Stereoselective synthesis of 3,4-trans-disubstituted pyrrolidines and cyclopentanes via intramolecular radical cyclizations mediated by CAN

The stereoselective intramolecular cyclizations of bis(cinnamyl)tosylamides and dimethyl bis(cinnamyl)malonates mediated by cerium(IV) ammonium nitrate leading to the synthesis of 3,4-trans-disubstituted pyrrolidines and cyclopentanes are described.     

Synthesis, Characterization, Electrochemical Properties and Antibacterial Activity of Some Transiton Metal Complexes with [(2-hydroxy-1-naphthaldehyde)-3-isatin]-bishydrazone

A bishydrazone was prepared by reacting isatin monohydrazone with 2-hydroxy-1-naphthaldehyde and a series of metal complexes with this new ligand were synthesised by reaction with Mn^II, Fe^II, Co^II, Ni^II, Cu^II and Zn^II salts. The complexes were characterised on the basis of elemental analysis, molar conductance, magnetic susceptibility data, u.v.–visible, i.r., e.s.r. and n.m.r. spectral studies, wherever possible and applicable. Analytical data reveal that the nickel(II), copper(II) and zinc(II) complexes possess 1:1 metal–ligand ratios and that manganese(II), iron(II) and cobalt (II) complexes exhibit 1:2 ratios. Infrared spectral data suggest that the bishydrazone behaves as a monobasic tridentate ligand with ONO donor sequence towards the metal ions. X-ray diffraction study of the copper(II) complex indicated an orthorhombic crystal lattice. The e.p.r. spectral data show that the metal–ligand bond has considerable covalent character. The electrochemical behaviour of the copper(II) complex was investigated by cyclic voltammetry (CV). Antibacterial tests of the ligand and the metal complexes were also carried out and it has been observed that the complexes are more potent bactericides than the ligand.     

Cerium(IV) ammonium nitrate-mediated oxidative rearrangement of cyclobutanes and oxetanes

A facile CAN-mediated oxidative rearrangement of alkoxyaryl cyclobutanes and oxetanes is described.     

Scanning electron microscopic studies on different habits of gel grown doped manganese carbonate crystals

The effect of impurities on the growth of manganese carbonate crystals has been studied. Stereophotogrammetric analysis showed that all crystal faces have the same Miller indices and the peanut-shaped forms are twins with twin axis 0001.     

Response surface methodology for optimization of heavy metal removal by magnetic biosorbent made from anaerobic sludge

In this study, optimum conditions for adsorption of heavy metals such as Cu²⁺, Cd²⁺ and Pb²⁺ onto a low-cost, magnetically modified-alkali conditioned anaerobically digested sludge (MADS) adsorbent were obtained. Response Surface Methodology (RSM) incorporating Central Composite Design (CCD) of experiments was applied to optimize four independent process variables. Statistical analysis was executed by ANOVA and the quadratic model developed had regression coefficients of 0.959, 0.957 and 0.95 for Cu²⁺, Cd²⁺ and Pb²⁺, respectively. The independent variables such as pH, time and initial concentration positively influenced adsorption capacity, q_e, whereas the value of q_e decreased with an increase in MADS dosage. Model validation experiments for optimization of adsorption process showed comparable results with predicted values. The adsorption capacity of MADS adsorbent at optimum conditions found through RSM analysis was 29.721 mg L^?1, 28.551 mg L^?1 and 28.601 mg L^?1 for Cu²⁺, Cd²⁺ and Pb²⁺ respectively.     

A CAN-induced cyclodimerization-Ritter trapping strategy for the one-pot synthesis of 1-amino-4-aryltetralins from styrenes

[reaction: see text]. A facile one-pot synthesis of 1-amino-4-aryl-tetralin derivatives by the CAN-induced cyclodimerization of various styrenes in acetonitrile and acrylonitrile is described.     

Characterization of amyloidogenic immunoglobulin light chains directly from serum by on-line immunoaffinity isolation

Primary systemic amyloidosis (AL) is characterized by the overproduction of immunoglobulin light chain proteins by a monoclonal, terminally differentiated B-lymphocyte or plasma cell clone. The free immunoglobulin light chains are deposited in an abnormal conformation as amyloid in a variety of organs in the body. The mechanism of amyloid formation is not well understood, but appears to be associated with some form of cleavage of the immunoglobulin light chain with subsequent aggregate formation. In an attempt to characterize the structure of amyloid-forming light chain proteins we developed an on-line immunoaffinity purification and subsequent characterization of free kappa and free lambda immunoglobulin light chains by electrospray ionization mass spectrometry. The methodology is totally automated and requires 20 micro L of serum. Mass spectral analysis of Bence Jones proteins under non-denaturing conditions was also utilized to examine the tertiary and quaternary structure of light chain proteins and clearly shows covalent dimer formation of lambda type light chain. This type of on-line assay may prove helpful in elucidating distinguishing features capable of discriminating AL from benign monoclonal gammopathies of undetermined significance as well as diagnosing AL.     

Dielectric,thermal, and mechanical properties of CeO2‐filled HDPE composites for microwave substrate applications

Cerium oxide‐filled high density polyethylene (HDPE) composites for microwave substrate applications were prepared by sigma‐blend technique. The HDPE was used as the matrix and the dispersion of CeO₂ in the composite was varied up to 0.5 by volume fraction, and the dielectric properties were studied at 1 MHz and microwave frequencies. The variations of thermal conductivity (k_eff), coefficient of thermal expansion (α_c) and Vicker's microhardness with the volume fraction of the filler were also measured. The relative permittivity (ε_eff) and dielectric loss (tan δ) were found to increase with increase in CeO₂ content. For 0.4 volume fraction loading of the ceramic, the composite had ε_eff = 5.7, tan δ = 0.0068 (at 7 GHz), k_eff = 2.6 W/m °C, α_c = 98.5 ppm/°C, Vicker's microhardness of 18 kg/mm² and tensile strength of 14.6 MPa. Different theoretical approaches have been used to predict the effective permittivity, thermal conductivity, and coefficient of thermal expansion of composite systems and the results were compared with the experimental data. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 998–1008, 2010     

(1-x)MgAl2O4-xTiO2 dielectrics for microwave and millimeter wave applications

The MgAl₂O₄ ceramics were prepared by the conventional solid-state ceramic route and the dielectric properties studied in the microwave frequency region (3–13 GHz). The phase purity and crystal structure were identified using the X-ray diffraction technique. The MgAl₂O₄ spinel ceramics show interesting microwave dielectric properties (ε_r=8.75, Q_uxf=68900 GHz (loss tangent = 0.00017 at 12.3 GHz), τ_f=-75 ppm/°C). The MgAl₂O₄ has high negative τ_f, which precludes its immediate use in practical applications. Hence the microwave dielectric properties of MgAl₂O₄ spinels were tailored by adding different mole fractions of TiO₂. The ε_r and Q factor of the mixed phases were increased with the molar addition of TiO₂ into the spinel to form mixtures based on (1-x)MgAl₂O₄-xTiO₂ (x=0.0-1.0). For x=0.25 in (1-x)MgAl₂O₄-xTiO₂, the microwave quality factor reaches a maximum value of Q_uxf=105400 GHz (loss tangent = 0.00007 at 7.5 GHz) where ε_r and τ_f are 11.035 and -12 ppm/°C, respectively. The microwave dielectric properties of the newly developed 0.75MgAl₂O₄-0.25TiO₂ dielectric is superior to several commercially available low loss dielectric substrates. PACS 77.22.-d; 84.40.-x; 81.05.Je     

Novel synthesis of highly functionalized pyrazolines and pyrazoles by triphenylphosphine-mediated reaction of dialkyl azodicarboxylate with allenic esters

[reaction: see text] Reaction of the Huisgen zwitterion, derived from triphenylphosphine and dialkyl azodicarboxylate, with allenic esters affords highly functionalized pyrazolines and pyrazoles. The crystal structure of pyrazoline derivative 7a showed extensive C-H...O interactions. Pyrazole formation proceeds via a novel nitrogen to carbon migration of the carboalkoxy group.