material science. The synthesis of this privileged scaffold from readily available chemicals remains a primary focus for the synthetic chemistry community. In this review, efforts have been made to focus on the latest information available on the different synthetic strategies such as solution phase, multicomponent, green and solid phase chemistry and applications of different benzoxazole derivatives. Furthermore, the updated synthetic information incorporated in this review article will help to improve future synthesis of this scaffold. 1 Introduction 2 Solution-Phase Synthetic Approach to Substituted Benzoxazoles 2.1 Condensation of o-Aminophenol with Carboxylic Acids 2.2 Condensation of o-Aminophenol with Aldehydes 2.3 Condensation of o-Aminophenol with Orthoesters, ortho-Haloamides, or 1,1-Dihaloalkenes 2.4 Synthesis of Benzoxazoles from Schiff Bases 2.5 Miscellaneous 3 Multicomponent Synthetic Approach to Substituted Benzoxa­zoles 4 Solid-Phase Synthetic Approach to Substituted Benzoxazoles 5 Green Synthetic Approach to Substituted Benzoxazoles 5.1 Condensation of o-Aminophenol with Aldehydes 5.2 Condensation of o-Aminophenol with ortho-Substituted Benz­amides 5.3 Condensation of o-Aminophenol with Carboxylic Acid and its Derivatives 5.4 Condensation of o-Aminophenol with Alcohols or Amines 5.5 Miscellaneous 6 Bioactive Derivatives of Benzoxazoles 7 Conclusion and Outlook

A mechanochemical route toward the rational, systematic, and cost-effective green synthesis of strongly luminescent copper iodide based hybrid phosphors

Mechanochemical synthesis via simple manual grinding is one of the most commonly used green synthetic approaches and is applied here for the synthesis of new hybrid phosphors Cu2I2(tpp)2(L)n (n = 1, 2).

Aqueous Extract of Saraca indica Leaves in the Synthesis of Copper Oxide Nanoparticles: Finding a Way towards Going Green

The present study is mainly aimed at the synthesis of copper oxide nanoparticles of varied size by green synthetic approach. The structural and morphological behavior of as-synthesized CuO nanoparticles were investigated using ultraviolet-visible spectral studies (UV-Vis), Fourier transform-Infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). The reduction of copper ions using aqueous extract of S. indica leaves produces nanoparticles of varied size and morphology. The images from SEM investigation revealed that the particles are spherical in shape with average diameter of 40–70 nm. TEM and HRTEM images clearly indicate the crystallinity and spherical nature of as-synthesized CuO nanoparticles with interplanar distance between two neighboring lattice fringes of 0.315 nm.

Green synthetic approach to prepare silver nanoparticles using longan (Dimocarpus longan) peel extract and evaluation of their antibacterial activities

Silver nanoparticles have been gaining popular interest as a potent antibacterial agent. The methods for obtaining silver nanoparticles using plant extracts offer a number of advantages over other processes as it is simple, cost effective, reproducible, biocompatible and environmentally friendly. Herein, the biosynthesis of silver nanoparticles was developed through the use of longan peel extract as reducing and stabilizing agent. The reaction was performed at room temperature for 24 h. Several spectroscopic and microscopic techniques were introduced for the characterization of synthesized silver nanoparticles. In addition, the quantification of phytochemical content as well as reducing power of the peel extract was carried out using colorimetric method. UV-Vis spectrum showed the surface plasmon resonance peak of silver nanoparticles, observed between 400-500 nm. The silver nanoparticles was irregular spherical in shape with an average of the particle size of 38.6±7.0 nm. FTIR analysis demonstrated the functional groups of phytochemicals in the peel extract involving in the synthesis of silver nanoparticles. XRD and EDX spectra indicated that the synthesized silver nanoparticles were crystalline in nature with face centered cubic symmetry and the presence of silver element. A good stability of silver nanoparticles was confirmed by zeta-potential measurement. Furthermore, the biogenic silver nanoparticles also exhibited an antibacterial activity against tested pathogenic bacteria.

Synthesis of cationically charged photoluminescent coinage metal nanoclusters by sputtering over a liquid polymer matrix

A generic green synthetic approach to synthesize photoluminescent metal nanoclusters of known plasmonic elements via sputtering on a biocompatible polymer matrix.

Inexpensive ionic liquid mediated green synthetic approach of multi-functionalized regioselective β-lactam fused isoxazolidine heterocyclic hybrids

A novel efficient eco-friendly on “ionic liquid” method has been developed for the synthesis of multi-functionalized isoxazolidines through a nitrone 1,3-dipolar cycloaddition reaction. The low cost and eco-benign room temperature ionic liquid, acetylcholine iodide-ethylene glycol (ACI/EG) accelerates the formation of the desired regioselective mono-/di isoxazolidine analogues and reduced the reaction time with high level of chemical yield. Furthermore, the recyclability of ACI/EG has also been investigated.

Preparation and <i>in-vitro</i> cytotoxicity of zinc oxide nanoparticles against osteoarthritic chondrocytes

Purpose: To prepare zinc oxide nanoparticles (ZnO NPs) using Piper betle leaf extract by a green synthetic approach, and to evaluate their cytotoxicity towards human osteoarthritic chondrocytes. Methods: ZnO NPs were prepared by heating 30 mL of 0.1 M zinc nitrate (ZnNO 3 ) with 10 mL of Piper betle leaf extract at 90°C for 4 h. The ZnO NPs produced were characterized by various techniques, including x-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV–Vis), energy-dispersive x-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The cytotoxicity of the NPs against human osteoarthritic chondrocytes was studied using eosin Y test method. Results: The change in color of the reaction solution from colorless to pale white within 1 h indicated the formation of ZnO NPs. FTIR results revealed coating of plant polyphenols on ZnO NPs surface while XRD and EDS demonstrated the hexagonal structure of crystalline ZnO NPs. Dynamic light scattering (DLS) and TEM analyses indicate hexagonal NPs with a mean particle size of 32 nm. In-vitro cytotoxicity data showed that the NPs exhibited concentration-dependent cytotoxicity towards osteoarthritic chondrocytes. Conclusions: A simple, fast and eco-friendly method for the preparation of ZnO NPs using Piper betle leaf extract is reported here. The NPs exhibit concentration-dependent toxicity towards human osteoarthritic chondrocytes. Keywords: Zinc oxide nanoparticles, Piper betle, Cytotoxicity, Osteoarthritic chondrocytes, Energydispersive x-ray spectroscopy, Transmission electron microscopy

A novel fluorimetric sensing platform for highly sensitive detection of organophosphorus pesticides by using egg white-encapsulated gold nanoclusters

Assays for organophosphorus pesticides (OPs) with high sensitivity as well as on-site screening have been urgently required to protect ecosystem and prevent disease. Herein, a novel fluorimetric sensing platform was constructed for quantitative detection of OPs via tyrosinase (TYR) enzyme-controlled quenching of gold nanoclusters (AuNCs). One-step green synthetic approach was developed for the synthesis of AuNCs by using chicken egg white (CEW) as template and stabilizer. Initially, TYR can catalyze the oxidation of dopamine to dopaminechrome, which can efficiently quench the fluorescence intensity of AuNCs at 630nm based on dynamic quenching process. However, with the presence of OPs, the activity of TYR was inhibited, resulting in the fluorescence recovery of AuNCs. This proposed fluorescence platform was demonstrated to enable rapid detection for OPs (paraoxon as model) and to provide excellent sensitivity with a detection limit of 0.1ngmL−1. Significantly, the fluorescence probe was used to prepare paper-based test strips for visual detection of OPs, which validated the excellent potential for real-time and on-site application.

Synthesis of Monoalkyl Glyceryl Ethers by Ring Opening of Glycidol with Alcohols in the Presence of Lewis Acids.

The present work deals with the production of monoalkyl glyceryl ethers (MAGEs) through a new reaction pathway based on the reaction of glycidol and alcohols catalyzed by Lewis acid-based catalysts. Glycidol is quantitatively converted with high selectivity (99 %) into MAGEs under very mild reaction conditions (80 °C and 0.01 mol % catalyst loading) in only 1 h using Al(OTf)3 or Bi(OTf)3 as catalyst. The proposed method enhances the choice of possible green synthetic approaches for the production of value-added products such as MAGEs.

Green Synthetic Approach for Synthesis of Fluorescent Carbon Dots for Lisinopril Drug Delivery System and their Confirmations in the Cells.

In this work, highly luminescent carbon dots (CDs) were synthesized by the hydrothermal method at 170°C for 12h using pasteurized milk as a carbon source. The prepared CDs exhibited bright blue fluorescence under UV light illumination at 365nm. The CDs show fluorescence life time of ~4.89ns at excitation wavelength of 370nm. The effect of different solvents on the fluorescence property of CDs was also investigated. The lisinopril (Lis)-loaded CDs were fabricated by self-assembly of lisinopril on the surfaces of CDs, which were characterized by UV-visible and FT-IR spectroscopic techniques. The controlled release of lisinopril from the Lis-CDs was realized at pH values of 5.2, 6.2 and 7.4, respectively. The results of the cytotoxicity and confocal laser scanning microscopic images indicate that the Lis-CDs were successfully uptaken by HeLa cells without apparent cytotoxicity. The synthesized CDs show great potential as drug vehicles with good biocompatibility, sustained release of lisinopril from CDs, indicating that the CDs can act as a promising drug delivery system for therapeutic delivery and/or bioimaging applications.

Simple and green synthesis of protein-conjugated CdS nanoparticles and spectroscopic study on the interaction between CdS and zein

The present study demonstrates the role of zein molecules in synthesizing CdS nanoassemblies through protein-directed, green synthetic approach. Zein molecules can as capping ligand and stabilizing agent to regulate the nucleation and growth of CdS nanocrystals, and the obtained products are organic–inorganic nanocomposites. The analysis of surface charge and conductivity indicates that strong electrostatic force restricts mobility of ions, which creates a local supersaturation surrounding the binding sites of zein and reduces the activated energy of nucleation. The interaction between Cd2+/CdS and zein molecules was systematically investigated through spectroscopy techniques. Fourier transform infrared (FT-IR) spectra were used to envisage the binding of the functional groups of zein with the surface of CdS nanoparticles. Ultraviolet visible (UV–Vis) and photoluminescence (PL) spectra results show that Cd2+/CdS might interact with the aromatic amino acids of protein molecules and change its chemical microenvironment. The quantum-confined effect of nanocrystals is confirmed by optical absorption spectrum due to the small size (3–5 nm) of CdS particles. The data of circular dichroism (CD) spectra indicate that the formation of CdS nanocrystals could lead to the conformational change of zein molecules. Moreover, the possible mechanism of CdS nanocrystals growth in zein solution was also discussed. The weak interactions such as Van der Waals, hydrophobic forces and hydrogen bonds in zein molecules should play a crucial factor in the self-assembly of small nanoparticles.

Self-assembly of CeO2 nanostructures/reduced graphene oxide composite aerogels for efficient photocatalytic degradation of organic pollutants in water

Reduced graphene oxide aerogels (RGAs) are excellent candidates for water remediation due to their lightweight, high surface area and high absorbance rate. Here, we report a simple green synthetic approach for the self-assembly of CeO2-RGA aerogels using vitamin-C as the reducing agent. The photocatalytic degradation performance of the as-synthesized CeO2-RGA aerogels was studied as a function of simulated sunlight irradiation, using the organic dye Rhodamine-B (RhB) as a test molecule. The CeO2/RGA composites displayed highly enhanced photocatalytic activity in comparison to bare CeO2 nanostructures. This enhancement is ascribed to efficient charge transfer from the CeO2 nanostructures to the reduced graphene oxide (RGO) sheets due to the high degree of interconnectivity between the RGO and CeO2 nanostructures. In addition, photoluminescence studies strongly support this charge separation mechanism. The microstructures and optical properties of the as-synthesized nanostructures were characterized using HRTEM, XRD, FTIR, XPS and DRS. These results demonstrated that the CeO2 nanostructures are grown on interconnected three-dimensional RGO nanosheets. We believe that the findings of this study provide a versatile pathway to induce self-assembly of reduced graphene sheets with other semiconductor nanostructures in the form of lightweight aerogels for a variety of environmental applications.

The green synthetic approach to prepare PbS/chitosan nanocomposites and its new optical sensing active properties for 2-isonaphthol

PbS nanoparticles were successfully synthesized in the presence of chitosan (CS) through an in situ method. This method is an effective, simple, and green synthetic approach to preparing nanomaterial films. The structure, morphology, and stability of the materials were examined via Fourier transform infrared spectroscopy, and the characteristic peak of the NH2 group shifted from 1554 to 1598 cm-1 after PbS was formed in the film. The Pb–S bond exhibited a vibrational absorption peak at 605 cm-1, which further confirmed the generation of PbS nanoparticles. Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) procedures were performed as well; well-defined nanoparticles were detected in the CS matrix by SEM. As per DSC findings, the thermal stabilities of the PbS/CS film were 50°C higher than those of pure CS. Moreover, the fluorescence emission of the films was sensitive to the presence of 2-isonaphthol. The effect of 2-isonaphthol concentration on the emission of films increases significantly with an increase in this concentration. The concentration-dependent fluorescence can be described by a correlation equation when 2-isonaphthol concentration ranges from 0 to 12.56 mg/L, and fluorescence results revealed that the PbS/CS nanoparticles were sensitive to 2-isonaphthol in the liquid phase. The proposed method may be applied to detect 2-isonaphthol in the environment and in the chemical industry.

Branched Biobased Diesters with Exceptional Low Temperature and Flow Properties for Use in Lubricant Formulations

A vegetable oil based diester (1,6-hexyldioleate) was branched with propanoic acid (C3) using a green synthetic approach involving solvent- and catalyst-free epoxide ring opening followed by in situ normal esterification. A total of three branched ester derivatives possessing varied numbers of internal protruding branched ester and hydroxyl groups were obtained. All of the pure branched derivatives were comprised of mixtures of positional and/or stereoisomers. Differential scanning calorimetry showed that, regardless of the compositional inhomogeneity of each branched derivative, crystallization was suppressed completely in all of the branched compounds and they all demonstrated glass transitions below −65 °C. This unique thermal behavior is attributed to the internal protruding branched moieties and hydroxyl groups which dramatically slowed mass transfer. The viscosity of the branched compounds was 1 order of magnitude larger than that of the starting diester due to the increased resistance to flow assoc...

Direct Decarboxylative Alkynylation of α,α‐Difluoroarylacetic Acids under Transition Metal‐Free Conditions

AbstractAn efficient and generally applicable protocol for decarboxylative coupling of α,α‐difluoroarylacetic acids with ethynylbenziodoxolone (EBX) reagents has been developed, affording α,α‐difluoromethylated alkynes bearing various functional groups in moderate to excellent yields. Remarkably, this potassium persulfate (K2S2O8)‐promoted reaction employs water as solvent under transition metal‐free conditions, thus providing a green synthetic approach to α,α‐difluoromethylated alkynes.magnified image

ChemInform Abstract: Recent Advances in Research of Natural and Synthetic Bioactive Quinolines

AbstractReview: 124 refs.

ChemInform Abstract: Y(OTf)3‐Catalyzed Heterocyclic Formation via Aerobic Oxygenation: An Approach to Dihydro Quinazolinones and Quinazolinones.

Abstract The Y(OTf) 3 -catalyzed aerobic oxidative cyclization reaction for the selective synthesis of dihydroquinazolinones and quinazolinones has been developed. This method provides a practical, effective and green synthetic approach to dihydroquinazolinones and quinazolinones which both are important units in many biologically active compounds.