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Arynes (aromatic systems containing, formally, a carbon-carbon triple bond) are among the most versatile of all reactive intermediates in organic chemistry. They can be 'trapped' to give products that are [...]

BACKGROUND: Computational modeling of the absorption, distribution, metabolism, and excretion of chemicals is now theoretically able to describe metabolic interactions in realistic mixtures of tens to hundreds of substances. That [...]

Metal-organic frameworks (MOFs) have received great attention due to their fascinating structures and intriguing potential applications in various fields. Herein, we report the first example of the utilization of MOFs for solid-phase microextraction (SPME). MOF-199 with unique pores and open metal sites (Lewis acid sites) was employed as the coating for SPME fiber to extract volatile and harmful benzene homologues. The SPME fiber was fabricated by in situ hydrothermal growth of thin MOF-199 films on etched stainless steel wire. The MOF- 199-coated fiber not only offered large enhancement factors from 19 613 (benzene) to 110 860 (p-xylene), but also exhibited wide linearity with 3 orders of magnitude for the tested benzene homologues. The limits of detection for the benzene homologues were 8.3-23.3 ng [L.sup.-1]. The relative standard deviation (RSD) for six replicate extractions using one SPME fiber ranged from 2.0% to 7.7%. The fiber-to-fiber reproducibility for three parallel prepared fibers was 3.5%-9.4% (RSD). Indoor air samples were analyzed for the benzene homologues using the SPME with the MOF- 199-coated fiber in combination with gas chromatography-flame ionization detection. The recoveries for the spiked benzene homologues in the collected indoor air samples were in the range of 87%-106%. The high affinity of the MOF-199-coated fiber to benzene homologues resulted from the combined effects of the large surface area and the unique porous structure of the MOF-199, the [pi]-[pi] interactions of the aromatic rings of the analytes with the framework 1,3,5-benzenetriearboxylic acid molecules, and the [pi]-complexation of the electron-rich analytes to the Lewis acid sites in the pores of MOF-199. 10.1021/ac901663x

This experiment performed was to determine the effect of the length of incubation time on the generation of benzene from ascorbic acid and potassium benzoate in Sierra Mist Free. The results would provide useful information on storage methods for soda which might allow people to reduce their benzene intake from soda, thus decreasing their carcinogen accumulation and possibly lowering their risk for developing associated cancers. A headspace gas chromatography and mass spectrometry method was used for the analysis of benzene. Quantitation was preformed using Agilent Enhanced Chem Station D.01.02. A calibration curve was generated by creating dilutions of benzene in deionized water. The range of detection was between 0.52 ng/mL and 20.0 ng/mL. Each sample of Sierra Mist Free was prepared for incubation by adding 10 mL of Sierra Mist Free to a headspace vial. There were 4 samples per group. Groups 1-8 were incubated at 50 °C for a certain amount of time over a 14 day period. Group 9 was the control group, incubated at room temperature. The data showed that no benzene was generated in any sample for any given period of incubation time at 50 °C or room temperature. The hypothesis, which stated that samples incubated at for a longer time at 50 °C would generate more benzene than samples incubated at 50 °C for a shorter period of time or at room temperature, was rejected, and the null hypothesis, which stated that incubation time would have no effect on the amount of benzene generated, was accepted., Introduction Anyone who indulges in Coke, Sprite, Mountain Dew, or other sodas generally recognizes the negative effects of drinking carbonated drinks: for example, the caffeine, the high sugar, the empty [...]

BACKGROUND: Studies relying on outdoor pollutants measures have reported associations between air pollutants and birth weight. OBJECTIVE: Our aim was to assess the relation between maternal personal exposure to airborne [...]

BACKGROUND: Recent evidence has shown that humans metabolize benzene more efficiently at environmental air concentrations than at concentrations > 1 ppm. This led us to speculate that an unidentified metabolic [...]

BACKGROUND: Careful evaluation of the quality of human observational studies (HOS) is required to assess the suitability of HOS for quantitative risk assessment (QRA). In particular, the quality of quantitative [...]

BACKGROUND: Benzene is a human carcinogen. Exposure to benzene occurs in occupational and environmental settings. OBJECTIVE: I evaluated variation in benzene-related leukemia with age at exposure and time since exposure. [...]

The synthesis, isolation, and characterization of hexakis(4-(N-butylpyridylium))benzene as both a hexacation and neutral molecule are reported.

Photochromic systems can convert light energy into mechanical energy, thus they can be used as building blocks for the fabrication of prototypes of molecular devices that are based on the photomechanical effect. Hitherto a controlled photochromic switch on surfaces has been achieved either on isolated chromophores or within assemblies of randomly arranged molecules. Here we show by scanning tunneling microscopy imaging the photochemical switching of a new terminally thiolated azobiphenyl rigid rod molecule. Interestingly, the switching of entire molecular 2D crystalline domains is observed, which is ruled by the interactions between nearest neighbors. This observation of azobenzene-based systems displaying collective switching might be of interest for applications in high-density data storage. scanning tunnel microscopy | molecular switches | photochromic system | data storage

The systematic studies of pressure dependence of Raman spectra of benzene/C[O.sub.2] two-component system is carried out at different temperatures and compositions. The observation of the shift of the peak composition of the inhomogeneous bandwidth suggests that inter-molecular interaction between benzene and C[O.sub.2] molecules grow at low temperatures.

Abstract -- The mechanism of the electrochemical oxidation of iodide in the presence of 4-toluenesulfinic acid was studied in an aqueous solution using cyclic voltammetry and controlled-potential coulometry. The results [...]

The oxidation of several fluoroanilines with potassium ferricyanide and potassium hydroxide is described. In this oxidation, the major products are fluoroazobenzenes. In the case of 2-fluoro-substituted anilines, heterocyclic fluorophenazines were obtained in low to moderate yields. The optimal conditions for the reaction and the mechanism are presented. Key words: oxidation, fluoroanilines, fluoroazobenzenes, fluorophenazines.

Using molecular dynamics (MD) simulations of a single solute in water the hydration structures of the hydrophobic solutes benzene and cyclohexane were investigated. Three-dimensional maps of the density of the water O and H atoms surrounding either benzene or cyclohexane were generated from the simulation data.

The effect of aromatic swelling agents on the pore geometry and pore size of mesoporous M41S materials is investigated, where benzene and 1,3,5-trisubstituted aromatic compounds are used as swelling agents. Benzene is incorporated and immobilized close to the surface of the micelle, whereas the more hydrophobic trisubstituted aromatic compounds are located in the hydrophobic core of the micelle, where they retain some mobility.

An ab initio calculations-backed model that allows the estimation of several ground-state charge separated systems is presented. It is observed that the charge separation is not associated with the aromatic nature of the precursor but with the ionization of the amino group and electron affinity of the dioxoallyl radical.

Optical and conductivity detection were used to study the reaction between deoxyribose radicals (dR) and benzotriazine compounds. The results give a mechanistic model showing the way tirapazamine interacts with the ribose component of DNA after the one-electron reductions.

The threshold photoelectron spectrum of benzene has been recorded up to 26.5 eV photon energy under high-resolution conditions using synchrotron radiation and employing the penetrating-field threshold electron collection method. By means of a direct comparative study with a recent HeI pbotoelectron spectrum of benzene of equally high resolution, numerous autoionization effects are observed in the formation of the ionic band systems of benzene in the outer valence ionization region in the threshold photoelectron spectrum. The Rydberg states responsible for these effects are identified. Autoionization does not appear to play a role in the formation of the two lowest-energy, innervalence bands of [C.sub.6][H.sup.+.sub.6]. Key words: threshold photoelectron spectroscopy, photoelectron spectroscopy, benzene, ionization, autoionization, Rydberg states.

Oil exploration causes huge volumes of oily wastewater and produced waters show a wide range of salinities with spilled brine inhibiting plant growth. A highly enriched halophilic culture was established with benzene as the sole carbon source using brine soil obtained from an oil production facility and community structure analysis showed that Marinobacter spp. was a dominant member of the enrichment.

The interaction energies of the alkaline-earth-metal dication/benzene complexes were calculated at the MP2 level using the 6-311G-basis set. The calculations of benzene under an electric field show that the electric field produced by the diction is a cause of the C-C bond elongation in the alkaline-earth-metal dication/benzene complexes.

The ultraviolet and infrared spectra of the C6H6-(C4H2)(sub n) complexes with n=1 and 2 were formed and studied in a supersonic expansion. A T-shaped structure is deduced for the complex, with the C4H2 centered, end on, over the benzene ring.

Study of the electrochemistry of a novel organic-inorganic material in which 4,4-bipyridinium units (BP) are covalently attached to the walls of a periodic mesoporous organisilica (PMO) of the MCM-41 type is reported. It was observed that the electrochemical response of regular mesoporous organosilica of the MCM-41 type containing bipyridinium units covalently attached vary significantly for as-synthesized material, BP@PMO.

Byline: Sasan Karimi (1), Marty Lewinter (2), Julian Stauffer (3) Keywords: perfect matching; diminished mesh; benzenoid Abstract: If a hexacyclic graph, G, represents a benzenoid, a perfect matching corresponds to the location of double bonds (pi-bonds). We present an algorithm for counting the number of configurations of double bonds for various benzenoids. Author Affiliation: (1) Chemistry Department, Queensborough Community College, Bayside, NY, 11364, USA (2) Mathematics Department, Purchase College, Purchase, NY, 10577, USA (3) High School Intel, 31 Woodland Rd., Bedford, NY, 10506, USA Article History: Registration Date: 08/10/2004

Density-functional theory calculation, Monte Carlo simulations and thermodynamic perturbation theory calculations were carried out to analyze the differences between the solvation of phenol and phenoxy radical in benzene and acetonitrile. The theoretical calculations in this study indicated that the differences between the solvation which enthalpies of phenol (PhOH) and phenoxy radical (PhO(super .) in both benzene and acetonitrile are smaller.

Experimental evidence for a strong polar ordering induced by wire poling under high electric field conditions in the amorphous pDR1M azobenzene polymer is reported. A comparative study of the electronic spectra of a DR1 solution in chloroform and of an unpoled, a poled and a thermally depoled film is discussed.

The results of the research conducted on van der Waals complexes of aniline and 4-aminobenzonitrile with polar solvents formed in a supersonic jet is reported. It also reports the solvatochromism studies of all substituted benzenes and napthalenes.

The voltage sensitivity of hemicyanine dyes ANNINE-6 and ANNINE-5 with anellated benzene rings and without free CC single and double bonds is studied in Retzius neurons from Hirudo medicinalis. The Annine dyes are the most efficient fluorescent probes of neuronal activity on the basis of a well-defined physical mechanism.

Well-resolved spectra of styrene-methanol binary clusters SM(sub n), with n = 1-9, is obtained by the resonant two-photon ionization technique. It is proposed that the interaction of the methanol molecules with the olefin center of styrene promotes the proton transfer from the styrene dimmer to the hydrogen-bonded methanol cluster.

Density functional theory and ab initio calculations were used to investigate the structures of the chlorine atom-benzene complex and other halogen atom-benzene complexes. The n6 benzene-CI complex was found to have two degenerate imaginary vibrational frequencies and was estimated to have no strong absorptions above 300nm.

Hybrid density functional calculations are used to elucidate the mechanisms by which benzene is converted to phenol, benzene oxide, and ketone by the active species of the enzyme, the high-valent iron-oxo porphyrin species. In general, the computationally discovered mechanism of a porphyrin proton shuttle suggests that there is an enzymatic pathway that converts benzene directly to a phenol and ketone.

A pulse radiolysis study of six parasubstituted benzenediazonium salts is carried out in strongly acidic aqueous solution , where the principal reductant is the hydrogen atom. The characteristics of the corresponding hydroxyl adducts of the diazonium salts are described.

The absolute absorption spectrum of the benzyl radical in the visible region measured by ring-down spectroscopy in the visible region measured by cavity ring-down spectroscopy is presented. The absorption cross sections reported would facilitate the quantification of the benzyl radical in future kinetic studies.

The study presented provides explanations to the addition of the first and the second hydrogen atoms to benzene. The methods used for this purpose are density functional theory and generalized gradient.