Synthesis and characterization of graphene oxide‐based hybrid ligand and its metal complexes: Highly efficient sensor and catalytic properties

A new graphene oxide‐based hybrid material (HL) and its Co(II), Cu(II) and Ni(II) metal complexes were prepared. Firstly, graphene oxide and (3‐aminopropyl)trimethoxysilane were reacted to give graphene oxide–3‐(aminopropyl)trimethoxysilane (GO‐APTMS) hybrid material. After that, hybrid material HL was synthesized from the reaction of GO‐APTMS and 2,6‐diformyl‐4‐methylphenol. Finally, Co(II), Cu(II) and Ni(II) complexes of HL were obtained. All the materials were characterized using various techniques. The chemosensor properties of HL were investigated against Na⁺, K⁺, Cd²⁺, Co²⁺, Cu²⁺, Hg²⁺, Ni²⁺, Zn²⁺, Al³⁺, Cr³⁺, Fe³⁺ and Mn³⁺ ions and it was found that HL has selective chemosensing to Fe³⁺ ion. All the graphene oxide‐supported complexes were used as heterogeneous catalysts in the oxidation of 2‐methylnaphthalene (2MN) to 2‐methyl‐1,4‐naphthoquinone (vitamin K₃, menadione) in the presence of hydrogen peroxide, acetic acid and sulfuric acid. The Cu(II) complex showed good catalytic properties compared to the literature. The selectivity of 2MN to vitamin K₃ was 60.23% with 99.75% conversion using the Cu(II) complex.     

Antitumor,cytotoxic, and antioxidant evaluation of six heterocyclic compounds containing different heterocycle moieties

Heterocyclic compounds with different heterocycle moieties, namely benzoxazinone, benzimidazole, quinazolinone, and benzofuranone heterocyclic rings, were synthesized, characterized, and evaluated for their anticancer activity against human hepatocellular carcinoma cell line (HepG2) using sulforhodamine B (SRB) and dimethylthiazol-diphenyltetrazolium bromide (MTT) assays. Also, their cytotoxic activities were tested against human epithelioid carcinoma (Hela) cell line in comparison with normal cell, amniotic epithelial (WISH) cell line, as an in vitro toxicity estimation model. The results showed clearly that 2-(2-benzyl-4-oxoquinazolin-3(4H)-yl)acetohydrazide 4 is the most potent antioxidant and anticancer agents. Although, 3-amino-2-benzylquinazolin-4(3H)-one 5 is less potent anticancer agent against Hela but it is more safe against normal cell (WISH).     

Effet d'un champ magnétique transversal sur la stabilité de l'écoulement de Hartmann : les modes tridimensionnels

A numerical study is conducted in order to determine the influence of a transverse magnetic field on the three-dimensional instabilities of the Hartmann flow. We prove that the Squire transformation currently used to characterize such instabilities give satisfactory results only in the case where Ha is weak and 3D modes are slightly deviated from the 2D modes. Such a study is justified by the fact that the two-dimensional instabilities could not always explain successfully the experimental observations relating to the transition phenomenon. To cite this article: M. Jédidi et al., C. R. Mecanique 333 (2005).     

Controlling J‐aggregate formation for increased short‐circuit current and power conversion efficiency with a squaraine donor

A squaraine dye is tested for novel application in a near‐infrared‐active organic photovoltaic cell that is subsequently optimized to obtain a power conversion efficiency of 2.4 ± 0.3%. The optimization utilizes an Alq3 buffer layer and macroscopic structure control through the addition of co‐solvents in the spin‐casting process. Co‐solvent addition increases the amount of aggregates present as measured through linear absorption spectroscopy, and there is a concurrent increase in both efficiency and short‐circuit current. An interpretation of the greatly increased current density is presented that describes how increased J‐aggregation likely increases hole mobility and, as a result, charge separation of the photogenerated excited state. Copyright © 2012 John Wiley & Sons, Ltd.     

Using of Modified Plastic Waste Based on Poly(ethylene‐co‐acrylic acid) Grafts to Solve Transportation Problem of Petroleum Crude Oil

Polyethylene acrylic acid copolymer (PEAA) was modified with different types of alkanols and hydroxybenzoic acids to produce three types of esterified grafts. The molecular structures of the synthesized dispersants were performed using ¹H NMR analysis. The molecular weights of the synthesized dispersants were determined by GPC technique. The activity of PEAA derivatives as asphaltene stabilizer in the crude oil was evaluated by means of flocculation measurements. The effect of asphaltenes on the rheological behavior of highly asphaltenic crude oils was studied to evaluate the transportation parameters of crude oils. The rheological properties were measured at different temperature ranges of 5°C to 25°C in presence and absence of PEAA additives. It was observed that the PEAA having side chain lengths below C₁₆ show non‐Newtonian pseudoplastic relationships at temperatures from 25°C to 5°C. While, PEAA additives having side chain lengths equal or above C₁₆ show Newtonian relationship even at low temperature (5°C) for all tested crude oils.     

Thermotropic behaviour,self-assembly and photophysical properties of a series of squaraines

A series of squaraine dyes, based on 2,4-bis[4-(N,N-di-n-alkylamino)-2-hydroxyphenyl] squaraine including ethyl, propyl, butyl, pentyl, hexyl and heptyl derivatives, were synthesised by condensation of the corresponding 4-(N,N-di-n-alkylamino)-2-hydroxyphenol with squaric acid. The thermal behaviour of the series was recorded using both thermogravimetic analysis and differential scanning calorimetry while their crystalline structures were elucidated via single-crystal X-ray diffraction. The length of the alkyl chain proved to have a significant effect on both the thermotropic behaviour and the crystalline structure of the squaraine series. Two derivatives, butyl and heptyl, revealed the presence of liquid crystalline mesophases, smectic and nematic, respectively, which were confirmed and characterised via polarised light microscopy and X-ray diffraction. Several of the derivatives formed H- and/or J-aggregates upon thin film formation via spin coating before and after the thermal annealing treatment as indicated by UV–vis spectroscopy. The molecular and crystal structure, aggregation and thermal behaviour provide insight into the supramolecular assembly of this important class of materials. Photophysical measurements revealed large molar absorptivity, reasonably high fluorescence quantum yields and significant fluorescence anisotropy by making these derivatives suitable candidates for a number of electro-optic and photonics applications.     

Quadrupole Mass Filter: Design and Performance for Operation in Stability Zone 3

The predicted performance of a quadrupole mass filter (QMF) operating in Mathieu stability zone 3 is described in detail using computer simulations. The investigation considers the factors that limit the ultimate maximum resolution (R_max) and percentage transmission (%Tx), which can be obtained for a given QMF for a particular scan line of operation. The performance curve (i.e., the resolution (R) versus number (N) of radio frequency (rf) cycles experienced by the ions in the mass filter) has been modeled for the upper and lower tip of stability zone 3. The saturation behavior of the performance curve observed in practice for zone 3 is explained. Furthermore, new design equations are presented by examining the intersection of the scan line with stability zone 3. Resolution versus transmission characteristics of stability zones 1 and 3 are compared and the dependence of performance for zones 1 and 3 is related to particular instrument operating parameters.

NONCONVENTIONAL FRIEDEL-CRAFTS CHEMISTRY III. ON THE REGIOSPECIFIC SYNTHESIS OF SPIRO[CYCLOALKANE-1,1′-ISOTHIOCHROMAN]-4′-ONE DERIVATIVES

Abstract

The reaction of 1-oxa-4-thiaspiro[4,4]nonan-2-one (4) and/or 1-oxa-4-thiaspiro[4,5]decan-2-one (5) with arenes (6) under the catalytic action of aluminum chloride afforded in all cases spiro[cycloalkane-1,1′-isothiochroman]-4′-ones (7a-g and 8a-g), [(arylcycloalkyl)thio]-acetic acid, (9a-g and 10a-g), cy-cloalkylthioacetic acids, (11 and 20) aryl cycloalkyl sulfides, (14 and 23) diaryl sulfides (15), diaryl disulfides and dicycloalkyl disulfides (13 and 22). The mechanisms of these reactions are discussed.