Sol-Gel Processing of PbZrO3 Thin Films

PbZrO₃ (PZ) thin films have been prepared by 2-methoxyethanol route from lead oxide or lead acetate and zirconium n-butoxide. The use of lead oxide as lead source and the seeding layer of TiO₂ on Pt/TiO₂/SiO₂/Si substrate facilitate the formation of the perovskite phase.     

A Study of Amorphous Precursors for PbZrO3-PbTiO3 Based Ceramic Materials

Amorphous precursors for PbZrO₃ and PbTiO₃ ceramics were prepared from lead acetate and the transition metaln-propoxide inn-propanol orn-butoxide inn-butanol and hydrolysed with an excess of water. According to GLC and TGA/EGA analyses, the type of alkoxide group influences distinctly the structure of heterometallic precursors, i.e., oxo or acetate bridging, and the amounts of hydroxyl and organic groups bound to the metal network. The local environments of metal atoms in the amorphous precursors were also studied by EXAFS. The analysis reveals that in Pb−Zr precursors alkoxide groups modify the coordination spheres of the zirconium atoms. Conversely, local environments of both lead and titanium atoms within the analysed range of 3.4 A depend weakly on the type of alkoxide used.     

Detecting proximities between quadrupolar nuclei by double-quantum NMR

A robust, easy to optimize, and efficient homonuclear correlation NMR experiment for half-integer quadrupolar nuclei in solids is described and has been experimentally tested on anhydrous Na2HPO4-(23Na, S= 3/2 nucleus) and as-synthesized AlPO4-14 (27Al, S= 5/2 nucleus), an aluminophosphate molecular sieve.     

A diastereoselective C–C bond formation at C-5 of d-gulose. A convenient approach to (5S)-5-C-alkyl-β-l-lyxo-hexofuranoses

A flexible approach to the stereoselective synthesis of (5S)-5-C-methyl- and (5S)-5-C-ethyl-β-l-lyxo-hexofuranoses 15a, 22 starting from 1,2:5,6-di-O-isopropylidene-α-d-gulofuranose 3 as the source of chirality is described. The corresponding C-5 alkyl groups were introduced via a Wittig olefination followed by Pd/C-mediated hydrogenation of the conformationally restricted alkenes in a highly diastereoselective manner.     

Chitosan hydrochloride mediated efficient,green catalysis for the synthesis of perimidine derivatives

Chitosan hydrochloride as biopolymer‐based, renewable, and recyclable heterogeneous catalyst was used for efficient one‐pot synthesis of perimidine derivatives. This newly developed greener methodology provides a very simple and greener route for the synthesis of perimidines in short time with excellent yield.     

Alkylation of Unsaturated Aldehyde and Allylic Bisacetate With Organomanganese Reagents in Presence of Tetrakis Acetonitrile Copper(I) Tetrafluroborate

The conjugate addition of organomanganese reagents to α,β‐unsaturated aldehydes and allylic bisacetate in presence of Me₃Si‐Cl and tetrakis acetonitrile copper(I) tetrafluroborate is described.     

Molecular diversity from aromatics. A tandem oxidative dearomatization,cycloaddition and reactivity modulation in excited states: synthesis of tricyclo[5.3.1.0]undecanes and bicyclo[4.2.0]octanes from common precursors

Stereoselective route to tricyclo[5.3.1.0^1,5]undecane and bicyclo[4.2.0]octane ring systems present in the molecular structure of tricycloillicinone, cedrenoids and endiandric acid, elysiapyrones, respectively, is described. A tandem oxidative dearomatization of o-hydroxymethylphenol, π⁴s+π²s cycloaddition, reactivity modulation in excited state and ring-closing metathesis are the key features of our approach.     

Analytical application of poly [dibenzo-18-crown-6] for chromatographic separation of thorium(IV) from uranium(VI) and other elements in glycine medium

A selective and effective chromatographic separation method for thorium(IV) has been developed by using poly [dibenzo-18-crown-6] as stationary phase. The separations are carried out from glycine medium. The sorption of thorium(IV) was quantitative from 1 × 10^?2 to 1 × 10^?4 M glycine. The elution of thorium(IV) was quantitative with 2.0–8.0 M HCl, 4.0–7.0 M HBr, 1.0–2.0 M HClO₄ and 5.0 M H₂SO₄. The capacity of poly [dibenzo-18-crown-6] for thorium(IV) was found to be 0.215 ± 0.01 mmol/g of crown polymer. The effect of concentration of glycine, metal ion, foreign ion and eluents has been studied. Thorium(IV) was separated from a number of cations in ternary as well as in multicomponent mixtures. The applicability of the proposed method was checked for the determination of thorium(IV) in real as well as geological sample. The method is simple, rapid, and selective with good reproducibility (approximately ±2 %).