Intermolecular stacking in pyrazolo[3,4‐d]pyrimidine‐based pentamethylene‐linked flexible ­molecules

The crystal structures of 1‐{5‐[4,6‐bis­(methyl­sulfanyl)‐2H‐py­razolo­[3,4‐d]­pyrimidin‐2‐yl]­pentyl}‐6‐methyl­sulfanyl‐4‐(pyr­rolidin‐1‐yl)‐1H‐pyrazolo­[3,4‐d]­pyrimidine, C₂₂H₂₉N₉S₃, and 6‐methyl­sulfanyl‐1‐{5‐[6‐methyl­sulfanyl‐4‐(pyrrolidin‐1‐yl)‐2H‐pyrazolo­[3,4‐d]­pyrimidin‐2‐yl]­pentyl}‐4‐(pyrrolidin‐1‐yl)‐1H‐pyrazolo­[3,4‐d]­pyrimidine, C₂₅H₃₄N₁₀S₂, which differ in having either a pyrrolidine substituent or a methylsulfanyl group, show intermolecular stacking due to aromatic π–π interactions between the pyrazolo­[3,4‐d]­pyrimidine rings.     

The reaction of iodine with vinyltrialkylborates derived from trialkylboranes and trisylhydrazones of methyl ketones. A new method for synthesis of 1,1-dialkylethenes

1,1-Dialkylethenes are readily prepared in good yields from vinyltrialkylborates derived from trialkylboranes and trisylhydrazones of methyl ketones by treatment with iodine.     

Interaction of oxygen (O+7) ion beam on polyaniline thin films

High-energy ion beam irradiation of the polymers is a good technique to modify the properties such as electrical conductivity, structural behaviour and mechanial properties. Polyaniline thin films doped with hydrochloric acid (HCl) were prepared by oxidation of ammonium persulphate. The effect of Swift Heavy Ions irradiation on the electrical and structural properties of polyaniline has been measured in this study. Polyaniline films were irradiated by oxygen ions (energy 80 MeV, charge state O⁺⁷) with fluence varying from 1 × 10¹⁰ to 3 × 10¹² ions/cm². The studies on electrical and structural properties of the irradiated polymers were investigated by measuring V-I using four probe set-up and X-ray diffraction (XRD) using Bruker AXS, X-ray powder diffractometer. V-I measurements shows an increase in the conductivity of the film, XRD pattern of the polymer shows that the crystallinity improved after the irradiation with Swift Heavy Ions (SHI), which could be attributed to cross linking mechanism.      

Chemistry of 1,6-diazaphenalene. Reaction with alkylating and acylating agents

A study of the reactivity of 1,6-diazaphenalene ( 1 ) toward alkylating and acylating agents has been carried out in order to investigate the chemistry of this new heterocycle. Attempts to alkylate 1 were successfully completed by stirring the lithium stabilized anion of 1 with either methyl iodide or benzyl bromide to provide N-alkyldiazaphenalenes 4 and 5, respectively, whereas, experiments performed to alkylate 1 under conditions employed for alkylation of imidazole were unsuccessful. Studies directed toward acylation of 1 did not lead, in general, to isolable acyldiazaphenalenes; however, in one specific case successful acylation of 2-chloro-9-methoxy-1,6-diazaphenalene ( 10 ) did provide a characterisable amide ( 14 ). Where possible the chemistry of 1,6-diazaphenalene has been compared to that reported for imidazole.     

Evolution of microstructure and crack pattern in NiO thin films under 200 MeV Au ion irradiation

NiO thin films grown on Si (100) substrate by electron beam evaporation method and sintered at 700 °C were irradiated with 200 MeV Au¹⁵⁺ ions. The fcc structure of the sintered films was retained up to the highest fluence (1×10¹³ ions cm^?2) of irradiation. However the microstructure of the pristine film underwent a considerable modification with increasing ion fluence. 200 MeV Au ion irradiation led to compressive stress generation in NiO medium. The diameter of the stressed region created by 200 MeV Au ions along the ion path was estimated from the variation of stress with ion fluence and found to be ～11.6 nm. The film surface started cracking when irradiated at and above the fluence of 3×10¹² ions cm^?2. Ratio of the fractal dimension of the cracked surface obtained at 200 MeV and 120 MeV (Mallick et al., 2010a) Au ions was compared with the ratio of the radii of ion tracks calculated based on Coulomb explosion and thermal spike models. This comparison indicated applicability of thermal spike model for crack formation.     

Normal coordinate analysis of tantalum(I) and niobium(I) hexahalide anions

Urey-Bradley force field (UBFF) and orbital valence force field (OVFF) techniques have been applied to the hexachloride and the hexabromide anions (O _h symmetry) of tantalum(I) and niobium(I). Trends in stretching force constants have been discussed on the basis of (i) the periodic position of the central metal atom and (ii) the nature of the halide ligands. Comments have been made also on the suitability of the force fields used.     

Self-assembly of a heterometallic molecular triangle using an ambidentate ligand and self-selection for a single linkage isomer

Self-assembly and self-selection of a single linkage isomer of a mixed-metal molecular triangle with ferrocene functionality have been achieved using an ambidentate ligand, and the product was characterized by multinuclear NMR spectroscopy and X-ray single crystal structure determination.