2-Halo-subsituted tetracenes: their generation and single crystal OFET characteristics

2-Chlorotetracene and 2-bromotetracene were generated in high purity from their monoketone precursors either by heating or upon irradiation of light. Crystals of two compounds were prepared by physical vapor transport method. Organic field effect transistors made with the single crystals of these two compounds were fabricated effectively. Their p-type transistor characteristics are described.     

New Urea Biosensor Based on Urease Enzyme Obtained from Helycobacter pylori

The urease enzyme of Helicobacter pylori was isolated from biopsy sample obtained from antrum big curvature cell extracts. A new urea biosensor was prepared by immobilizing urease enzyme isolated from Helicobacter pylori on poly(vinylchloride) (PVC) ammonium membrane electrode by using nonactine as an ammonium ionophore. The effect of pH, buffer concentration, and temperature for the biosensor prepared with urease from H. pylori were obtained as 6.0, 5 mM, and 25 °C, respectively. We also investigated urease concentration, stirring rate, and enzyme immobilization procedures in response to urea of the enzyme electrode. The linear working range of the biosensor extends from 1 × 10(-5) to 1 × 10(-2) M and they showed an apparent Nernstian response within this range. Urea enzyme electrodes prepared with urease enzymes obtained from H. pylori and Jack bean based on PVC membrane ammonium-selective electrode showed very good analytical parameters: high sensitivity, dynamic stability over 2 months with less decrease of sensitivity, response time 1-2 min. The analytical characteristics were investigated and were compared those of the urea biosensor prepared with urease enzyme isolated from Jack bean prepared at the same conditions. It was observed that rapid determinations of human serum urea amounts were also made possible with both biosensors.     

Synthesis of Novel Thioethers and Sulfoxide Compounds

Abstract

Thiosubstituted butadiene and butenyne compounds were synthesized from the reactions of 1,1,3,3,4,4-hexachloro-1-butene or 1,1,2,4,4-pentachlorobuta-1,3-diene with different thiols in EtOH/H₂O solution of NaOH. Tris(thio)substituted butadiene compound was treated with potassium tert-butoxide to obtain tris(thio)substituted butatrienyl halide compound. The novel sulfoxide compounds were synthesized from the reactions of polyhalobutadiene compounds with aliphatic thiols in CHCl₃ with m-CPBA at 0°C. The structures of the novel compounds were characterized by micro analysis, FT-IR, ¹H-NMR, ¹³C-NMR, and MS.     

Light Emitting Materials and Devices of PPV Type Compounds Containing Quinolines

Five derivatives of 1,4‐bis(2′‐quinolinylethenyl)benzene were prepared through Wittig reaction of a diylide of p‐xylene and two molar equivalents of quinolinyl carbaldehyde. Dyes 1a,b and 2a‐c thus obtained exhibit fluorescence in quantum yields of 0.44–0.78. They are fabricated to light‐emitting diodes in the form of ITO/NPB/CBP/TPBI: dye(5% wt)/Mg: Ag. The devices can be turned on at 6 V, and they displayed blue and green light at intensities up to 5000 cd/m² at 15 V. The compounds containing methoxy substituents, i.e. 1b and 2b,c , performed more effectively than those without, i.e. 1a and 2a . The former derivatives also showed a red‐shift in their emission spectra with respect to the latter.     

Bromination of Binor-S

Bromination of binor-S resulted in a mixture of products containing several pairs of isomers. Three major processes were found to be involved in the reaction mechanism, i.e., bromination, hydrobromination, and dehydrobromination. The structures of nine compounds derived from dibromide 6 were identified by spectroscopic methods. Yields between isomers were rationalized by comparison of their relative strain energies calculated by force field model (MM2). The crystal structures of a tribromide (9) and a pentabromide (15) were solved by X-ray diffraction analyses. Their crystal packing patterns indicated the existence of attractive interactions among the bromine atoms.     

Macrocyclic anthracene-anchored calix[4]arene as a sensitive and selective fluorescent chemosensor for ytterbium ions

ABSTRACT

A novel anthracene anchored cone calix[4]arene pyridine amide receptor C4PA was synthesized and characterized by combination of spectroscopic and spectrophotometric techniques. Ion binding properties of C4PA towards a series of metal cations were investigated by UV and fluorescence spectra. A remarkable increase for receptor C4PA in fluorescence intensity in the presence of trace amounts of Yb³⁺ was observed. C4PA showed “turn on” type fluorescence response toward Yb³⁺ with high selectivity and C4PA also retained its selectivity toward Yb³⁺ in the presence of most competing metal ions.     

Assessment of Glucose Oxidase Based Enzymatic Fuel Cells Integrated With Newly Developed Chitosan Membranes by Electrochemical Impedance Spectroscopy

Considerably stable enzymatic fuel‐cells (single cell and 5‐cells stack) were prepared by using chitosan based membranes along with glucose oxidase attached bioanode. Continuous operation of fuel‐cells were monitored under short circuit conditions reaching half‐life over a week. Detailed analysis for the effects of pH, temperature, buffer types and concentration on different type of in‐house produced chitosan membranes were performed by electrochemical impedance spectroscopy (EIS). EIS was utilized to observe, total electrolyte resistance, charge transfer properties, mass transfer and double layer effects on integrated fuel cells (single cell and 5‐cells stack). Performance of the fuel cells was also analyzed by the polarization experiments. Current density of the fuel cell increased at higher operation temperatures not only due to better enzyme kinetics, but also due to increase in electrolyte (membrane+buffer solution) conductivity. Buffer concentration in the fuel (glucose) solution was found as an important parameter. Under optimum fuel cell operation conditions (i. e. 30–40 °C, pH 5 0.3 M buffer solution), maximum current densities of 3.0–3.2 mA cm^?2 were reached. Low‐power devices (i. e. a calculator, step motor) were powered with 5‐cell stack producing 3 mW at 1.3 V.     

Design,synthesis, and characterization of some new benzimidazole derivatives and biological evaluation

A new series of benzimidazole derivatives ( 1-15 ) containing 1,2,4-triazole, 1,3,4-thiadiazole, 1,3,4-oxadiazole, and thiazolidinon rings have been synthesized. All new synthesized benzimidazole compounds were confirmed by ¹H NMR, ¹³C NMR spectra, and LC-MS, and they were examined for their antioxidant and antimicrobial activities. Compounds 7 and 1 showed the highest and the lowest antioxidant activities, respectively. The lowest minimum inhibition concentration value found in compound 5 against Enterobacter aerogenes.