Temperature dependent exchange narrowing of line width in EPR on interacting donors in germanium and silicon

An expression has been derived for the temperature dependent exchange integral for a pair of interacting shallow donors substituted in a dielectric material. This has been achieved by taking into account the phonon induced mixing of excited orbital states with the ground orbital states of the impurity centres. The results have been used to explain the temperature narrowing of the EPR line width observed by some workers in phosphorus doped germanium at low temperatures. Good agreement between theory and experimental results seems to favour the proposed mechanism in preference to one of motional narrowing due to hopping.     

Utilization of cascade chemo-bio catalysis for the synthesis of R -1-phenylethyl acetate

Liquid phase tert-butylation of m-cresol was carried out using 12-tungstosilicic acid supported on neutral alumina by varying different parameters. The reaction has also been carried out by using calcined samples under optimized conditions. The present catalyst shows an excellent activity of 93.2%, conversion of 100% selectivity for the o-isomer, an important industrial product.     

A facile and one-pot synthesis of N-Fmoc/Bsmoc/Boc/Z-protected ureidopeptides and peptidyl ureas employing diphenylphosphoryl azide [DPPA]

Diphenylphosphoryl azide (DPPA) mediated one-pot synthesis of N^α-Fmoc/Bsmoc/Boc/Z-protected ureidopeptides and peptidyl ureas as well as phenyl/succinimidyl (N^α-urethane protected) methyl carbamates starting from N^α-protected amino acids is reported. The formation of an azide, its rearrangement and coupling with an amino component is accomplished in a sequence of one-pot operations. The protocol has incorporated urea linkages in a sterically hindered peptide.     

T-CAM, a fastatin-FIII 9-10 fusion protein, potently enhances anti-angiogenic and anti-tumor activity via alphavbeta3 and alpha5beta1 integrins

We made fusion protein of fastatin and FIII 9-10, termed tetra-cell adhesion molecule (T-CAM) that can interact simultaneously with alphavbeta3 and alpha5beta1 integrins, both playing important roles in tumor angiogenesis. T-CAM can serve as a cell adhesion substrate mediating adhesion and migration of endothelial cells in alphavbeta3 and alpha5beta1 integrin-dependent manner. T-CAM showed pronounced anti-angiogenic activities such as inhibition of endothelial cell tube formation, endothelial cell proliferation, and induction of endothelial cell apoptosis. T-CAM also inhibited angiogenesis and tumor growth in mouse xenograft model. The anti-angiogenic and anti-tumoral activity of molecule like fastatin could be improved by fusing it with integrin-recognizing cell adhesion domain from other distinct proteins. The strategy of combining two distinct anti-angiogenic molecules or cell adhesion domains could facilitate designing improved anticancer agent of therapeutic value.     

Synthesis and evaluation of novel N-substituted-6-methoxynaphthalene-2-carboxamides as potential chemosensitizing agents for cancer

A novel class of molecules with structure N-[3-(heteroaryl)propyl]-6-methoxynaphthalene-2-carboxamides 8-13 were synthesized by condensing 6-methoxy-2-naphthoyl chloride 1 with 3-(heteroaryl)propyl amines 2-7. Compounds 8-12 were evaluated in vitro, in P388 murine lymphocytic leukemia cell line (P388) using SRB assay for cytotoxicity and in adriamycin resistant P388 murine lymphocytic leukemia cell line (P388/ADR) using MTT assay for resistant reversal activity. Compounds 8-12 were non-toxic at lower dose of 20 microg/ml, and effectively reversed adriamycin resistance. However, at higher doses (40, 80 microg/ml) they showed significant cytotxicity and hence reversal potency was not determined at these concentrations.     

Review of synthesis and various biological activities of spiro heterocyclic compounds comprising oxindole and pyrrolidine moities

Spirocyclic compounds isolated from plant and animal origins have important applications in medicinal chemistry. Spiro compounds having cyclic structures fused at a central carbon are of recent interest because of their interesting conformational features and their structural implications for biological systems. Spiro heterocycles like spiropyrrolidines and oxindole moieties have been found to play fundamental roles in biological processes and have exhibited diversified biological activity and pharmacological and therapeutical properties. In view of these facts we decided to present a representative synthetic scheme and various biological activities of the heterocycles like spiropyrrolidines and oxindole moieties derivatives, especially in relation to microbial infections like cancer and tubercular, viral, HIV, bacterial, and fungal infections.     

Metal-free decarboxylative acylation of isoquinolines using α-keto acids in water

An efficient method for acylation of isoquinolines has been developed using α-ketoacids under metal- and additive-free conditions in water. The protocol involves C(sp²)H functionalization of isoquinolines providing an easy access to C1-benzoylated isoquinolines, which constitute the core structure of a number of biological active compounds and serve as key intermediate in the synthesis of many alkaloids.     

Fabrication of newly developed pectin –GeO2 nanocomposite using extreme biomimetics route and its antibacterial activities

The combination of pectins and germanium dioxide may generate novel materials with excellent and unique properties combining the advantages of macromolecules, derived from renewable resources and metal oxide nanoparticles. Pectin–GeO₂ nanocomposite was prepared by hydrothermal method at room temperature. Structural morphology and chemical interactions between GeO₂ and pectin were analyzed using Fourier Transform Infrared Spectroscopy Equipped with Attenuated Total Reflectance (FTIR-ATR), AC impedance spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-ray Spectrophotometer (SEM-EDS) Thermo gravimetric analysis (TG) and Differential Scanning Calorimetry (DSC). According to the TEM observation, the average composite granules size was about 70 nm and the embedded GeO₂ nanoparticles were uniform with an average diameter of 20 nm. The pectin-germanium dioxide degradation was observed in one single DSC endoderm peak at 100°C (Area swept 276.4 mJ and enthalpy change 48.1 J/g) and three DTG peaks in the temperature range between 165 and 570°C. All the results suggest the pectin–GeO₂ nanocomposite as a promising candidate for biomedical and environmental applications.     

Synthesis of Ag/AgCl-mesoporous silica nanocomposites using a simple aqueous solution-based chemical method and a study of their antibacterial activity on E. coli

Simple aqueous solution-based chemical methods have been developed for the synthesis of Ag/AgCl nanoparticle-mesoporous silica nanocomposites. Ag loading in the mesoporous silica was accomplished using a wet-impregnation method. The AgCl-mesoporous silica nanocomposite material(AgCl-mSi) was synthesized by using a 'one pot' method. Synthesized materials were characterized using X-ray diffraction,N2 adsorption-desorption analysis and high-resolution transmission electron microscopy. Antibacterial activity of...     

Enantioselective synthesis of cocaine C-1 analogues using sulfinimines (N-sulfinyl imines)

The first examples of cocaine analogues having substituents (methyl, ethyl, n-propyl, n-pentyl, and phenyl) at the C-1 position of the cocaine tropane skeleton were prepared by heating sulfinimine-derived α,β-unsaturated pyrrolidine nitrones. In the presence of the Lewis acid Al(O(t)Bu)(3) the nitrones undergo an intramolecular [3 + 2] cycloaddition to give tricyclic isoxazolidines that were transformed in three steps to the cocaine analogues. In the absence of the Lewis acid, lactams were formed resulting from rearrangement of the nitrone to an oxaziridine. A novel Pd- and base-promoted rearrangement of methanesulfonate salts of isoxazolidine to bridge bicyclic[4.2.1]isoxazolidines was discovered.