Direct sulfonylation of Baylis-Hillman alcohols and diarylmethanols with TosMIC in ionic liquid-[Hmim]HSO4: an unexpected reaction

A Brønsted acidic ionic liquid-[Hmim]HSO₄ promoted unexpected reaction of Baylis-Hillman alcohols and diarylmethanols with p-toluenesulfonylmethyl isocyanide (TosMIC) affording the corresponding sulfone derivatives instead of N-tosylmethyl amides is reported. After isolation of the product, the ionic liquid [Hmim]HSO₄ was easily recycled for further use.     

CuBr(PPh3)3] for azide-alkyne cycloaddition reactions under strict Click conditions

A careful methodological study revealed a true Click catalytic system based on commercially available [CuBr(PPh(3))(3)]. This system is active at room temperature, with 0.5 mol % [Cu] (or less), in the absence of any additive, and it does not require any purification step to isolate pure triazoles.     

Synthesis,spectroscopic studies and biological screening of 18-membered octaazamacrocyclic complexes derived from acetonylacetone and thiocarbohydrazide

A series of the macrocyclic complexes is synthesized by condensation of acetonylacetone and thiocarbohydrazide in the presence of divalent metal salts in the methanolic medium. The complexes are of the type: [M(TML)X₂] where, M = Co(II), Ni(II), Cu(II), Zn(II) and Cd(II); X = Cl⁻ CH₃COO⁻ and TML is a tetradentate macrocyclic ligand. The complexes have been characterized with the help of various physicochemical techniques like elemental analyses, conductance measurements, magnetic measurements, NMR, infrared and electronic spectral studies. The low value of molar conductance indicates them to be non-electrolyte. On the basis of various studies a distorted octahedral geometry may be proposed for all the complexes. All the synthesized metal complexes were also tested for their in vitro antibacterial activities against some bacterial strains. The results obtained were compared with standard antibiotic: Ciprofloxacin. Some of the tested complexes shows good antibacterial activities against some bacterial strains.     

Experimental determination and comparison of rain attenuation in free space optic link operating at 532 nm and 655 nm wavelength

The demand for high data rate, security and reliable communication is driving the development of free space optic communication (FSO) technology. The atmospheric effects such as scintillation, absorption and scattering severely affect the availability and range of the FSO system. The atmospheric rain absorbs and scatters the laser beam energy resulting in attenuation of the propagating signal. Initial development of FSO technology primarily used wavelength from infrared spectrum. In the recent years, the interest in visible light carrier for FSO applications is consistently increasing. In this paper, the effect of rain over two optical wavelengths from the visible spectrum i.e. 532 nm and 655 nm has been experimentally evaluated and results for the specific rain attenuation at 532 nm and 655 nm wavelengths have been compared.     

Performance analysis of optical WDM system based on unequal spaced channel allocation (USCA) scheme

Unequal spaced channel allocation (USCA) is a technique to reduce Four wave mixing (FWM). In this paper, system performance of 8 channel WDM system considering different optical transmitter formats (RZ, NRZ, Raised cosine and Gaussian) using USCA has been evaluated in terms of Q-factor. The simulation results reveal that four wave mixing is minimum for NRZ format. Also the effect of changing the laser power and increasing the bit rate has been observed.     

XPS and some surface characterizations of electrodeposited MgO nanostructure

Growth conditions, structural, and optical properties of MgO nanostructure have been investigated. Surface composition and shift in binding energy of Mg at 50.8 eV due to oxidation were examined by core‐level spectroscopy. The SEM showed that the film is dense, and grain growth and crystallinity are enhanced by post‐deposition annealing. Grain distribution was appraised within the confinement of 24.51 µm² from the selected scan areas. X‐ray diffraction studies indicated prominent peaks, which are attributed to (111), (200), and (220) reflections from fairly crystallized and randomly oriented MgO thin film. Plane (111) is found to be the preferred orientation of the film. The film transmitted well across the visible spectrum and the estimated energy band gap is 5.41 eV. Absence of catalyst in the electrolyte solution aided the purity of the sample. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis,characterization and evaluation of nanocrystalline anatase titania for the degradation of dibutyl phosphate

Degradation of dibutyl phosphate (DBP) in aqueous solution was successfully demonstrated in this paper using nanoparticles of anatase titania. Nanocrystalline anatase titania employed for the degradation study was synthesized in house by solgel route under stirring mode using titanium ethoxide precursor. The catalyst was characterized using XRD, DRS, BET, TEM, TG–DTA and Raman spectroscopy to establish the catalytic activity and surface morphology. A cylindrical photoreactor was used for the photocatalytic experiments. 10 mg of nano anatase titania and 0.5 mL of 30 % H₂O₂ were used as catalysts for the degradation of 1,000 mL of 240 mg/L DBP. Ion chromatographic procedure was used for following the DBP degradation. More than 95 % of DBP degradation could be in less than 45 min and the kinetics of DBP was found to follow pseudo first order. It was demonstrated that the photocatalytic efficiency of the synthesized titania was better than P-25 titania.     

Role of photoadduct of K4Fe(CN)6 and C3H4N2 in improving thermal stability of polyaniline composite

This paper involves the synthesis of polyaniline composite with photoadduct of potassium hexacyanoferrate and imidazole via photochemical route by oxidative polymerization technique by ammonium persulphate. The photoadduct has been synthesized by photoirradiation followed by substitution with imidazole ligand. The photoaquation, substitution and successful synthesis has been proved by recording pH, UV visible spectra before and after irradiation and XRD of photoadduct. The as synthesized composite has been subjected to various characterizations like elemental analysis, UV–Visible spectra, FTIR, XRD, SEM, and TG/DTG. XRD of photoadduct shows crystalline structure which has been retained in the composite, changing the amorphous structure of polyaniline into the crystalline one, hence proving the insertion of photoadduct in the polymer chain. Various parameters like crystallite size (L), interplanar distance (d), micro strain (ε), dislocation density (δ) and distortion parameters (g) were calculated from XRD data. Thermal analysis shows the high thermal stability of composite which can be due to strong interaction between polymer chain and the photoadduct which restricts the thermal motion of polyaniline and thus enhances the thermal stability of composite.     

Exclusive Detection of Sub‐Nanomolar Levels of Palladium(II) in Water: An Excellent Probe for Multiple Applications

A new colorimetric probe has been developed for the detection and estimation of Pd^II at sub‐nanomolar concentrations. The probe consisted of rhodamine (signaling unit), which was linked with a bis‐picolyl moiety (binding site) through a phenyl ring. Pd^II induced opening of the spirolactam ring of the probe with the generation of a prominent pink color. The excellent selectivity of the probe towards Pd^II over Pd⁰ or Rh^II ensured its potential utility for the detection of residual palladium contamination in pharmaceutical drugs and in Pd‐catalyzed reactions. The probe showed a “turn‐on” (bright yellow) fluorescence upon the addition of Pd^II, which made it suitable for the detection of Pd contaminants in mammalian cells.     

Novel aziridination of α-halo ketones: an efficient nucleophile-induced cyclization of phosphoramidates to functionalized aziridines

A novel and efficient aziridination of α-halo ketones is reported. The reaction of α-halo ketones with diethyl N-arylphosphoramidates affords diethyl N-aryl-N-(2-oxoalkyl)phosphoramidates which undergo reductive (H⁻-induced) cyclization with sodium borohydride followed by sodium hydride to give 1,2-disubstituted and 1,2,3-trisubstituted aziridines. The cyclization induced by NCS⁻ or PhS⁻ affords substituted aziridines functionalized at C-2. The reactions give excellent yields and are highly diastereoselective in favour of cis aziridines.