Hydrotalcite catalysis in ionic liquid medium: a recyclable reaction system for heterogeneous Knoevenagel and nitroaldol condensation

Knoevenagel condensation proceeds efficiently in recyclable [bmim]PF₆ and [bmim]BF₄ without any catalyst, and hydrotalcites in ionic liquid serve as a safe and recyclable reaction system for both Knoevenagel as well as nitroaldol condensations.     

Unambiguous evidence for wurtzite phase in capped CdS quantum dots

The problem of identification of the correct crystalline structure of CdS nanoclusters below 2.5 nm in size is outlined. Structure of thiophenol capped CdS nanoclusters in the size range 1.2–4.3 nm, synthesized using cadmium acetate solution in methanol, is discussed using powder XRD and electron diffraction data. Unambiguous confirmation of the wurtzite phase in CdS nanoclusters below 2.5 nm size is reported. The observation of 102 wurtzite peak in the XRD patterns of such nanoclusters indicates low stacking fault concentration.     

Benzyl isobornyl amines: a simple and practical class of NMR discriminating agents for effective chiral recognition of acids

The design and synthesis of a few simple N-benzyl derivatives of isobornyl amine is presented. The derivatives have been assessed as chiral solvating agents for effective discrimination of the signals of some acids in NMR analysis. The single crystal X-ray analysis of the salts of (R)-mandelic acid with two of the title derivatives help to understand the supramolecular interactions and assign the induced chemical shifts in ¹H NMR analysis. The title derivative is found to be suitable for quantitative determination of the enantiomeric excess of unknown enantiomeric purity as well as being efficient in resolving racemic mandelic acid.     

Modeling the effect of mutual interference in a delay-induced predator-prey system

In this paper, we investigate the effect of mutual interference on the dynamics of a predator-prey system with gestation delay. It has been observed that there is stability switches and system becomes unstable due to the combine effect of mutual interference and time delay. We determine the conditions under which the model system becomes globally asymptotically stable around the non-zero equilibria. By applying the normal form theory and the center manifold theorem, the explicit formulae which determine the stability and direction of the bifurcating periodic solutions are determined. Computer simulations have been carried out to illustrate different analytical findings.     

Untersuchungen über die Chelate einiger seltenerer Übergangsmetalle,I. Mitt: Ir(III), Pt(IV) und Au(III)

Chelates of bidentate ligands, p-dimethylamino and p-diethylaminoanils of 3-benzoylmethylglyoxal with Ir(III), Pt(IV) and Au(III) ions have been studied for their stoichiometry, electrolytic nature, infrared, magnetic, and electronic spectra. In addition to the elucidation of stereochemistry and structures various ligand field parameters have been calculated and unusual paramagnetic behaviour has been accounted for.     

Improved and rapid synthesis of new coumarinyl chalcone derivatives and their antiviral activity

Two closely structurally related coumarins, 4-hydroxy-8-isopropyl-5-methylcoumarin and 4-hydroxy-6-chloro-7-methylcoumarin were acylated at C-3 and further converted to the respective chalcones and two series of eighteen new compounds, which were evaluated for possible antiviral activity.     

Insertion of a small peptide of six amino acids into the β7–β8 loop of the p51 subunit of HIV-1 reverse transcriptase perturbs the heterodimer and affects its activities

Background  

HIV-1 RT is a heterodimeric enzyme, comprising of the p66 and p51 subunits. Earlier, we have shown that the β7-β8 loop of p51 is a key structural element for RT dimerization (Pandey et al., Biochemistry 40: 9505, 2001). Deletion or alanine substitution of four amino acid residues of this loop in the p51 subunit severely impaired DNA binding and catalytic activities of the enzyme. To further examine the role of this loop in HIV-1 RT, we have increased its size such that the six amino acids loop sequences are repeated in tandem and examined its impact on the dimerization process and catalytic function of the enzyme.