Synthesis of chalcones and flavanones using Julia-Kocienski olefination

A new application of Julia-Kocienski olefination for the synthesis of chalcones and flavanones has been described. 2-(Benzo[d]thiazol-2-ylsulfonyl)-1-phenylethanones have been developed as new reagents for direct Julia-Kocienski olefination with aldehydes in the presence of a base, afforded chalcones in good to excellent yields. Whereas, 2-(benzo[d]thiazol-2-ylsulfonyl)-1-(2-hydroxyphenyl)ethanone reacted with the aromatic aldehydes to furnish flavanones in good yields via one-pot intra-molecular cyclization.     

Photodegradation of Methanol Under UV–Visible Irradiation by Titania Dispersed on Polyester Cloth

Titania supported on polyester fabric (TiO₂–PY) with varying titania loadings (2–7 wt%) were prepared via the dip-coating method at room temperature using an aqueous slurry of anatase titania. Structural and morphological characterizations by X-ray diffraction and scanning electron microscopy revealed that the titanium dioxide crystallites deposited on the surface of the polyester fabric were in the micrometer range while their phase remained to be anatase. Photocatalytic activity of TiO₂–PY fabric catalysts was evaluated for vapor-phase oxidation of methanol in air as a test reaction in the presence of UV as well as solar radiation under ambient conditions. These catalysts were found to be quite active in both UV and solar irradiation with activity being higher in the former case. CO₂ yield from photo-oxidation of methanol depended on titania content and also on its dispersion over polyester fabric support.     

Synthesis and characterization of Pb(II) complexes of Schiff bases derived from 3-methyl-4-fluoroacetophenone and amino acids

A series of Pb(II) complexes of the type Pb(L)₂ have been synthesized with fluorinated Schiff bases derived from 3-methyl-4-fluoroacetophenone and amino acids (viz phenylalanine, alanine, tryptophan, valine, isoleucine, and glycine). These complexes are insoluble in common organic solvents but soluble in DMF and DMSO. The measured molar conductance values in DMF indicate that the complexes are non-electrolytes. On the basis of analytical and spectral (IR, UV–visible, and ¹H, ¹³C and ¹⁹F NMR) studies, it has been concluded that all the metal complexes have square planar geometry in which the ligand is coordinated to the metal ion through the azomethine nitrogen atom and the carboxylate oxygen atom via deprotonation.     

Sol–gel synthesis of Eu<Superscript>3+</Superscript>: Tb<Subscript>3</Subscript>Al<Subscript>5</Subscript>O<Subscript>12</Subscript> nanophosphor

Eu (0.1, 0.5 and 1.0 mol%) doped Tb₃Al₅O₁₂ (TAG) was prepared by sol–gel technique through nitrate-citrate route followed by sintering in air (1,100 °C maximum temperature). XRD analysis showed that Eu³⁺ enters the TAG lattice substitutionally replacing the Tb³⁺ ion. Both XRD as well as FTIR investigation showed improvement in crystalline phase with the increase in the sintering temperature. SEM and TEM analysis showed that the powder contains the particles in 5–20 nm size with almost spherical morphology. The excitation spectrum recorded in 300–500 nm showed dominant absorption due to Tb³⁺ while the emission spectra recorded with 380 nm excitation had strong red emission characteristic of Eu³⁺. The intensity of this emission increases with the increase of the Eu concentration from 0.1 to 0.5 mol%. However, the emission intensity decreased on further increase in Eu concentration to 1.0 mol%. This intensity variation with dopant concentration is attributed to well-known “concentration quenching” observed in rare-earth doped materials. Reasonably strong red emission due to Eu was observed when excited with the blue (480 nm) radiation of a Xe lamp indicating the usefulness of the material for the realization of white light LED.     

Nano-sized polycrystalline bismuth silicon oxide powder by sol–gel technique

Bismuth silicon oxide (Bi₁₂SiO₂₀, BSO) nano crystalline powder was prepared by sol–gel technique using bismuth nitrate and tetraethyl orthosilicate as starting materials. The prepared samples were sintered at various temperatures (750 °C maximum) and characteristic sillenite single cubic phase with crystallite size ~38 nm (calculated from room temperature powder XRD measurements) was realized at 750 °C sintering temperature. SEM analysis showed that the powder contains the nano-sized particles with almost spherical morphology. The observed frequencies in room temperature FTIR spectrum could be assigned to Bi–O, Si–O and Bi–O–Si bonds. The FWHM (full width at half maximum) of the diffraction peaks decreased while the intensity of FTIR absorption lines increased with the increase in the sintering temperature indicating better bond formation and crystallization. The thermograph of the samples recorded in the temperature range 50–1,000 °C showed almost no weight loss after ~575 °C further confirmed the conclusion arrived at from XRD and FTIR analysis. The samples sintered at 750 °C showed about 50% absorbance in 400–600 nm region which was consistent with the pale yellow color of the sample. Broad blue emission centered ~478 nm was observed when excited by 350 nm radiation from a Xe-lamp. The intensity of this broad emission band increased while its FWHM decreased with the increase in sintering temperature. Self-trapped excitons could be responsible for this emission.     

A new certified reference material for benzene measurement in air on a sorbent tube: development and proficiency testing

A certified matrix reference material (CRM) for the measurement of benzene in ambient air has been developed at Laboratoire National de Métrologie et d’Essais. The production of these CRMs was conducted using a gravimetric method fully traceable to the International System of Units. The CRMs were prepared by sampling an accurate mass of a gaseous primary reference material of benzene, using a high-precision laminar flowmeter and a mass flow controller, with a PerkinElmer sampler filled with Carbopack™ X sorbent. The relative standard deviations obtained for the preparation of a batch of 20 tubes loaded with 500 ng of benzene were below 0.2%. Each CRM is considered independent from the others and with its own certified value and an expanded uncertainty estimated to be within 0.5%, lower than the uncertainties of benzene CRMs already available worldwide. The stability of these materials was also established up to 12 months. These CRMs were implemented during proficiency testing, to evaluate the analytical performances of seven French laboratories involved in benzene air monitoring.     

A BODIPY-based colorimetric and fluorometric chemosensor for Hg(II) ions and its application to living cell imaging

A new monostyryl boron dipyrromethene derivative (MS1) appended with two triazole units indicates the presence of Hg(2+) among other metal ions with high selectivity by color change and red emission. Upon Hg(2+) binding, the absorption band of MS1 is blue-shifted by 29 nm due to the inhibition of the intramolecular charge transfer from the nitrogen to the BODIPY, resulting in a color change from blue to purple. Significant fluorescence enhancement is observed with MS1 in the presence of Hg(2+); the metal ions Ag(+), Ca(2+), Cd(2+), Co(2+), Cu(2+), Fe(2+), Fe(3+), K(+), Mg(2+), Mn(2+), Ni(2+), Pb(2+), and Zn(2+) cause only minor changes in the fluorescence of the system. The apparent association constant (K(a)) of Hg(2+) binding in MS1 is found to be 1.864 × 10(5) M(-1). In addition, fluorescence microscopy experiments show that MS1 can be used as a fluorescent probe for detecting Hg(2+) in living cells.     

Anti-inflammatory activity of Abutilon indicum extract

Abutilon indicum Linn. had been broadly used for its reported biological activities in indigenous system of medicine. The ethanolic extract of the whole plant of A. indicum Linn. was evaluated for its anti-inflammatory activity at doses 250, 500 and 750?mg?kg?1 using the carrageenan-induced paw oedema in healthy Wistar albino rats. Results of in vivo activity led to the conclusion that the ethanolic extract of A. indicum showed predominantly significant activity in a dose-dependent manner, which is comparable to the reference standard ibuprofen. The results prove the traditional use of plant in the treatment of inflammation.     

Bioinspired Bioadhesive Polymers: Dopa‐Modified Poly(acrylic acid) Derivatives

The one‐step synthesis and characterization of novel bioinspired bioadhesive polymers that contain Dopa, implicated in the extremely adhesive byssal fibers of certain gastropods, is reported. The novel polymers consist of combinations of either of two polyanhydride backbones and one of three amino acids, phenylalanine, tyrosine, or Dopa, grafted as side chains. Dopa‐grafted hydrophobic backbone polymers exhibit as much as 2.5× the fracture strength and 2.8× the tensile work of bioadhesion of a commercially available poly(acrylic acid) derivative as tested on live, excised, rat intestinal tissue.