Coupling of anthrone by mercury (II) salts

1287-1288Coupling of anthrone 1 in ethanol or glacial acetic acid medium using mercuric acetate or mercuric chloride under refluxing condition furnishes bianthronyl 2 in 60-70% yield. The structure of the product has been established from detailed spectral evidences.</span

Spectrophotometric Determination of Gold(III) through Kinetic Reduction of Gold(III)-Gelatin Complex by Hydrazine in Aqueous Medium

987-99

Micelle catalysed methylene blue reduction by ascorbic acid: A procedure for the determination of Vitamin C in pharmaceutical samples

632-635A new spectrophotometric method for ascorbic acid determination has been described. Methylene blue (MB) being a water-soluble, non- toxic, cationic dye (λmax 660 nm), has been observed to be immobilized successfully in the Stern layer of a cationic micelle (cetyl trime thyl ammonium bromide, CTAB) through hydrophobic interaction. The immobilized dye (λmax 660 nm) is quantitatively reduced by ascorbic acid (AA) in the alkaline medium (pH > 8.5). The progress of the reaction and stepwise bleaching of the blue colour of the dye gives a quantitative measure of ascorbic acid concentration. A single aliquot of the micelle stabilized MB could be used for the determination of ascorbic ac id in the range or 50-400ppm

Glutathione-induced aggregation of gold nanoparticles: electromagnetic interactions in a closely packed assembly

Gold nanoparticles of variable sizes have been prepared by reducing HAuCl4 with trisodium citrate by Frens' method. The synthesized gold particles show intense surface plasmon band in the visible region. The optical resonances in the visible are due to the surface plasmon oscillation, which is a function of geometry of the particles. The work reported here describes the interaction between nanoscale gold particles and a biomolecule, glutathione at low pH. Glutathione, which is a major cellular antioxidant and consists of amino acids glutamic acid, cysteine, and glycine, has been used as a molecular linker between the gold nanoparticles. In glutathione, the reactivity of the a-amines (adjacent to -COOH) is found to be pH-dependent. Linking via the a-amines are activated at low pH but suppressed at high pH due to electrostatic repulsive forces between the gold surfaces and the charged carboxylate groups. In colloidal solutions, the colour of gold nanoparticles may range from red to purple to blue, depending on the degree of aggregation as well as orientation of the individual particles within the aggregates. The citrate-functionalized gold nanoparticles with glutathione in variable acidic pH condition produce different but well-ordered aggregates. It is observed that a new peak appearing at a longer wavelength intensifies and shifts further to the red from the original peak position depending on the particle size, concentration of glutathione, and pH of the solution. The aggregates have been characterized by UV/Vis, FTIR, XRD, and TEM. On the basis of the first appearance of a clearly defined new peak at longer wavelength, a higher sensitivity of glutathione detection has been achieved with gold nanoparticles of larger dimension

Naphthalene derivatives as fluorescent probe

850-853The electronic and fluorescence spectral properties of several synthesized naphthalene derivatives have been examined in acetone and in an anionic micelle. The change in fluorescence emission process of several naphthalene compounds have been compared with their parent moiety after hydroxylation, acetylation and with the increase in their skeletal rigidity. This report supplements the first hand information to choose naphthalene compounds as probe molecules in organic solvents as well as organized medium

Hydroxyanthraquinones in micellar media: Improved spectrophotometric reagents for beryllium(II) and aluminium(III)

346-348Enhancement of absorption spectral intensities have been observed for Be(ll) and Al(III) complexes of alizarin and quinalizarin in the presence of cationic and nonionic micelles. This effect has been successfully exploited for the spectrophotometric determination of Be(II) and Al(III). Optimum conditions for complexation, composition of complexes and statistical analysis of the results have also been reported