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Author(s): A. K. Pautova [sup.1] , N. A. Burnakova [sup.2] , N. V. Beloborodova [sup.1] , A. I. Revelsky [sup.2] Author Affiliations: (1) grid.513061.0, Federal Research and Clinical Center of [...], Aromatic, short-chain fatty and dicarboxylic acids are low-molecular-weight microbial and mitochondrial metabolites; therefore, their simultaneous screening in biological samples, including cerebrospinal fluid, is a promising solution to an important problem - the timely differential diagnosis of various diseases and pathologies, in particular, those associated with the disruption of the central nervous system. There is a need in developing a sensitive method for the simultaneous determination of these compounds, because they are most often present in biological samples in trace amounts. Blood serum and cerebrospinal fluid are complex matrices including various compounds. Aromatic, short-chain fatty and dicarboxylic acids were isolated and preconcentrated in the present study by traditional liquid-liquid extraction modified at the derivatization stage: the organic extractant was not evaporated and derivatization was carried out directly in the volume of diethyl ether. The different volatilities and polarities of the compounds was taken into account; therefore, derivatization was carried out with moderate heating (60°C) using various silylating reagents. Depending on the type of silyl derivatives, we set the analysis mode of gas chromatography-mass spectrometry method in order to achieve an acceptable analysis time, increase sensitivity to target compounds, and carry out a complete gas chromatographic separation of all analytes. To assess the applicability of the developed conditions, analytical characteristics were determined in model solutions and in the blood serum of healthy donors. For all the developed analysis conditions, linearity was observed in a clinically significant range; the lower limits of quantitation were in the range from 0.06 to 0.9 mol L.sup.-1, which made it possible to analyze samples of the cerebrospinal fluid of neurosurgical patients (n = 6).

Author(s): E. S. Markova [sup.1] , A. N. Furman [sup.1] , S. P. Shekhtman [sup.1] , A. V. Pirogov [sup.1] , M. V. Popik [sup.1] , O. A. Shpigun [sup.1] [...], A domestic composite material based on silicon carbide and nitrile butadiene rubber was used to identify volatile substances of banana, banana flavor, and creamy chewing candies by passive adsorption in combination with thermal desorption GC-MS. This method can be used to determine a wide range of compounds, for example, esters of carboxylic acids, terpenoids, aldehydes, aromatic hydrocarbons, alkanes, heterocyclic compounds, phenols, glycerides, and fatty acids. The obtained chromatographic profiles of the samples were compared. In the chromatogram of "Banana" flavor, five peaks (out of eight) corresponded to the compounds that form the aroma of a banana, and in the chromatogram of "Love is" candies with banana flavor, three corresponding peaks (out of 21) were found.

Pseudomonas putida CSV86 utilizes aromatic compounds in preference to glucose and coutilizes aromatics and organic acids. Protein analysis of cells grown on different carbon sources, either alone or in combination, revealed that a 43-kDa periplasmic-space protein was induced by glucose and repressed by aromatics and succinate. Two-dimensional gel electrophoresis and liquid chromatography-tandem mass spectrometry analysis identified this protein as closely resembling the sugar ABC transporter of Pseudomonas putida KT2440. A partially purified 43-kDa protein showed glucose binding activity and was specific for glucose. The results demonstrate that the aromatic- and organic acid-mediated repression of a periplasmic-space glucose binding protein and consequent inhibition of glucose transport are responsible for this strain's ability to utilize aromatics and organic acids in preference to glucose.

The anaerobic degradation of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds with amorphous ferric oxide as electron acceptor was examined. The electron balances showed a complete anaerobic oxidation of the aromatic compounds to CO2.

Abstract -- The laws of the adsorption of aromatic compounds on the trialkylphosphine oxide-modified electrodes of a piezoelectric quartz resonator were studied. Differences in the time parameters of adsorption were [...]

The monoelectronic or cathodic reduction of hexakis(alkylsulfonyl) benzenes in aprotic solvent is investigated to determine the kinetic and thermodynamic constants associated with reduction phenomena, as a function of the alkyl substituents. A four-member square scheme for which the neutral and radical anion species can exist in both boat and chair conformers, are proposed based on electrochemical data supported by molecular modeling calculations like density functional theory (DFT) and semiempirical methods (PM3).

Results reveal that the inner-sphere reorganization energy is influenced mainly by CN and NN bond lengths and the CNN bond angle. Further, the B3LYP/6-31G* level calculations are the most suitable for calculating inner-sphere reorganization energies for the single electron-transfer reaction between cation/neutral arenediazonium ion couples.

Results indicate that sulfinyl substitution in arenes decreases the fluorescence quantum yield without increasing the triplet yield. Racemization and nonradiative decay are closely associated with the singlet excited state. In aryl methyl sulfoxides, sulfur inversion quantum yield is as high as 0.8.

Results demonstrate the interphase polarity of the bimolecular aromatic nucleophilic substitution reactions between 1-fluoro-2,4-dinitrobenzene and piperidine in the anionic benzene/AOT/water and the cationic benzene/BHDC/water solvent systems. Data indicate that the distribution of reactants in the micelle interface is negligible in the anionic medium whereas in medium containing piperidine, a slight micellar effect is observed.

Results show that cyano-substituted carbon is critical for phototransposition in acetonitrile as revealed by dimethylbenzonitriles reaction mechanism. Data indicate that the excited nitrile combines with abicyclo[3.1.0]-hexenyl biradical with a sigma bond formed between the two carbons at ortho position to the functional nitrile group.

Results demonstrate Diels-Alder reactions of quinodimethanes with C(sub)60 with reference to their aromaticity effects. Data point out that the degree of aromatization increases with increases in quinodimethane-fullerene reaction rate and exothermicity.

Based upon the magnetic properties, geometries, triplet-singlet energy differences, and stability characteristics 7-carbenanorbornene and 3-carbenabicyclo[3.1.0]hexane are determined to be homoaromatic and 2-carbenabicyclooctadiene antihomoaromatic.

Research has been conducted on the white-rot fungus Pleurotus ostreatus. The ability of this fungus to degrade polycyclic aromatic hydrocarbons has been investigated.

Results demonstrate that the NO(sub)2(sup)+ nitration of an aromatic compound 1,8-dimethylnaphthalene follows an electrophilic as well as a direct charge-transfer process. The other reactions occurring during the process are ipso attack of NO(sub)2(sup)+, the 1,2-shift of the NO(sub)2 group, and an alternative charge-transfer reaction.

Research has been conducted on the aromatic sulfonates from Pseudumonas putida S-313. Strain S-313 mutants have been isolated and found to carry transposon insertions in the ssuEADCBF operon.

The synthesis of heterodisubstituted p-carboranes proceeds via triphenylsilyl-p-carborane, which serve as intermediary products for the preparation of liquid crystalline materials. Data reveal that p-carborane can be converted into its lithium and copper derivatives, which react with alkyl halides, such as an aryl , an acetylene bromide, and a sulfenyl chloride.

Research has been conducted on the phenylthioheptane and phenylthiononane synthesis. Results indicate that their conformations have been studied in a solid state and in solutions.

Research has been conducted on the reaction of symmetrically hindered methylphenols with NBS. The formation of the transient intermediates that produce hydroxybenzaldehydes is discussed.

The electronic and vibrational relaxation of tetracene were investigated in solution by femtosecond time-resolved fluorescence spectroscopy. Tetracene was initially photoexcited to the highly excited singlet (Sn) state 1Bb, and the dynamics of the fluorescence from the 1Bb state and the 1La state (S1) were studied by fluorescence up-conversion. Different kinds of fluorescence/anisotropy dynamics were seen from the femtosecond to the picosecond time region, which reflect a series of the relaxation processes occurring in the molecule after photoexcitation.

The efficient syntheses of secondary and tertiary 2-aryl- and 2-heteroaryl-allyl alcohols have been undertaken. The alcohols are products of the reactions between ketones and aldehydes with alpha-aryl, alpha-heteroaryl and alpha-heteroatom-substituted masked alkenyllithiums. An aryl or heteroaryl has been substituted at the beta position and aryl, heteroaryl or alkyl substituents in the alpha position via a (1,4)-C-->O silicon rearrangement. The allylic alcohols form stable trimethylsilyl ethers and cleave at the O-Si bond under basic or acidic conditions.

The contention between electron transfer (ET) and triplet energy transfer (TT) in the quenching of benzophenone, xanthene and anthraquinone in the triplet state by molecules with both a sufficiently small oxidation potential and low triplet state was examined in the picosecond to microsecond time scales. During the longer time scale, the product distribution had a strong dependence on the relative exogenicity of ET and TT processes. Picosecond transient grating measurements showed that if TT is more exogenic than ET, then the TT product is mostly formed by two sequential ET reactions.

High-order ab initio techniques were used to investigate anti-sesquinorbornene and its derivatives. Specifically, ab initio computations were performed on bicyclo(2.2.2)octadiene to study the parameters affecting the observed pi-facial selectivity. Results showed that the facial selectivity in the (2.2.2) systems parallels the double-bond pyramidalization and also causes the minimization of steric interactions.

A novel approach involving the introduction of ester moieties was applied in constructing calix{8}arene with regioselectively functionalized upper rim. Two other compounds which may potentially support the formation of supramolecules were then prepared. The compounds contained different substituents at the upper rim and exhibited similar spectral variations over the temperature range from -50 to 90 degrees C. One of the compounds cannot be analyzed further due to the superposition of the mythelene signals of benzylic bridges and ethyl groups.

Yields ranging from 62 to 99% were obtained for 3,3-diaryloxindoles by reacting isatins or substituted isatins with aromatics in the presence of triflic acid. The reaction was found to be dependent on the concentration of the acid, thereby indicating the formation of diprotonated, superelectrophilic intermediates. Moreover, the reaction of acid systems, benzene and isatin of different strength revealed that the acid strength must exceed Ho = -11.5 for completion of the conversion to the end product.

A study was conducted to examine the effects of methyl-substituted aromatic isomers on the metabolic pathways in washed cell suspensions of Sphingomonas paucimobilis strain which was grown on 2,6 dimethylnaphthalene as a carbon and energy source. An isolate taken from a phenanthrene enrichment culture of Sphingomonas paucimobilis was utilized. Results revealed that enzymes with relaxed substrate specificity initiated the metabolism of the methyl group.

Research was conducted to examine Chaperon effect in the nitration of aromatics. Several reagents and solvents were used in the study while nitrations were performed according to a single procedure. Results showed that the ether function characterized a weak ortho orientation effect while the hydroxyl group was prone to oxidation. They also indicated that 1-methylethyl benzenacetate undergoes nitration to produce the same isomeric ratio as methyl and ethyl esters.

An examination of the structure and bonding of 1,3,5,7-cyclooctatetraene (COT) with the silicon(001) surface was performed to address the dearth of research on the bonding of organic molecules to silicon surfaces. Findings revealed that a spontaneous ordering of the COT molecules on Si(001) occurs at room temperature, with each molecule separated by 7.7 angstrom. Moreover, the COT molecules bond to Si(001) through the direct interaction of two C=C units with two adjoining Si=Si dimers within an individual dimer row. Lastly, the lowest-energy geometry bonding of two C=C groups with two S=S dimers is a di-sigma configuration through a double [2+2] cycloaddition.

Laser flash photolysis (LFP) of 11,11-dibromotricyclo[4.4.1.0(super 1.6)]undeca-2,4,8-triene (1) or 1-0,10-dibromotricyclo[4.3.1.0(super 1.6)]deca-2,4-diene (2a) formed CBr2 and an aromatic compound. Bromochlorocarbene was formed by LFP of 10-bromo-10-chlorotricyclo[4.3.1.0(super 1.6)]deca-2,4-diene (2b). The relative reactivity of CBr toward alkenes was in excellent agreement with that previously obtained by chemical analysis of reaction mixtures. Rate constant data showed that the absolute reactivity of CBrCl is more similar to that of CBr2 compared to that of CCl2.

The bonding of pi-electron rich guests exhibiting pseudorotaxane-like geometries with cyclobis(paraquat-p-phenylene) was analyzed to determine the bonding properties of pi-electron deficient bipyrimidinium-based receptors. The binding efficiency of cyclobis(paraquat-p-phenylene) was mediated by edge-to-face T type interactions, hydrogen bonding and pi-pi stacking. The template-directed synthesis of cyclobis(paraquat-p-phenylene) was also enhanced by 1,5-bis(2-(2-methoxyethoxy)ethoxy)naphthalene due to high association binding constants.

A modified method for the synthesis of C2-symmetric biaryls without boronic acid isolation was developed based on a one step modified in situ Suzuki cross coupling strategy. The synthetic process involves the formation of halorene and arylboronic acid by the reaction of the starting haloarene with n-butyllithium. The yield of the desired binaphthyl was not affected by alterations in reaction or treatments with a saturated aqueous solution of Ba(OH)2.

A method for the synthesis of the polyspirodiene derivatives of p-tert-butylcalix[6]-arene and p-tert-butylcalix[5]arene was developed based on exhaustive oxidation with phenyltrimethylammonium tribromide. The synthetic strategy involves the formation of two chiral tris(spirodiennone) calix[6]arene derivatives which react with benzene to form all-exo tris adducts. Equilibration studies of the products indicated the relative stability of the isomers of the calixarene polyspirodienone derivatives.

A method for the construction of bile acid-based molecular tweezers with a rigid bile acid backbone was developed by utilizing 1-acetylpyrene. The bile acid-based molecular tweezers exhibited binding properties with polynitroaromatic compounds that have moderate association constants in CDCl3. The molecular tweezers exhibited a novel organization of bile acid backbone with two pyrene planes that are almost parallel with each other.

The oxidation kinetics of alkanes and alcohols by peracids was analyzed during the reaction of m-chlorobenzoic acid (m-CPBA) with adamantane, cyclohexane, cyclohexanol, cyclopentanol, 1-heptanol and benzyl alcohol. Selective oxidation of alkanes and alcohols by m-CPBA was characterized by the formation of products from aryl radical and induced homolysis of peracids by alkanes and alcohols. Furthermore, the novel mechanism also involved halogen transfer from halogenated solvents or reagents toward the carbon-centered radicals.

A novel method of synthesizing condensed aromatic compounds developed through the utilization of superacidic dehydrative cyclization of aryl pinacols and epoxides. The design featured the dehydrative cyclization of benzopinacol, triphenylacetophenone, and tetraphenylethyloene oxide. It was indicated that dicationic substrates mediated the dehydrative cyclizations. deactivation of substituents on the aryl rings resulted in regulation of the regiospecificity of the cyclization of substituted benzopinacols.

The role of 2,3-dichloro-5,6-dicyanobezoquinone (DDQ) on the mechanism of selective oxidation of bisbenzyl ethers was probed through synthetic studies. It was found that DDQ acted as an efficient reagent mediating high selectivity and chemical yields in benzylic oxidation. Electronic density and steric environment were critical for the selective oxidation in the presence of DDQ.

A novel method of synthesizing trans-N-cyclohexyl-2',5'-10b,10c-tetramethylpyrrolo{3,4-e}-10b,10c- dihydropyrene, as well as its heteroaromaticity was described through the use of furan-annelated thiacyclophane as the precursor. The approach featured the use of P2S5 or sulfur melt on the 1,4-diketone to yield furan instead of thiophene. The compound which was the first example of an iso{17}annulenopyrrole has increased energy barriers of rotation secondary to the 2,5-dimethyl groups on the pyrrole ring.

A novel method of synthesizing medium-sized metacyclophanediynes was designed through incorporation of one or more benzene rings in the skeleton of the a cyclic diyne. The design featured the significance of altering the configuration of the cyclic frame relative to its reactive property. The hydrogen atoms which share the benzylic and propargylic positions had a greater preponderance to tautomerize.

A novel method of isolating fugitive species in crystalline form suitable for crystallography was developed through the use of electron-poor arene diazonium salts and aromatic hydrocarbons as electron acceptors. The design featured the interaction between aromatic diazonium cations with aromatic hydrocarbons to generate transient electron donor-acceptor which can be isolated as crystalline (colored) complexes. X-ray crystallography revealed that the aromatic donor interacted directly with the aromatic cations through direct pi-pi nonbonded coordination.

A novel methodology of synthesizing functionalized aromatic oligomers from diphenylmethane template was developed based on latent phenol group as the starting material. Simple alkylation, Mitsunobu etherification, and transition-metal-mediated C-C bond formation allowed the interaction of various appendages onto the diphenylmethane scaffold. Diphenylmethane was used as the key building block in the synthesis of the elastase inhibitor.

The effectiveness of bromodimethylsulfonium bromide as a reagent for electrophilic aromatic bromination in comparison with solutions of bromine was investigated. Two general procedures were utilized consisting of the use of hydrobromic acid and acetic acid. Results revealed that bromodimethylsulfonium bromide displayed a milder reactivity and a greater selectivity towards arene than the conventional solution of bromine.

A novel method for the alkyne synthesis of esters and benzotriazol derivatives was developed based on the formation and utilization of alpha-(benzotriazol-1-yl) ketones as starting materials. The reaction of the ketones with a (p-toluenesulfonyl)hydrazine led to the formation of p-tosylhydrazones. The tosyl group, dinitrogen and benzotriazolyl groups of the intermediate p-topsylhydrazones also undergo base-assisted eliminations to afford the desired alkynes.

The mechanisms that mediate aromatic nucleophilic substitutions during the reaction of halide anions with halobenzenes and halonitrobenzenes were analyzed based on ab initio computations. Ab initio analysis of the identity of the halide-exchange reaction indicated the presence of multistep SNAr reactions that involved the formation of an intermediate sigma-complex. Furthermore, the first stage of the gas phase aromatic nucleophilic substitution reaction induced the formation of a loose ion-molecule prereaction complex.