Chymotrypsin inhibitory triterpenoids from Silybum marianum

Marianine, the new lanostane triterpene (1) and marianosides A (2) and B (3) have been isolated from the whole plant of Silybum marianum. Their structures were elucidated on the basis of extensive analysis of their one dimensional and two dimensional nuclear magnetic resonance (1D, 2D-NMR) spectral data. All inhibited chymotrypsin in a concentration-dependent manner.     

Temperature and solvent dependent NMR studies on mangiferin and complete NMR spectral assignments of its acyl and methyl derivatives

By employing concerted 1 and 2D NMR techniques, exact NMR spectral assignments have been made of the acyl (2-7) and methyl (8 and 9) derivatives of mangiferin (1) isolated from the leaves of Bombax ceiba. Derivatives 2, 8 and 9 have been reported in literature, while 3-7 represent new compounds. The acetates 2 and 3 were found to be unstable and were converted into the same penta-acetate 4 at room temperature. Extensive NMR studies on mangiferin (1) and its derivatives showed that H-4 exchanges with deuterium of the solvent molecule more easily. This exchange under acidic conditions occurred at that position (C-4) where electrophilic substitution reactions can easily take place. This is the first report describing the exchange of C-4 proton of mangiferin (1), or any other xanthone, with deuterium of solvent molecules.     

Facile synthesis of 1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives by a one-pot, three-component reactions

Protonation of the highly reactive 1:1 intermediate produced in the reaction between alkyl or aryl isocyanides and electron-deficient acetylenic esters with 3,6-dihydroxypyridazine, leads to a vinylisonitrilium cation, which undergoes an addition reaction with the conjugate base of the 3,6-dihydroxypyridazine to produce dialkyl 3-(alkyl or arylamino)-5,8-dioxo-5,8-dihydro-1H-pyrazolo[1,2-a]pyridazine-1,2-dicarboxylates in good yields at room temperature.     

Bioassay studies of cobalt (II) complexes of modified diamine

Coordination compounds of modified diamine, the basic unit of which are ethylenediamine, with that of Co (II) are prepared. The modified diamines are ethylenediaceticacid (EDDA) and N,N,N,N-tetaraethylene-1,2-diamine (TEEDA). These diamines are characterized through ¹H-NMR, ¹³C-NMR, elemental analysis and IR techniques. Cobalt (II) complexes of these two ligands were prepared and characterized by physical measurements including elemental analysis, IR, UV-Visible, magnetic susceptibilities and conductance measurements. Antibacterial activities are also carried out in order to investigate the biological activity upon complexation. They were screened against four pathogenic bacteria like Escherichia coli, Pseudomonas aeroginosa, Klesbella pneumonia and Staphylococcus aureus. The results showed significant enhancement in activities.     

Cyclometalated rhodium(III) complex with phen-dione ligand

The novel cyclometalated Rh(III) complex, [Rh(phpy-κ²N,C^2′)₂(phen-dione)]PF₆, where phpy-κ²N,C^2′ is pyridine-2-yl-2-phenyl and phen-dione is 1,10-phenanthroline-5,6-dione has been prepared and characterized by elemental analysis, IR, ¹H NMR, and electronic absorption spectroscopies, cyclic voltammetry, and X-ray crystallography. The crystal structure of [Rh(phpy-κ²N,C^2′)₂(phen-dione)]PF₆·CH₃CN shows that the coordination geometry around the Rh(III) is a distorted octahedron, with bite angles of 76.13°-81.09° for all three bidentate ligands.     

Yttrium Doped Copper (II) Oxide Hole Transport Material as Efficient Thin Film Transistor

This work reports development of yttrium doped copper oxide (Y−CuO) as a new hole transport material with supplemented optoelectronic character. The pure and Y-doped CuO thin films are developed through a solid-state method at 200 °C and recognized as high performance p-channel inorganic thin-film transistors (TFTs). CuO is formed by oxidative decomposition of copper acetylacetonate, yielding 100 nm thick and conductive (40.9 S cm⁻¹) compact films with a band gap of 2.47 eV and charge carrier density of ∼1.44×10¹⁹ cm⁻³. Yttrium doping generates denser films, Cu₂Y₂O₅ phase in the lattice, with a wide band gap of 2.63 eV. The electrical conductivity increases nine-fold on 2 % Y addition to CuO, and the carrier density increases to 2.97×10²¹ cm⁻³, the highest reported so far. The TFT devices perform remarkably with high field-effect mobility (μ_sat) of 3.45 cm² V⁻¹ s⁻¹ and 5.3 cm² V⁻¹ s⁻¹, and considerably high current-on/off ratios of 0.11×10⁴ and 9.21×10⁴, for CuO and Y−CuO films, respectively (at −1 V operating voltage). A very small width hysteresis, 0.01 V for CuO and 1.92 V for 1 % Y−CuO, depict good bias stability. Both the devices work in enhancement mode with stable output characteristics for multiple forward sweeps (5 to −60 V) at −1V_g.     

Ion‐Induced Fragmentation of Amino Acids: Effect of the Environment

In general, radiation‐induced fragmentation of small amino acids is governed by the cleavage of the C? C_α bond. We present results obtained with 300 keV Xe²⁰⁺ ions that allow molecules (glycine and valine) to be ionised at large distances without appreciable energy transfer. Also in the present case, the C? C_α bond turns out to be the weakest link and hence its scission is the dominant fragmentation channel. Intact ionised molecules are observed with very low intensities. When the molecules are embedded in a cluster of amino acids, a protective effect of the environment is observed. The fragmentation pattern changes: the C? C_α bond becomes more protected and stable amino acid cations are observed as fragments of the molecular clusters. Evidently, the molecular cluster acts as a “buffer” for the excess energy, capable of rapidly redistributing excess energy and charge.     

Targeted highly sensitive detection of multi-drug resistant Salmonella DT104 using gold nanoparticles

Monoclonal antibody-conjugated popcorn-shape gold nanotechnology-driven approach to selectively detect multiple drug resistant (MDRB) Salmonella typhimurium DT104 bacteria has been developed. We demonstrate that the gold nanotechnology based assay is capable of measuring the amount of MDRB in food samples.