A novel Ce<Superscript>III</Superscript>-cyclam type complex and its redox chemistry in aqueous solutions

A new Ce^III complex was synthesized by mixing the ligand “dioxocyclam” with Ce^III ions at pH 8.0 and its redox properties were investigated.

Core-shell structured electrode materials for lithium ion batteries

Recent progress in studies of several types of core-shell structured electrode materials, including TiO₂/C, Si/C, Si/SiO _x , LiCoO₂/C, and LiFePO₄/C nanocomposites, including details of their preparation and their electrochemical performance is briefly reviewed. Results clearly show that the coating shell can effectively prevent the aggregation of the nanosized cores, which are the electrochemically active materials. In addition, the diffusion coefficients of lithium ions can be increased, and the reversibility of lithium intercalation and deintercalation is improved. As a result, the cycling behavior is greatly improved. The reviewed results suggest that core-shell nanocomposites are a good starting point for further development of new promising electrode materials.

---

Recent advances in polymer monoliths for ion-exchange chromatography

The use of polymeric materials in ion-exchange chromatography applications is advantageous because of their typically high mechanical stability and tolerance of a wide range of pH conditions. The possibility of using polymeric monoliths in ion-exchange chromatography is therefore obvious and many of the same strategies developed for polymeric particles have been adapted for use with polymeric monoliths. In this review different strategies for the synthesis of polymeric monoliths with ion-exchange functionality are discussed. The incorporation of ion-exchange functionality by co-polymerization is included, as also are different post-polymerization alterations to the monolith surface such as grafting. The formulations and strategies presented include materials intended for use in analytical separations in ion-exchange chromatography, sample pre-treatment or enrichment applications, and materials for capillary electrochromatography. Finally, examples of the use of polymeric monoliths in ion-exchange chromatography applications are included with examples published in the years 2003 to 2008.

Semicrystalline morphology in thin films of poly(3-hexylthiophene)

The thermodynamic phase behavior and the morphology in thin films of poly(3-hexylthiophene) (P3HT) has been studied using calorimetry, X-ray scattering, and scanning force microscopy (AFM). Around 225 °C a phase transition from the crystalline state to a layered, liquid crystalline structure occurs in regioregular P3HT, while the regiorandom counterpart material is disordered at all temperatures and displays a glass transition temperature T_g–3 °C. Regioregular P3HT is semicrystalline and forms needle or plate like crystallites which in solution cast thin films are oriented with respect to the substrate. Films produced by spin coating display a non-equilibrium structure with reduced order and orientation. Annealing of these films in the liquid crystalline state leads to the formation of a morphology similar to the one observed in solution cast films.

Kinetics of substitution at [tris(3,5-dimethylpyrazolyl)-hydroborato]molybdenum nitrosyl dihalides by alcohols and by aniline

The kinetics of substitution by alcohols and by aniline at [tris(3,5-dimethylpyrazolyl)hydroborato]molybdenum nitrosyl dihalides in toluene solution at 298.2 K and at atmospheric pressure are reported and interpreted in terms of an associative mechanism.

---

Encapsulating of single quantum dots into polymer particles

Single semiconductor quantum dots were embedded into polymer particles with diameters below 0.1 μm by an emulsion polymerization procedure or via a secondary dispersion approach. The photoluminescence properties of the nanocrystals are retained upon encapsulation, as demonstrated by fluorescence confocal microscopy.

Carbon–Carbon Bond Forming and Cleavage in the Reactions of Isopropenyl-acetylene and 2-Methyl-hex-1-en-3-yne with Fe3(CO)12 in Basic Methanolic Solution. The X-ray Structure of Fe2(CO)5[μ-η7-{RCC(H)C(CH3)CR}] (R=CH3(=CH2))

The title complex is the main product of the reaction of Fe₃(CO)₁₂ with isopropenylacetylene in basic methanolic solution (followed by acidification); it is obtained upon carbon–carbon bond forming and dimerization of the alkyne. The same complex is also obtained by reacting Fe₃(CO)₁₂ in CH₃OH/KOH solution with 2-methyl-hex-1-en-3-yne; carbon–carbon bond cleavage presumably occurs to form isopropenylacetylene, which then reacts with the iron carbonyl. The unprecedented structure of the complex has been determined with a X-ray diffraction analysis.

Food anaphylaxis

    Figure Avoidance is the primary measure in food allergy confirmed

---

Conversion of Ethene to Propene on Nickel Ion-loaded Mesoporous Silica Prepared by the Template Ion Exchange Method

Although surface of amorphous silica is widely accepted to be neutral or slightly acidic, siliceous mesoporous materials have been found to act as excellent acid catalysts by us and other groups. On the other hand the increment in propene production is one of the significant objectives to be achieved in the present petroleum chemistry. Especially the one-path conversion of ethene to propene (ETP reaction, 3C₂H₄ → 2C₃H₆) is the most desired process. In our efforts, the specific acid catalysis of mesoporous silica was combined with the catalysis of nickel ion, which could turn the new type of ETP reaction into reality. The one-path conversion of ethene was 68% and the propene selectivity was 48% with 43% of butenes in a continuous gas-flow system at 673 K and an atmospheric pressure. The reactivity of lower olefins and the dependences of the ETP reaction on the contact time and the partial pressure of ethene followed the reaction mechanism consisting of dimerization of ethene to 1-butene, isomerization of 1-butene to 2-, and metathesis of 2-butene and ETP. The Ni-loaded mesoporous silica catalysts were characterized mainly by EXAFS and TPR techniques. The local structures of the nickel species active for the ETP reaction were very similar to that of layered nickel silicate, while those on the inert catalysts were the same as that of NiO particles.

Chemistry, commentary, and community: discussion of “an examination of the vaporization enthalpies and vapor pressures of pyrazine, pyrimidine, pyridazine, and 1,3,5-triazine” by Lipkind and Chickos

Vaporization enthalpies for the isomeric diazines were discussed within the context of recent measurements and estimation techniques. It is suggested that pyridazine shows enigmatic behavior.

Nanostructured SnO2-TiO2 films as related to lithium intercalation

The difference in degradation behavior of titania-doped tin dioxide films is explained by a pronounced effect of the doping level on the film dispersity and fine distribution of titania. A two to three times decrease in nanoparticles sizes in the doped films compared with nanoparticles in SnO₂ film (20–30 nm) is revealed by using scanning tunneling microscopy (STM). Such STM data (measured in ex situ configuration) combined with XRD and Mössbauer spectroscopy analysis confirm that the nanoparticles are composed of nanostructured heavily disordered SnO₂ and TiO₂ rutile solid solution or of amorphous phase containing both SnO₂ and TiO₂, the content of the crystalline and amorphous phases being approximately equal.

Surface-enhanced Raman scattering (SERS) for probing internal cellular structure and dynamics

Surface-enhanced Raman scattering (SERS) provides vibrational information about molecules that are located within several nanometers of the surface of a metallic nanoparticle. This review describes the various challenges and successes of applying SERS inside living cells in order to gain information about the internal structure and dynamic processes occurring in the intracellular matrix. In particular, the challenges associated with the introduction of metal nanoparticles into cells are described, as well as the complexity of interpreting SERS spectra from within complex biological environments. Strategies for understanding and improving the specificity of SERS in vivo are also presented.

Electrochemical studies of bi- and polymetallic complexes featuring acetylide based bridging ligands

Acetylide-based bridging ligands have been widely used in the preparation of complexes that display a degree of electronic interaction between metal-based redox groups located at the ligand termini. The electrochemical response of these systems has been selectively reviewed, with a focus on the variation in properties that accompany changes in the structure of the bridging ligand and the nature of the metal groups.

Update on COMAR: the Internet database for certified reference materials

This paper describes the COMAR database for certified reference materials (CRMs). The Web-based version of COMAR is freely accessible via the Internet. COMAR was established to assist laboratories in finding the CRMs needed. The database is maintained in a collaboration of the world’s major CRM producers. The planned changes in the database as agreed at the last COMAR council meeting in Prague in May 2006 are indicated.

Do we need to rethink collaborative trials?

The currently recommended design of collaborative trials (interlaboratory method performance studies) is examined in relation to the usefulness of the resulting statistics. It is suggested that larger experiments, without duplicate analysis, would be more informative.

A note on Michael Weisberg’s: challenges to the structural conception of chemical bonding

Michael Weisberg’s recent 2007 paper on the chemical bond makes the claim that the chemical notion of the covalent bond is in trouble. This note casts doubts on that claim.

Structure and chromotropic properties of mono- and binuclear mixed-ligand nickel(II) complexes containing 1,3-diketonate and polyamine ligands

Abstract  Mixed-ligand Ni^II complexes have been synthesized with 1,3-diketonate and bulky tri- or tetra-amine ligands. Their structures were determined by X-ray crystallography, and solvatochromic behavior was examined by UV–vis–NIR spectroscopy. Steric effects of the bulky ligands on the coordination distances and spectral properties are discussed. Graphical Abstract  

Core-shell effects of functionalized oxide nanoparticles inside long-range meso-ordered spray-dried silica spheres

Core-shell and homogeneous distributions of functionalized cerium oxide nanoparticles within spray-dried mesostructured silica spheres are achieved by modification of synthesis parameters such as the templating agent and nanoparticle capping functions. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

Comparison of synthetic procedures for the preparation of sol–gel derived phenoxy-silica hybrid materials

Novel phenoxy-silica hybrid materials (with 3 wt.% SiO₂) have been synthesized using different synthetic procedures. Differential scanning calorimetric (DSC) (T_g), FT-IR and transmission electron microscopy (TEM) results, as well as thermal and mechanical properties, are reported for these hybrids, which can be classified into three different groups, depending on the number of components synthesized in situ. Best results in terms of homogeneity (TEM) and mechanical properties have been obtained when the sol–gel process has been carried out in the presence of a phenoxy resin modified with a pendant alkoxysilane monomer.

Stress generation and fracture in lithium insertion materials

A mathematical model that calculates volume expansion and contraction and concentration and stress profiles during lithium insertion into and extraction from a spherical particle of electrode material has been developed. The maximum stress in the particle has been determined as a function of dimensionless current, which includes the charge rate, particle size, and diffusion coefficient. The effects of pressure-driven diffusion and nonideal interactions between the lithium and host material have also been described. The model predicts that carbonaceous particles will fracture in high-power applications such as hybrid-electric vehicle batteries.

---