Electron microscopic investigations of precipitates in doped NaCl crystals

Precipitation morphology of NaCl:CdCl₂ and NaCl:SrCl₂ crystals is investigated by high voltage transmission electron microscopy. The volume fraction of the precipitates and the content of CdCl₂ has been evaluated using the theory developed by Hillard. Selected area diffraction patterns of the precipitates and investigations of the misfit dislocations around the precipitates is presented.     

Asymmetric synthesis of naturally occurring spiroketals

Spiroketals are widely found as substructures of many naturally occurring compounds from diverse sources including plants, animals as well as microbes. Naturally occurring spiroketals are biologically active and most of them are chiral molecules. This article aims at reviewing the asymmetric synthesis of biologically active spiroketals for last 10 years (1998-2007).     

Bidentate P, N-P Ligand for nickel-catalyzed cross-coupling of aryl or benzyl chlorides with ArMgX

A cross-coupling reaction of a variety of aryl, heteroaryl, and benzyl chlorides with ArMgX is catalyzed by 2 mol % of a nickel-phosphine complex prepared in situ from an equimolar amount of Ni(CH(3)CN)(2)Cl(2) and ligand (L2) to yield products in excellent yield in THF at room temperature. This new bidentate ligand (L2) is stable in air and forms a stable complex upon reaction with Ni(CH(3)CN)(2)Cl(2). Structures of the ligand and the complex were confirmed by single-crystal X-ray diffraction.     

Synthesis and antimicrobial activity of 5,5′‐dimethyl‐2‐oxido‐[1,3,2]‐dioxaphos‐phorinane‐2‐yl‐amino carboxylates

Synthesis of several 5,5‐dimethyl‐2‐oxido‐[1,3,2]‐dioxaphosphorinane‐2‐yl‐amino carboxylates ( 4a–j ) was accomplished through a two‐step process. This involves prior preparation of the intermediate monochloride ( 2 ), 2‐chloro‐5,5‐dimethyl [1,3,2]dioxaphosphorinane‐2‐oxide and its subsequent reaction with various amino acid esters ( 3a–j ) in dry tetrahydrofuran in the presence of triethyl amine at room temperature. They were characterized by elemental analysis, IR, ¹H, ¹³C, ³¹P NMR, and mass spectral data. Their antifungal and antibacterial activity is also evaluated. Majority of these compounds exhibited moderate antimicrobial activity in the assay. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:256–260, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20426     

Iso-epitaxial growth of n-octacosane crystals

Iso-epitaxial(epilayer)growth of n-octacosane crystals is reported. The morphology of the epilayers is in the form of triangular growth islands with or without truncature. Epilayer growth precedes spiral growth mechanism which occurs at medium and low supersaturations, respectively. The occurrence of triangular and truncated rhombic platelets is found to be a manifestation of growth at medium supersaturations.     

Effect of stress field on spiral step patterns on n-octacosane crystals

Modifications in spiral step patterns on n-octosane crystals resulting from stress fields is considered. Stress field seems to impede the propagation of growth fronts across it and leads to the formation of bunched step patterns. Effect of cylindrical stress fields with axes parallel and perpendicular to the direction of step motion is considered in altering the shapes of the bunched steps. Shear modulus of n-octacosane crystals is estimated from the microtopographical features.