Procedure In Aqueous Medium Research Articles

Tetra-cyanostilbene macrocycle: An effective “turn-on” fluorescence sensor for oxalic acid in aqueous media

• A novel tetra-cyanostilbene macrocycle was synthesized. • It exhibited “turn-on” fluorescence on sensing oxalic acid in aqueous media. • The detection limits was 3.82 × 10 −6 M for oxalic acid. • The sensing mechanism was clarified as oxalic acid in the cavity of the macrocycle. • It was applied on the detection of oxalic acid in test paper, taros and rust treatment. Although some detection methods for oxalic acid have been reported, the rapid, simple and on-site detection on oxalic acid was rarely presented. In this work, a “turn-on” fluorescence sensor for oxalic acid was realized by the simple and on-site procedure in aqueous media. A tetra-cyanostilbene macrocycle was synthesized by simple “2 + 2” condensation in 72 % yield. It displayed the strong “turn-on” blue fluorescence on selectively detecting oxalic acid among various ions and biomolecules. It possessed the high sensing sensitiveness with the detection limit of 3.82 × 10 −6 M. The sensing mechanism was clarified by pH influence on complexation, fluorescence Jobs’ plot, MS spectra, and 1 H NMR spectra, confirming that non-dissociated oxalic acid was bound in the cavity of the macrocycle based on hydrogen bonds. This sensing ability for oxalic acid was successfully applied in test paper, on-site detection for real samples of taros and rust treatment, suggesting the good application prospect in the rapid, simple and on-site detection for oxalic acid in daily life and industry.

Production of antimicrobial powders of guaiacol oligomers by a laccase-catalyzed synthesis reaction

Guaiacol oligomers were synthesized by enzyme-catalyzed polymerization with laccase as the catalyst. The polymerization procedure in aqueous media was followed by UV–vis spectra. The oligomers were characterized by NMR and MALDI-TOF spectra. The UV–vis spectra observation showed a new peak formed in the range of 380−530 nm indicating that new substances formed. The NMR results indicated that phenolic hydroxyl participated in the polymerization. The MALDI-TOF spectra revealed the weight average polymerization degree of guaiacol oligomers is 10 and the mass of the repeating unit is 122. The thermal stability was studied by TGA/DSC analysis. Guaiacol oligomers were more thermally stable than guaiacol, which can be ascribed to the long π-conjugated chains. Antioxidant behavior based on ABTS+ radical showed a concentration-dependent activity and reached a plateau at 800 μg/mL. The prepared guaiacol oligomers displayed antimicrobial activity against Staphylococcus aureus and Escherichia coli, in which the inhibition percentage is up to 99 %.

Composite Hydrogel Spheroids Based on Cellulose Nanofibrils and Nanofibrous Chiral Coordination Polymer by Green Synthesis

AbstractCellulose‐based hydrogels are promising sustainable materials for a variety of applications, including tissue engineering, water treatment, and drug delivery. However, the tailoring of diverse properties by efficient green chemistry methods is an ongoing challenge. Here, composite hydrogels of consistent spheroidal structure, incorporating TEMPO‐oxidized cellulose nanofibrils and nanofibrous chiral Cu(II) aspartate coordination polymer, are presented. The hydrogels are prepared by a single‐step procedure in aqueous media at ambient temperature and pressure, adhering to the principles of green chemistry. With a view to adapting this method for a variety of alternative coordination polymers (to tailor functional properties), the following critical factors for formation of robust composite hydrogel spheroids are identified: rheological properties of the primary matrix used for spheroidal hydrogel formation and coordination polymer self‐assembly rate.

Palladium(II)-Containing Tungstoarsenate(V), [PdII4(As2W15O56)2]16-, and Its Catalytic Properties.

We have synthesized and structurally characterized the 4-palladium(II)-containing 30-tungsto-4-arsenate(V), [Pd4(As2W15O56)2]16- (1), which represents the first palladium(II)-containing tungstoarsenate(V). The title polyanion 1 was prepared by a simple one-pot procedure in aqueous medium and characterized by single-crystal X-ray diffraction (XRD), thermogravimetric analysis (TGA), cyclic voltammetry, elemental analysis, and 183W nuclear magnetic resonance (NMR), infrared (IR), and ultraviolet-visible (UV-vis) spectroscopies. Polyanion 1 consists of four Pd2+ ions that are coordinated in a square-planar geometry to two trilacunary [As2W15O56]12- Wells-Dawson fragments resulting in a sandwich-type assembly. Catalytic studies on 1 revealed that it is an efficient catalyst precursor for the Suzuki-Miyaura cross-coupling reactions of various aryl halides in aqueous and nonaqueous media.

Effective coupling of BiPO4/g-C3N4 hybrid composites in ciprofloxacin photodegradation

A BiPO4/g-C3N4 photoactive system has been prepared by means of a practical ultrasound-assisted procedure in aqueous medium. The obtained hybrid composites were widely characterized by X-ray powder diffraction, Fourier-transform infrared spectroscopy, UV–vis diffuse reflectance spectroscopy, scanning electron microscopy and N2 adsorption–desorption measurements. The photocatalytic features of the samples were examined through the degradation of orange G dye and ciprofloxacin antibiotic, where the higher photocatalytic performance for the degradation of both pollutants was achieved for the g-C3N4 with 1 wt% loading of BiPO4 (1-BiPO4 sample). To explain this outstanding performance, a possible mechanism involving the delocalization of the photogenerated charge carriers in the BiPO4/g-C3N4 system is discussed. Also, total organic carbon analysis and photocatalytic tests with radical scavengers were performed to elucidate the importance of the reactive oxidizing species during the photocatalytic process.

Synthesis of highly-specific stable nanocrystalline goethite-like hydrous ferric oxide nanoparticles for biomedical applications by simple precipitation method

Exploration of novel types of iron oxide nanoparticles as well as novel versatile ways to prepare them in a controlled manner keeping in mind necessity of narrow size distributions and high colloidal and chemical stability is an important task for modern nanochemistry. Most of the procedures for preparation of nanocrystalline iron oxides require drastic conditions and complex mixtures of reagents, therefore there is a high demand for methods of synthesis of such nanoparticles (NPs) in mild conditions. In this study, we discovered a new way to prepare crystalline goethite-like hydrous ferric oxide (HFO) NPs by fast and simple precipitation procedure in aqueous media and probed modification strategies aimed at the development of modified HFO nanoparticles for biomedical applications, including express-diagnostics and specific cell targeting.

Fe3O4@SiO2 nanoparticle supported ionic liquid for green synthesis of antibacterially active 1-carbamoyl-1-phenylureas in water.

In the present work, we have designed a novel, heterogeneous and recyclable magnetic Brønsted acidic ionic liquid based on 5-phenyl-1H-tetrazole. The {Fe3O4@SiO2@(CH2)35-phenyl-1H-tetrazole-SO3H/Cl} ([FSTet-SO3H]Cl) was prepared via the immobilization of 5-phenyl-1H-tetrazole-bonded sulfonic acid onto the surface of silica-coated magnetic nanoparticles using 3-chloropropyltriethoxysilane as a linker. The catalyst was characterized by XRD, TEM, FESEM, EDS, TG-DTA, and FT-IR. The ability and high activity of this catalyst were demonstrated in the synthesis of 1-carbamoyl-1-phenylureas with good to excellent yields via a new, simple and one-pot procedure in aqueous media under reflux conditions. This procedure has advantages such as high yields, short reaction times, a simple methodology and work-up process, green reaction conditions, high stability, catalytic activity, and easy preparation, separation and reusability of the catalyst. The synthesis of these compounds was confirmed by FT-IR, 1H NMR, 13C NMR and CHN. In addition, we investigated the biological properties of the 1-carbamoyl-1-phenylureas as newly synthesized compounds. The described catalyst could be easily separated from the reaction mixture by additional magnetic force and reused several times without a remarkable loss of its catalytic activity and any considerable changes in the product yield and the reaction time.

Structural characterization and functional evaluation of lactoferrin–polyphenol conjugates formed by free-radical graft copolymerization

Covalent modifications of lactoferrin with EGCG, chlorogenic acid and gallic acid were performed by adopting a free-radical grafting procedure in aqueous media and they affect both structural and functional properties of the protein.

One-pot two-step sequential transformation: Highly efficient construction of o-2,3,5,6-tetrafluorobenzonitrile substituted oximes ethers

A practical variety of o-2,3,5,6-tetrafluorobenzonitrile substituted oximes ethers bearing broad functional groups were synthesized in moderate to good yields. The key highlight of this disclosure involving a one-pot two-step tandem procedure in aqueous media: the in situ formation of aryl aldehydes or ketones oximes followed by the SNAr reaction with pentafluorobenzonitrile via the high selective CF bond cleavage.

Structure sensitive chemical reactivity by palladium concave nanocubes and nanoflowers synthesised by a seed mediated procedure in aqueous medium.

Palladium nanocubes and their transformation to concave nanocubes and nanoflowers are realised by a seed mediated procedure in aqueous medium and at room temperature using cationic surfactants. The concave nanocubes and nanoflowers were found to be enclosed by high index facets. The under co-ordinated atoms present on the high index facets make these nanostructures chemically more active towards Suzuki coupling and Heck coupling reactions compared to the conventional nanocubes and spherical nanoparticles of similar size.

Laccase-catalysed oxidation of ferulic acid and ethyl ferulate in aqueous medium: A green procedure for the synthesis of new compounds

The enzymatic oxidation of ferulic acid (FA) and ethyl ferulate (EF) with Myceliophthora thermophila laccase, as biocatalyst, was performed in aqueous medium using an eco-friendly procedure to synthesize new active molecules. First, the commercial laccase was ultrafiltrated allowing for the elimination of phenolic contaminants and increasing the specific activity by a factor of 2. Then, kinetic parameters of this laccase were determined for both substrates (FA, EF), indicating a higher substrate affinity for ethyl ferulate. Additionally, enzymatic oxidation led to the synthesis of a FA-major product, exhibiting a molecular mass of 386g/mol and a EF-major product with a molecular mass of 442g/mol. Structural analyses by mass spectrometry allowed the identification of dimeric derivatives. The optical properties of the oxidation products showed the increase of red and yellow colours, with FA-products compared to EF-products. Additionally, enzymatic oxidation led to a decrease of antioxidant and cytotoxic activities compared to initial substrates. Consequently, this enzymatic procedure in aqueous medium could provide new compounds presenting optical, antioxidant and cytotoxic interest.

Synthesis of polymerizable vinyltriazoles: development of an optimized one-pot strategy starting from 4-bromobutyne

The development and implementation of a safe and scalable process for the preparation of isomeric vinyl-1,2,3-triazoles under mild conditions are described. Key aspects of the route reside in a one-pot click-elimination procedure in aqueous media leading to simple work-up and purification steps with increased overall yields.

Ciprofloxacin-collagen conjugate in the wound healingtreatment.

The synthesis of a novel functional biomaterial for wound healing treatment was carried out by adopting a free-radical grafting procedure in aqueous media. With this aim, ciprofloxacin (CFX) was covalently incorporated into collagen (T1C) chains employing an ascorbic acid/hydrogen peroxide redox pair as biocompatible initiator system. The covalent insertion of CFX in the polymeric chains was confirmed by FT-IR and UV analyses, while an antibacterial assay demonstrated the activity of the synthesized conjugate against Staphylococcus aureus and Escherichia coli, microorganisms that commonly infect wounds. A catechin blended conjugate was also tested in order to evaluate the ability to influence fibroblast cell growth. The observed antibacterial activity and stimulation of fibroblast growth support the applicability of CFX-T1C conjugate in wound treatment encouraging the healing process.

Molybdenum Peroxo Nanohybrid Compounds in Different Structures and Catalytic Properties

The new nanohybrid of molybdenum peroxo compounds based on pyridine dicarboxylate ligands were synthesized by employing one-pot procedure in aqueous media and characterized by infrared (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermal analysis (TGA/DTA). The prepared compounds were used as catalysts for the epoxidation of cyclohexene and cyclooctene in a mild condition. Results showed that these molybdenum peroxo compounds have significant potentials as oxidants in oxygen atom transfer reactions. These reagents oxidized olefins to epoxides in presence of hydrogen peroxide with high conversions and selectivity. Comparison of the relative reactivity of those compounds shows that the electronic nature of ligands influences the rate and activity of oxygen transfer reaction. It is also found that the addition of organic ligands not only prevented the formation of diols in epoxidation of alkenes, but also increased the reaction rate.

Synthesis of polystyrene/polybutylacrylate/layered silicate nanocomposites in aqueous medium

Synthesis of nanocomposites based on polystyrene/polybutylacrylate with layered silicates using emulsion polymerization procedure in aqueous medium allowed obtaining stable nanolatexes with sodium dodecyl sulfate as surfactant. Monomer and layered silicate nature influences the average diameter of the particles and the zeta potential appeared on the particle-disperse medium interface, as it was shown by dynamic light scattering analyses. In order to evidence the layered silicate structure, two structural evaluation methods were used. A new approach was used based on Fourier transform infrared analyses as a method to asses the clay delamination. The method was followed in conjunction with X-ray diffraction patterns and showed the pronounced delamination of the clay in the polymer matrix. The thermal stability was investigated by thermogravimetric analyses and the morphologies in solid state observed by environmental scanning electron microscope measurements.

A green method for the preparation of highly stable organic-inorganic hybrid anion-exchange membranes in aqueous media for electrochemical processes

Alkaline membranes also termed as anion exchange membranes (AEMs) have recently become important materials for electrochemical technology, alkaline fuel cells, and electrolyzers. We report a simple synthesis procedure for an anion-exchange silica precursor (AESP) by epoxide ring opening reaction using 3-aminopropyltriethoxysilane (APTEOS) and glycidyltrimethylammonium chloride (GDTMAC). The AESP-poly(vinyl alcohol) (PVA) organic-inorganic hybrid AEM was prepared by the sol–gel method in acidic medium followed by chemical crosslinking of –OH groups via formal reaction. The reported method is a “green” alternative for the production of AEM without the use of any solvent residues or hazardous chemicals. This simplified procedure in aqueous media avoids the use of chloromethyl methyl ether (CME), a carcinogen and harmful to human health. These AEMs (especially AEM-70) were designed to possess all the required properties of a highly anion conductive membrane such as high water uptake (67.3%), ion-exchange capacity (1.36 mequiv g−1), and permselectivity (0.94), along with reasonable conductivity (7.61 mS cm−1) due to quaternary ammonium group functionality. Electroosmotic studies revealed quite low mass drag and equivalent pore radius (2.31–5.28 A°) of the membrane, which are also desirable properties of an efficient AEM. Electrodialytic performance of the AEM-70 membrane revealed its suitability for applications in electro-membrane processes.

N-phosphorylation of amino acids by trimetaphosphate in aqueous solution—learning from prebiotic synthesis

Inspired by a reactivity study between sodium trimetaphosphate (P3m) and amino acids in prebiotic chemistry, a one-step reaction with efficient purification procedure in aqueous media has been developed for the synthesis of N-phosphono-amino acids (NPAA). P3m was used to phosphorylate amino acids to NPAA with yields of 60∼91%. The by-products, inorganic polyphosphates, were recycled to regenerate the phosphorylation reagent P3m.

The origin of the molecular interaction between amino acids and gold nanoparticles: A theoretical and experimental investigation

This study describes the synthesis of novel biological hybrid materials, where 3D structures were obtained using gold nanoparticles (AuNps) and methionine (Met) in a one-step procedure in aqueous media. The type of nanostructure can be controlled by tuning the intermolecular interactions between Met and AuNp, which strongly depends on the pH used for the synthesis. Computational simulation using the density-functional theory (DFT) showed that the AuNp–Met 3D structures are formed upon reorientation of Met molecules so that the backbone amine groups interact via H-bonds. These findings were experimentally confirmed using FTIR and UV–vis spectroscopy.

Determination of Gamma-hydroxybutyrate in Water and Human Urine by Solid Phase Microextraction-Gas Chromatography/Quadrupole Ion Trap Spectrometry

A simple method of detection was developed for gamma-hydroxybutyrate (GHB). The method involves the derivatization of GHB using a hexyl-chloroformate procedure in aqueous media (such as water or urine), extraction of the derivatization product directly from the sample using solid-phase microextraction, and subsequent separation and detection with gas chromatography quadrupole ion trap mass spectrometry. The deuterated form of GHB (GHB-D6) is used as an internal standard for quantitation. The method was linear for GHB-spiked pure water samples from 2 to 150 microg/mL GHB with a detection limit of 0.2 microg/mL. Spiked urine samples showed linearity from 5 to 500 microg/mL GHB with a detection limit of 2 microg/mL. The SPME-GC/MS method is applied to actual case samples, and the results are compared to those values obtained using a conventional GC/MS method. Sensitivity and linearity are comparable to those seen using traditional methods of separation, yet the SPME method is superior due to the simplicity, speed of analysis, reduction in solvent waste, and ability to differentiate between GHB and gamma-butyrolactone (GBL).

ChemInform Abstract: P‐CARBOXYSTYRENE: A WITTIG PROCEDURE IN AQUEOUS MEDIUM

Chemischer InformationsdienstVolume 10, Issue 18 Isocyclic Compounds ChemInform Abstract: P-CARBOXYSTYRENE: A WITTIG PROCEDURE IN AQUEOUS MEDIUM R. BROOS, R. BROOSSearch for more papers by this authorD. TAVERNIER, D. TAVERNIERSearch for more papers by this authorM. ANTEUNIS, M. ANTEUNISSearch for more papers by this author R. BROOS, R. BROOSSearch for more papers by this authorD. TAVERNIER, D. TAVERNIERSearch for more papers by this authorM. ANTEUNIS, M. ANTEUNISSearch for more papers by this author First published: May 1, 1979 https://doi.org/10.1002/chin.197918211Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume10, Issue18May 1, 1979 RelatedInformation