Synthesis of New Aza Macrocyclic Diamides 2,2′‐Diaminodiphenyl Sulfide Using Crab‐Like Method

Six new aza crown ethers (4–9) were synthesized based on the conventional route crab‐like method with the reaction of corresponding bis‐α‐chloroacetamidediphenylsulfide (BCADPS) (3) and aliphathic diamines (a–e) in refluxing acetonitrile in good yields. BCADPS (3) was synthesized with the reaction of 2,2′‐diaminodiphenyl sulfide (2) and chloroacetyl chloride. Interestingly, only the macrocyclization of BCADPS (3) with diamine (e) was led to the cryptand (9) in which methylene hydrogens were found as diastereotopic nucleis which is attributed to the rigidity of the cryptand ( 9 ). The formation of this cryptand ( 9 ) may be related the template effect of potassium ion. The structures of all compounds were confirmed using IR, ¹H‐NMR, ¹³C‐NMR, mass spectroscopies, and elemental analysis.     

Purification of L-Lysine in Simulated Moving Bed and Fixed-Bed Chromatography

 L-Lysine was produced by a microbial process utilizing a Corynebacterium glutamicum (ATCC 21799) strain. L-Lysine was purified from the cultivated medium by fixed-bed and simulated moving bed （SMB） chromatography. The separation conditions including pH, eluent concentration and Lys+ and Lys2+ adsorption isotherms were studied in batch adsorption. The column capacity, eluent flow rate and eluent concentration have been studied in fixed-bed chromatography. Maximum purification rate of lysine was obtained as 0.066 g/(g·h) (per gram resin and per hour) at an eluent flow rate of 10 mL/min in fixed-bed chromatography. The results obtained from SMB were 0.11 g/(g·h) for L-lysine purification rate and 96% for L-lysine recovery.     

Efficient Solvent‐Free Synthesis of Benzothiazine‐Fused Pyrrolo[3,4‐c]coumarins: Cycloaddition Reactions between Coumarin‐Based Dihydrobenzothiazoles and Isocyanides

A new and unusual synthesis of benzothiazine‐fused pyrrolo[3,4‐c]coumarins, involving the ring‐opening of coumarin‐based dihydrobenzothiazoles and subsequent [4+1] cycloaddition reaction with isocyanides, was described. Thus, simple heating of various 3‐(2,3‐dihydro‐2‐methylbenzo[d]thiazol‐2‐yl)coumarins with isocyanides produced the title compounds in good yields under solvent‐free conditions.     

Ultrasensitive Simultaneous Quantification of Nanomolar Level of Cd and Zn by Cathodic Adsorptive Stripping Voltammetry in Some Real Samples

A novel, simple and sensitive adsorptive stripping voltammetry method was developed for simultaneous determination of Cd and Zn using N‐Nitrozo‐N‐phenylhydroxylamine (Cupferron) as a selective complexing agent. Cadmium and zinc metals gave peaks that were distinctly separated by 450–1200 mV, allowing their determination over a wide range of concentrations. The influence of pH and the nature of supporting electrolytes, concentration of ligand, preconcentration time and applied potential were investigated. The detection limits were 0.058 ng/mL for Zn and 0.092 ng/mL for Cd, and the RSD at a concentration level of 50 ppb, were 1.8–2.1 % for both zinc and cadmium, respectively. The method was applied to the determination of cadmium and zinc in blood, drug, food and water samples with the satisfactory results.     

Aggregation of nanosized colloidal silica in the presence of various alkali cations investigated by the electrospray technique

The slow aggregation process of a concentrated silica dispersion (Bindzil 40/220) in the presence of alkali chlorides (LiCl, NaCl, KCl, RbCl, and CsCl) was investigated by means of mobility measurements. At intervals during the aggregation, particles and aggregates were transferred from the liquid phase to the gas phase via electrospray (ES) and subsequently size selected and counted using a scanning mobility particle sizer (SMPS). This method enables the acquisition of particle and aggregate size distributions with a time resolution of minutes. To our knowledge, this is the first time that the method has been applied to study the process of colloidal aggregation. The obtained results indicate that, independent of the type of counterion, a sufficient dilution of the formed gel will cause the particles to redisperse. Hence, the silica particles are, at least initially, reversibly aggregated. The reversibility of the aggregation indicates additional non-DLVO repulsive steric interactions that are likely due to the presence of a gel layer at the surface. The size of the disintegrating aggregates was monitored as a function of the time after dilution. It was found that the most stable aggregates were formed by the ions that adsorb most strongly on the particle surface. This attractive effect was ascribed to an ion-ion correlation interaction.     

Validated TLC-densitometry method for the simultaneous analysis of pyrethroid insecticides in agricultural and domestic products

ABSTRACT: BACKGROUND: Pyrethroids are widely used for the control of pests and insects, as pyrethroids are believed to pose very little risk to human health and environment. However, exposure to the pyrethroids exceeding the label directions might adversely affect human health and environment. Hence a careful selection of environment friendly household product is required that must contain exactly the label claimed pyrethroids amount. RESULTS: A sensitive and robust TLC-densitometric method for simultaneous quantification of commonly used synthetic pyrethroids including esbiothrin, alpha-cypermethrin and cis/trans permethrin in agricultural and domestic products has been developed and validated. TLC aluminum plates, precoated with 0.2 mm thick layer of silica gel 60 F-254, were used for chromatographic process. Densitometric analysis of chromatoplates was carried out in absorbance mode at corresponding lamdamax of each pyrethroid. Equally valid common mobile phase for all pyrethroids consisted of hexane-dichloromethane-ethylacetate-formic acid (8:1.5:0.4:0.1 v/v/v/v) which provided sharp and symmetrical peaks of esbiothrin, alpha-cypermethrin, trans-permethrin and cis-permethrin, at Rf 0.31, 0.53, 0.6 and 0.65, respectively. Linear regression data for respective calibration curves showed a good linearity for all pyrethroids with r = 0.991-0.996. Limits of detection (LOD) and limits of quantification (LOQ) for all pyrethroids were found in the range of 1.6-2.8 and 4.9-8.5 ng/spot, respectively. CONCLUSIONS: The developed method is applicable for separating the mixture of pyrethroids and at the same time, it is also valid for separating their isomers. The method is reproducible, precise and accurate for the quantitative determination of pyrethroids in agricultural and domestic products.     

Silver(I)‐N‐heterocyclic carbene complexes of bis‐imidazol‐2‐ylidenes having different aromatic‐spacers: synthesis,crystal structure,and in vitro antimicrobial and anticancer studies

A series of Ag(I) complexes ( 6 , 7 , 8 , 9 ) derived from imidazol‐2‐ylidenes was synthesized by reacting Ag₂O with an o‐, m‐, p‐xylyl or 1,3,5‐triazine‐linked imidazolium salts ( 1 , 2 , 3 , 4 ) and then characterizing these using various spectro‐analytical techniques. Additionally, triazine‐linked bis‐imidazolium salt 5 was characterized using the single‐crystal X‐ray diffraction method. Complexes 6–9 were formed from the N‐heterocyclic carbene ligand precursors 1–3 as PF₆^‐ salts in good yields. Conversely, salt 5 does not form Ag(I) complex even under various reaction conditions. Using ampicillin as a standard, complexes 6–9 were tested against bacteria strains Escherichia coli and Staphylococcus aureus as Gram‐negative and Gram‐positive bacteria, respectively, showing potent antimicrobial activities against the tested bacteria even at minimum inhibition concentration and bacterial concentration levels. Furthermore, the potential anticancer activities of the reported complexes were evaluated against the human colorectal cancer (HCT 116) cell lines, using 5‐fluorouracil as a standard drug. The highest anticancer activities were observed for complex 8 with an IC₅₀ value of 3.4 μm , whereas the lowest was observed for complex 9 with an IC₅₀ value of 18.1 μm . Copyright © 2013 John Wiley & Sons, Ltd.     

Solvent Free Synthesis of Coumarins

An efficient synthesis of 3-substituted coumarins under solventless system is described.     

Charge carrier mobility,photovoltaic, and electroluminescent properties of anthracene‐based conjugated polymers bearing randomly distributed side chains

This article reports on the synthesis, characterization, and properties of various anthracene‐containing poly (p‐phenylene‐ethynylene)‐alt‐poly(p‐phenylene‐vinylene) (PPE‐PPV) polymers (AnE‐PVs) bearing statistical distributions of various side chains. Primarily, the ratio of linear octyloxy and branched 2‐ethylhexyloxy side chains at the poly(p‐phenylene vinylene) (PPV) parts was varied, leading to the polymers stat, stat1, and stat2. Furthermore, polymers also containing asymmetric substituted PPV and poly(p‐phenylene ethynylene) units (bearing methoxy and 2‐ethylhexyloxy side chains) were prepared yielding stat3, stat4, and stat5. These materials exhibit a broad variation in their photovoltaic properties. It is once more shown that side chains and their distribution can crucially affect the photovoltaic device performance. The introduction of units with asymmetric substitution into these systems seems to be harmful for their utilization in photovoltaic applications. Organic field‐effect transistors were fabricated to investigate hole mobilities in these new materials. Large variance was observed, falling in the range of almost two orders of magnitude, indicating rather different π–π stacking behavior of the polymer backbones owing to side‐chain modifications. Moreover, a selection of the new polymeric systems was investigated regarding their potential for light‐emitting diode (LED) applications. Polymer LEDs using the polymers AnE‐PVstat, ‐stat3, ‐stat4, and ‐stat5, as the active layer showed turn‐on voltage of ～2 V and exhibited red light emission. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012