• T Pradeep

      Articles written in Journal of Chemical Sciences

    • Buckminsterfullerene, C60: Improved synthesis, electron microscopy, electron states, anions and related aspects

      T Pradeep F D’Souza G N Subbanna V Krishnan C N R Rao

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      Buckminsterfullerene, obtained in good yields at high rates by a suitably designed generator, has been characterized by electron microscopy and in terms of an approximate energy level diagram; C60 undergoes four reversible one-electron reductions giving rise to anionic species and interacts with tetrathiafulvalene to form a charge-transfer complex in the ground state.

    • M4C9+(M = Ti, V): New gas phase clusters

      R Selvan L Gowrishankar T Pradeep

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      New metal-carbon clusters, M4C9+ (M = Ti, V), generated using a combined thermal arc discharge evaporation set-up, have been studied with quadrupole mass spectrometry. Reactivities of these clusters have been investigated by means of association reactions with H2O. Metal-carbon clusters of other compositions have also been studied. We speculate on the mechanism of formation of larger metal-carbon clusters.

    • Aniline incorporated silica nanobubbles

      M J Rosemary V Suryanarayanan Ian Maclarenb T Pradeep

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      We report the synthesis of stearate functionalized nanobubbles of SiO2 with a few aniline molecules inside, represented as C6H5NH2@SiO2@stearate, exhibiting fluorescence with red-shifted emission. Stearic acid functionalization allows the materials to be handled just as free molecules, for dissolution, precipitation, storage etc. The methodology adopted involves adsorption of aniline on the surface of gold nanoparticles with subsequent growth of a silica shell through monolayers, followed by the selective removal of the metal core either using sodium cyanide or by a new reaction involving halocarbons. The material is stable and can be stored for extended periods without loss of fluorescence. Spectroscopic and voltammetric properties of the system were studied in order to understand the interaction of aniline with the shell as well as the monolayer, whilst transmission electron microscopy has been used to study the silica shell.

    • Growth of anisotropic gold nanostructures on conducting glass surfaces

      P R Sajanlal T Pradeep

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      In this paper, we describe a method for the growth of gold nanowires and nanoplates starting from a bilayer array of gold seeds, anchored on electrically conducting indium tin oxide (ITO) substrates. This is based on a seed-mediated growth approach, where the nanoparticles attached on the substrate through molecular linkages are converted to nanowires and nanoplates at certain cetyltrimethylammonium bromide (CTAB) concentration. Our modified approach can be used to make nanowires of several tens of micrometers length at a lower CTAB concentration of 0.1 M. The length of the nanowires can be varied by adjusting the time of the reaction. As the concentration of CTAB was increased to 0.25 M, the nanoparticles got converted to nanoplates. These Au nanoplates are (111) oriented and are aligned parallel to the substrate.

    • Foreword

      T Pradeep Umesh V Waghmare

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    • Removal of phase transfer agent leads to restricted dynamics of alkyl chains in monolayer protected clusters

      V R Rajeev Kumar R Mukhopadhyay T Pradeep

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      The effect of phase transfer agent in the dynamics of monolayer protected gold nanoparticles has been investigated by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies. The experiments were performed with octadecane thiol and dodecane thiol protected gold nanoparticles. The materials prepared were characterized by UV-Visible spectroscopy, transmission electron microscopy and IR spectroscopy. Repeated purification of the monolayer protected gold clusters made the alkyl chains defect-free. Such effects are reflected in the infrared spectra. Interdigitation of the monolayers that followed the purification leads to alkyl chains with limited mobility. This was reflected in 13C and 1H NMR linewidths. The NMR measurements indicate that the removal of phase transfer agent affects the dynamics of isolated clusters and those with interdigitated monolayers in different ways.

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