Magnetic Graphene Oxide Anchored Sulfonic Acid as a Novel Nanocatalyst for the Synthesis of N‐aryl‐2‐amino‐1,6‐naphthyridines

Magnetic graphene oxide functionalized with sulfonic acid (Fe₃O₄‐GO‐SO₃H) was used as a new recyclable nanocatalyst for one‐pot synthesis of N‐aryl‐2‐amino‐1,6‐naphthyridine derivatives under solvent free conditions. The catalyst could be easily recovered from the reaction mixture by an external magnet and reused without significant decrease in activity even after 4 runs. This nanocatalyst exhibited better activities to other commercially available sulfonic acid catalysts.     

Microwave assisted syntheses of 2,5-disubstituted 1,3,4-oxadiazoles

2,5-Disubstituted 1,3,4-oxadiazoles have been synthesized by oxidation of 1-aroyl-2-arylidene hydrazines with potassium permanganate on the surface of a solid mineral support as well as in mixtures of acetone and water under microwave irradiation.     

Dielectrically induced sensitivity enhancements in electro-optic field sensors

The sensitivity of an electro-optic (EO) field sensor depends inversely on the dielectric constant of the nonlinear crystal. In EO sensors based on lithium niobate the effective value of this dielectric constant is affected by dielectric relaxation effects and is identified with its smaller, high-frequency component. Because of this effect, the EO modulation is significantly enhanced, thus improving the field strength sensitivity.     

Structural and magnetic properties of FeB microfibers

Structural and magnetic properties of FeB microfibers, obtained by electroless deposition on cellulose fibers, were investigated. X-ray diffraction (XRD) showed the presence of an amorphous phase. Extended X-ray absorption fine structure spectroscopy (EXAFS) studies confirmed an amorphous-like structure with the nearest coordination numbers around Fe atom to be 8.7 for Fe and 3.5 for B. The magnetic moment of 2.12 Bohr magnetons/Fe atom is consistent with composition obtained from EXAFS measurements. PACS 61.43.Dq; 61.10.Ht; 75.70.-i; 61.10.Eq; 81.15.Pq     

Tributyltin(IV)[3‐(3′,5′‐dimethylphenylamido)propanoate] as a potent HCV inhibitor,its delivery study,controlled release and binding sites using CTAB as a standard cell membrane

Gaussia luciferase assay was used to measure the anti‐hepatitis C (anti‐HCV) potency of tributyltin(IV)[3‐(3′,5′‐dimethylphenylamido)propanoate] in infected Huh 7.5 cells (human hepatocellular cell). Interaction of the organotin(IV) complex with cetyl N,N,N‐trimethylammonium bromide (CTAB) micelles was studied using UV–visible and steady‐state florescence spectroscopy. The anti‐HCV study showed a log IC₅₀ value of 0.96 nm for the complex. The complex–CTAB interaction parameter showed that partition of the complex from bulk water to the CTAB micelle was a spontaneous process, and the red shift in visible spectra of the complex confirmed its increased solubility into micelles. Copyright © 2013 John Wiley & Sons, Ltd.     

Iminobiotin Binding Induces Large Fluorescent Enhancements in Avidin and Streptavidin Fluorescent Conjugates and Exhibits Diverging pH-Dependent Binding Affinities

The pH-dependent binding affinity of either avidin or streptavidin for iminobiotin has been utilized in studies ranging from affinity binding chromatography to dynamic force spectroscopy. Regardless of which protein is used, the logarithmic dependence of the equilibrium dissociation constant (K_d) on pH is assumed conserved. However a discrepancy has emerged from a number of studies which have shown the binding affinity of streptavidin for iminobiotin in solution to be unexpectedly low, with the K_d at values usually associated with non-specific binding even at strongly basic pH levels. In this work we have utilized a Bodipy fluorescent conjugate of avidin and an Oregon Green fluorescent conjugate of streptavidin to determine the K_d of the complexes in solution in the pH range of 7.0 to 10.7. The study was made possible by the remarkable fluorescent enhancement of the two fluorescent conjugates (greater than 10 fold) upon saturation with iminobiotin. The streptavidin-iminobiotin interaction exhibited almost no pH dependence over the range studied, with K_d consistently on the order of 10⁻⁵ M. In contrast, under identical experimental conditions the avidin-iminobiotin interaction exhibited the expected logarithmic dependence on pH. We discuss the possible origins for why these two closely related proteins would diverge in their binding affinities for iminobiotin as a function of pH.     

MCM‐41‐SO3H as a nanoreactor for the one‐pot,solvent‐free synthesis of 1,8‐dioxo‐9‐aryl decahydroacridines

One‐pot four‐component synthesis of 1,8‐dioxo‐9‐aryl decahydroacridines in solvent‐free condition was efficiently performed in the presence of MCM‐41‐SO₃H as a nanocatalyst and nanoreactor in good yields. The method provides several advantages such as low cost, operational and experimental simplicity, high yields, and short reaction times. J. Heterocyclic Chem., (2012).