Environmental Friendly Conditions Research Articles

New olefin metathesis catalyst bearing N-mesitylimidazole and nitrate ligands – Synthesis, activity, and performance in aqueous media

A new 18-electron ruthenium complex, where ruthenium catalytic center is coordinated with the N-mesitylimidazole and nitrate ligands, as well as o-isopropoxystyrene moiety, is reported. The synthesis and detailed characterization of the Ru complex, together with density functional theory calculations (DFT), are presented. The complex is air- and moisture-stable, although has weak catalytical activity in the model metathesis reactions. However, its activity increases upon the addition of an aqueous HCl 1 M solution. Activated Ru complex successfully promotes metathesis in organic solvents as well as in water, enabling efficient performance (even up to 100%) of the catalyst under environment-friendly conditions. The activation mechanism of the reported catalyst is supported by time-dependent DFT calculations and ab initio molecular dynamics simulations.

Surface functionalization of polyester.

Surface functionalization such as hydrophilization is an important step in the polymer manufacturing process and a key requirement for application of polyesters. Conventional methods like chemical or plasma treatment are often toxic, expensive and adversely affect the mechanical properties of the polymer. Enzymes have proven to be an attractive alternative for surface hydrolysis and functionalization of synthetic polymers since they work under mild and environmental friendly process conditions while preserving the mechanical properties. This chapter deals with the enzymatic surface treatment of polyesters and in particular with current methods for the analysis of polymer hydrolysis and of changes of surface properties.

Green reusable Pd nanoparticles embedded in phytochemical resins for mild hydrogenations of nitroarenes

Reusable biosourced Pd NPs are prepared and used under environment-friendly conditions for mild and chemospecific hydrogenations of nitroarenes.

Photocatalytic Micro/Nanomotors: From Construction to Applications.

Synthetic micro/nanomotors (MNMs) are a particular class of micrometer or nanometer scale devices with controllable motion behavior in solutions by transferring various energies (chemical, optical, acoustic, magnetic, electric, etc.) into mechanical energy. These tiny devices can be functionalized either chemically or physically to accomplish complex tasks in a microcosm. Up to now, MNMs have exhibited great potential in various fields, ranging from environmental remediation, nanofabrication, to biomedical applications. Recently, light-driven MNMs as classic artificial MNMs have attracted much attention. Under wireless remote control, they can perform reversible and repeatable motion behavior with immediate photoresponse. Photocatalytic micro/nanomotors (PMNMs) based on photocatalysts, one of the most important light-driven MNMs, can utilize energy from both the external light source and surrounding chemicals to achieve efficient propulsion. Unlike other kinds of MNMs, the PMNMs have a unique characteristic: photocatalytic property. On one hand, since photocatalysts can convert both optical and chemical energy inputs into mechanical propulsion of PMNMs via photocatalytic reactions, the propulsion generated can be modulated in many ways, such as through chemical concentration or light intensity. In addition, these PMNMs can be operated at low levels of optical and chemical energy input which is highly desired for more practical scenarios. Furthermore, PMNMs can be operated with custom features, including go/stop motion control through regulating an on/off switch, speed modulation through varying light intensities, direction control through adjusting light source position, and so forth. On the other hand, as superoxide radicals can be generated by photocatalytic reactions of activated photocatalysts, the PMNMs show great potential in environment remediation, especially in organic pollutant degradation. In order to construct more practical PMNMs for future applications and further extend their application fields, the ideal PMNMs should be operated in a fully environmentally friendly system with strong propulsion. In the past decade, great progress in the construction, motion regulation, and application of PMNMs has been achieved, but there are still some challenges to realize the perfect system. In this Account, we will summarize our recent efforts and those of other groups in the development toward attractive PMNM systems. First, we will illustrate basic principles about the photocatalytic reactions of photocatalysts and demonstrate how the photocatalytic reactions affect the propulsion of PMNMs. Then, we will illustrate the construction strategies for highly efficient and biocompatible PMNMs from two key aspects: (1) Improvement of energy conversion efficiency to achieve strong propulsion of PMNMs. (2) Expansion of the usable wavelengths of light to operate PMNMs in environment-friendly conditions. Next, potential applications of PMNMs have been described. In particular, environment remediation has taken major attention for the applications of PMNMs due to their photocatalytic properties. Finally, in order to promote the development of PMNMs which can be operated in fully green environments for more practical applications, an outlook of key challenges and opportunities in construction of ideal PMNMs is presented.

Zinc oxide nanoparticles as efficient catalyst for the synthesis of novel di-spiroindolizidine bisoxindoles in aqueous medium

Developing environmentally benign synthetic protocols such as reaction in water is a major challenge. However, many of the known methods carried out in an aqueous medium are not efficient at large scale and need purification involving volatile solvents. Heterogeneous catalysis by nanoparticles in aqueous medium is a possible solution. Therefore, we tested the use of heterogeneous zinc oxide nanoparticles to catalyse the synthesis of di-spiroindolizidine bisoxindoles at room temperature by three-component condensation in an aqueous medium via azomethine ylide-mediated 1,3-dipolar cycloaddition reaction. The products were obtained with regio- and diastereoselectivities, with yields ranging from 83 to 94%, in 60 min. Absolute structures of products were confirmed by single-crystal X-ray crystallography. A gram-scale reaction along with recyclability experiment of the heterogeneous catalyst was also performed. To establish the sustainability of the reaction presented, green chemistry matrixes were calculated and found to possess a high atom economy of 96.59% and small E-factor of 0.098. The presented method has advantages such as environmental friendly reaction conditions, use of inexpensive heterogeneous zinc oxide nanoparticle as catalyst, broad substrate scope, short reaction times, quantitative yields of complex di-spiroindolizidine bisoxindoles and absence of tedious purification procedure like column chromatography.

A Domino Approach for the Synthesis of α,β‐Epoxy Ketones from Carbonyl Compounds under Neat Conditions at Ambient Temperature

AbstractAn efficient method has been developed for the synthesis of α,β‐epoxy ketones from one pot reaction between aldehydes and ketones in presence of cesium carbonate and tert‐butyl hydrogen peroxide (TBHP) under neat conditions. In this methodology we have used the one pot domino type reaction with aldehydes and ketones to get α,β‐epoxy ketones without presynthesized chalcone precursors. A library of α,β‐epoxy ketones having a variety of substituents has been synthesized. Clean reaction, mild reaction conditions, ease of product isolation/purification, easily accessible reactants, wide substrates scope and metal and solvent‐free and environmental friendly reaction conditions are the notable advantages of the present method. The present methodology is applicable to gram scale synthesis.

Preparation of Superhydrophobic Magnetic Polyurethane Sponge for Removing Oil Pollutants from Water

The superhydrophobic magnetic sponge were prepared by Fe3O4 nanoparticals and stearic acid which were coated on the surface of polyurethane sponge. The preparation process of the superhydrophobic materials are prepared under mild, low-cost and environment-friendly conditions. pieces of PU sponges were decorated immersed in a ethanol solution which uniform suspension Fe3O4 nanoparticles ethanol by ultrasonication, and the obtained PU sponges were modified with stearic acid. The Fe3O4 and stearic acid were coated onto the skeleton surface of the sponge, which make the as-prepared sponge possess magnetic and hierarchically microstructure. The high elasticity sponge can through the simple squeeze realize oil recovery. After 5 cycles, the as-prepared sponge retains excellent absorption properties. The superhydrophobic magnetic polyurethane sponge has great potential in industrial oil separation and oil spill recovery in future.

Simultaneously facilitating dispersion and thermal reduction of graphene oxide to enhance thermal conductivity of poly(vinylidene fluoride)/graphene nanocomposites by water in continuous extrusion

Poly(vinylidene fluoride)/graphene oxide (PVDF/GO) nanocomposites were fabricated by a melt mixing extrusion especially with water injection. It was found for the first time that the injected water simultaneously facilitated the dispersion and in situ thermal reduction of the unfunctionalized GO in the PVDF matrix under environmental friendly conditions in melt extrusion. The injected water accelerated the removal of oxygen-containing groups especially CO group and the transformation of carbon sp3 into sp2 bonds of the GO through enhancing the interaction between the PVDF and GO and facilitating the hydrothermal dehydration of GO. The interfacial interaction between the GO and PVDF facilitated the nucleation of crystallites at the PVDF-GO interfaces, which can reduce the interfacial thermal resistivity. Thus, the thermal conductivity of the PVDF/GO nanocomposites prepared with water injection was significantly improved. Compared with the neat PVDF sample, the enhancements in the thermal conductivities were 64.1% and 132.5% for the nanocomposites with low loading of 1.0 wt% GO prepared without and with water injection, respectively. The results provide a scalable and environmentally benign approach for fabricating thermally conductive nanocomposites without complex dispersion and reduction processes.

Recovering ferulic acid from wheat bran enzymatic hydrolysate by a novel and non-thermal process associating weak anion-exchange and electrodialysis

Abstract Agricultural by-products such as wheat bran and straw are rich in arabinoxylans. Composed of a main chain of β-(1,4) linked xylose ramified by arabinose and ferulic acid, these polymers are sources of valuable molecules, in particular ferulic acid and monomeric (xylose, arabinose and glucose) and oligomeric carbohydrates. Enzymatic hydrolysis using hemicellulasic cocktails obtained from Thermobacillus xylanilyticus provide an eco-friendly alternative to acid or alkaline deconstruction. In this article, downstream purification of the enzymatic hydrolysate of wheat bran with a weak anion-exchange resin (Amberlyst A21- Dow) in free-base form was studied and optimized to reach concentrated ferulate fractions in environment-friendly conditions. A demineralization step by homopolar electrodialysis prior to anion-exchange allowed most of the competing inorganic anions to be removed from the hydrolysate. The capacity of fixation of ferulic acid on the active sites of the resin was increased, as well as purity and concentration of the basic eluate, consequently. Ferulic acid could therefore be crystallized by adjusting the pH of the eluate. 83% was crystallized and purity (NMR) reached 90–95%. At last, 52% of ferulic acid released from wheat bran by the hemicellulasic cocktail was purified and recovered as a solid. Moreover, more than 50 BV (Bed Volume) of the hydrolysate could be recovered during the resin saturation step as rather pure carbohydrates under monomeric (xylose, arabinose and glucose) and oligomeric (xylobiose, xylotriose and xylotetraose) form.

Optimization of Ion‐Dependent Green Synthesis of Fmoc‐Amino Acids in Phosphate Buffer

AbstractHere we show the optimization of Fmoc amino acid conjugation reaction in physiological relevant phosphate buffer using ethanol as a green solvent. Using Phenylalanine as model amino acid, different parameters including water, temperature, stirring, pH, buffer composition, ions and solvents were tested to optimize the product yield. Using the optimized method, Fmoc conjugation of other amino acids and a dipeptide are reported. Important role of buffer ions in the catalyst free Fmoc‐Phenylalanine synthesis and implication of phosphate ions through 31P Nuclear Magnetic Resonance (NMR) in the product formation have been demonstrated. The characterization of the final products was carried using reverse phase chromatography, mass spectrometry and NMR spectroscopy. Optimized method using phosphate buffer and ethanol as green solvent might provide substitute for borate buffer and pave the way for amino acid detection in biological fluids under physiologically relevant and environmental friendly conditions.

Efficient microwave-assisted diastereoselective synthesis of indole-based 4,5-dihydrofurans via a one-pot, three-component reaction in water

The combination of two or more different heterocyclic moieties in a single molecule would enhance biological activity significantly. The indole and furan scaffolds are promising candidates in drug design, and they have been widely found in natural products and therapeutic agents. Owing to their pharmaceutical importance, there is an urgent need to design rapid, efficient and environmentally benign protocols for the synthesis of indole–dihydrofuran biheterocycles. Herein, we have developed a novel ecofriendly approach for the diastereoselective synthesis of indole-based 4,5-dihydrofurans through a three-component reaction of 3-cyanoacetyl indoles with various aldehydes and N-phenacylpyridinium bromides in the presence of potassium carbonate as an inexpensive and non-toxic base in water under low power microwave irradiation. The findings show that aromatic and heteroaromatic aldehydes tolerated well in this reaction. The products were obtained in 85–98% yields in 4–20 min. The advantages of this method consist of the environmental friendly reaction conditions, use of green solvent and safe base, availability of raw materials, wide range of usable substrates, short reaction times, excellent yields and absence of any tedious workup or purification.

Selective debenzylation of 1-benzyloxy-4-methoxy benzene over 5-sulfosalicylic acid-functionalized ordered mesoporous silica (SBA-15/SFSA) catalyst

5-Sulfosalicylic acid (SFSA) functionalized mesoporous silica nanocomposites (SBA/APTS/SFSA) were synthesized by post grafting technique for selective debenzylation of 1-benzyloxy-4-methoxy benzene. The uniform incorporation of SFSA inside the mesoporous SBA-15 framework was confirmed by standard characterization techniques (PXRD, adsorption studies, FT-IR, etc.). Total surface area, pore size and pore volume of the SBA/APTS/SFSA catalysts decreased with increase in the concentration of SFSA confirming the uniform insertion of SFSA into mesoporous SBA-15 matrix. Catalytic activity studies showed highest conversion and selectivity of the desired product on SBA/APTS/SFSA catalyst compared to homogeneous SFSA and other solid support (Al2O3 and SiO2). All the reaction parameters such as reaction time, reaction temperature and catalyst weight were optimized under environmental friendly conditions. Finally, the possible mechanism of the reaction was explained.

Amberlite IR-120 (H) mediated “on water” synthesis of fluorescent Ruthenium(II)-arene 8-hydroxyquinoline complexes for cancer therapy and live cell imaging

A series of Ruthenium-Quinolinol complexes (3a–d &4a–d) has been synthesized by employing a simple, efficient and environmental friendly condition. Catalytic role of Amberlite IRA-120(H) has been demonstrated. The structures of the new compounds were elucidated by the analysis of spectroscopic data. The stability of these complexes was measured by UV spectroscopy & time dependent NMR spectroscopy. These newly developed complexes were represented as potential anticancer agent against human breast carcinoma cell line (MCF-7), human Epitheloid Cervix Carcinoma (HeLa), human lung adenocarcinoma epithelial cell line (A549) and human colon cancer cell line (Caco-2). Most of the ruthenium complexes showed higher anticancer activity in MCF-7, HeLa and Caco-2 cell lines than cisplatin. A high selectivity (9–28 folds) was observed with these newly developed organoruthenium compounds in human cancer cell lines (MCF-7, HeLa and Caco-2) with respect to normal fibroblast cell line (MRC-5). Complex [(η6-hexamethylbenzene)RuCl(κ2-O,N-5-chloro-HyQ)]·Cl (4b), [(η6-hexamethylbenzene)RuCl(κ2-O,N-5,7-dibromo-HyQ)]·Cl (4c) and [(η6-hexamethylbenzene)RuCl(κ2-O,N-5-chloro-7-iodo-HyQ)]·Cl (4d) exhibited best cytotoxicity profiles in three reported human cancer cell lines (MCF-7, HeLa, Caco-2). Cellular imaging study was also performed with these newly developed organoruthenium compounds. Compound 4c might be utilized for cancer theranostic agents because of its significant quantum yield in water, high potency, selectivity and high cellular uptake in cancer cell lines.

Intramolecular functionalization of C(sp3)[sbnd]H bonds adjacent to an amide nitrogen atom: Metal-free synthesis of 2-hydroxy-benzoxazinone derivatives

An intramolecular C(sp3)H bond functionalization adjacent to an amide nitrogen atom was successfully developed for synthesis of 2-hydroxybenzoxazinone derivatives under environment-friendly conditions. The method featured no metal catalyst, broad substrate scopes and high yields. Besides, a radical mechanism was proposed in the reaction process. Additionally, most of target compounds exhibited potent anti-proliferative activities against MCF-7 and Hela cells.

Controlling gold nanoparticle seeded growth in thermophilic ferritin protein templates

Ferritin protein cages provide templates for inorganic nanoparticle synthesis in more environmentally-friendly conditions. Thermophilic ferritin from Archaeoglobus fulgidus (AfFtn) has been shown to encapsulate pre-formed 6-nm gold nanoparticles (AuNPs) and template their further growth within its 8-nm cavity. In this study, we explore whether using a gold complex with electrostatic complementarity to the anionic ferritin cavity can promote efficient seeded nanoparticle growth. We also compare wt AfFtn and a closed pore mutant AfFtn to explore whether the ferritin pores influence final AuNP size.

Shape and structural effects of R5-templated Pd nanomaterials as potent catalyst for oxygen electroreduction in alkaline media

Bio-inspired metal nanomaterials are receiving increasing research attentions in catalytic field recently, while peptide-based method represents new revenues to fabricate stable and reactive catalyst under mild and environmental friendly conditions. Among all kinds of noble metals, peptide-based palladium nanomaterials have demonstrated excellent catalytic capabilities in a variety of organic reactions. However, their electrocatalytic properties have not been systematically studied. Herein, R5-templated Pd nanomaterials have been fabricated and employed as potent catalysts for oxygen reduction reaction (ORR). The shape and morphology of these Pd nanomaterials were manipulated by tuning the metal-to-R5 ratio. The as-prepared Pd nanomaterials demonstrated excellent ORR activity in alkaline media. R5-Pd-90 exhibited the best activity which is superior than commercial Pt/C, in terms of onset potential, diffusion-limited current density as well as long-term stability. The correlation between the shape and/or morphology of the peptide-templated Pd nanomaterials and their ORR activity has been successfully established.

Synthesis and antioxidant evaluation of lipophilic oleuropein aglycone derivatives.

Oleuropein is the most important phenolic compound present in olive cultivars, but it is scarcely present in extra virgin olive oil (EVOO) due to its high hydrophilicity and degradability. Thus, a set of oleuropein aglycone derivatives were synthesized by transacetylation under mild conditions with the aim of circumventing these drawbacks and making the active moiety in oleuropein suitable to be added to food fats. The oleuropein aglycone (closed ring form) is obtained by hydrolyzing oleuropein using Lewis acid catalysis. Then, the permeation profiles as well as the antioxidant capacity of the oleuropein aglycone derivatives were evaluated by ORAC, DPPH assays and by ROS formation using the SH-SY5Y cell line. The biological activities of the obtained compounds exhibited a dependence on their level of lipophilicity.

ChemInform Abstract: An Efficient Solvent‐Free Synthesis of Isoxazolyl‐1,4‐dihydropyridines on Solid Support SiO2 under Microwave Irradiation.

Abstractvia a multicomponent reaction strategy

Surface modified mesoporous silica polymer nanocomposites for adsorption of dyes from aqueous solution

Functionalized mesoporous silica nanocomposites were synthesized via in situ radical polymerization of vinyl monomers (vinylcarbazole, vinyl imidazole and vinyl sulphonic acid) and characterized for adsorption of dyes from aqueous solution. Physicochemical characterization (PXRD, SEM, adsorption studies etc.) of the functionalized nanocomposites showed the presence of mesoporous nature of the nanocomposites. Different adsorption parameters such as adsorption weight, adsorption time, temperature, pH etc., were optimized for adsorption of dyes under environmental friendly conditions. The adsorption studies showed 96.8 and 80.49 % removal for cationic and anionic dyes respectively. Adsorption kinetics of the dyes on the functionalized nanocomposites can be well depicted theoretically by using pseudo-second-order kinetic model.

Molecular docking studies and synthesis of novel bisbenzimidazole derivatives as inhibitors of α-glucosidase

A series of bisbenzimidazole derivatives starting from o-phenylenediamine and 4-nitro-o-phenylenediamine were prepared with oxalic acid. Most of the reactions were conducted using both the microwave and conventional methods to compare yields and reaction times. The operational simplicity, environmental friendly conditions and high yield in a significantly short reaction time were the major benefits. All substances’ inhibitory activities against α-glucosidase were evaluated. The results may suggest a significant role for the nature of bisbenzimidazole compounds in their inhibitory action against α-glucosidase. They showed different range of α-glucosidase inhibitory potential with IC50 value ranging between 0.44±0.04 and 6.69±0.01μM when compared to the standard acarbose (IC50, 13.34±1.26μM). This has described a new class of α-glucosidase inhibitors. Molecular docking studies were done for all compounds to identify important binding modes responsible for inhibition activity of α-glucosidase.