Efficient Synthesis of Urea Derivatives via a Sequential One-Pot Nucleophilic Addition/Ugi Five-Component Reaction Under Solvent-Free Conditions

Urea polyfunctional derivatives were successfully synthesized via a one-pot, five-component nucleophilic addition/Ugi reaction sequence. Simplicity, solvent-free conditions, and good yields of products are advantages of this method.     

Hollow Reticular Shaped Highly Ordered Rice Husk Carbon for the Simultaneous Determination of Dopamine and Uric Acid

We have prepared activated porous carbon material through simple pyrolysis method from rice husks (rhAC) for sensitive detection of dopamine (DA) and uric acid (UA). The prepared rhAC material was thoroughly characterized using various spectroscopic, microscopic, and electroanalytical techniques. Analysis of the voltammetric data showed that the analytes followed a first order reaction kinetics while following a 2e^?/2H⁺ transfer process. We have discussed the possible oxidation mechanism for the analytes based on the results from our experimental analysis. The rhAC_GCE sensor was tested for interference, reproducibility, and stability. The sensor was also tested to evaluate its applicability in real life.     

Synthesis,spectroscopic studies,and antioxidant activities of novel thio/carbohydrazones and bis-isatin derivatives from terephthalaldehyde

New bis(isatins-thio/carbohydrazones) based on Schiff bases were prepared from terephthalaldehyde biscarbohydrazone and 5-substituted isatins in the presence of a drop of sulfuric acid under reflux in ethanol. Terephthalaldehyde bis(thio/carbohydrazone) was synthesized by the reaction of (thio)/carbohydrazide and terephthalaldehyde in the presence of a few drops of acetic acid under reflux in ethanol. The structures of these synthesized compounds were determined using IR, ¹H NMR, and ¹³C NMR spectroscopy and elemental analysis. The in vitro antioxidant activity of all the compounds was determined by the 1,1-diphenyl-2-picryl hydrazyl (DPPH.) free radical scavenging method. Compound 2 showed the best antioxidant activity.     

New β-isatin aldehyde-N,N′-thiocarbohydrazones: preparation,spectroscopic studies and DFT approach to antioxidant characteristics

Research on Chemical Intermediates - Five new Schiff bases of isatin and its derivatives were prepared from monothiocarbohydrazides and 5-chloro isatin. The chemical structures of the synthesized...     

Design and evaluation of functionalized multi-walled carbon nanotubes by 3-aminopyrazole for the removal of Hg(II) and As(III) ions from aqueous solution

Carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) were chemically modified with 3-aminopyrazole (MWCNTs-f) and applied as an efficient adsorbent to mercury and arsenic adsorption from aqueous solutions. The adsorbents were characterized by FT-IR, EDX, FE-SEM, TGA, and BET. The effects of pH, adsorbent dose, and initial ions concentration on the adsorption efficiency and the optimum conditions were investigated by central composite design. The optimum conditions were obtained at pH 7.6–7.9, adsorbent dose 20 mg, and initial ions concentration 20 ppm. So the maximum adsorption efficiencies in these conditions were 80.5 and 72.4% for the removal of Hg(II) and As(III) by MWCNTs-f, respectively. The quadratic model was used for the analysis of variance and indicated that adsorption of metal ions strongly depends on pH. Also, the pseudo-second-order model has been achieved from the adsorption kinetic studies. Furthermore, the experimental data were well fitted to the Langmuir isotherm and the maximum adsorption capacities obtained were 112 and 133 mg g^?1 for the adsorption of Hg(II) and As(III) by MWCNTs-f, respectively. Moreover, a thermodynamic study revealed that the adsorption reactions were spontaneous and endothermic with the increase in randomness. In addition, a desorption study showed the favorable regeneration ability of MWCNTs-f even after three adsorption–desorption cycles. Therefore, the MWCNTs-f adsorbent has good potential for the removal of Hg(II) and As(III) pollutants from aqueous solutions.     

The effect of radiolabeled antibiotics on biofilm and microorganism within biofilm

Journal of Radioanalytical and Nuclear Chemistry - The aim of this study was to investigate the 131I and 127I labeled linezolid and moxifloxacin effects of minimum inhibitory concentration, and...     

Crystallographic and conformational analysis of 1,3-bis(2,4-dimethoxyphenyl)imidazolidine-2-thione

The molecular and crystal structures of the title compound, C₁₉H₂₂N₂O₄S, were determined by single crystal X-ray diffraction technique. The title compound crystallizes in space group F d d 2, with a = 30.785(3) ?, b = 10.6455(9) ?, c = 11.0036(8) ?, Z = 8, D _calc = 1.379(2) g cm⁻³, μ(Mo-K_α) = 0.207 mm⁻¹, and its crystal system is orthorhombic. The structure was solved by direct methods and refined to a final R = 0.042 for 1530 reflections with I > 2σ (I). There is a half-independent molecule in the asymmetric unit. The title molecule has twofold rotational symmetry along with the C–S bond. Classically no hydrogen bond is found in the crystal structure. The crystal structure is stabilized by π–π stacking and edge to face (C–H…π-ring) interactions. To elucidate conformational features and steric hindrances of the title molecule, selected torsion angle is varied from −180° to +180° in every 10° and thus molecular energy profile is calculated by PM3 semi-empirical method.Supplementary materials CCDC 261789 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, by emailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK; fax: $+$44 1223 336033.     

Angular Dependence of L X-ray Relative Intensities of Uranium and Thorium at 59.5 keV

INTRODUCTION

The knowledge of relative intensities of K, L and higher shell X-rays is needed for the investigation of various phenomena in atomic physics. In earlier studies, L X-ray relative intensities and energies have been reported for many elements by several investigators [1–5], but the angular dependence of L X-ray relative intensity has not been reported. According to Flugge et a1 [6], if the angular momentum J=1/2 and J>1/2 of the originating shell, then the angular distribution of X-rays is isotropic and anisotropic, respectively. From this idea, L_α, L_l and some of L_β, intensities are dependent on changing the scattering angles. In this study, we have measured the angular dependence of L_α, La_l, L_α/L_β, and L_α/L_γ, intensity ratios of U and Th at different angles varying from 45° to 135°.     

Synthesis and characterization of conductive silver ink for electrode printing on cellulose film

Silver nanoparticles with size less than 50 nm were synthesized from silver nitrate, polyvinylpyrrolidone (PVP) and ethylene glycol, where these chemicals acted as metal precursor, stabilizer and reducing agent, respectively. Then a conductive silver ink was prepared with a suitable solvent by adding a viscosifier, hydroxyethyl-cellulose (HEC), and a surfactant, diethylene glycol (DEG). The combined effect of both viscosifier and surfactant on the physical property of the silver ink was analyzed by measuring the contact angle of the silver ink on a cellulose film. Moreover, the influences of PVP molecular weight and reaction temperature on the size of the silver nanoparticles were analyzed. Then the silver ink was coated on the cellulose film by spin coating and the effects of different solvents, sintering temperatures and solid contents on its electrical resistivity were examined. It was found that, with 50 % co-solvent of deionized water and DEG and solid content of around 50 %, the silver ink exhibited the lowest resistivity. This ink can be used for inkjet printing of conductive patterns on cellulose films.