Label-free fluorescence detection of the depurination activity of ribosome inactivating protein toxins

Development of a simple label-free fluorescence hybridization assay to monitor the depurination activity of toxic ribosome inactivating proteins by using a fluorescent ligand that specifically pseudo base pairs with a cytosine residue opposite an abasic site is described. This method could be potentially implemented in screening platforms for the discovery of small molecules that inhibit the activity of these toxins.     

Structural and electronic properties of sulphur-doped boron nitride nanotubes

First-principles calculations based on density functional theory were performed to study the structural and electronic properties of sulphur substitution-doped boron nitride (BN) nanotubes, using the theory as implemented in SIESTA code, which uses non-conserving pseudo-potentials in fully non-local form and atomic orbitals as the basis set. The generalized gradient approximation (GGA) was used for the exchange–correlation (XC) potential. The tube selected was a (10, 0) BN nanotube that fell in the range of energy gap independent of the tube diameter. The electronic and structural properties for sulphur substitution in the boron and the nitrogen sites were studied. The structural arrangement in equilibrium conditions for S shows an outward radial deformation around the sulphur atom in the tube. The bandgap of the pristine BN nanotubes was found to be significantly modified on doping.     

Structural and electronic properties of CuSbS2 and CuBiS2: potential absorber materials for thin-film solar cells

As the demand for photovoltaics rapidly increases, there is a pressing need for the identification of new visible light absorbing materials for thin-film solar cells that offer similar performance to the current technologies based on CdTe and Cu(In,Ga)Se(2). Metal sulphides are the ideal candidate materials, but their band gaps are usually too large to absorb significant fractions of visible light. However, by combining Cu(+) (low binding energy d(10) band) and Sb(3+)/Bi(3+) (low binding energy s(2) band), the ternary sulphides CuSbS(2) and CuBiS(2) are formed, which have been gathering recent interest for solar cell applications. Using a hybrid density functional theory approach, we calculate the structural and electronic properties of these two materials. Our results highlight the stereochemical activity of the Sb and Bi lone pair electrons, and predict that the formation of hole carriers will occur in the Cu d(10) band and hence will involve oxidation of Cu(I).     

Ultrafast strain engineering in complex oxide heterostructures

We report on ultrafast optical experiments in which femtosecond midinfrared radiation is used to excite the lattice of complex oxide heterostructures. By tuning the excitation energy to a vibrational mode of the substrate, a long-lived five-order-of-magnitude increase of the electrical conductivity of NdNiO(3) epitaxial thin films is observed as a structural distortion propagates across the interface. Vibrational excitation, extended here to a wide class of heterostructures and interfaces, may be conducive to new strategies for electronic phase control at THz repetition rates.     

Exploration of a binding mode of benzothiazol-2-yl acetonitrile pyrimidine core based derivatives as potent c-Jun N-terminal kinase-3 inhibitors and 3D-QSAR analyses

C-Jun N-terminal kinase (JNK) is a therapeutic target for inhibitors which may provide clinical benefit in the pathogenesis of rheumatoid arthritis (RA) as well as in various apoptosis-related disorders. The benzothiazol-2-yl acetonitrile derivatives, recently reported by Pascale et al. (J. Med. Chem. 2005, 48, 4596-4607), are the first generation JNK inhibitors of this class. To understand inhibitory mechanisms and elucidate pharmacophoric properties of these derivatives molecular docking and 3D-QSAR studies were performed on a set of 44 compounds. Ligand Fit module of Cerius2 (4.9) was employed to locate the binding orientations of all the compounds within the JNK-3 ATP binding site. A good correlation (r2=0.810) between the calculated binding free energies (-PMF score) and the experimental inhibitory activities suggests that the identified binding conformations of these potential inhibitors are reliable. Based on the binding conformations, robust and highly predictive 3D-QSAR models were developed with conventional r2 0.886 and 0.802, full cross-validation r2 0.980 and 0.788, and predictive r2 0.965 and 0.968 for MFA and MSA, respectively. The interaction mode was demonstrated taking into consideration inhibitor conformation, hydrogen bonding, and electrostatic interaction. The 3D-QSAR model built in this study will provide clear guidelines for a novel inhibitor design based on the benzothiazole derivatives against JNK-3 for the treatment of inflammatory disorders.     

Toxicological effects,biological aspects and spectral characterization of organoboron(III) complexes of sulfonamide‐imines

The toxicological effects, biological aspects and spectral characterization of organoboron(III) complexes of sulfonamide‐imines derived by the condensation of salicylaldehyde with different sulfa‐drugs are described. The benzene‐soluble, high‐molecular‐weight complexes have been characterized using a wide range of analytical and spectroscopic techniques, viz. UV, IR, ¹H and ¹¹B NMR. On the basis of these studies, it is inferred that the imines derived from sulfa drugs and salicylaldehyde behave as dibasic tridentate ligands and thus provide a tetrahedral environment around the boron atom. Finally, all these complexes have been screened for their antimicrobial activity against a variety of fungal and bacterial strains and their toxicological effects on male albino rats examined at the dosages employed. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthesis of novel fluorescent benzo[a]pyrano[2,3-c]phenazine and benzo[a]chromeno[2,3-c]phenazine derivatives via facile four-component domino protocol

An efficient and practical route to novel fluorescent benzo[a]pyrano[2,3-c]phenazine framework has been developed by one-pot, four-component reaction of 2-hydroxynaphthalene-1,4-dione, 1,2-phenylenediamines, aromatic aldehydes, and Meldrum’s acid in glacial acetic acid at 70 °C. Photophysical studies of these compounds have been reported. Reactions involving cyclohexane-1,3-dione/5-methylcyclohexane-1,3-dione/dimedone in the place of Meldrum’s acid yielded corresponding benzo[a]chromeno[2,3-c]phenazine derivatives. Crystal structure of 3k established the regioisomer formed. Mild reaction conditions, good yields, short reaction time, and easy separation are some of the salient features of the present protocol.     

Review of the synthesis,characterization, and properties of LaAlO3 phosphors

In this review different methods of preparing lanthanum aluminate (LaAlO₃) phosphors are discussed. The molten salt method, the combustion method, the sucrose method, and the coprecipitation technique are the best methods for preparing LaAlO₃ phosphors with small particle size and high surface area by low-temperature synthesis. LaAlO₃ usually has a rhombohedral structure. It has good dielectric properties and, hence, is regarded as an attractive alternative to SiO₂ in microelectronic devices. LaAlO₃ phosphors have excellent chemical and thermal stability, mechanical durability, and exploitable optical and electronic properties, leading to a wide range of potential applications. LaAlO₃ phosphors doped with rare-earth ions have luminescence properties and can, hence, be used in optical display systems.     

Facile Iodine(III)-Mediated Approach for the Regioselective Chlorination of 2-Aryl-2,3-dihydro-4(1H)-quinolones

Oxidation of 2-aryl-2,3-dihydro-4(1H)-quinolones (1) with 1.5 equivalents of (dichloroiodo)benzene in dichloromethane at room temperature leads to regioselective chlorination, thereby offering an efficient method for the synthesis of new 2-aryl-6-chloro-2,3-dihydro-4(1H)-quinolones (3).