Interacting nanoparticles with functional surface groups

Functionalized nanoparticles with ionizable groups have generated a large variety of structures with important potential applications in technology. The nature of their interactions is crucial to determining their solubility and to exploring assemblies with diverse symmetries. Here, we use a molecular theory to describe the interactions between two nanoparticles coated with short polymer chains that contain ionizable (functional) end‐groups immersed in aqueous salt solution. It is shown here that the fraction of ionized functional groups in the system depends on factors such as the ionic strength and pH of solution, grafting density of polymer chains, the chain length, as well as the separation distance between the nanoparticles. The interactions between two neighboring nanoparticles influence the charge regulation of the end‐groups, which consequently induces an asymmetric distribution of these charged end‐groups on the nanoparticles, and thus confers a preferred directionality in nanoparticle–nanoparticle interactions. We show that the charge regulating system is less repulsive than an equivalent system with a fixed charge distribution. This is due to a decrease in the charge density of the weak acid end‐groups, to avoid a local increase in counterion confinement (condensation) in the region between neighboring nanoparticles, when their separation decreases. The anisotropic degree of ionization found in our results can be used to design aggregates of nanoparticles with reduced symmetries. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Phase Transitions and Electrochemical Properties of Ionic Liquids and Ionic Liquid—Solvent Mixtures

Recent advances in studies of ionic liquids (IL) and ionic liquid–solvent mixtures are reviewed. Selected experimental, simulation, and theoretical results for electrochemical, thermodynamical, and structural properties of IL and IL-solvent mixtures are described. Special attention is paid to phenomena that are not predicted by the classical theories of the electrical double layer or disagree strongly with these theories. We focus on structural properties, especially on distribution of ions near electrodes, on electrical double layer capacitance, on effects of confinement, including decay length of a dissjoining pressure between confinig plates, and on demixing phase transition. In particular, effects of the demixing phase transition on electrochemical properties of ionic liquid–solvent mixtures for different degrees of confinement are presented.     

Crystal structure of bis[1-{(3,5-dimethyl-1H-pyrazol-1-yl)methyl}-3,5-dimethyl-1H-pyrazol-2-ium] hexachlorouranate(IV): [H2C(3,5-Me2pz)(3,5-Me2pzH)]2[UCl6]

Journal of Structural Chemistry - The X-ray diffraction study of a single crystal with the composition [H2C(3,5-Me2pz)(3,5-Me2pzH)]2[UCl6] (1) is performed. This compound is the product of an...     

A one-dimensional Mn(II)-based metal organic oxide: structure and properties

A one-dimensional metal organic oxide of Mn(II), with formula [Mn₃(OH)₂(Hpdc)₂]_n (H₃pdc = 3,5-pyrazoledicarboxylic acid), was prepared via the hydrothermal method and its structure solved by single-crystal X-ray diffraction. The compound exhibits a three-dimensional framework structure, comprising three crystallographically unique Mn atoms bridged by OH ligands (O9 and O10) and O atoms from the Hpdc ligands, forming one-dimensional metal–organic oxide chains. Two kinds of magnetic exchange are observed: a strong antiferromagnetic intra-chain interaction, arising from the short distance between Mn(II) centers, and a ferromagnetic inter-chain interaction, due to the larger distances between the chains. The compound shows good photocatalytic activity for the decomposition of methylene blue in aqueous medium under simulated sunlight.     

Synthesis of BiOI photocatalyst by microwave method using EDTA as retarder of the reaction

Research on Chemical Intermediates - BiOI photocatalyst was successfully synthesized following a rapid synthesis by using microwave irradiation and EDTA as retarder of the reaction in aqueous...     

Detailed peak fitting analysis of the Zn 2p photoemission spectrum for metallic films and its initial oxidation stages

The metallic Zn 2p photoemission spectra hold a complex background that requires individual assignment of Shirley background for each peak comprising the spectra. For this reason, a close fit requires the use of the Shirley‐Vegh‐Salvi‐Castle background‐type under the active background approach. We found that the intensity of the plasmon peaks and their associated background cannot be described through existing energy loss (intrinsic and extrinsic) formalisms. We also analyzed the Zn 2p and O 1s spectra for the initial stages of oxide formation at various oxygen exposures. We found that the composition of the oxide layer is ZnO_1.00±0.10 for all exposures, suggesting that our assessment of the primary function of metallic Zn is accurate and can be employed for quantitative studies. We also present a set of parameters to accurately fit and resolve the metallic and oxide Zn 2p peaks.