Asymmetric transfer hydrogenation of prochiral ketones catalyzed by aminosulfonamide-ruthenium complexes in ionic liquid

Chiral aminosulfonamides containing imidazolium group were used as ligands for the ruthenium(II)-catalyzed asymmetric transfer hydrogenation of prochiral ketones in ionic liquid, affording good to excellent conversions and enantiomeric excesses. The catalytic system could be easily recovered and reused several times.      

Preparation and examination of multilayer graphene nanosheets by exfoliation of graphite in high efficient attritor mill

Graphene multilayers have been prepared by mechanical method based on milling graphite in high efficient attritor mill. The results showed that the best dispersion media is ethanol, and 10 hours of intensive milling proved to be the most efficient way to separate the graphite layers as it was shown by scanning electron microscopy and X-ray diffraction measurements.      

Removal of cadmium and copper ions by <Emphasis Type="Italic">Trichosporon cutaneum</Emphasis> R57 cells immobilized onto polyvinyl alcohol/tetraethoxysilane hybrid matrices

Polyvinyl alcohol (PVA) and tetraethoxysilane (TEOS) hybrid materials were prepared by sol-gel methods and tested as matrices for immobilization of Trichosporon cutaneum R57, capable of removing cadmium and copper ions from aqueous solutions. A kinetic model was applied and the effects of matrix TEOS content on the copper and cadmium uptake equilibria and rate constants were investigated.      

Methylcellulose/SiO<Subscript>2</Subscript> hybrids: sol-gel preparation and characterization by XRD,FTIR and AFM

Methylcellulose (MC) / SiO₂ organic / inorganic hybrid materials have been prepared from MC and methyltriethoxysilane or ethyltrimethoxysilane, and characterized by XRD, FTIR and AFM. XRD showed peak shifts. FTIR shows intermolecular hydrogen bonding between MC and SiO₂. AFM depicts surface roughness which depends on the silica precursor and MC content.      

Efficient and solvent-free synthesis of 1-amidoalkyl-2-naphthols using <Emphasis Type="Italic">N,N,N’,N’</Emphasis>-tetrabromobenzene-1,3-disulfonamide

N,N,N,’N’-Tetrabromobenzene-1,3-disulfonamide [TBBDA] is found to be a reusable catalyst for efficient synthesis of various amidoalkyl naphthols from β-naphthol, aromatic aldehydes and urea in good to high yields under solvent-free conditions.      

Efficient Lewis acid-assisted Br?nsted acid (LBA) catalysis in the iron-catalyzed Friedel-Crafts alkylation reaction of indoles

Lewis acid-assisted Br?nsted acid (LBA) catalysis was proposed for the iron-catalyzed Friedel-Crafts alkylation of indoles with chalcones. This proposal was supported by the ESI-MS and cyclic voltammetry. The addition of acac to the iron-catalyzed Friedel-Crafts alkylation of indoles with chalcones created a powerful catalytic system, which makes the alkylation reactions occur easily under mild conditions.      

One-pot, three-component condensation of 2-hydroxybenzaldehyde derivatives, primary amines with alkyl isocyanides to N-alkyl-2-(2-hydroxyphenyl)-2-imino-acetamides

One-pot, three-component condensation of 2-hydroxybenzaldehyde derivatives, primary amines with alkyl isocyanides is reported. N-alkyl-2-(2-hydroxyphenyl)-2-iminoacetamide derivatives are generated presumably via the preliminary formation of N, N′-disubstituted benzo[b]furan-2,3-diamines and subsequent oxidation with molecular oxygen.      

Equilibrium and kinetic study of the proton transfer reactions between nitroalkanes and strong organic bases — phosphazenes in tetrahydrofuran solvent

Proton transfer reactions rates between carbon acids 1-nitro-1-(4-nitrophenyl)ethane (NPNE), 2-methyl-1-nitro-1-(4-nitrophenyl)propane (MNPNP)) and phosphazenes (BEMP, BTPP, P₁-t-Oct) in tetrahydrofuran have been measured, and the activation parameters were determined. The results are compared with those previously obtained for P₁-t-Bu phosphazene, guanidines and amidines.      

Silver nanoparticles: synthesis through chemical methods in solution and biomedical applications

Chemical methods provide an easy way to synthesize silver nanoparticles (Ag NPs) in solution. These metal nanoparticles have a great potential for biomedical applications as an antibacterial, antifungal, and antiviral agent or in wound healing. The adjustment of the parameters involved in these reactions permits a precise control over the size, shape, monodispersity, and the surfaces of the nanoparticles. These nanoparticles are being used in the design of new hybrid organic-inorganic or inorganic nanomaterials for biomedical applications.      

Stability-indicating derivative spectrophotometry method for the determination of biapenem in the presence of its degradation products

A first-derivative UV spectrophotometric method, with or without the subtraction technique, was developed for the determination of biapenem in pharmaceutical dosage form in the presence of its degradation products. The method was based on the measurement of first-derivative amplitudes at zero crossing point (λ = 312 nm) and the peak-to-zero technique and validated with regard to linearity, limits of detection and quantitation, selectivity and precision. The observed rate constants for the degradation of biapenem were comparable to those obtained in the stability-indicating HPLC method.      

Nano-hydroxyapatite preparation from biogenic raw materials

Hydroxyapatite (HAp) was successfully produced from recycled eggshell, seashell and phosphoric acid. The phases obtained depended on the ratio of calcined eggshell/ seashell to phosphoric acid, the calcination temperature and the mechanochemical activation method (ball milling or attrition milling). The HAp structures were characterized by X-ray diffraction, scanning electron microsopy and infrared spectroscopy. Attrition milling was more effective than ball milling, yielding nanosize, homogenous and pure Hap.      

Ugi products containing boronate esters

The Ugi reaction with formylphenylboronic acid derivatives as the carbonyl component proceeds to give the corresponding boron-containing dipeptide derivatives (Ugi products) in good yields.      

Ionic liquids - deanol derivatives as the Diels-Alder reaction solvents

The Diels-Alder reaction between cyclopentadiene and dienophiles in deanol derivatives containing bis(trifluoromethylsulfonyl)imide anion as media have been studied. The effect of the substituents attached to the cation on the endo:exo selectivity as well as the reaction yield have been evaluated in the absence and presence of Lewis acid catalyst - Y(OTf)₃. Catalytic activity of metal triflates and the recycling of chosen catalytic systems have also been investigated      

Spectral study of coumarin-3-carboxylic acid interaction with human and bovine serum albumins

Fluorescence spectroscopy and circular dichroism (CD) spectroscopy were used to investigate the interaction of coumarin-3-carboxylic acid with human serum albumin (HSA) and bovine serum albumin (BSA) under physiological conditions in a buffer solution of pH 7.4.      

Characterization of sorption gels used for determination of mercury in aquatic environment by diffusive gradients in thin films technique

The influence of pH, ionic strength and selected natural ligands on the measurement of mercury by the diffusive gradients in thin films technique (DGT) using recently introduced sorption gels was determined. Sorption gels containing Chelex 100, Spheron-Thiol, Duolite GT73 and modified Iontosorb AV resins were investigated, with the sorption capacity determined for all used sorption gels. The minimum DGT measurable concentrations were calculated from 3 times the standard deviation of mercury amount in unexposed sorption gels.      

The bifunctionality of silica gel modified with Congo red

Silica gel was chemically modified with Congo red and characterized by Fourier transform infrared spectroscopy, elemental and thermogravimetric analysis. The pH-sensitive immobilized Congo red retains the same properties as its solution counterpart and could be applied as solid indicator. The functionalized silica gel was also employed to extract different cations from water solutions. The concentration of cations extracted was determined by inductively coupled plasma optical emission spectrometry. The solid support is able to selectively extract silver and copper from water solutions and retains its properties after treatment with different organic and inorganic solvents.      

Kinetics and thermodynamics of adsorption of congo red on cellulose

Thermodynamics and kinetics of adsorption of congo red (CR) on cellulose are studied at 308–328 K. In the used concentration range of CR, interaction of CR with cellulose is exothermic and CR molecules adsorb chemically on cellulose surface. The effects of contact time, temperature and initial concentration of CR on kinetics of its adsorption on cellulose were investigated. The process proceeds according to the pseudo-second-order equation. Initial adsorption rate of adsorption is first-order in CR and the intraparticle diffusion of CR molecules within cellulose is identified as the main rate-limiting step.      

Ionic liquid promoted synthesis of bis(indolyl) methanes

1-benzyl-3-methyl imidazolium hydrogen sulphate [bnmim][HSO₄] was found to be an effective catalyst for the condensation reaction of indoles and derivatives with benzaldehydes in microwave irradiation with lower reaction time and higher yields to give bis(indolyl) methanes.      

Recent development in capillary ion chromatography technology

This review summarizes the development of capillary ion chromatography (CIC) over approximately the last 5 years. It mainly focuses on the technologic aspects of several key components associated with CIC, including micropump, microscale electrodialytic eluent generator, microscale suppressor and the detector.