Novel Synthesis of Pyrido[2,1-B]Benzothiazoles and 1,3-Benzothiazole Derivatives

Abstract

A variety of new pyrido[2,1-b]benzothiazole and benzothiazoles, have been prepared via the reaction of 2-substituted methylthiazole with α,β-unsaturated nitriles and activated methylene compounds. The structures of the reaction products were established based on the elemental analyses and spectral data (IR, ¹H-, ¹³C-NMR, MS).     

Molecular docking and biological assessment of substituted phthalazin-1(2H)-one derivatives

2, 4-Disubstituted phthalazin-1(2H)-one derivatives were synthesized via nucleophilic attack of N-2 of phthalazin-1(2H)-one derivatives on different alkyl halides. In addition, reactive phthalazinone acetohydrazide derivative was utilized as a scaffold to synthesize different heterocyclic systems. The assigned structures for all the newly synthesized derivatives were confirmed on the basis of elemental analyses and spectral data. Mechanistic illustrations for some of the synthesized compounds were also discussed. The synthesized compounds were evaluated for in vitro antimicrobial and antitumor activity. Most of the tested compounds exhibited significant potency as antimicrobial and antitumor agents. Moreover, MOE 2014.09 software was utilized to carry out computational studies to support the biological activity results.     

Electrohydrodynamic linear stability of finitely conducting flows through porous fluids with mass and heat transfer

In this work, a linear stability analysis is used to investigate a capillary surface waves between two horizontal finite fluid layers. The system is acted upon by a vertical periodic electric field. The problem examines few representatives of porous media. It is also includes finite conductivity, mass and heat transfer. It is assumed that the basic flow is two-dimensional streaming flow. A general dispersion relation governing the linear stability is derived. In contrast with our previous work [23], the present problem shows that the stability criterion depends on the mass and heat transfer parameter. The present study recovers some special cases upon appropriate data choices. The presence of finite conductivity’s together with the dielectric permeability’s make the uniform electric field plays a dual role in the stability criterion. This shows some analogy with the nonlinear stability theory. In addition, the mass and heat transfer parameter as well as the Darcy’s coefficients play a stabilizing role in the stability picture. In case of the Rayleigh–Taylor instability, by means of the Whittaker technique, the parametric excitation of the electrohydrodynamic surface waves is obtained. The transition curve equations are calculated up to the fourth order for a small dimensionless parameter. The analytical results are numerically confirmed.     

Electrochemical Sensing Platform Based on Nano‐Perovskite/Glycine/Carbon Composite for Amlodipine and Ascorbic Acid Drugs

People suffered from essential hypertension have increased oxidative stress. Thus, adding vitamin C to their medical therapy resulted in decreasing the oxidative stress and increasing the antioxidant status. This may prevent further vascular damage due to the oxidative stress, leading to a better diagnosis in critical hypertension patients. A novel sensor was fabricated based on NdFeO₃ nano‐perovskite/glycine/carbon nanotubes modified carbon paste electrode in presence of sodium dodecyl sulfate; GLNFCNTCP‐SDS for electrochemical sensing and simultaneous determination of antihypertensive and antioxidant drugs, Amlodipine (AML) and ascorbic acid. The developed nanocomposite showed interactive characteristics of all the modifiers as high conductivity, enhanced surface area, surface fouling resistance and stability. This leads to accelerated electron transfer rate and increased current response of electro‐oxidation of AML by 8.3 folds compared to unmodified electrode. The method validity was investigated successfully by the quantitative analysis of AML in human urine samples and Norvasc tablets with acceptable recovery results. The featured merits of the proposed composite in the analysis of AML in human urine samples were; wide concentration range of 0.003 μmol L^?1 to 200 μmol L^?1, sensitivity of 113.2 μA/μmol L^?1, detection limit of 0.704 nmol L^?1, and quantification limit of 2.35 nmol L^?1.     

Electrochemically Aided Control of Solid Phase Micro-Extraction (EASPME) Using Conducting Polymer-Coated Solid Substrates Applicable to Neutral Analytes

A method for the extraction and selective determination of the neutral species arsenobetaine (AsB) is proposed using electro-synthesized organic conducting polymer (OCP) films. The polymer films are used as solid phase micro-extraction (SPME) elements for the direct and specific extraction of trace levels of AsB. The separation and detection of the arsenic (As) species is attained using an HPLC-ICP-MS interfaced system. The selectivity of the method towards neutral AsB in the presence of other anionic As-species is explained in terms of the change in the hydrophobic nature of the film during the doping/undoping processes. The type of OCP, the thickness of the film, the applied potential during uptake and release of AsB are among the factors studied for the method. The uptake and release time/potential profiles are given, and a thermodynamic model is proposed. The performance of poly(3-octylthiophene), poly(3-dodecylthiophene), and poly(3-hexadecylthiophene) films were compared, with the best results obtained using poly(3-octylthiophene). The detection limit and linear dynamic range using this method are 14ngmL^–1 and 70–1200ngmL^–1, respectively. The method was validated using a standard reference material and tested for the determination of AsB in artificial environmental soil samples.     

Studies on 5-aminoisoxazole derivatives: Synthesis of some new fused isoxazoles

Several new fused isoxazole derivatives could be obtained utilising 5-amino-4-ethoxycarbonyl-3-ethoxycarbonylmethyl and 5-amino-4-cyano-3-trichloromethyl-isoxazoles as starting components.

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Untersuchungen an 5-Aminoisoxazol-Derivaten: Synthese einiger neuer kondensierter Isoxazole

Zusammenfassung Es konnten einigen neue Isoxazolderivate über 5-Amino-4-ethoxycarbonyl-3-ethoxycarbonylmethyl-und 5-Amino-4-cyano-3-trichlormethyl-isoxazol als Ausgangsverbindungen erhalten werden.

     

Development of metal oxide incorporated Al-Zn-Sn sacrificial anodes processed by stir casting and heat treatment

Aluminum sacrificial anodes are currently the first choice for cathodic protection in numerous applications. The galvanic performance of aluminum-based sacrificial anodes is considerably enhanced by addition of certain alloying elements called activators. Recent researches proved that incorporation of specific metal oxides like MnO₂, CeO₂, RuO₂, and IrO₂ into the aluminum matrix could enhance the galvanic efficiency of aluminum anodes; however, the mechanism by which metal oxides improve galvanic properties of aluminum is still subject to discussion. The present work investigates the effect of incorporating commercially available low-cost manganese dioxide concentrate into Al-5Zn-0.1Sn sacrificial anodes in different volume fractions. It also studies the influence of heat treatment on anode’s galvanic performance by performing solution treatment at 3 different temperatures (250 °C, 400 °C, 550 °C). The electrochemical testing results proved an increase in efficiency of anodes incorporated with metal oxides and solution treated at 550 °C. The SEM imaging and EDX elemental mapping declared that the presence of SiO₂ particles in the anode matrix which might cause effective and uniform corrosion of Al anodes and decreased non-coulombic losses.

Graphical abstract

     

Conducting polymer ion sensor electrodes-III. Potentiometric sulfide ion selective electrode

A new potentiometric sensor electrode for sulfide based on conducting polymer films is introduced. The electrode is formed by electrochemically depositing a film of poly(3-methylthiophene) and poly(dibenzo-18-crown-6) onto an alloy substrate. Different methods were used for the electrode preparations. The alloy used has a low melting point, which allowed its use for manufacturing a microsize version of this electrode. The electrode response is stable for 3 days. The working temperature range for this electrode is between 10 and 40 degrees C. The linear dynamic range is 1.0x10(-7)-1.0x10(-2) M and measures total sulfide concentration over a range of pH from 1 to 13. The polymer electrode showed high selectivity for sulfide in the presence of many common interfering anions. The electrode is useful for the measurement of total sulfide in biological environments and can be manufactured in the micron scale. Therefore, it will be useful for the measurement within biofilms.     

Insight into the relationship between the Fourier's law of heat conduction and Fick's law over a Riga device: Fourth grade analysis

Mixed convective flow of fourth grade (Non-Newtonian) fluid model by a Riga stretchable plate is addressed. The aim of the current research work is therefore to explain the role of the fourth grade (Non-Newtonian) fluid model in the field of fluid dynamics. Energy and concentration equations are modeled subject to both Fourier's law of heat conduction and Fick's law. Radiation aspects and heat source/sink phenomenon are also accounted. Entropy analysis is discussed through second thermodynamics law. The (OHAM) approach is used to achieve a meaningful solution. Finally, the emerging variables behavior on the velocity, temperature, concentration and entropy rate are discussed graphically. Here, velocity enhances for increasing range of fourth grade variable. Temperature boosts against rising radiation and thermal relaxation variables, but opposite trend is noted for solutal relaxation parameter on concentration.     

Miniaturized membrane sensors for the determination of rivastigmine hydrogen tartrate

Novel miniaturized polyvinyl chloride (PVC) membrane sensors in all-solid state graphite and platinum wire supports were developed, electrochemically evaluated and used for the assay of rivastigmine hydrogen tartrate drug (RIV). The RIV sensors are based on the formation of an ion-association complex between the drug cation and tetrakis(4-chlorophenyl)borate (TpClPB) anionic exchanger as electroactive material dispersed in a PVC matrix. Linear responses of 10(-2) - 10(-5) M and 10(-2) - 10(-4) M with cationic slopes of 56.4 mV and 53.6 mV over the pH range 4 - 7 were obtained by using the RIV-coated graphite (sensor 1) and platinum wire (sensor 2) membrane sensors, respectively. The proposed method displays useful analytical characteristics for the determination of RIV in Exelon capsules with average recoveries of 100.01+/-0.835, 100.09+/-0.896, and in plasma with average recoveries of 99.47+/-0.97, 99.58+/-0.82, and in rat brain homogenate with average recoveries of 98.16+/-1.62, 99.02+/-1.57, for sensors 1 and 2, respectively. The methods were also used to determine the intact drug in the presence of its degradation product and thus could be used as stability indicating methods. The results obtained by the proposed procedures were statistically analyzed and compared with those obtained by using a reported method. No significant difference for both accuracy and precision was observed.