Crystal structure of 2-thiophene-2-yl-3(thiophene-2-carboxylideneamino)-1,2-dihydroquinazolin-4(3H)-one and the synthesis, spectral and thermal studies of its transition metal(II) complexes

The synthesis of manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes of a new ligand 2-thiophene-2-yl-3(thiophene-2-carboxylidene-amino)-1,2-dihydroquinazolin-4(3H)-one (TTCADQ) is described. The ligand and metal complexes were characterized by elemental analysis, conductivity measurements, spectral (u.v.-vis., i.r., 1D n.m.r., 2D hetcor and e.p.r.) and thermal studies. The formation of 1,2-dihydroquinazolin-4(3H)-one rather than hydrazone, in the reaction of aromatic aldehyde and o-aminobenzoylhydrazide is proved by single crystal X-ray diffraction and 2D hetcor n.m.r. studies. On the basis of elemental analysis, u.v.-vis.spectroscopy and magnetic moment studies, six coordinate geometry for all the complexes was proposed. The i.r. spectral studies reveal the bidentate behaviour of the ligand.

Towards a green synthesis of LAB's: Effect of rare earth metal ions on the benzene alkylation with 1-dodecene over NaFAU-Y zeolites

Chemically modified microporous materials can be prepared as robust catalysts suitable for application in vapor phase processes such as Friedel-Crafts alkylation. In the present paper we have investigated the use of rare earth metal (Ce3+, La3+, RE3+, and Sm3+) exchanged Na-Y zeolites as catalysts for the alkylation of benzene with long chain linear 1-olefin; 1-dodecene. Thermodesorption studies of 2,6-dimethylpyridine adsorbed catalysts (in the temperature range 573 to 873 K) show that the rare earth zeolites are highly Bronsted acidic in nature. A perfect correlation between catalyst selectivity towards the desired product (2-phenyldodecane) and Bronsted acid sites amount has been observed. (c) 2006 Springer Science + Business Media, Inc.

Total synthesis of (+/-)-herbertenediol

A formal total synthesis of the sesquiterpene (+/-)-herbertenediol and its dimers mastigophorenes A-D has been accomplished, starting from vanillin via 2,3-dimethoxy-5-methylbenzaldehyde. A combination of Claisen rearrangement and ring-closing metathesis reactions were employed for the generation of the two vicinal quaternary carbons on a cyclopentane ring.

A simple synthesis and characterization of CuS nanocrystals

Water-soluble CuS nanocrystals and nanorods were prepared by reacting copper acetate with thioacetamide in the presence of different surfactants and capping agents. The size of the nanocrystals varied from 3-20 nm depending on the reaction parameters such as concentration, temperature, solvent and the capping agents. The formation of nanocrystals was studied by using UV-visible absorption spectroscopy.

The first total synthesis of (+/-)-lagopodin A

The first total synthesis of (±)-lagopodin A and a formal total synthesis of enokipodins A and B is described. The requisite precursors containing two vicinal quaternary carbon atoms were assembled employing Claisen rearrangement and an RCM reaction as key steps starting from 2,5-dimethoxy-4-methylacetophenone.

Improved synthesis of carbon nanotubes with junctions and of single-walled carbon nanotubes

Pyrolysis of thiophene over nickel nanoparticles dispersed on silica is shown to yield Y-junction carbon nanotubes with smaller diameters than those obtained by the pyrolysis of organometallic-thiophene mixtures. In the presence of water vapour, the pyrolysis of organometallic-hydrocarbon mixtures yields single-walled nanotubes, as well as relatively narrow-diameter carbon nanotubes with Y-junctions. Pyrolysis-of organometallic-hydrocarbon mixtures, in the absence of water vapour, only gives nanotubes with T- and Y-junctions.

Synthesis and characterisation of co-evaporated tin sulphide thin films

Tin sulphide films were grown at different substrate temperatures by a thermal co-evaporation technique. The crystallinity of the films was evaluated from X-ray diffraction studies. Single-phase SnS films showed a strong (040) orientation with an orthorhombic crystal structure and a grain size of 0.12 mu m. The films showed an electrical resistivity of 6.1 Omega cm with an activation energy of 0.26 eV. These films exhibited an optical band gap of 1.37 eV and had a high optical absorption coefficient (> 10(4) cm(-1)) above the band-gap energy. The results obtained were analysed to evaluate the potentiality of the co-evaporated SnS films as an absorber layer in solar photovoltaic devices.

Low-temperature polymer precursor-based synthesis of nanocrystalline particles of lanthanum calcium manganese oxide (La0.67Ca0.33MnO3) with enhanced ferromagnetic transition temperature

We report a simple modified polymeric precursor route for the synthesis of highly crystalline and homogenous nanoparticles of lanthanum calcium manganese oxide (LCMO). The LCMO phase formation was studied by thermal analysis, x-ray powder diffraction, and infrared spectroscopy at different stages of heating. These nanocrystallites (average particle size of 30 nm) possess ferromagnetic-paramagnetic transition temperature (T-c) of 300 K, nearly 50 K higher than that of a single crystal. The Rietveld analysis of the powder x-ray diffraction data of the nanopowders reveals significant lattice contraction and reduction in unit cell anisotropy-these structural changes are correlated to the enhancement in T-c.

Isoselenocyanates derived from Boc/Z-amino acids: synthesis, isolation,characterization, and application to the efficient synthesis of unsymmetrical selenoureas and selenoureidopeptidomimetics

Isoselenocyanates derived from Boc/Z-amino acids are prepared by the reaction of the corresponding isonitriles with selenium powder in presence of triethylamine at reflux. The utility of these new classes of isoselenocyanates in the preparation of selenoureidodipeptidomimetics possessing both amino as well as carboxy termini has been accomplished. The H-1 NMR analysis confirmed that the protocol involving the conversion of isonitriles to isoselenocyanates and their use as coupling agents in assembling selenour-eido derivatives is free from racemization. (C) 2010 Elsevier Ltd. All rights reserved.

Synthesis of S-functionalized thioesters using thioaroylate ions derived from carboxylic acids and tetrathiomolybdate via acyloxyphosphonium intermediates

Thioaroylate ions generated in situ from acyloxyphosphonium salts and tetrathiomolybdate upon Michael addition or ring opening of three membered systems led to a facile synthesis of S-funcationalized thioesters. While the ring opening of aziridines gave very good yield of the products, Micheal addition and epoxide ring opening gave moderate yields.(C) 2010 Elsevier Ltd. All rights reserved.

Synthesis, characterization and photoluminescence properties of Gd2O3:Eu3+ nanophosphors prepared by solution combustion method

Gd2O3:Eu3+ (0.5-8.0 mol%) nanophosphors have been prepared by low temperature solution combustion method using metal nitrates as oxidizers and oxalyl dihydrazide (ODH) as a fuel. The phosphors are well characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and photoluminescence (PL) techniques. PXRD patterns of as-formed and calcined (800 degrees C, 3 h) Gd2O3 powders exhibit monoclinic phase with mean crystallite sizes ranging from 20 to 50 nm. Eu3+ doping changes the structure from monoclinic to mixed phase of monoclinic and cubic. SEM micrographs shows the products are foamy, agglomerated and fluffy in nature due to the large amount of gases liberated during combustion reaction. Upon 254 nm excitation the photoluminescence of the Gd2O3:Eu3+ particles show red emission at 611 nm corresponding to D-5(0)-> F-7(2) transition. It is observed that PL intensity increases with calcination temperature. This might be attributed to better crystallization and eliminates the defects, which serve as centers of non-radiative relaxation for nanomaterials. It is observed that the optical energy gap (E-g) is widened with increase Eu3+ content. (C) 2010 Elsevier B.V. All rights reserved.

Synthesis of ethyl arylacetates by means of Friedel-Crafts reactions of aromatic compounds with ethyl alpha-chloro-alpha-(ethylthio)acetate catalysed by ytterbium triflate

An efficient Friedel-Crafts alkylation of aromatic compounds with ethyl alpha -chloro-alpha-(ethylthio)acetate catalysed by ytterbium triflate, followed by desulfurisation of the product provides a convenient methodology for the synthesis of ethyl arylacetates of aromatic and heteroaromatic compounds. (C) 2000 Elsevier Science Ltd. All rights reserved.

Synthesis of both enantiomers of 1-phenylethane-1,2-diol via chirality transfer from bile acid derivatives

Both enantiomers of 1-phenylethane-1,2-diol were synthesized with good to excellent enantioselectivities via selective reduction of the phenylglyoxalates derived from bile acids, followed by reductive cleavage. (C) 2000 Elsevier Science Ltd. All rights reserved.