Synthesis of 3‐arylazo‐6‐oxopyridazin‐5‐carbonitriles: A versatile precursor for condensed arylazopyridazin‐6‐ones

1‐[2‐Phenyl‐1‐diazenyl]‐1‐[2‐phenylhydrazono]acetone or 1‐[‐2‐(4‐methylphenyl)‐1‐diazenyl]‐1‐[‐2‐(4‐methylphenyl)hydrazono]‐butan‐2‐one were produced via coupling the (E) 2‐oxopropanal‐1‐phenyl‐hydrazone or (E) 2‐oxobutanal‐1‐(4‐methylphenyl)hydrazone with aromatic diazonium salts. These formazanes condensed readily with ethyl cyanoacetate to yield 5‐methyl‐3‐oxo‐2‐phenyl‐6‐phenylazo‐2,3‐dihydropyridazine‐4‐carbonitrile compound ( 9a ), 5‐ethyl‐3‐oxo‐2‐p‐tolyl‐6‐p‐tolylazo‐2,3‐dihydro‐pyridazine‐4‐carbonitrile and/or 5‐ethyl‐3‐oxo‐2,6‐di‐p‐tolyl‐2,3‐dihydropyridazine‐4‐carbonitrile that reacted with sulphur in presence of piperidine to yield the aminothienopyridazinones. The latter reacted with electron poor olefins and acetylenes to yield aminophthalazines. Compound ( 9a ) reacted also with benzylidenemalononitrile to yield the arylazophthalazinone.     

Synthesis and structural characterization of (COT)Pr(C13H8CH2CH2OMe)(THF) containing the chelating 9-(2-methoxyethyl)fluorenyl ligand

Treatment of 9-(2-methoxyethyl)fluorene, C₁₃H₉CH₂CH₂OMe (1), with potassium hydride in THF/toluene in the presence of 18-crown-6 afforded orange-red crystalline K(18-crown-6)C₁₃H₈CH₂CH₂OMe (2) in 59% yield. A “constrained geometry”-type praseodymium complex containing the 9-(2-methoxyethyl)fluorenyl ligand, (COT)Pr(C₁₃H₈CH₂CH₂OMe)(THF) (3), was prepared by treatment of dimeric [(COT)Pr(μ-Cl)(THF)₂]₂ (COT = η⁸-cyclooctatetraenyl) with in situ prepared KC₁₃H₈CH₂CH₂OMe. The molecular structures of 1, 2, and 3 were determined by single-crystal X-ray diffraction.     

Investigation of 500 keV Si ion induced surface structuring of Ni and Ti for enhancement of field emission properties

The present paper reports the investigation of surface morphology, elemental composition, phase changes and field emission properties of Si ion irradiated nickel (Ni) and titanium (Ti). The Ni and Ti targets have been irradiated with 500 keV Si ions generated by Pelletron accelerator at various fluences ranging from 6.9 × 10¹³ to 77.1 × 10¹³ ions/cm². Stopping range of ions in matter analysis revealed higher values of electronic stopping and sputtering yield for Ni as compared with Ti. For both irradiated metals, electronic energy loss dominant over the nuclear stopping. The growth of induced surface structures have been analysed by using field emission scanning electron microscopy (FESEM) analysis. In case of Ni, as the ion fluence increases from 6.9 × 10¹³ to 65.8 × 10¹³ ions/cm², the formation of spherical particulates, agglomers and sputtering is observed. Although in the case of Ti, with the increase of Si ion fluence from 11.6 × 10¹³ to 77.1 × 10¹³ ions/cm², the formation of irregular-shaped particulates along with crater and sputtered channels is observed. X-ray diffraction (XRD) analysis shows that no new phase is identified. However, a significant increase in peak intensity is observed with increasing ion fluence. The variation in crystallite size and dislocation line density is also observed as a function of Si ion fluence. Fourier transform infrared spectroscopy analysis shows that no bands are formed after the Si ion irradiation. Field emission properties of ion-structured Ni and Ti are well correlated with the growth of surface structures observed by SEM and dislocation line density evaluated by XRD analysis.     

Electrochemical Sensing Platform Based on Graphene Oxide-chitosan for Simultaneous Determination of some Antihypertensive Drugs

The development of selective and simple methods for the determination of different analytes is of great interest. This is the first time to show the applicability of graphene oxide-chitosan (GO-CS) nanocomposite for designing an electrochemical nanosensor for determination of Amlodipine, Valsartan, and Hydrochlorothiazide, simultaneously. Differential pulse voltammetrics current of AML, HCT, and VAL increased linearly in the ranges of 0.1–110, 0.1–110, and 1–230 μM with LOD of 5.5×10⁻², 3.5×10⁻² and 8.6×10⁻² μM, respectively. Finally, GO-CS/GCE was used for the detection of these drugs in commercial tablets and compared with the reference method (HPLC).     

Synthesis and characterization of dual‐responsive micrometer‐sized core‐shell composite polymer particles

Dual‐responsive micrometer‐sized core‐shell composite polymer particles were prepared by dispersion polymerization followed by seeded copolymerization. Polystyrene (PS) particles prepared by dispersion polymerization were used as core particles. N‐isopropyl acrylamide (NIPAM) and methacrylic acid (MAA) were used to induce dual‐responsive that is thermo‐ and pH‐responsive properties in the shell layer of composite polymer particles, prepared by seeded copolymerization with PS core particles. Temperature‐ and pH‐dependent adsorption behaviors of some macromolecules on composite polymer particles indicate that produced composite polymer particles exhibit dual‐responsive surface properties. Copyright © 2007 John Wiley & Sons, Ltd.     

Ion-exchange selectivity of a sulfonic cation exchanger based on immobilized cis-tetraphenylcalix[4]resorcinolarene

The ion-exchange equilibrium of protons in SO₃H groups of a sulfonic cation exchanger based on immobilized cis-tetraphenylcalix[4]resorcinolarene with cations of Li⁺, Na⁺, Ag⁺, Cu²⁺, In³⁺, and protonated 1,3,5,7-tetraazaadamantane in aqueous solutions of electrolytes at 293 K was studied. The corrected coefficients of the cation exchange selectivity were calculated.     

Evaluation of a new matrix-free laser desorption/ionization method through statistic studies: comparison of the DIAMS (desorption/ionization on self-assembled monolayer surface) method with the MALDI and TGFA-LDI techniques

This work demonstrates that the desorption/ionization on self-assembled monolayer surface (DIAMS) mass spectrometry, a recent matrix-free laser desorption/ionization (LDI) method based on an organic target plate, is as statistically repeatable and reproducible as matrix assisted laser desorption ionization (MALDI) and thin gold film-assisted laser desorption/ionization (TGFA-LDI) mass spectrometries. On lipophilic DIAMS of target plates with a mixture of glycerides, repeatability/reproducibility has been estimated at 15 and 30% and the relative detection limit has been evaluated at 0.3 and 3 pmol, with and without NaI respectively. Salicylic acid and its d(6)-isomer analysis confirm the applicability of the DIAMS method in the detection of compounds of low molecular weight.     

A Müntz space having no complement in

in . In the present paper, we prove that there is a Müntz space not complemented in .

     

Permanganate transfer and reduction by D‐glucose in benzene–cetyltrimethylammoniumbromide aqueous solution: A kinetic study

The addition of cationic surfactant, cetlytrimethylammoniumbromide (CTAB), in benzene and aqueous potassium permanganate solution brought the MnO from the aqueous phase to the organic phase. At 525 nm, the absorbance of the organic phase increased until it reached a maximum, and then decreased with [CTAB]. The effect of [CTAB] on the reduction of permanganate by D ‐glucose in a benzene–CTAB system has been studied spectrophotmetrically. The observed effect on the rate constant is catalytic up to a certain concentration of CTAB; thereafter, a saturation phenomenon is observed with an increased concentration of CTAB. The oxidation reaction obeyed the first‐order kinetics with respect to the D ‐glucose. On addition of H₂SO₄, there was a decrease in the rate constants. There is evidence for the existence of manganese as a water‐soluble colloidal MnO₂. A detailed mechanism with the associated reaction kinetics is presented and discussed. © 2008 Wiley Periodicals, Inc. 40: 496–503, 2008