New heterocyclic metallomesogens: synthesis,mesomorphic and thermal behaviours of Cu(II) complexes with 1,2,3-triazole-based Schiff bases ligands

Two series of new Cu(II) complexes derived from the reaction of copper acetate with the non-linear 1,2,3-triazole-based Schiff bases have successfully been synthesised. The structures of the ligands and its complexes were elucidated by elemental analysis, FT-IR, ¹H-NMR and UV–visible spectroscopic techniques. The differential scanning calorimetry and polarizing optical microscopy supported the anisotropic properties of uncoordinated ligands in which the focal conic fan-shaped texture and/or broken fan-shaped texture characteristics of respective SmA and SmC phases were recorded. However, not all of their corresponding Cu(II) complexes are mesogenic. Although the iodo-substituted ligands with even parity C₁₀H₂₉ to C₁₄H₃₃ are non-stable and exhibit SmA phase which is not reproducible, the ultimate Cu(II) complexes show exclusively stable SmA phase. This observation can be ascribed to the enhanced colinearity and molecular anisotropic by the presence of Cu-N and Cu-O coordination modes. On the other hand, the comparison studies show that different positions of ortho-hydroxyl group affect the mesomorphic and thermal behaviour of ligands and Cu(II) complexes.     

CH_4 reforming with CO_2 for syngas production over La_2O_3 promoted Ni catalysts supported on mesoporous nanostructured γ-Al_2O_3

Nanostructured γ-Al2O3 with high surface area and mesoporous structure was synthesized by sol-gel method and employed as catalyst support for nickel catalysts in methane reforming with carbon dioxide. The prepared samples were characterized by XRD, N2adsorption-desorption,TPR, TPO, TPH, NH3-TPD and SEM techniques. The BET analysis showed a high surface area of 204 m2 g-1and a narrow pore-size distribution centered at a diameter of 5.5 nm for catalyst support. The BET results revealed that addition of lanthanum oxide to aluminum oxide decreased the specific surface area. In addition, TPR results showed that addition of lanthanum oxide increased the reducibility of nickel catalyst. The catalytic evaluation results showed an increase in methane conversion with increasing lanthanum oxide to 3 mol% and further increase in lanthanum content decreased the catalytic activity. TPO analysis revealed that the coke deposition decreased with increasing lanthanum oxide to 3 mol%. SEM and TPH analyses confirmed the formation of whisker type carbon over the spent catalysts. Addition of steam and O2 to dry reforming feed increased the methane conversion and led to carbon free operation in combined processes.     

Homogeneous Liquid–Liquid Microextraction Via Flotation Assistance (HLLME-FA) Method for the Pretreatment of Organochlorine Pesticides in Aqueous Samples and Determination by GC–MS

This work proposes a new, rapid and simple homogeneous liquid–liquid microextraction via flotation assistance technique for the analysis of six organochlorine pesticides in water samples. A special extraction cell was used to facilitate collection of the low-density solvent extract. No centrifugation was required in this procedure. Determination was carried using gas chromatography–mass spectrometry. The water sample solution was then added into the extraction cell containing appropriate mixture of extract and homogeneous solvents. In the first step, a homogeneous solution and then with the continuation of water sample injection, a cloudy solution was formed. Using air flotation, the organic solution was collected at the conical part of the designed cell. The optimized levels of effective parameters were found based on response surface methodology approach. Applying the optimized conditions to the system understudy, the limits of detection of all target analytes were obtained in the range of 1.4–7 ng mL^?1, while the precisions were found to be in the range of 11.08–14.87 (RSD, n = 3). The linearity of the method lay in the range of 10–150 ng mL^?1 with the coefficients of correlation (r ² ) ranging from 0.998 to 0.999.     

Synthesis of Diaryl Ethers Through the Copper-Catalyzed Arylation of Phenols with Aryl Iodides Using KF/Al2O3

An efficient synthesis of diaryl ethers by the copper-catalyzed arylation of phenols with a variety of aryl iodide susing KF/Al₂O₃ as a suitable base and CuI and 1,3 diphenyl-1,3 propandione as the catalyst is described.     

Mild and Efficient Procedure for Michael Addition of N-Heterocycles to α,β-Unsaturated Compounds Using Anhydrous K3PO4 as Catalyst

Imidazole, 1,2,4-triazole, indole, and benzotriazole undergo conjugate additions with α, β-unsaturated carbonyl compounds in the presence of anhydrous potassium phosphate at ambient temperature to afford the corresponding Michael adducts in excellent yields.     

Sedimentation rate in the Sungai Linggi estuary using excess 210Pb and 137Cs

The purpose of this study was to estimate the sedimentation rate in the Sungai Linggi estuary using the constant initial concentration of unsupported or excess ²¹⁰Pb model and verified with ¹³⁷Cs method. Five sediment cores were collected on 25 January 2011 using gravity corer with the inner tube of 50 cm length and 7.5 cm diameter. The total ²¹⁰Pb activities in the sediment cores profile at all sampling stations were varied and upper than those obtained for supported ²¹⁰Pb i.e. ²²⁶Ra, indicated disequilibrium among ²¹⁰Pb and its grandparents in the ²³⁸U decay series. Meanwhile, the lower ¹³⁷Cs activities were observed at all sampling stations due to no significant sources of ¹³⁷Cs releases were transferred into Malaysian marine. The estimation of sedimentation rate indicated the agreement of ²¹⁰Pb and ¹³⁷Cs method with a general presence of deep mixing in the Sungai Linggi estuary. Therefore, the apparent sedimentation rates calculated from ²¹⁰Pb profiles generally reflect the true value with the range from 0.70 to 1.97 cmyr^?1. High sedimentation rate was observed at some sampling stations which are located in river channel, estuary and closer to mainland. This suggested that land-use development, agriculture activities, channelization etc. introduced a large amount of sediment loaded into those areas.     

Introducing Organic Gas Steam-Liquid Extraction as a New Preconcentration Method for Benzene,Toluene, Ethylbenzene and Xylene Determination in Water Samples by Gas Chromatography-Flame Ionization Detection

Journal of Analytical Chemistry - In this study, for the first time, the organic gas steam-liquid extraction by a special hand-made cell was used as a simple and inexpensive preconcentration...