Electrochemical determination of captopril in the presence of acetaminophen,tryptophan, folic acid,and l-cysteine at the surface of modified carbon nanotube paste electrode

Ionics - A novel carbon paste electrode (CPE) modified with 2,2′-[1,7–heptanediylbis(nitrilomethylidene)]-bis(4-hydroxyphenol) (DHB) and carbon nanotubes (CNTs) was prepared. At first,...     

Ionic Liquid Iodinating Reagent for Mild and Efficient Iodination of Aromatic and Heteroaromatic Amines and Terminal Alkynes

Hexamethylene bis(N-methylimidazolium) bis(dichloroiodate) (HMBMIBDCI), an ionic liquid iodinating reagent, have been prepared and characterized. Its ability to perform iodination reactions with a variety of substrates has been explored. In general, iodination reactions of aromatic and heteroaromatic amines proceed with good yields in the absence of solvent. Reactions of terminal alkynes in the presence of 1,8-diazabicyclo [5.4.O] undec-7-ene and tetrahydrofuran have been investigated as well.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.]     

尿酸和叶酸存在下改性碳纳米管糊电极上多巴胺电催化氧化MohammadMazloum-Ardakani,MahboobeAbolhasani,Bibi-FatemehMirjalili,MohammadAliSheikh-Mohseni,AfsanehDehghani-Firouzabadi,AlirezaKhoshroo简

A chemically modified carbon paste electrode (CPE), consisting of 2,2''-[(1E)-(1,2-phenylenebis(azanylylidene)] bis(methanylylidene)]bis(benzene-1,4-diol) (PBD) and multiwalled carbon nanotubes (CNTs), was used to study the electrocatalytic oxidation of dopamine using cyclic voltammetry, chronoamperometry, and differential pulse voltammetry (DPV). First, the electrochemical behavior of the modified electrode was investigated in buffer solution. Then the diffusion coefficient, electrocatalytic rate constant, and electron-transfer coefficient for dopamine oxidation at the surface of the PBD-modified CNT paste electrode were determined using electrochemical approaches. It was found that under optimum conditions (pH = 7.0), the oxidation of dopamine at the surface of such an electrode occurred at about 200 mV, lower than that of an unmodified CPE. DPV of dopamine at the modified electrode exhibited two linear dynamic ranges, with a detection limit of 1.0 μmol/L. Finally, DPV was used successfully for the simultaneous determination of dopamine, uric acid, and folic acid at the modified electrode, and detection limits of 1.0, 1.2, and 2.7 μmol/L were obtained for dopamine, uric acid, and folic acid, respectively. This method was also used for the determination of dopamine in a pharmaceutical preparation using the standard addition method.     

Sonochemical synthesis and characterization of nano-sized zirconium(IV) complex: new precursor for the preparation of pure monoclinic and tetragonal zirconia nanoparticles

In this study, synthesis and characterization of two polymorphs of a new nano-sized zirconium(IV) complex, [ZrO(dmph)I₂] (1), {dmph = 2,9-dimethyl-1,10-phenanthroline (neocuproine)}, have been investigated in two different solvents. The reaction between zirconyl nitrate pentahydrate and potassium iodide with dmph as a ligand under ultrasonic irradiation in methanol and mono-ethylene glycol (MEG) leads to the formation of the nano-sized Zr(IV) complex. Characterization of the Zr(IV) complex has been performed using scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and elemental analysis. The thermal stability of the compound 1 has been studied by thermal gravimetric and differential thermal analyses. Particle sizes of the compound 1 have been decreased after thermal treatments in an autoclave. Pure monoclinic (m) and tetragonal (t) zirconia (ZrO₂) nanoparticles were readily synthesized from thermal decomposition of the Zr(IV) complex as a new precursor in presence of methanol and MEG as solvents, respectively. Zirconium oxide was characterized by FT-IR, XRD, and SEM to depict the phase and morphology. The results showed that, pure zirconia was produced with particle size about 59 nm and crystal system was monoclinic when methanol was used as a solvent during complexation process. On the other hand, particle sizes of zirconia with tetragonal structure were significantly reduced to about 39 nm, when MEG was used as solvent.     

Ionic Liquid Oxidant for Efficient and Selective Oxidation of Benzylic Alcohols

Hexamethylenebis (N-methylimidazolium) dichlorochromate was easily prepared by addition of N-methylimidazole to 1,6-dibromohexane to form the corresponding dibromide salt and subsequent treatment with CrO₃ in 6 N HCl solution. It is a low-melting orange salt that selectively oxidized benzylic alcohols.

Ultrasound mediated efficient ring opening of epoxides by in situ generated dithiocarbamates in green reaction media

Ultrasound accelerated a safe, clean and environmentally benign one-pot, three-component synthesis of 2-hydroxy dithiocarbamate, from amine, carbon disulfide and epoxide in good to excellent yields and short reaction time with excellent chemo-, regio-, and stereoselectivities in green reaction media (water, deep eutectic solvent [DES] and polyethylene glycol [PEG]). The one-pot, three-component condensation of primary and secondary amine with carbon disulfide and epoxides under ultrasonic irradiation was developed as a green and fast protocol for the rapid high-yielding preparation of 2-hydroxy dithiocarbamate in green reaction media without organic solvent and tedious workup.     

An image analysis strategy to study cell adhesion

A semi-automated in situ technique has been developed for the study of the extent and kinetics of cell adhesion at the individual cell level. Our investigation involves the static sedimentation of glutaraldehyde-fixed human erythrocytes suspended in 10 mM NaCl or 10 mM NaCl containing 2% (v/v) 1-propanol onto flat, horizontal, and transparent surfaces. The surfaces used are glass, poly(ethylene terephthalate), polystyrene, and fluorinated ethylene propylene. An inverted microscope is utilized for observations. Brownian motion is used as the distinguishing criterion between adherent and non-adherent cells. The extent of adhesion is expressed as the percentage of adherent cells. Two digital image processing techniques, image averaging and image subtraction, are presented for automation of the methodology. Although all non-adherent cells undergo Brownian motion, they exhibit this behavior to varying degrees. Factors under consideration are the liquid medium's surface tension (γ_LV) and the solid substrate surface tension (γ_SV). Preliminary results reveal that, in general, variations of γ_SV and γ_LV have a statistically significant effect on the extent of adhesion at the 99% and 96% confidence levels, respectively. A time depepdence for the adhesion of populations of cells is observed. However, individual cells either instantly or gradually adhere. Image subtraction generally overestimates the number of adherent cells due to the difficulty in detection of minute oscillations. The deviation between the adhesion percentage obtained from visual observations of the monitor and image subtraction is less than 10%.