Diffusion doping of cobalt in rod-shape anatase TiO nanocrystals leads to antiferromagnetism.

Cobalt(ii) ions were adsorbed to the surface of rod-shape anatase TiO nanocrystals and subsequently heated to promote ion diffusion into the nanocrystal. After removal of any remaining surface bound cobalt, a sample consisting of strictly cobalt-doped TiO was obtained and characterized with powder X-ray diffraction, transmission electron microscopy, UV-visible spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectroscopy, SQUID magnetometry, and inductively-coupled plasma atomic emission spectroscopy. The nanocrystal morphology was unchanged in the process and no new crystal phases were detected.

Anisotropic Growth of Silver Nanoparticles Is Kinetically Controlled by Polyvinylpyrrolidone Binding.

Polyvinylpyrrolidone (PVP) is used in the synthesis of Ag nanoparticles (NPs) with controlled shape, most commonly producing cubes. The mechanism for shape control is unclear but believed by many to be caused by preferential binding of PVP to Ag(100) facets compared to Ag(111) facets and assumed by most to be the result of thermodynamic control, whereby facets with lower interfacial free energy predominate. To investigate this mechanism, we measured adsorption isotherms of PVP on different-shaped Ag NPs, to determine the thermodynamics of PVP adsorption to Ag(100) and Ag(111) facets.

Quantitative Attachment of Bimetal Combinations of Transition-Metal Ions to the Surface of TiO Nanorods.

We report the sequential, quantitative loading of transition-metal ions (Cr, Mn, Fe, Co, Ni, and Cu) onto the surface of rod-shaped anatase TiO nanocrystals in bimetallic combinations ( C = 15) to form M,M'-TiO nanocrystals. The materials were characterized with transmission electron microscopy (TEM), powder X-ray diffraction (XRD), elemental analysis, X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. TEM and XRD data indicate that the sequential adsorption of metal ions occurs with the retention of the phase and morphology of the nanocrystal.

A new route for the preparation of enriched iso-polylactide from rac-lactide via a Lewis acid catalyzed ring-opening of an epoxide.

Tetraphenylporphyrin aluminum(iii) salts, TPPAlX, where X = Me, OEt, OiPr, OCHMeCHCl, and Cl, and bis(triphenylphosphine)imminium chloride, PPNCl (1 : 1) react with rac-lactide, rac-LA, in neat propylene oxide, PO, to yield chains of enriched isotactic polylactide, PLA, with end groups of PO-Cl and with time these yield cyclic polymers (PO)(PLA) where n = 2 or 3 and even higher. There is no reaction between TPPAlOR (R = Et or Pr), PPNCl, and rac-LA in neat THF at 25 °C even though TPPAlOR (R = Et or Pr) and PPNCl in neat PO yields polypropylene oxide with a terminal OR group, H(PO)OR. Taken together, Al(iii) acts as a Lewis acid in the ring-opening of PO, in which PPNCl is present and the incipient ClCHCHMeO initiates the ROP of LA to yield anion chains of [(PLA)-OCHMeCHCl], and then the ring-opening of PO yields cycles, (PO)(PLA), with the liberation of Cl.

Self-limiting adsorption of Eu³⁺ on the surface of rod-shape anatase TiO₂ nanocrystals and post-synthetic sensitization of the europium-based emission.

The surface of oleic acid stabilized rod-shape anatase TiO2 nanocrystals was modified by adsorption of Eu(3+) ions. The Eu(3+) attachment showed Langmuir adsorption behavior, thus the loading of Eu(3+) could be controlled precisely up to surface saturation coverage. The Eu(3+)-TiO2 nanorods show weak Eu(3+) based luminescence.

Facile method to attach transition metal ions to the surface of anatase TiO(2) nanorods.

We report a robust, low-cost method to attach transition metal ions directly to the surface of anatase TiO2 rod-shaped nanocrystals with preservation of the host nanocrystal morphology and phase. The procedure has been optimized to achieve quantitative control of metal ion loading on the surface of the nanorods. The metal ion can be attached to the nanocrystal surface up to fullmonolayer coverage, after which the surface becomes saturated and there is no further addition.