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In this work, an environmentally friendly and cost-effective synthetic method of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) was successfully performed using aqueous extract of Phlogacanthus turgidus (PT) leaves. The biosynthesis of nanoparticles was optimized for reaction conditions including concentration of metallic ions, temperature, and time using the measurement of UV–Vis spectroscopy. The nanoparticles were well characterized by analytic techniques such as Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscope (HR-TEM), and selected area electron diffraction (SAED). The morphological data showed that PT-AgNPs possessed the spherical shape with the size distribution ranging from 5 to 15 nm with a mean size of 10 nm while PT-AuNPs existed in the multiple shape with the size distribution ranging from 5 to 20 nm with a mean size of 12 nm. The antibacterial behavior showed that PT-AgNPs possessed high bioactivity against four bacterial strains including Bacillus subtilis, Staphylococcus aureus, Salmonella typhi, and Escherichia coli. Moreover, the catalytic activity of the biogenic nanoparticles was investigated for catalytic reduction of 2-nitrophenol, 3-nitrophenol, and rhodamine B. The kinetic data showed that the nanoparticles were excellent catalysts with potential applications for environmental treatment. [ABSTRACT FROM AUTHOR]

Chemical investigation on chloroform extract of Phlogacanthus turgidus led to the isolation of one new compound namely turgidol, together with five known triterpenoids, lupeol, lupenone, betulin, betulinic acid, and taraxerol. Their structures and stereochemistry have been determined by 1 D and 2 D NMR analysis, high resolution mass spectrometry, and compared with those in literatures. The relative configuration of turgidol was defined using DFT-NMR chemical shift calculations and subsequent DP4+ probability method. Turgidol, betulin, and betulinic acid were evaluated for cytotoxic activity toward K562 cancer cell line and the alpha-glucosidase inhibition. [ABSTRACT FROM AUTHOR]

The plant extract has been used extensively for biosynthesis of noble metallic nanoparticles due to cost efficiency and simple technology. However, influence of plant growth condition can induce changes in composition and content of bioactive compounds, leading to difficulty in reproducing the metallic nanoparticles. In this work, we first utilized the plant embryos (Panax vietnamensis embryos—PVE) cultured under laboratory condition as a biosource for the synthesis of silver nanoparticles (AgNPs). This method can reduce unwanted changes of bioactive composition in the plant. The formation of AgNPs was optimized to afford the best colloidal solution. The physicochemical properties were characterized using analysis techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), Fourier transform infrared spectroscopy (FTIR) and thermal properties. Size of crystalline AgNPs was determined in the range of 3–20 nm with a mean size of 10 nm. The applications were investigated for antibacterial and catalytic effect. The biosynthesized AgNPs exhibited high antibacterial activity against Bacillus subtilis, Staphylococcus aureus and Escherichia coli. The excellent catalysis behavior of PVE-AgNPs has been investigated for the reduction of o-, m-, p-nitrophenols and toxic organic dyes including methyl orange, rhodamine 6G and rhodamine B. The effect of catalyst amount on the reaction performance was studied via kinetic investigation. This work unfolds a potential method for scalable reproduction of metallic nanoparticles. [ABSTRACT FROM AUTHOR]

This study develops an effective method for the in situ synthesis of palladium nanoparticles (PdNPs) using Cyclea barbata pectin as a green reducing and stabilizing reagent. The PdNP@pectin nanocomposite was well characterized by analysis techniques such as UV-vis, FTIR, EDX, XRD, SEM, HR-TEM and STEM-mapping. Crystalline PdNPs were found to be distributed in the size range of 1–25 nm with the highest frequency of 6–12 nm. PdNP@pectin exhibited excellent recyclable catalysis activity for the Heck coupling reaction in water medium. The kinetics and recyclability of nanoparticles were investigated for the catalytic reduction of o-, m- and p-nitrophenol. The result showed a good catalysis efficiency with five successful recycles without compromising much. In particular, the nanocomposite was used as a catalyst for the conversion of alkynes into cis-alkenes with KOH/DMF as a hydrogenation source. The reaction was also utilized effectively for the synthesis of sex pheromones, including Plutella xylostella ((Z)-11-hexadecen-1-yl acetate) and Cylas formicarius ((Z)-3-dodecen-1-yl(E)-2-butenoate) with the total yields of 70% and 68%, respectively. Therefore, PdNPs supported on C. barbata pectin are promising catalysis materials for application in various fields. [ABSTRACT FROM AUTHOR]

The extraction of essential oils from Cinnamomum cassia bark and leaf was carried out by hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD). Chemical compositions of volatile compounds were determined by GC/MS, 1H-NMR and infrared spectroscopy analysis. The dominant constituents found in the essential oils were aromatic compounds (> 90%) including (E)-cinnamaldehyde (CAL) and (E)-cinnamyl acetate (CAC) as the major components. The thermogravimetry (TG) method was used to study thermal stability and volatilization of the oils at room temperature. The bark essential oils exhibited inhibitory effects against a bacterial strain, S. aureus and a yeast strain, S. cerevisiae at MIC value 200 µg/mL. The decomposition kinetic of the essential oils was studied via the isoconversional kinetic models using the TG data. Two the isoconversional models, Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) were used to determine activation energies (Ea) for decomposition of the essential oils. [ABSTRACT FROM AUTHOR]

The study reports a versatile, cost-efficient and ecofriendly protocol for the synthesis of biogenic silver nanoparticles (AgNPs) using the aqueous extracts of Quao Binh Chau, Stereospermum binhchauensis and Che Vang, Jasminum subtriplinerve and their application in antibacterial activity and catalysis. The AgNPs with varying morphology and physical properties have been optimized using the absorption measurements. The biogenic AgNPs have been characterized by Fourier transform infrared spectroscopy, UV–Vis spectroscopy, transmission electron microscopy, X-ray diffraction analysis, energy-dispersive X-ray spectroscopy and thermal behaviors. Stable crystalline AgNPs with average particle sizes of 20.0 nm and 8.0 nm were fabricated from aqueous extract of Quao Binh Chau and Che Vang, respectively. The phytochemicals from the extracts involved in reduction and stabilization of AgNPs are identified by FTIR spectra and thermal gravimetric analysis. Both the biosynthesized AgNPs show the potent antibacterial activity against four tested bacterial strains including Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Agrobacterium tumefaciens. High catalytic activity of the biogenic AgNPs in the degradation of toxic contaminants (4-nitrophenol and methyl orange) was observed. The antibacterial and catalytic activities are found to be size and phytochemical dependent. The antibacterial and catalytic activities of the biogenic nanoparticles would find applications in the biomedical and environmental fields. [ABSTRACT FROM AUTHOR]

The present study describes an eco-friendly approach for the synthesis of colloidal solution of silver and gold nanoparticles (L-AgNPs and L-AuNPs) from the aqueous extract of Lactuca indica leaf. Major parameters affecting on the formation of L-AgNPs and L-AuNPs were optimized using UV–Vis analysis at absorption maximum around 423 nm and 531 nm, respectively. The plant extract as reducing and capping agents of MNPs was demonstrated by Fourier-transform infrared (FTIR) spectroscopy. The nanoscale of metals was confirmed by Transmission electron microscopy (TEM) measurements. TEM studies revealed that L-AgNPs were mostly spherical with average size of 13.5 nm and L-AuNPs possessed multi shapes with an average size of 14.5 nm. Selected area electron diffraction (SAED) analysis and X-ray diffractometer (XRD) data confirm their crystalline structure. The nanomaterials showed efficient catalysis in the degradation of 4-nitrophenol and methyl orange. [ABSTRACT FROM AUTHOR]

Novel multi-functional nanocomposites were fabricated from polysaccharides, alginate (Alg) and β-cyclodextrin (β-CD) via the ionotropic gelation mechanism. Different procedures for capping silver nanoparticles (AgNPs) were used to synthesize the nanocomposites AgNPs@β-CD/Alg. The aqueous extract of L. indica served as a green reductant for the optimized synthesis of the AgNPs. The AgNPs were incorporated and stabilized by using different β-CD/Alg capping methods, which induced changes in their morphology. The average sizes (10–30 nm) can be controlled by different stabilization agents. The effects of the capping methods were evaluated for the catalytic activity of the degradation reaction of methyl orange. The results demonstrated that the synthetic methods induced an obvious influence on the catalytic efficiency and recyclability. It was demonstrated that the mechanism of AgNPs catalysis relied on the Langmuir–Hinshelwood model of heterogeneous catalysis. Moreover, the AgNPs-loaded nanocomposites were studied for silver release in various media and the antibacterial activity against E. coli was evaluated for all samples. [ABSTRACT FROM AUTHOR]

Oil extracted from spent coffee ground (SCG) has been well known as a potential feedstock for high quality biodiesel production. This work was to investigate extraction, physical and chemical characterizations of Robusta coffee oil (CO) and its application for biodiesel production. Analysis of seven coffee ground (CG) samples showed that oil content in CGs depended on technique of the manufacturer. Morphological changes of CGs surface were recorded by FESEM technique which showed the particle size significantly increased with the oil loss. Infrared spectroscopies revealed absence of SCG oil in the de-oiled SCG, confirmed that soxhlet method in hexane was used efficiently for the oil extraction. Thermal properties of SCG oil, fresh coffee ground (FCG), SCG and de-oiled SCG samples were investigated by simultaneous TG–DTA measurement. The obtained data showed the oil content relating to thermal changes of SCG samples. Comparison between chemical components of Robusta coffee bean (RCB) and SCG reflected a fact that most of oil content in the SCG could be originated in manufacturing process of FCG. Quality biodiesel product has prepared from SCG oils via a two-step process. After pre-treatment process, transesterification of SCG oils was carried out with methanol (v/v, 30%) and NaOH (w/v, 1%) in yield 89.2%. [ABSTRACT FROM AUTHOR]

This study presents an efficient and facile method for biosynthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using aqueous extract of burdock root (BR), A. lappa, and their applications. The nanoparticles were characterized by ultraviolet-visible spectrophotometry, X-ray diffraction, transmission electron microscopy, energy dispersive X-ray, thermogravimetry, and differential thermal analysis. AgNPs capped the BR extract (BR-AgNPs) possessed roughly spherical geometry with an average diameter of 21.3 nm while uneven geometry of AuNPs capped the BR extract (BR-AuNPs) showed multi shapes in average size of 24.7 nm. The BR-AgNPs strongly inhibited five tested microorganism strains. In particular, the nanoparticles showed excellent catalytic activity for the conversion of pollutants within wastewater. Pseudo-first-order rate constants for the degradation of 4-nitrophenol, methyl orange, and rhodamine B were respectively found 6.77 × 10−3, 3.70 × 10−3, and 6.07 × 10−3 s−1 for BR-AgNPs and 6.87 × 10−3, 6.07 × 10−3, and 7.07 × 10−3 s−1 for BR-AuNPs.ᅟ [ABSTRACT FROM AUTHOR]

Content of essential oils in flower and leaf of Citrus microcarpa was 1.1 and 0.8% (v/w), respectively. The flower oil was dominated by monoterpene hydrocarbons in which limonene (74.5%) was determined as a major component. The dominant constituents found in the calamondin leaf oil were sesquiterpene (82.0%) with elemol (37.5%) as a major component. The obtained thermal data showed that thermal stability of flower and leaf oils was up to 80 and 110 °C, respectively. A study of TG isothermal volatilization at 42.5 °C showed the mass loss of the essential oils as a function of exposition time. Antioxidant assays using both DPPH and ABTS radical scavenging methods exhibited antioxidant activity of flower and leaf essential oils was higher than that of vitamin C. The leaf essential oil exhibited inhibitory effects against six microbial strains while the flower oil inhibited only one fungus strain, A. niger. [ABSTRACT FROM AUTHOR]

We have reported synthesis of monoalkynyl- and dialkynyl-quinoxalines using Pd(0)/PEG nanoparticles as a catalyst and the tandem cyclization of the dialkynequinoxalines with sodium azide in high yields. The structures of all synthesized compounds were confirmed by IR, NMR and ESI-MS. The derivatives showed the absorption maxima at the region of 370 to 442 nm and emission maxima at the region of 386 to 539 nm with high fluorescence intensity in chloroform. It suggests that compounds 4b, 4c, 5b and 5c can be potential candidates for optical device applications. [ABSTRACT FROM AUTHOR]

A mixture of stereoisomers of the corn rootworm pheromones was synthesised via the Grignard coupling of protected bromohydrins with alkylcuprate as a key step. The synthesis of 8-methyldec-2- yl propanoate (I ), the northern corn rootworm Diabrotica longicornis Say pheromone, was achieved from pentane-1,5-diol in four steps with an overall yield of 35.1 % and 10-methyltridecan-2-one (II ), the southern corn rootworm Diabrotica undecimpunctata howardi Barber pheromone, was synthesised from octane-1,8-diol as commercially available starting material in five steps with an overall yield of 28.7 %. [ABSTRACT FROM AUTHOR]

The sex pheromone of the cabbage looper Trichoplusia ni Hubner, ( Z)-7-dodecen-1-yl acetate, was synthesized via a bimolecular nucleophilic substitution reaction between the Grignard reagent of the protected bromohydrin with ( Z)-2-hepten-1-yl acetate in the presence of CuI catalyst as a key step. An efficient synthetic method of preparation of the pheromone was achieved from ( Z)-2-butene-1,4-diol in four steps with an overall yield of 22.1%. [ABSTRACT FROM AUTHOR]

A series of poly-3-alkylthiophenes (P3ATs) with butyl (P3BT), hexyl (P3HT), and octyl (P3OT) side-chains and well-defined molecular weights (MWs) were synthesized using Grignard metathesis polymerization. The MWs of P3HTs and P3OTs obtained via gel permeation chromatography agreed well with the calculated MWs ranging from approximately 10 to 70 kDa. Differential scanning calorimetry results showed that the crystalline melting temperature increased with increasing MWs and decreasing alkyl side-chain length, whereas the crystallinity of the P3ATs increased with the growth of MWs. An MW-dependent red shift was observed in the UV–Vis and photoluminiscence spectra of the P3ATs in solution, which might be a strong evidence for the extended effective conjugation occurring in polymers with longer chain lengths. The photoluminescence quantum yields of pristine films in all polymers were lower than those of the diluted solutions, whereas they were higher than those of the phenyl-C61-butyric acid methyl ester-blended films. The UV–Vis spectra of the films showed fine structures with pronounced red shifts, and the interchain interaction-induced features were weakly dependent on the MW but significantly dependent on the alkyl side-chain length. The photovoltaic device performances of the P3BT and P3HT samples significantly improved upon blending with a fullerene derivative and subsequent annealing, whereas those of P3OTs mostly degraded, particularly after annealing. The optimal power conversion efficiencies of P3BT, P3HT, and P3OT were 2.4%, 3.6%, and 1.5%, respectively, after annealing with MWs of ~11, ~39, and ~38 kDa, respectively. [ABSTRACT FROM AUTHOR]