Polystyrene-supported Palladium(II) Ethylenediamine Complex: A Recyclable Catalyst for the Syntheses of 2-Benzyl- imidazo[2,1-b][1,3]benzothiazoles by Sonogashira Reaction

The polymer-supported palladium(II) ethylenediamine complex was used as a catalyst for the heterocyclization during Sonogashira reaction between a substituted phenyl iodide and 2-amino-3-(2-propynyl)-1,3-benzothiazolium bromide, which could readily be recovered from the reaction medium by a simple filtration, and reused without a significant loss in its activity.     

Unique cascade ring-opening/cyclization reaction of azlactones and DBU or DBN: Synthesis of new pyrrolam A analogues

1-Azabicyclo[3.3.0]oct-3-en-2-one derivatives were synthesized efficiently through the facile cascade reaction of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) with arylidene azlactones. This research provides a straightforward procedure for the synthesis of a novel class of multicyclic semi-alkaloids which shows good antimicrobial activity. Under catalyst-free, mild, and solventless condition, a wide range of fused tricyclic derivatives was obtained in high yields.     

Fe+3-Montmorillonite K10, as effective,eco-friendly,and reusable catalyst for the synthesis of bis(1H-indol-3-yl)methanes under grinding condition

Russian Journal of General Chemistry - Bis(indoyl)methanes have been synthesized via electrophilic reaction of indole and aldehydes in excellent yields under mild reaction conditions in the...     

Influence of water on localized and delocalized molecular mobility of cellulose

The influence of hydration on cellulose molecular mobility is investigated by two dielectric methods at different molecular scale. The mobility of side groups, assigned to γ mode, for dried cellulose increases. The water molecules have an anti-plasticizer effect on γ mode due to the water–polymer hydrogen bonding. For the β relaxation mode, only observed by the Thermo Stimulated Current technique, the hydration plays a role of plasticizer. The α relaxation mode assigned to the delocalized cooperative mobility of long chain segments of cellulose is plasticized by water. The study of activated parameters deduced from fractional polarization procedure, shows an increase of the activation enthalpy range with dehydration. It permits to conclude that reduction of hydrogen bonds density leading to a more extended cooperative mobility.     

An integrated method for mutation detection using on-chip sample preparation, single-stranded conformation polymorphism, and heteroduplex analysis

This work integrates rapid techniques for mutation detection by producing single-stranded DNA and (renatured) double-stranded DNA on-chip, labeling these with fluorescent DNA stains and then performing two complementary methods of mutation detection-single stranded conformation polymorphism (SSCP) analysis and heteroduplex analysis (HA). This involves the denaturation of double-stranded polymerase chain reaction (PCR) product into single-stranded DNA, the mutation analysis of the single-stranded DNA by SSCP and the rehybridized double-stranded DNA by HA. These steps were performed entirely on-chip within several minutes of operation. The combination of these two mutation detection methods on-chip provides a highly sensitive method of mutation detection for either genotyping or screening. Many mutation analysis methods rely upon fluorescently labeled samples from a PCR with fluorescently labeled primers. By labeling on-chip we not only attain improved signal strength, but the method is considerably more versatile. Although we used PCR products in this work, this method could be used to analyze DNA from any source. We believe that this combination of several procedures on a single chip represents a significant step in the development of higher levels of integration upon microfluidic devices.     

Biomimetic Sensor for Dobutamine Employing Nano‐ TiO2/Nafion/Carbon Nanoparticles Modified Electrode

A novel voltammetric biosensor based on nano‐TiO₂/nafion/carbon nanoparticles modified glassy carbon electrode (TiO₂/N/CNP/GCE) was developed for the determination of dobutamine (DBA). Characterization of the surface morphology and property of TiO₂/N/CNP layer was carried out by the scanning electron microscopy and atomic force microscopy. The electrochemical performance of the modified electrode was investigated by means of the cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy techniques. Effective experimental variables, such as the scan rate, pH of the supporting electrolyte, drop size of the casted modifier suspension and accumulation conditions of DBA on the surface of TiO₂/N/CNP/GCE were optimized. Under the optimized conditions, a significant electrochemical improvement was observed toward the electro‐oxidation of DBA on the surface of TiO₂/N/CNP/GCE compared to the bare GCE. Under the optimized conditions, a wide linear dynamic range (6 nM–1 µM) with a low detection limit of 2 nM for DBA was resulted. The prepared modified electrode shows high sensitivity, stability and good reproducibility in the determination of DBA concentrations. Satisfactory results were obtained for DBA analysis in the pharmaceutical and clinical preparations using TiO₂/N/CNP/GCE.     

Synthesis of 2-benzylimidazo[2,1-b][1,3]benzothiazoles through palladium-catalyzed heteroannulation of acetylenic compounds

The reaction of 2-imino-3-(2-propynyl)-1,3-benzothiazole with various iodobenzenes in the presence of a palladium catalyst leads to the production of 2-benzylimidazo[2,1-b][1,3]benzothiazoles.     

Preconcentration and determination of lead(II) by microextraction based on suspended cadion covered zirconia nanoparticles in a surfactant media

We have developed a method for the microextraction of lead(II) ion. It is based on the use of suspended zirconia nanoparticles modified with the reagent cadion. Pb(II) ions in the sample are adsorbed onto the modified zirconia nanoparticles suspended in the solution of a non-ionic surfactant. After cloud formation and phase separation by sedimentation, the surfactant rich phase was acidified and diluted to 100 μL with 3.0 mol L^?1 nitric acid and ultrasonicated for a few seconds to desorb the analyte from the sorbent. The mixture was centrifuged and 10 μL of the supernatant liquid phase along with 10 μL of the Pd/Mg modifier were submitted to the electrothermal atomic absorption spectrometer. The parameters affecting the extraction efficiency were optimized by the univariable method. Under the optimized conditions, a sample volume of 40 mL resulted in an enhancement factor of 384 and a detection limit (defined as 3S_b/m) of 2.2 ng L^?1. The method was successfully applied to the determination of Pb(II) in water, tea and rice samples. Accuracy was determined by the recovery experiments and the analysis of two certified reference materials.

Four-Component,One-Pot Synthesis of Tetra-Substituted Imidazoles Using a Catalytic Amount of MCM-41 or p-TsOH

An improved and rapid one-pot synthesis of tetrasubstituted imidazoles by condensing benzil, ammonium acetate, amines, and aromatic aldehydes and using a catalytic amount of silica structure MCM-41 or p-toluenesulfonic acid (p-TsOH) as efficient, green, reusable catalysts in excellent yields is reported.     

Ionic liquid-functionalized magnetic nanostructures as an efficient catalyst for the synthesis of 6H-chromeno[4,3-b]quinolin-6-ones

A novel imidazole ionic liquid (IL)-functionalized \(\hbox {silica}@\gamma \)-\(\hbox {Fe}_{2}\hbox {O}_{3}\) (\(\hbox {IL-SiO}_{2}@\hbox {MNP}\)) is prepared by the functionalization of \(\hbox {SiO}_{2}@\hbox {MNP}\) by 1-butyl-3-(3-trimethoxypropyl)-1H-imidazol-3-ium chloride as the IL moiety. The catalyst is characterized by transmission electron microscopy, scanning electron microscope, vibrating sample magnetometer, dynamic light scattering and Fourier transform infrared spectroscopy. \(\hbox {IL-SiO}_{2}@\hbox {MNP}\) showed good activity in the synthesis of 6H-chromeno[4,3-b]quinolin-6-one derivatives via multicomponent reaction of 4-hydroxycoumarin, anilines and benzaldehydes. The nanocatalyst is magnetically separable and easily recoverable and showed successful activity up to 10 runs.