Spectroelectrochemistry of intrinsically conducting furan-3-chlorothiophene copolymers

Electrochemical copolymerization of furan and 3-chlorothiophene was performed at constant electrode potential in a binary solvent system consisting of boron trifluoride diethyl etherate + ethyl ether (BFEE + EE; ratio 1:2) and trifluoroacetic acid (10% by volume). The homopolymers and copolymers obtained were studied with cyclic voltammetry, in situ ultraviolet–visible spectroscopy, in situ resonance Raman spectroscopy, and in situ conductivity measurements. The spectroelectrochemical properties of the copolymers show intermediate features between polyfuran and poly(3-chlorothiophene). The conductivity changes of homo- and copolymer films are almost completely reversible when the potential shift direction is reversed.

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.

Blue-emitting mesoporous films prepared via incorporation of luminescent Schiff base zinc(II) complex

Highly fluorescent materials have been prepared by incorporation of a zinc complex in mesoporous silica thin films with ordered pore structure. The zinc complex has been introduced into the mesoporous materials via impregnation in an ethanol solution. The incorporation into the films has been monitored by UV–Vis, Fourier transform infrared spectroscopy and spectroscopic ellipsometry. After 18 h of immersion in the doping solution the films showed strong blue emission, increase in the refractive index. Leaching experiments performed by immersing the samples in ethanol or tetrahydrofuran have shown that the chromophore is retained in the porous matrix.

The use of LCMS as an analytical tool for hydrolysis/polycondensation monitoring of a chiral ORMOSIL precursor

The kinetic of the sol–gel hydrolysis and polycondensation reactions of a chiral ORMOSIL precursor was investigated by LCMS technique as a function of water excess and pH. While the amount of water does not significantly change the kinetics, the reactions strongly depend on the [H]⁺ concentration. At pH ≤ 3, the hydrolysis is very fast and the conversion of the precursor is completed within less than 1 h whereas at 80% of the precursor is still present after 50 h at pH = 3.5. This kinetic study allows to define a set of initial conditions and time ranges required to provide good optical quality dip coated films .

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.

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.

Preparation, structural, and optical features of two-dimensional cross-linked DNA/gold-nanoparticle conjugates

The formation and the optical features of two-dimensional aggregates formed by DNA-directed immobilization and cross-linking of bifunctional DNA–gold nanoparticles at flat gold substrates are analyzed. The samples are structurally characterized by atomic force microscopy to evaluate the particle size, the particle densities, and the degree of aggregation. The optical characteristics determined by UV/visible measurements are correlated with the structural features observed.

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.

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.

Paneth, Kant, and the philosophy of chemistry

Immanuel Kant has built up a dualistic epistemology that seems to fit to the peculiarities of chemistry quite well. Friedrich Paneth used Kant’s concept and characterised simple and basic substances which refer to the empirical and to the transcendental world, respectively. This paper takes account of the Kantian influences in Paneth’s philosophy of chemistry, and discusses pertinent topics, like observables, atomism and realism.

The meaning of ‘concentration’

Terminology within a small laboratory community can be informal without danger of misunderstanding, but communication with a wider audience and not least in publications, needs unequivocal terms for defined concepts. As an example, the many meanings of “concentration” are explored to present a systematic nomenclature, including a concept diagram.

Vocabulary of terms in protometrology

Protometrology is a new term recently proposed to designate the science of observation. As any field of knowledge needs a terminological system, in this article a system of terms and definitions on protometrology, with examples belonging to clinical laboratory sciences, is presented. This terminological system starts with the definitions of the two primitive concepts “object” and “property”.

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  

Molecular and crystal structure of ethylene acetal of <Emphasis Type="Italic">endo</Emphasis>-<Emphasis Type="Italic">endo</Emphasis>-3-trityloxymethylbicyclo[3.3.1]nonane-2-on-7-ol

Molecular structure of ethylene acetal of 3-trityloxymethylbicyclo[3.3.1]nonane-2-on-7-ol (3) was determined by X-ray investigation. It was revealed that 3 has endo-endo-configuration and adopt chair-boat-conformation. The distortion of rings was evaluated by calculation of the Zefirov–Palyulin and Cremer–Pople puckering parameters. Failure of esterification of 3 was rationalized in terms of steric hindrance and intramolecular hydrogen bonding.

Modeling of solvent viscosity effects on the electroreduction of Pt(II) aquachlorocomplexes

Solvent dynamics effects on the electroreduction of [PtCl₃(H₂O)]⁻ at a mercury electrode are explored in the framework of Sumi–Marcus model using an efficient computational scheme. According to results of density functional calculations, the second electron transfer step may be regarded as rate controlling. The nonmonotonous influence of solvent viscosity on the reaction rate is predicted and explained in terms of the saddle point avoidance. The results of model calculations are employed to interpret experimental data reported earlier in the literature.

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.

Food anaphylaxis

    Figure Avoidance is the primary measure in food allergy confirmed

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A century on from Dmitrii Mendeleev: tables and spirals,noble gases and Nobel prizes

Mendeleev’s failure to represent the periodic system as a continuum may have hidden from him the space for the noble gases. A spiral format might have revealed the significance of the wide gaps in atomic mass between his rows. Tables overemphasize the division of the sequence into ‘periods’ and blocks. Not only do spirals express the continuity; in addition they are more attractive visually. They also facilitate a new placing for hydrogen and the introduction of an ‘element of atomic number zero’.

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.

Hermann Jahn and Rudolf Renner of the Jahn–Teller and Renner–Teller effects

Vibronic interactions have received increasing attention in modern structural chemistry. Edward Teller played a pioneering role in understanding and describing them during the “molecular physics” period of his scientific career. Very little is known about the two scientists who contributed significantly to our knowledge about these effects and whose names have become associated with Teller’s. This Editorial is devoted to Hermann Jahn and Rudolf Renner and attempts to lift them out of oblivion by paying them tribute for their contributions.