Copper(II) Bromide–Catalyzed C-C/C-N Bond-Forming Reactions: Synthesis of Pyrrole-Incorporated Triarylmethanes

We have achieved a facile copper(II) bromide–catalyzed synthesis of 2,3,4-trisubtitued pyrrole incorporated into unsymmetrical triarylmethanes through direct replacement of hydroxyl group in the pyrrolyl phenyl methanol with electron-rich aromatic and heteroaromatic compounds. The newly developed method has been applied to a facile synthesis of a C2 symmetric bis-triarylmethane in which the two triarylmethanes were bridged through piperzine. The copper(II) bromide catalysis led to C-C bond formation at the C(5) position when the reacting partner was imidazole. In contrast, C-N bond formation took place with benzimdazole or 2-methylbenzimidazole.     

Speciation of 30 % tri-n-butyl phosphate solvent during extraction of nitric acid

Several solutions of 30 % TBP/n-dodecane were equilibrated with different concentrations of aqueous nitric acid solutions at 298.15 K at a phase ratio of unity. The resultant equilibrated aqueous and organic solutions were analyzed for acidity. A three-solvate model with molecular HNO₃ based mechanism was assumed for nitric acid extraction by TBP. With nonlinear chemometric methods, the coefficients were evaluated. With the set of optimized coefficients, derived on the basis of experiments reported in this work, the estimated solvate species and free-TBP species in the TBP containing organic phase were found to be in good agreement with the reported concentrations in the literature.     

Sol–gel synthesis and optical behavior of Mg–Ce–O nano-crystallites

The Mg–Ce–O powder are shown to contain periclase-type MgO and/or fluoride-type cerium oxide (CeO₂) depending upon the composition (x) defined by Ce/(Ce + Mg) atomic ratio. Lattice contraction of pariclase phase of MgO (average crystallite size ~8.8 nm) at Ce content of ‘x’ = 0.20 in comparison to pure MgO (crystallite size ~9.5 nm) has been realized due to oxygen vacancy formation. The optical band gap values of CeO₂ varies (3.0–3.2 eV) due to oxygen vacancy formation in CeO₂ phase, crystallite size and/or Ce³⁺/Ce⁴⁺ ratio. Further, the addition of Ce has shown to reduce the physisorption and chemisorption of water significantly as reflected by (1) suppression of related absorption peaks and (2) absence of magnesium hydroxide, Mg(OH)₂, bands in Fourier transform infrared spectra.     

Antimicrobial effects of vanillin-based pyridyl-benzylidene-5-fluoroindolins

In this study, the antimicrobial effect and DNA gyrase inhibitor potential of vanillin-based pyridyl–substituted fluoro-indolines were evaluated. These compounds are synthesized and established through green-chemistry approaches. The inhibition effect on both DNA gyrase A and B was evaluated in silico and in vitro. Agar well diffusion method–based antimicrobial activity against Gram-ve Pseudomonas aeruginosa (MTCC 424) and Escherichia coli (MTCC 443), Gram+ve Streptococcus pyogenes (MTCC 442) and Staphylococcus aureus (MTCC 96), and a clinical isolate of Candida albicans (Fungi) was evaluated. The cytotoxicity of the compounds was assessed over macrophages using the MTT assay. In the results, the target compounds exhibited a broad-spectrum antimicrobial activity against both bacterial types and fungal.     

Synthesis,thermal decomposition and dielectric behavior of bis(thiourea)silver(I)nitrate

New semi-organic bis(thiourea)silver(I)nitrate (TuAgN) single crystals have been grown from slow evaporation solution growth technique. Single crystal X-ray diffraction study reveals that the crystal belongs to orthorhombic system with the non-centrosymmetric space group C2221 and the calculated cell parameters are a = 33.3455 (6) Å, b = 45.2957 (7) Å, c = 20.3209 (5) Å, α = β = γ = 90°, and V = 30692.8 (10) Å ³. The thermal stability and decomposition behavior of TuAgN compound have been studied by thermogravimetric analysis at three different heating rates 5, 10, and 15 °C min^?1. The effective activation energy (E _a) and pre-exponential factor (ln A) of thermal decomposition of thiourea from TuAgN compound at three different heating rates are estimated by model free methods: Arrhenius, Flynn–Wall, Kissinger, and Kim–Park. The calculated effective activation energies were found to vary with the fraction (α) reacted. The compensation effect between the (ln A) and (E _a) has also been studied. Dielectric properties of TuAgN crystal have been studied in a wide range of frequencies and temperatures. AC conductivity has also been carried out.     

Review on influencing parameters in the performance of concentrated solar power collector based on materials,heat transfer fluids and design

Journal of Thermal Analysis and Calorimetry - The solar collector (reflector and receiver) is the primary device being used in the concentrating solar power technologies for tapping the solar...     

A fluorogenic 1,3-dipolar cycloaddition reaction of 3-azidocoumarins and acetylenes

Copper(I)-catalyzed 1,3-dipolar cycloaddition reaction of nonfluorescent 3-azidocoumarins and terminal alkynes afforded intense fluorescent 1,2,3-triazole products. The mild condition of this reaction allowed us to construct a large library of pure fluorescent coumarin dyes. Since both azide and alkyne are quite inert to biological systems, this reaction has potential in bioconjugation and bioimaging applications. [reaction: see text]     

On cardinal interpolation by Gaussian radial-basis functions: Properties of fundamental functions and estimates for Lebesgue constants

Suppose λ is a positive number. Basic theory of cardinal interpolation ensures the existence of the Gaussian cardinal functionL _λ(x)

Synthesis of peptide-nanotube platinum-nanoparticle composites

Nanotubes prepared by the self-assembly of D-Phe-D-Phe molecules are investigated by electron microscopy and Monte Carlo simulations; the nanotubes appear to be porous and are capable of forming novel peptide-nanotube platinum-nanoparticle composites.