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The diastereoselectivity of adducts in the addition reaction via the Felkin-Anh model is affected significantly by the steric effect of bulky groups. However, the influence of steric alkyl chain length has not been studied for the diastereoselectivity. In this work, we present a new strategy for the racemic synthesis of β-methyl alcohols to obtain various diastereomer ratios using the Felkin-Anh model. The addition of alkyl Grignard reagents to α-methyl aldehydes afforded diastereomer ratios of threo/erythro ≈ 2:1, while the reduction in structurally related ketones using LiAlH4 afforded ratios of threo/erythro ≈ 1:1. The experimental data showed no effect of alkyl chain length on either side on the stereoselectivity of adducts. All synthesized analogues were evaluated for attractiveness to Rhynchophorus ferrugineus weevils in the field. Five novel derivatives, including two alcohols and three ketones, were found to attract weevils in the field trials. Among them, 3-methyldecan-4-one (5b) and 4-methyldecan-5-ol (11a) were found to be the most attractive to the insects.

In this study, BiVO4 was successfully synthesized via the solvothermal process using a solvent mixture of ethylene glycol and water under different synthesis conditions of temperature and pH. Physicochemical properties such as crystal phase, morphology, and optical absorption of the as-synthesized BiVO4 samples were characterized by X-ray diffraction (XRD), Raman spectra, field emission scanning electron microscopy (FE-SEM), and ultraviolet–visible diffraction reflection spectroscopy (UV–vis DRS). The XRD analysis showed that different synthesis conditions of temperature and pH significantly affected the growth of monoclinic BiVO4 crystals oriented along (0 4 0) facets. Form SEM results, the synthesis conditions, including pH and temperature, have a great effect on the morphology of monoclinic structured BiVO4. As the pH value increases in the range of 0–9 and temperature increases from 80 °C to 180 °C, the morphology of BiVO4 changed from peanut-, rod-, and leaf-like shapes. The photocatalytic activities of as-synthesized BiVO4 photocatalysts were evaluated by the photodegradation of methylene blue (MB) dye under irradiation of white LED light. We have found that by using appropriate synthesis conditions (the synthesis temperature of 140 °C and the synthesis pH of 7) the BiVO4 exhibited high photocatalytic efficiency for MB degradation (about 82.30% after 180 min of irradiation). This result is due to the development of the BiVO4 crystals oriented along (0 4 0) facets with an increase in the intensity ratio of I(0 4 0)/I(1 2 1). The growth of BiVO4 crystals oriented along (0 4 0) facets may be beneficial to enhance the photocatalytic activity of monoclinic scheelite BiVO4.

Biogenic synthesis of noble metal nanoparticles is particularly interested due to the effective applications for plasmonic catalysis and bioactivity. In this work, aqueous extract of waste Nypa fruticans (NF) fruit husk was utilized to synthesize silver nanoparticles (NF-AgNPs) and gold nanoparticles (NF-AuNPs). The effected parameters on the green reduction of metallic nanoparticles (MNPs) were investigated. Under optimum conditions of concentration, temperature and time, the biosynthesized NF-AgNPs and NF-AuNPs showed spherical nanoparticles with average size of 10–15 nm and 15–20 nm, respectively. The presence of AgCl in NF-AgNPs has been demonstrated by X-ray diffraction analysis. The elemental components of all samples confirmed the presence of anions and cations come from the aqueous extract. The biosynthesized nanoparticles were evaluated bacterial activity against three bacterial strains. NF-AgNPs exhibited selective antibacterial activity against Bacillus cereus but no activity against Staphylococcus aureus and Salmonella typhimurium at all tested concentrations. The recyclable catalysis activity of the biosynthesized nanoparticles was evaluated for the reduction of nitrophenols in the presence of sodium borohydride which possessed good catalytic performance in six running numbers. Additionally, AgCl played role as a source supplying AgNPs has been demonstrated in catalytic reduction of p-nitrophenol. For study of catalytic kinetic, NF-AgNPs possessed higher rate constant in comparison with NF-AuNPs whereas TOF values of NF-AuNPs was determined to be higher than those of NF-AgNPs.

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.

Two series of sulfonamides were synthesized from 4-hydrazinyl­ben­zenesulfonamide as the key starting material. 1,3,5-Tri­arylpyrazoline sulfon­amides ( 2a – i ) were obtained by cyclocondensation of various chalcones in 53–64 % yields, while 4-thiazolidinone derivatives ( 4a – e ) were synthesized by cyclocondensation between mercaptoacetic acid and different phenylhydra­zones in 43–62 % yields. The synthesized compounds were characterized based on FTIR, 1H-NMR, 13C-NMR and HRMS data. The sulfonamides were evaluated for their in vitro antimicrobial activities against four bacterial strains (E. coli, P. aeruginosa, B. subtillis and S aureus), two filamentous fungal strains (A. niger and F. oxysporum) and two yeast strains (C. albicans and S. cerevisiae). Seven pyrazolines, 2a – c and 2e – h , exhibited significant inhibition of different microbial strains. Among them, compound 2b displayed good anti­fungal activity against A. niger (MIC value at 12.5 mg mL-1) over the reference drug.

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.

Multiple sharp-edged gold nanostars were efficiently assembled on nanopipette tips through electrostatic interactions for use as a potent intracellular hypoxia-sensing Raman probe. Colloidal stability and surface immobilization were checked using scanning electron microscopy, light scattering, and zeta potential measurements. Site-specific intracellular hypoxia levels can be estimated in vitro and in vivo using Raman lancets (RL). Distinct Raman spectral changes for the nitro-(NO2 ) functional group of the redox marker 4-nitrothiophenol (4NTP) can be quantified according to the intracellular oxygen (O2 ) content, ranging from 1 % to 10 %. Redox potential changes in mitochondrial respiration were also examined through serial injections of inhibitors. 3D-cultured cells and in vivo tests were used to validate our method, and its application in the assessment of the aggressiveness of cancer cells by differentiating spectral changes between malignant and benign cells was demonstrated.

This paper develops a simple and green process of synthesizing palladium nanoclusters (PdNCs) capped on the hybrid nanocomposite based on biodegradable polysaccharides, 2-hydroxypropyl-β-cyclodextrin (HPCD) and alginate (Alg) through an ionotropic gelation mechanism. PdNCs were biosynthesized from aqueous extract of Burdock root (BR), Arctium lappa. The nanocomposite PdNCs/HPCD/Alg was characterized by techniques like UV–Vis, FTIR, EDX, FESEM, TEM, HR-TEM and TG-DTA. The crystal palladium nanoparticles were found to distribute in cluster shape with a size of 4–10 nm. EDX data showed that average amount of palladium capped on the hybrid nanocomposite was approx. 4.7% (w/w). PdNCs/HPCD/Alg exhibited highly catalytic activity for degradation of pollutants including 4-nitrophenol, methyl orange and rhodamine B in wastewater and leaching mechanism of the nanocatalyst was showed. In particular, the nanocomposite showed excellent aqueous-phase catalytic performance for free-triphenylphosphine Sonogashira cross-coupling reaction. The nanocatalyst could be efficiently reused without much compromising with its activity.

k-Oligocarrageenan (OC) is an effective biostimulator and a protector against disease infections for plants. However, the effect of OC molecular weight (MW) on plant growth is not fully understood. In this work, OCs with three different MWs (42, 17 and 4 kDa) was prepared by varying the degradation reaction time using ascorbic acid as a reagent. The product structure was confirmed by Fourier-transform infrared spectroscopy (FTIR) data. The growth promotion for maize (Zea mays L.) plants was investigated by foliar spray application of the prepared OCs. Field trials were carried out in two years, 2018 and 2019. The results showed that among treatments, OC with 4 kDa exhibited the best performance in both crop growth and grain yield parameters which indicated increases compared to the control in plant height (6.9&ndash, 19.9%), length of ears (12.2%), diameter of ears (9.1%), fresh grain weight (17.8%), dry grain weight (20.0%) and grain yield (21.3%). Moreover, low MW OC augmented NP uptake in the plant growth while no effect on K uptake was observed. Therefore, OC with low MWs is potentially promising to apply as a promoter to enhance yield of crops.

This study reports a simple process to synthesize and separate of 2-(substituted-phenyl) benzimidazole derivatives with high yield and efficiency. Specifically, by reacting ortho-phenylenediamines with benzaldehydes using sodium metabisulphite as an oxidation agent in a mixture of solvent under mild condition, twenty-three compounds of benzimidazoles were obtained and separated easily using hexane and water to wash, respectively. The structure of all obtained compounds was identified by FTIR, NMR and HRMS. The SAR analysis of synthesized benzimidazoles on human lung (A549), breast (MDA-MB-231) and prostate (PC3) cancer cell lines showed that the presence of methyl group at 5(6)-position on benzimidazole scaffold was a contributing factor influencing the anticancer activity. The presence of electron-donating groups (OH, OMe, –NMe2, –O–CH2–C6H5) also caused significant increase of anticancer activity, while the presence of electron-withdrawing groups (–NO2, –CF3) on the phenyl group at 2-position of benzimidazole ring decreased the ability of inhibition of synthesized benzimidazoles. The compounds 2f and 2g displayed the significant anticancer activity on both A549 and PC3 cell lines. Two series of 2-phenylbenzimidazoles were synthesized by simple process with high yield and efficiency and they were illumiated the effect of substituent groups in their structures on the bioactivity against three cancer cell line A549, MDA-MB-231 and PC3.

This work presents a simply new method for in situ synthesis of gold nanoparticles (AuNPs) using the biodegradable polysaccharides. A novel composite of lactose/alginate (Lac/Alg) could be prepared easily through ionotropic gelation mechanism which can reduce in situ gold ions into AuNPs. Lactose plays a crucial role as a reducing reagent which are demonstrated by FTIR analysis. The crystalline structure of AuNPs with a mean size of 10 nm has been confirmed by analysis techniques. The nanocomposite powder possesses highly catalytic performance for degradation of contaminants including 4-nitrophenol, methyl orange, rhodamine 6 G and rhodamine B. The dispersion solution of AuNPs@Lac/Alg was used as an effective probe for highly selective detection of Fe3+ ions. The detection mechanism replies on the aggregation of nanocomposite in the presence of Fe3+ ions. LOD value was found to be 0.8 μM in a linear range of 2.0–80.0 μM.

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.

The emergent occurrence of sulfonamide species involving sulfadiazine (SDZ) and sulfamethazine (SMZ) in aquatic systems can cause a wide range of potential risks; hence, remediation strategies need to be necessary. Here, we develop the novel metal-organic framework-derived nanocomposite, and apply for the adsorption of SDZ and SMZ antibiotics. To assess the best-fitting kinetic (pseudo first-order, pseudo second-order) and isotherm (Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Redlich-Peterson, Sips, Toth, and Khan) models, a series of numerous statistical analysis was performed. Numerous error functions including squares of the errors (SSE), hybrid fractional error function (HYBRID), Marquardt’s percent standard deviation (MPSD), and mean relative error (MRE) were also analyzed to assess the linear and nonlinear models. The results indicated that both linear and nonlinear kinetic models were mostly fitted well with pseudo second-order models (Radj)2 > 0.97. Although linear kinetics gave better (Radj)2, error functions (MRE, SSE, HYBRID, and MPSD) were mostly higher than those of nonlinear kinetics. For adsorption isotherm, nonlinear Redlich-Peterson was the most compatible model with extremely high adjusted coefficients of determination (Radj)2 ~ 1.0000. While nonlinear Langmuir model gave relatively high (Radj)2 (0.9898–0.9960) and acceptable error functions, we found the considerable difference of error functions and parameters among four types of linear Langmuir (Types I, II, III, IV). The findings indicate potential errors as selecting one of linearized Langmuir types in equilibrium study. It is suggested that nonlinear models should be applied for better fitness.

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%.

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 determ...

We herein report Mannich aminomethylation of variously structural flavonoids and their biological evaluation against human breast cancer cell. Mannich reaction showed that substitution at C-6 position depends on amine basicity and C-ring feature of flavonoids. All five flavonoid substrates reacted with strong amine bases to afford the bis(6,8-aminomethyl) derivatives, while with weak amines, the different products were obtained dependently on structural characteristic of flavonoid. 3-OH and 3-O-substituted groups on the C-ring exhibited the deactivated aminomethylation at C-6 position, whereas substitution at this position was independent on bond feature at C-2 and C-3 on the C-ring. Screening anti-proliferative activity showed six flavonoids possessed activity against breast cancer cell, MDA-MB-231. Among them, the flavonoids, luteolin (2) and 3′,4′,5,7-tetrahydroxy-6,8-bis(pyrrolidin-1-ylmethyl)-3-rutinosylflavone (3a), displayed the highest anti-proliferative activity with the lowest IC50 values.

Vibrational fingerprints of N6-methyladenine (NMA) and N6,N6-dimethyladenine (NDMA) on gold nanoparticles (AuNPs) were investigated by means of Raman spectroscopy. NMA and NDMA have one methyl group and two methyl groups, respectively, at the amino moiety of the adenine purine unit. Surface-enhanced Raman scattering (SERS) spectra were analyzed to explain the difference in the spectral features among adenine, NMA, and NDMA based on density functional theory (DFT) calculations on gold clusters. NMA has unique bands at 717 and 1101 cm−1 in their SERS spectra on AuNPs, which can be differentiated from those of adenine. After observing these unique spectra features, the SERS spectra of NMA and NDMA on AuNPs were dissimilar, suggesting that the methyl group at the amino groups of the adenine may be significantly affecting the binding on AuNPs, as supported by DFT calculations of NMA and NDMA on gold clusters. Our Raman study indicates that the methylation at the amino group in adenine may play a significant role in providing vibrational finger prints in the SERS spectra on metal surfaces.

We compared the adsorption and desorption of 1-pyrenecarboxylic acid (PyC), 1-pyreneacetic acid (PyA), and 1-pyrenebutyric acid (PyB) on silver nanoparticles (AgNPs) via interfacial spectroscopic tools to study the role of the aliphatic units between pyrene and carboxylic group. The negative surface charges of AgNPs at ca. −51 mV shifted up to −11 mV, after adsorbing hydrophobic pyrene compounds. The three pyrene acid compounds appeared to adsorb onto AgNPs via their carboxylate units by referring to the observation of the broad ν (COO − ) bands at 1380–1410 cm −1 in the Raman spectra. X-ray photoelectron spectroscopy (XPS) also supported the C O species in the C 1s region. AgNPs were found to efficiently quench the fluorescence of the three pyrene acid adsorbates. The highest Stern–Volmer constant of PyA may be due to the largest overlap integral with the surface Plasmon absorption band of AgNPs. The butyric unit was expected to lead a stronger binding on Ag, as suggested by density functional theory (DFT) calculations. The adsorbed pyrene acid compounds appeared to be released from AgNPs by thiol-containing glutathione (GSH). PyB with the butyric group exhibited larger quenched fluorescence intensities and smaller released amounts than PyC and PyA in aqueous solutions and A549 cancer cells. Our study will be helpful in designing pyrene-based fluorescence sensors in cellular imaging.

Spectral differences between cytosine (Cyt) and 5-methylcytosine (5MC) were investigated by means of Raman spectroscopy with a combination of density functional theory (DFT) calculations. Surface-enhanced Raman scattering (SERS) revealed discriminating peaks of 5MC from those of Cyt upon adsorption on gold nanoparticles (AuNPs). Among the notable features, the multiple bands between 850 and 700 cm− 1 for the ring-breathing modes of 5MC and Cyt could be correlated well with the simulated spectra based on the DFT calculations of the adsorbates on the gold cluster atoms. The relative energetic stabilities of the enol/keto and the amino/imino tautomeric forms of Cyt and 5MC have been estimated using DFT calculations, before and after binding six atom gold clusters. Among the six tautomeric forms, the 7H keto amino and the 4H imino trans forms are expected to be predominant in binding gold atoms, whereas the enol trans/cis conformers would coexist in the free gas phase. Our approach may provide useful theoretical guidelines for identifying 5MC from Cyt by analyzing Raman spectra on gold surfaces on the basis of quantum-mechanical calculations.

In the present study, cost-effective, and environmentally friendly fabrication of silver and gold nanoparticles was performed by using aqueous extract of waste corn-cob. The formation of the metallic nanoparticles (MNPs) was optimized by UV-Vis method. The phytoconstituents were responsible for reduction of silver and gold ions to silver nanoparticles (CC-AgNPs) and gold nanoparticles (CC-AuNPs) which were demonstrated by Fourier-transform infrared (FTIR) spectroscopy while formation of AgCl was attributed to the presence of chloride ions in the aqueous extract. The crystalline nature of the AgNPs, AgCl, and AuNPs was confirmed using the X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns. Morphological studies showed that the synthesized CC-AgNPs existed in spherical shape with the size ranging from 2 to 28 nm possessing an average value of 11 nm while CC-AuNPs were present in the multiple shapes with size ranging from 5 to 50 nm possessing an average value of 35 nm. For studies on bioactive application, the CC-AgNPs exhibited a high antibacterial activity against three bacterial strains including Salmonella typhimurium, Bacillus cereus, and Staphylococcus aureus. In addition, the catalytic efficiency of MNPs was investigated for reduction of o-, m-, p-nitrophenols, and degradation of organic dyes including Eosin Y and Rhodamine 6G. The rate constants calculated from the kinetical data revealed that the biosynthesized nanoparticles are excellent catalysts in potential applications for treatment of wastewater. Graphical abstract .

In this study, we investigated sulfate-modified BiVO4 with the high photocatalytic activity synthesized by a sol-gel method in the presence of thiourea, followed by the annealing process at different temperatures. Its structure was characterized by thermal gravimetric analysis (TGA), powder X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). The BiVO4 synthesized in the presence of thiourea and calcined at 600 &deg, C (T-BVO-600) exhibited the highest photocatalytic degradation efficiency of methylene blue (MB) in water, 98.53% MB removal was achieved within 240 min. The reaction mechanisms that affect MB photocatalytic degradation on the T-BVO-600 were investigated via an indirect chemical probe method, using chemical agents to capture the active species produced during the early stages of photocatalysis, including 1,4-benzoquinone (scavenger for O2&minus, ), ethylenediaminetetraacetic acid disodium salt (scavenger for h+), and tert-butanol (scavenger for HO&bull, ). The results show that holes (h+) and hydroxyl radicals (HO&bull, ) are the dominant species of MB decomposition. Photoluminescence (PL) measurement results of terephthalic acid solutions in the presence of BiVO4 samples and BiVO4 powders confirm the involvement of hydroxyl radicals and the separation efficiency of electron-hole pairs in MB photocatalytic degradation. Besides, the T-BVO-600 exhibits good recyclability for MB removal, achieving a removal rate of above 83% after five cycles. The T-BVO-600 has the features of high efficiency and good recyclability for MB photocatalytic degradation. These results provide new insight into the purpose of improving the photocatalytic activity of BiVO4 catalyst.

Recently, the waste agricultural materials have been widely considerable for green synthesis of noble metallic nanoparticles (MNPs) due to cost efficiency and environmental protection. This study has presented a simple method for the preparation of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) utilizing aqueous extract of waste Passiflora edulis peel (PEP) as reducing and stabilizing agents. The formation of MNPs was optimized reaction conditions to obtain the best colloidal solutions. The characterizations of the biosynthesized MNPs were performed by analysis techniques such as Fourier transmission infrared spectroscopy (FTIR), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED). The TEM data confirmed PEP-AgNPs and PEP-AuNPs in the spherical shape with mean size of 25 nm and 7 nm, respectively. The XRD and SAED patterns showed the synthesized nanoparticles existing in crystalline nature. Antibacterial and catalytic activities have been investigated for their applications. The PEP-AgNPs exhibited a strong antibacterial activity against three strains including Escherichia coli, Bacillus subtilis, and Staphylococcus aureus. The excellently catalytic activity of both the biosynthesized nanoparticles has been demonstrated for reduction of nitrophenols and degradation of toxic organic dyes via study on their kinetics.

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.

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.

This study presents an efficient and facile method for the trapping of Ag+ ions on hybrid nanocomposite based on 2-hydroxypropyl-β-cyclodextrin (HPCD) and alginate (Alg) in aqueous medium through ionotropic gelation mechanism and followed by in situ assembly of silver nanoparticles (AgNPs) using aqueous extract of Jasminum subtriplinerve leaves as a reducing agent. The nanocomposite AgNPs/HPCD/Alg was characterized by UV-vis, EDX, TEM, HR-TEM analysis. The AgNPs were found to be spherical shape and uniform size with an average diameter of 13.5 nm. EDX data showed about 4.0% (w/w) of AgNPs capped on the nanocomposite HPCD/Alg. The role of HPCD and Alg in the nanocomposites was observed from FTIR and thermal studies. The stability and distribution of the nanoparticles in the aqueous solution were determined by zeta potential and DLS measurements. The nanocomposites showed excellent catalytic performance for degradation of pollutants within industrial effluents including 4-nitrophenol, methyl orange and rhodamine B.

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%.

We report a facile method for sample preparation and sensitive on-site detection of melamine in powdered infant formula and chocolate using Raman spectroscopy on sharp-edged gold nanostars (AuNSs). The aggregation of AuNSs by sodium chloride (1.2 M) facilitates the more sensitive detection of melamine in comparison with spherical gold nanoparticles (AuNPs). Density functional theory quantum mechanical calculations were performed to determine the energetic stability on gold cluster atoms. Our spectroscopic data indicated that AuNSs are an efficient platform for detecting melamine in food mixtures. The detection limits of melamine in powdered infant formula and chocolate were found to be ~0.1 mg/kg and ~1 mg/kg, respectively, on AuNPs, whereas they were observed to be ~0.01 mg/kg and ~0.1 mg/kg, respectively, on AuNSs. Using a handheld Raman spectrometer, a sub-mg/kg detection of melamine in both powdered infant formula and chocolate could be achieved within a few minutes.

Zidovudine (AZT) adsorbed on colloidal gold nanoparticles (AuNPs) undergoes pH-induced conformational changes according to spectral changes in surface-enhanced Raman scattering (SERS). In acidic pH values conditions, AZT assumes the C(2ʹ)-endo conformer, which binds more weakly to AuNPs than under neutral and alkaline conditions. In this study, density functional theory (DFT) calculations were performed; these calculations also supported the conformation-dependent binding energies. A lactobionic acid-conjugated PEGylated (LA-PEG-SH; molecular weight: 3400) unit was attached to AuNPs to target the asialoglycoprotein receptors overexpressed in hepatocarcinoma cells of Huh7 and SNU-354. The loading efficiency values were measured to be ∼44–49% and ∼66–68% at pH values of 7 and 10, respectively. At an acidic pH of 4.5, they were estimated to be only ∼35–38%. pH-dependent spectral changes were observed for the asymmetric stretching modes of the azide (N N N) bands at 2183 cm−1 (in acidic pH) and at 2129 cm−1 (in basic pH). Cell viability analysis indicated that the LA-PEG-capped, AZT-coated AuNPs specifically inhibited the growth of the targeted hepatocarcinoma cells with better cancer cell killing efficiency than was observed with the LA-PEG-capped AuNPs without AZT.

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.

A surface-enhanced Raman scattering (SERS) detection method for environmental copper ions (Cu2+) was developed according to the vibrational spectral change of diethyldithiocarbamate (DDTC) on gold nanoparticles (AuNPs). The ultraviolet-visible (UV-Vis) absorption spectra indicated that DDTC formed a complex with Cu2+, showing a prominent peak at ~450 nm. We found Raman spectral changes in DDTC from ~1490 cm−1 to ~1504 cm−1 on AuNPs at a high concentration of Cu2+ above 1 μM. The other ions of Zn2+, Pb2+, Ni2+, NH4+, Mn2+, Mg2+, K+, Hg2+, Fe2+, Fe3+, Cr3+, Co2+, Cd2+, and Ca2+ did not produce such spectral changes, even after they reacted with DDTC. The electroplating industrial wastewater samples were tested under the interference of highly concentrated ions of Fe3+, Ni2+, and Zn2+. The Raman spectroscopy-based quantification of Cu2+ ions was able to be achieved for the wastewater after treatment with alkaline chlorination, whereas the cyanide-containing water did not show any spectral changes, due to the complexation of the cyanide with the Cu2+ ions. A micromolar range detection limit of Cu2+ ions could be achieved by analyzing the Raman spectra of DDTC in the cyanide-removed water.