Publications

Composites of nanowires of ZnO, RuO2 and Ag with polyaniline (PANI) as well as polypyrrole (PPy) have been prepared, for the first time, by an in-situ process, in order to investigate their electrical properties. Characterization by electron microscopy and IR spectroscopy indicates that there is considerable interaction between the oxide nanowires and the polymer. The room-temperature resistivity of the composites prepared in-situ varies in the 0.01–400 Ω cm range depending on the composition. While the resistivities of the PANI–ZnONW and PPy–ZnONW composites prepared by the in-situ process are generally higher than that of PANI/PPy, those of PANI–RuO2NW and PANI–AgNW are lower. Composites of ZnONW with polyaniline prepared by an ex-situ process exhibit a resistivity close to that of polyaniline.

Proton exchange in hydroxylamines, RNHOH, has been investigated by nuclear magnetic resonance spectroscopy. Hydrogen bonding of the hydroxylamines and their N,N-and N,O-disubstituted derivatives by self-association as well as by their interaction with electron donors has been studied by nuclear magnetic resonance and infrared spectroscopy. The results indicate that the OH group participates to a greater extent in hydrogen bonding than the NH group. The O-H⋯Y (Y = donor site) hydrogen bonds are found to be generally stronger than the N-H⋯Y bonds.

Brillouin scattering studies on single crystals of a charge-ordered manganite, Nd0.5Ca0.5MnO3, have been carried out for the first time. The spectra show two modes at (B-mode) and 60 GHz (S-mode). The B-mode frequency and intensity from 300 K to 27 K, covering both the charge ordering transition at 250 K and the antiferromagnetic transition, at 170 K, exactly follow the same temperature dependence as the d.c. magnetic susceptibility. The B-mode is associated with bulk magnetic excitations and the S-mode with surface magnetic excitations of the manganite with ferromagnetic correlations. The study is strongly indicative of the presence of ferromagnetic inhomogeneities in the charge-ordered as well as antiferromagnetic phases.

An amine‐templated 2D coordination polymer of Co II with the formula {[EDAH 2 ][Co 2 F 2 (SO 4 ) 2 (H 2 O) 2 ]} n ( 1 ) (EDA = ethylenediamine), has been synthesised and structurally characterised. It consists of a 1D chain bridged by F – ions, which are interconnected by SO 4 2– tetrahedra forming a 2D [Co 2 F 2 (SO 4 ) 2 (H 2 O) 2 ] n 2– corrugated sheet. The diprotonated cation [EDAH 2 ] is intercalated between the sheets. Temperature‐dependent magnetic measurements reveal the presence of spin‐canted antiferromagnetism and hard‐magnet‐like behaviour with large a magnetic hysteresis with a coercive field ( H c ) of 16.2 kOe and a remnant magnetisation ( M R ) of 1.64 μ B . The coordinated water molecules in 1 can be removed by heating at 250 °C under vacuum to obtain the dehydrated phase {[EDAH 2 ][Co 2 F 2 (SO 4 ) 2 ]} n ( 1′ ), which – upon exposure to water vapour for 24 h – gave the monoaqua compound, {[EDAH 2 ][Co 2 F 2 (SO 4 ) 2 (H 2 O)]} n ( 1″ ). This dehydration/rehydration process is accompanied by a structural transformation and a magnetic phase transition between the spin‐canted antiferromagnetic state of the hydrated phase to the antiferromagnetic state of the dehydrated phase.

V. Vijayakrishnan, A. K. Santra, T. Pradeep, R. Seshadri, R. Nagarajan and C. N. R. Rao, J. Chem. Soc., Chem. Commun., 1992, 198 DOI: 10.1039/C39920000198

Gas-phase pyrolysis of acetylene along with a metallocene or with a binary mixture of metallocenes in flowing Ar or Ar + H2 at 1100°C yields single-walled carbon nanotubes. Pyrolysis of Fe(CO)5-acetylene mixtures in Ar at 1100°C also gives single-walled nanotubes. The diameter of the nanotubes is generally around 1 nm, showing thereby that on pyrolysis under the dilute conditions employed, the organometallic precursors give rise to very fine metal particles essential for the formation of such nanotubes.

Individual carbon nanotubes being substantially smaller than the wavelength of light, are not much responsive to optical manipulation. Here we demonstrate how decorating single-walled carbon nanotubes with palladium particles makes optical trapping and manipulation easier. Palladium decorated nanotubes (Pd/SWNTs) have higher effective dielectric constant and are trapped at much lower laser power level with greater ease. In addition, we report the transportation of Pd/SWNTs using an asymmetric line trap. Using this method carbon nanotubes can be transported in any desired direction with high transportation speed.

Interaction of varying coverages of Ni metal with solid films of C60 and C70 has been investigated by UV and X-ray photemission spectroscopy. The shifts in the valence bands of C60 (as well as of C70) with increasing Ni coverage accompanied by a shift of the C is level of the fullerene to lower binding energies suggest charge-transfer from the metal to the fullerene as in transition metal complexes of π-systems.

Magnetic and dielectric measurements confirm the multiferroic nature of LuMnO3. Raman spectra of LuMnO3 have been recorded in the 77–800K range covering both the antiferromagnetic transition at 90K and the ferroelectric–paraelectric transition at 750K. The changes in the phonon modes frequencies and band-widths indicate the presence of phonon–spin coupling in the antiferromagnetically ordered phase. The ferroelectric–paraelectric transition is accompanied by the broadening and disappearance of many of the phonon modes. Some of the phonon modes also show anomalies at the ferroelectric transition.

The preparation of 1D WS2 and MoS2 flexible nanoribbons by laser-induced unzipping of the nanotubes is reported. The nanoribbons are of high quality, uniform width, and devoid of surface contamination. The zig-zag edges in WS2 nanoribbons give rise to ferromagnetism at room temperature. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.