Radical chemistry of alkyl aluminum with quinoxaline ligands

The behavior of organo-aluminum species with 2,3-bis(2-pyridyl) quinoxaline (DPQ), a well-known polyazine capable of performing interesting radical transformations, was examined in the presence and absence of chromium. In spite of proving the presence of chromium as essential for reactivity, only organic radicals, coupled to aluminum-containing residues, have been isolated and characterized. The electronic structure of the organic radicals has been elucidated by a combination of crystallographic, DFT calculations and EPR studies. Experimental and computational work has highlighted the co-existence of both singlet and triplet forms in one di-radical complex.     

Concise diastereospecific pyrrolo[1,2-a][1,4]benzodiazepinone synthesis

A concise synthesis of the novel pyrrolo[1,2-a]benzodiazepine system, by using the metallo carbenoid/spiro-[6,5]-ammonium ylide/Stevens[1,2]-shift with ring-expansion approach, was reported. The overall cascade process resulted stereospecific.     

Isolation and structure elucidation of three glycosides and a long chain alcohol from Polianthes tuberosa Linn

Three glycosides and a long chain alcohol were isolated from the bulbs of Polianthes tuberosa, these were identified as 3,29-dihydroxystigmast-5-ene-3-O-beta-D-galactopyranoside (1), ethyl beta-D-galactopyranoside (2), ethyl-alpha-D-galactopyranoside (3), and 1-tricosanol (4). The structures were determined by extensive spectroscopic and chemical methods. All four isolated compounds were screened for their cytotoxicity, antibacterial and antifungal activities, none of the compounds showed any significant activity.     

Voltammetric Behavior of 1,4‐Dimethoxypillar[m]arene[n]quinones

The electrochemical properties of a series of 1,4‐dimethoxypillar[m]arene[n]quinones (DMP[m]A[n]Qs) and the interactions between individual quinone units have been investigated on glassy carbon electrode in acetonitrile. All the quinone units showed relative electron uptake behavior except 1,4‐dimethoxypillar[5]quinones (DMP[5]Q). The results have shown that the electrochemical behavior of the DMP[m]A[n]Qs is comparatively different from that of their related linear quinone analogues. The resultant properties were attributed to the close proximity of redox‐active sites as well as the delocalization of electrons on the aromatic rings. Another aspect to be considered responsible for their electronic properties was suggested to be the electrostatic repulsions between adjacent quinone units in these complex structures. Current studies provide a better understanding on the voltammetric behavior of pillararene derivatives with different numbers of quinone units as well as their future scope in certain future electrochemical applications.     

Palladium supported on diaminoglyoxime‐functionalized Fe3O4 nanoparticles as a magnetically separable nanocatalyst in Heck coupling reaction

A hybrid material of palladium supported on diaminoglyoxime‐functionalized Fe₃O₄ was used as an effective and recyclable catalyst in Mizoroki–Heck coupling reactions. The catalyst was very effective for the Mizoroki–Heck reaction of aryl halides with styrene and conversion was in most cases excellent. The yields of the products were in the range 75–98%. The catalyst showed good stability and could be recovered and reused for six reaction cycles without significant leaching and loss its catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd.     

An Efficient and Green Procedure for Synthesis of Pyrrole Derivatives by Paal–Knorr Condensation Using Sodium Dodecyl Sulfate in Aqueous Micellar

A simple, economical, and green approach to the synthesis of N‐substituted pyrroles using sodium dodecyl sulfate as surfactant in water is described. The experiment protocol features simple operations, and the products are isolated in high to excellent yields (60–98%).     

Investigation of role of urea in morphologically controlled synthesis of calcium‐bismuth bimetallic nanoparticles from chicken egg shells and its catalytic and fuel additive applications

A comparative study on the role of urea in controlling the morphology of calcium‐bismuth (Ca₅Bi₃) bimetallic nanoparticles is carried out. Calcium‐bismuth bimetallic nanoparticles are synthesized in the presence and absence of urea using the solvothermal method. The morphology of the synthesized products is analyzed by scanning electron microscopy. The composition of the product is analyzed by energy‐dispersive X‐ray spectroscopic and X‐ray diffraction (XRD) analyses. Reitveld refinements are performed on the XRD data, and lattice parameters are optimized. Reitveld‐refined parameters are used to construct the structural model of the calcium‐bismuth product. The formation mechanism of needle like particles from an orthorhombic unit cell is also proposed. The degradation of Congo red dye is catalyzed by synthesized Ca₅Bi₃ bimetallic nanoneedles in an aqueous medium. The effect of catalyst dose on the apparent rate constant (k_app) of degradation is studied and compared with literature. Ca₅Bi₃ bimetallic nanoneedles are also used as an additive in commercial diesel obtained from Pakistan State Oil, Limited. The effect of an additive dose on the calorific value of diesel is studied. How the Ca₅Bi₃ additive influenced other fuel quality parameters such as flash point, fire point, pour point, cloud point, kinematic viscosity, and specific gravity is also studied.     

Thermodynamics of a 3 — D charged rotating hairy black hole

In this paper, we consider a charged rotating black hole in three dimensions with a scalar charge, and discuss thermodynamics quantities. We find effects of the black hole parameters on the temperature, entropy, free energy, total energy and specific heat. We also investigate the stability of the black hole and study phase transition. We consider the first law of thermodynamics and find that satisfied.     

Synthesis, characterization, and electrical conductivity of new Aurivillius-type oxide-ion conductor

A new oxide-ion conductor of Aurivillius family with a general formula Bi₂Al _x V_{1 − x} O_{5.5 − x − δ}; 0 ≤ x ≤ 0.20 (BIALVOX) was synthesized by the sol-gel citrate route. Powder X-ray diffraction and simultaneous thermogravimetric and differential thermal analyses confirmed that the calcination of BIALVOX xerogels is fully completed at around 500°C after three hours of thermal treatment. It has been found that the β-orthorhombic phase is stabilized with compositions x ≤ 0.07, whereas the stabilization of the γ′-phase takes place for x ≥ 0.10. AC impedance spectroscopic investigation suggested that the charge accumulation at grain boundaries is thermally activated process. However, the maximum electrical conductivity (7.73 × 10⁻⁵ S cm⁻¹) noticed for BIALVOX.13 at 300°C was attributed to the maximum vacancy concentration in the equatorial planes, responsible for the ion diffusion through the structure. This has been further evidenced by the temperature dependence of dielectric permittivity.