A simple and regioselective α-bromination of alkyl aromatic compounds by two-phase electrolysis

Electrochemical bromination of toluene and substituted toluenes by two-phase electrolysis yields the corresponding α-brominated products. The reaction has been carried out in a single compartment cell with platinum electrodes at 0 °C in chloroform using an aqueous sodium bromide solution (60%) containing a catalytic amount of HBr. Two-phase electrolysis results in high yields (60-95%) of monobromo compounds with very high regioselectivity (>95%).     

Copper(II) azide complexes of aliphatic and aromatic amine based tridentate ligands: novel structure, spectroscopy, and magnetic properties

Copper(II) azide complexes of three tridentate ligands namely 2,6-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L), 2,6-(pyrazol-1-ylmethyl)pyridine (L'), and dipropylenetriamine (dpt) yield three kinds of complexes with different azide-binding modes. The ligand L forms two end-on-end (mu-1,3) diazido-bridged binuclear complexes, [CuL(mu-N(3))](2)(ClO(4))(2) (1) and [CuL(mu-N(3))(ClO(4))](2).2CH(3)CN (2), and L' forms a perchlorato-bridged quasi-one-dimensional chain complex, [CuL'(N(3))(ClO(4))](n)() (3) with monodentate azide coordination. The ligation of dipropylenetriamine (dpt) gives a end-on (mu-1,1) diazido-bridged binuclear copper complex [Cu(dpt)(mu-N(3))](2)(ClO(4))(2) (4). The crystal and molecular structures of these complexes have been solved. Variable-temperature EPR results of 1 and 2 are identical and indicate the presence of both ferromagnetic and antiferromagnetic interactions within the dimer, the former dominating at low temperatures and the latter at high temperatures. The unusual temperature-dependent magnetic moment and EPR spectra of this dimer reveal the presence of temperature-dependent population of two triplet states, one being caused by antiferromagnetic and the other by ferromagnetic interaction, the former transforming to the latter on cooling. While the interaction of ground spin doublets of the two metal centers gives rise to a ferromagnetic coupling of J(g) = 90.73 cm(-1), the other coupling of J(e) = -185.64 cm(-1) is suggested to be caused by the interaction between an electron in one metal center and an electron from the azide of the other monomer by excitation of a d-electron to the empty ligand orbital. The ferromagnetic state is energetically favored by 104.39 cm(-1). Compound 3 exhibits axial spectra at room temperature and 77 K, and variable-temperature magnetic susceptibility data indicate that the copper centers form a weakly antiferromagnetic one-dimensional chain with J = -0.11 cm(-1). In the case of 4, the unique presence of two nonidentical dimeric units with different bond lengths and bond angles within the unit cell as inferred by crystal structure is proved by single-crystal EPR spectroscopy.     

Biosynthesis of TiO2 Nanoparticles Using Edible Mushroom (Pleurotus djamor) Extract: Mosquito Larvicidal,Histopathological, Antibacterial and Anticancer Effect

Journal of Cluster Science - The titanium dioxide nanoparticles (TiO2NPs) were synthesized by the aqueous extract from P. djamor. The UV–Vis spectrum of TiO2NPs showed maximum absorption at...     

Biological Applications of Synthesized ZnO Nanoparticles Using Pleurotus djamor Against Mosquito Larvicidal,Histopathology, Antibacterial,Antioxidant and Anticancer Effect

The present study pertained to biosynthesis, characterization and biomedical application (larvicidal, histopathology, antibacterial, antioxidant and anticancer activity) of Zinc oxide nanoparticles (ZnONPs) from Pleurotus djamor. The synthesized NPs were characterized using spectral and microscopic analyses and further confirmed by UV–Visible spectrophotometer with apeak of 350 nm. The ZnONPs showed strong antioxidant property (DPPH, H₂O₂ and ABTS⁺ radical assay) and expressed good larval toxicity against Ae. aegypti and Cx. quinquefasciatus (IVth instar larvae) with the least LC₅₀ and LC₉₀ values (10.1, 25.6 and 14.4, 31.7 mg/l) after 24 h treatment, respectively. We noticed the morphological changes (damaged anal papillae area and the cuticle layers) in the treated larvae. For the antibacterial assay, the highest growth inhibition zone was recorded in C. diphteriae (28.6?±?0.3 mm), followed by P. fluorescens (27?±?0.5 mm) and S. aureus (26.6?±?1.5 mm). The in vitro cytotoxicity assay depicted a significant level of cytotoxic effects (LC₅₀ values 42.26 μg/ml) of ZnONPs against the A549 lung cancer cells, even at low dose. The overall findings of the study suggest that P. djamor had the ability for the biosynthesis of ZnONPs and could act as an alternative biomedical agent for future therapeutic applications in medical avenues.

     

Modifications in band gap and optical properties of Zn0.96−xNd0.04CuxO (x = 0, 0.05, 0.1 and 0.15) nanoparticles

Nd-doped and Nd, Cu co-doped ZnO nanoparticles (Zn_0.96?xNd_0.04Cu_xO, x = 0, 0.05, 0.1 and 0.15) were synthesized by sol–gel method. The structural and optical properties of the samples were investigated by X-ray diffraction (XRD) and UV–visible photo-spectrometer. The synthesized nanoparticles have different microstructure without changing a hexagonal wurtzite structure. CuO phase was noticed in XRD spectra at 38.73° after Cu = 5 % which was formed from remaining un-reacted Cu²⁺ ions. The average crystal size was gradually increased from Cu = 0 % (17 nm) to 15 % (17.6 nm) having lowest value (16.7 nm) at Cu = 5 %. The change in lattice parameters confirmed the substitution of Cu in Zn–Nd–O lattice. The observed constant c/a ratio revealed that there was no change in hexagonal wurtzite structure by Cu-doping. The energy dispersive X-ray spectra confirmed the presence of appropriate amount of Nd and Cu in Zn–O lattice. The optical absorption was increased gradually from Cu = 0–10 % and showed maximum at Cu = 10 % due to the presence of more nucleation centres and defect states. The defects related green band between 487 and 493 nm was due to the oxygen vacancies and intrinsic defects. The higher transmittance (≈ 90 %) noticed at Cu = 15 % leads to the industrial applications. The observed blue shift in energy gap from 3.49 eV (Cu = 0 %) to 3.65 eV (Cu = 10 %) and the red shift from Cu = 10 % (3.65 eV) to Cu = 15 % (3.61 eV) can be explained by the Burstein–Moss effect. Presence of chemical bonding was confirmed by Fourier transform infrared spectra.     

The optimisation of ultrasonic cleaning procedures for dairy fouled ultrafiltration membranes

Ultrafiltration (UF) of whey is a major membrane based process in the dairy industry. However, commercialization of this application has been limited by membrane fouling, which has a detrimental influence on the permeation rate. There are a number of different chemical and physical cleaning methods currently used for cleaning a fouled membrane. It has been suggested that the cleaning frequency and the severity of such cleaning procedures control the membrane lifetime. The development of an optimal cleaning strategy should therefore have a direct implication on the process economics. Recently, the use of ultrasound has attracted considerable interest as an alternative approach to the conventional methods. In the present study, we have studied the ultrasonic cleaning of polysulfone ultrafiltration membranes fouled with dairy whey solutions. The effects of a number of cleaning process parameters have been examined in the presence of ultrasound and results compared with the conventional operation. Experiments were conducted using a small single sheet membrane unit that was immersed totally within an ultrasonic bath. Results show that ultrasonic cleaning improves the cleaning efficiency under all experimental conditions. The ultrasonic effect is more significant in the absence of surfactant, but is less influenced by temperature and transmembrane pressure. Our results suggest that the ultrasonic energy acts primarily by increasing the turbulence within the cleaning solution.     

Synthesis and characterization of water-soluble carbon nanotubes from mustard soot

Carbon nanotubes (CNT) has been synthesized by pyrolysing mustard oil using an oil lamp. It was made water-soluble (wsCNT) through oxidative treatment by dilute nitric acid and was characterized by SEM, AFM, XRD, Raman and FTIR spectroscopy. The synthesized wsCNT showed the presence of several junctions and defects in it. The presence of curved graphene structure (sp²) with frequent sp³ hybridized carbon is found to be responsible for the observed defects. These defects along with the presence of di- and tri-podal junctions showed interesting magnetic properties of carbon radicals formed by spin frustration. This trapped carbon radical showed ESR signal in aqueous solution and was very stable even under drastic treatment by strong oxidizing or reducing agents. Oxidative acid treatment of CNT introduced several carboxylic acid group functionalities in wsCNT along with the nicking of the CNT at different lengths with varied molecular weight. To evaluate molecular weights of these wsCNTs, an innovative method like gel electrophoresis using high molecular weight DNA as marker was introduced.     

A mild and efficient method for the oxidation of benzylic alcohols by two-phase electrolysis

Electrochemical oxidation of benzylic and substituted benzylic alcohols by two-phase electrolysis yields the corresponding aldehydes as products. The reaction was carried out in a single compartment cell with platinum electrodes at room temperature in chloroform using an aqueous sodium bromide solution (25%) containing a catalytic amount of HBr. The two-phase electrolysis resulted in high yields (74-96%) of benzaldehyde from primary alcohols and secondary alcohols were oxidized to the corresponding ketone but only in low yields under these conditions.     

Mono- and di-substituted urea derivatives of cyclodiphosphazane: [ClP(μ-NBu)2PN(Me)CON(H)Me] and [Me(H)NCON(Me)P(μ-NBu)]2

The reaction of cis-[ClP(μ-N^tBu)]₂ with N,N′-dimethylurea leads to the formation of both mono- and di-substituted derivatives [ClP(μ-N^tBu)₂P(NMeCON(H)Me)] and [(μ-N^tBu)P(NMeCON(H)Me)]₂, instead of monomeric, dimeric or higher oligomeric macrocycles. The structure of [ClP(μ-N^tBu)₂P(NMeCON(H)Me)] shows rare non-bonded P?Cl and intermolecular hydrogen bonding interactions leading to a 2D-sheet like structure.     

Influence of Sm<Superscript>3+</Superscript> ion in structural,morphological, and electrochemical properties of LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript> synthesized by microwave calcination

LiSm_xMn_2–xO₄ samples were synthesized via co-precipitation technique. The structural properties of the synthesized materials were studied using X-ray diffraction analysis and it confirmed the cubic spinel structure for all the compounds. The lattice parameter of LiMn₂O₄ was observed to be 8.2347 Ǻ and it decreased with Sm³⁺ concentration, due to the shrinkage in cell volume aided by higher binding energy between Sm-O bond. The SEM micrographs were analyzed using Image processing software (Image-J) to ascertain the pore and grain properties. The microwave synthesis had been observed to control the bulk grain formation and had yielded lesser porous and nanoparticles. The particle size distributions obtained through photocross correlation laser diffraction analysis had shown that LiMn₂O₄ with 60 nm and Sm-doped compounds with ∼30 nm, respectively. The cyclic voltammetry studies had revealed the decrease in electrocatalytic behavior in the initial cycle for compounds doped with Sm³⁺ ion. The initial capacities of LiMn₂O₄, LiSm_0.05Mn_1.95O₄ and LiSm_0.10Mn_1.90O₄ substituted compounds were observed to be 134.87 mAhg⁻¹, 132.22 mAhg⁻¹ and 126.41 mAhg⁻¹, respectively. The cells were simulated using 1D model namely Dualfoil5.1 program. The simulated results coincide well with the measured results. The cycle life studies reveal 93% capacity retention of samarium-0.05-doped samples when compared with 78.4% of the LiMn₂O₄.