Synthesis of 2-amino-2,4-anhydro-3-O-(2-tetrahydropyranyl)-psicofuranose: a versatile intermediate for S-type locked nucleosides

2-Amino-2,4-anhydro-psicofuranose derivative was synthesized starting from d-fructose.     

Recent study of nanomaterials prepared by inert gas condensation using ultra high vacuum chamber

The ultra high vacuum chamber was developed in the Department of Nuclear Physics, University of Madras with the funding from DST, India. This UHV chamber is used to prepare nanocrystalline materials by inert gas condensation technique (IGCT). Nanocrystalline materials such as PbF₂, Mn²⁺-doped PbF₂, Sn-doped In₂O₃ (ITO), ZnO, Al₂O₃, Ag₂O, CdO, CuO, ZnSe:ZnO etc., were prepared by this technique and characterized. Results of some of these materials will be presented in this paper. In solid-state²⁰⁷Pb NMR on PbF₂ a separate signal due to the presence of grain boundary has been observed. The structural phase transition pressure during the phase transformation from the cubic phase to orthorhombic phase under high pressure shows an increase with the decrease in grain size. Presence of electronic centres in nanocrystalline PbF₂ is observed from Raman studies and the same has been confirmed by photoluminescence studies. Al₂O₃ was prepared and⁵⁶Fe ions were implanted. After implantation segregation of⁵⁶Fe ions was examined by SEM. The oxidation properties of ITO were studied by HRTEM. As against the expectation of oxide coating on individual nanograins of In-Sn alloy, ITO nanograins grew into faceted nanograins on heat treatment in air and O₂ atmosphere. The growth of ITO under O₂ atmosphere showed pentagon symmetry. The PMN was initially prepared by solid-state reaction. Further, this PMN relaxor material will be used to convert into nanocrystalline PMN by IGCT with sputtering and will be studied     

Growth and characterization of 0.1 and 0.25 zinc magnesium ammonium sulphate

Mixed crystals of 0.1 and 0.25 zinc magnesium ammonium sulphate were grown by slow evaporation of aqueous solution at room temperature. The bright and transparent crystals obtained were characterized by thermal (TG–DTA), FTIR and XRD analyses. A fitting decomposition pattern for the compound was formulated on the TG curve which shows two stage mass losses between 133 and 478.75 °C. In this temperature range, DTA curve shows exothermic peaks supporting the formulated decomposition pattern. The FTIR spectra show the vibration frequencies due to the formation of zinc magnesium ammonium sulphate mixed crystals. Detailed structural analysis of the compound is under progress.     

A Simple and Convenient Method for the Deprotection of Tetrahydropyranyl Ether Using Iodine in Methanol

A simple and efficient method for the -deprotection of tetrahydropyranyl and 4,4′-dimethoxytrityl ethers using iodine in methanol is described.     

Effect of s-, p-, d-, and f-block elements on the structure and properties of ammonium dihydrogen phosphate crystals

The influence of the s-, p-, d-, and f-block elements (Cs, Sb, Pd, and Ce) doping on the properties of ammonium dihydrogen phosphate (ADP) crystals has been described. Incorporation of small quantity of dopants into the crystalline matrix is well confirmed by energy dispersive X-ray spectroscopy (EDS) and inductively coupled plasma (ICP) techniques. The reduction in the intensity observed in powder X-ray diffraction (XRD) of doped specimens and slight shifts in vibrational frequencies confirm the lattice stress. Surface morphological changes due to doping of metals are observed by scanning electron microscopy (SEM). The differential scanning calorimetry (DSC) curves show only a slight variation in endothermic peak temperatures. The sharpness of the DSC peaks shows the good degree of crystallinity of the material. The cell parameters have been determined using single crystal XRD analysis of pure ADP and ADP:Cs/ADP:Sb/ADP:Pd/ADP:Ce specimens. The influence of metals on the second harmonic generation (SHG) efficiency is also investigated.