Search results for "Acene"
showing 10 items of 204 documents
The magnetic properties of ferrocene based macromolecules
1993
Abstract Magnetic susceptibility data for conjugatively linked biferrocenes and a methylene bridged ferrocene polymer are presented. In 9,10-di((2-ferrocenyl)vinyl)anthracene a rigid divinylanthracene bridge is connecting two ferrocene units, and the oxidation of both iron centers leads to an antiferromagnetic coupling. In contrast, ferromagnetic coupling between iron centers is indicated for 2,2'-cis,trans-di((2-ferrocenyl)vinyl)biphenyl, where a twist around the phenyl-phenyl bond in the divinylbiphenyl bridging molecule is likely to occur.
The in vitro metabolic activation of dibenz[a,h]anthracene, catalyzed by by rat liver microsomes and examined by 32P-postlabelling.
1991
DNA has been incubated in vitro with dibenz[a,h]anthracene (DB[a,H]A) and the related 5,6-diol and 3,4-diol in the presence of 3-methylcholanthrene- or Aroclor 1254-induced rat liver microsomes. After incubation, the DNA was extracted and examined for the presence of aromatic adducts using the nuclease P1 modification of the 32P-postlabelling technique. The maps of PEI-cellulose plates and autoradiography showed that 92% of the radioactivity contained in DB[a,h]A-DNA adduct spots is derived from the related 3,4-diol and that about 50% of the adducts may be formed following the conversion of this diol to the bay-region anti- and syn-3,4-diol 1,2-oxides.
Morphological transformation and DNA adduct formation by dibenz[a,h]anthracene and its metabolites in C3H10T1/2CL8 cells.
1994
The major routes of metabolic activation of dibenz[a,h]-anthracene (DBA) have been studied in transformable C3H10T1/2CL8 (C3H10T1/2) mouse embryo fibroblasts in culture. The morphological transforming activities of three potential intermediates formed by metabolism of DBA by C3H10T1/2 cells, trans-3,4-dihydroxy-3,4-dihydro-DBA-(DBA-3,4-diol), trans-dihydroxy-3,4-dihydro-DBA-anti-1,2-oxide (DBA-3,4-diol-1,2-oxide) and DBA-5,6-oxide were determined. DBA-3,4-diol-1,2-oxide was a strong morphological transforming agent giving a mean of 73% dishes with Type II or III foci and 1.63 Type II and III foci per dish at 0.5 microgram/ml. DBA-3,4-diol produced a mean of 42% dishes with Type II or III fo…
The presence of KCl in the exposure medium strongly influences the mutagenicity of metabolites of polycyclic aromatic hydrocarbons in Escherichia col…
1994
Abstract Previous studies demonstrated that the ion composition of the exposure medium may strongly influence the mutagenicity of many compounds in the liquid preincubation modification of the reversion assay with his − Salmonella typhimurium strains. Similar influences were now observed in the reversion assay with trp − Escherichia coli strain WP2 uvrA . The exposure medium was 8 mM sodium phosphate buffer (pH 7.4), containing no other ions or 125 mM KCl. Omission of KCl resulted in an about 10-fold enhancement of the mutagenic activity of 7-methylbenz[ a ]anthracene 5,6-oxide, but in a strong decrease in the mutagenicity of 1-hydroxymethylpyrene sulphate, close to the limit of detection. …
The effect of the fused-ring substituent on anthracene chalcones: crystal structural and DFT studies of 1-(anthracen-9-yl)-3-(naphthalen-2-yl)prop-2-…
2018
Two new anthracene chalcones, namely 1-(anthracen-9-yl)-3-(naphthalen-2-yl)prop-2-en-1-one and 1-(anthracen-9-yl)-3-(pyren-1-yl)prop-2-en-1-one, have been successfully synthesized and the effect of the different fused ring substituent system attached to the anthracene chalcone derivative investigated. These compounds show a very narrow band gap due to the large p-conjugated systems, making them promising candidates as optoelectronic materials. Hirshfeld surface analysis has been carried out to show the contribution of intermolecular contacts and weak interactions to supramolecular stabilization.
DFT calculations of structures, 13C NMR chemical shifts, and Raman RBM mode of simple models of small-diameter zigzag (4,0) carboxylated single-walle…
2012
Linearly conjugated benzene rings (acenes), belt-shaped molecules (cyclic acenes), and models of single-walled carbon nanotubes (SWCNTs) with one carboxylic group at the open end were fully optimized at the B3LYP/6-31G* level of theory. These models were selected to obtain some insight into the nuclear isotropic changes resulting from systematically increasing the basic building units of open-tip-monocarboxylated SWCNTs. In addition, the position of radial breathing mode (RBM), empirically correlated with the SWCNT diameter, was directly related with the radius of model cyclic acene rings. A regular convergence of selected structural, NMR, and Raman parameters with the molecular system size…
Synthesis and Stereochemistry of Diepoxynaphthacenes and Tetraepoxyheptacenes
1997
Cycloaddition reactions of 1,4-dihydro-1,4-epoxynaphthalenes (2) and benzo[c]furans (4), generated in situ from the tetracyclone adducts of 2, yield the diepoxynaphthacenes 5 (Schemes 1, 2). Out of 4 possible stereoisomers an exo-exo and an exo-endo geometry (A and C in Scheme 3) can be realized. The ratio A:C varies from pure A to pure C depending on the substituents of 2 and 4. Stereoisomeric heptacenes 7 can be obtained by a twofold cycloaddition of the same type (Scheme 4). Only one π bond of reactive alkynes such as cyclooctyne or acetylenedicarboxylate is capable of an addition to 4 (Schemes 5, 6).
Chronic exposure to a GSM-like signal (mobile phone) does not stimulate the development of DMBA-induced mammary tumors in rats: results of three cons…
2002
Certain epidemiological and experimental studies raised concerns about the safety of radiofrequency (RF) electromagnetic fields because of a possible increased risk of leukemia and lymphoma. In this study, an RF field used in mobile telecommunication was tested using 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumors in female Sprague-Dawley rats as a model for human breast cancer. Three experiments were carried out under strictly standardized conditions and were started on the same day of three consecutive years. The field consisted of a GSM-like signal (900 MHz pulsed at 217 Hz, pulse width 577 micros) of relatively low power flux density (100 microW/cm(2) +/- 3 dB) and was appl…
Metabolism of Phenanthrene, Benz[a]anthracene, Benzo[a]pyrene, Chrysene and Benzo[c]phenanthrene by Eight cDNA-expressed Human and Rat Cytochromes P4…
1996
Abstract Phenanthrene, benz[a]anthracene, chrysene, benzo[c]phenanthrene, and benzo[a]pyrene have been studied for their regiospecific oxidation by five human (1A1, 1A2, 2A6, 2E1, 3A4) and three rat (1A1, 1A2, 2B1) CYP isoforms. All substrates are preferentially metabolized by CYP1A1 and CYP1A2 in human and rat. Other isoforms play a minor role if at all. Significant differences between human and rat CYP isoforms can be recognized with regard to the regiospecific oxidation of PAH. For instance, K-region oxidation is more pronounced in rat than in human CYP1A1 and CYP1A2. Hence, extrapolation from metabolism studies in rodents to human may be limited.
Application of Dopant-Assisted Atmospheric Pressure Photoionisation HPLC–MS Method for the Sensitive Determination of Polycyclic Aromatic Hydrocarbon…
2017
Multiple food research studies have shown that the polycyclic aromatic hydrocarbon (PAHs) are frequently found in processed cocoa products and chocolate. In a present study a method based on dopant-assisted atmospheric pressure photoionisation (DA-APPI) combined with a liquid chromatography/high-resolution mass spectrometer (HPLC-HRMS) for high-sensitivity analysis of four EU marker PAHs in dark chocolate samples was developed and fully validated according to the performance criteria set in EU guidelines. PAHs detection was achieved by HRMS in positive electrospray ionization mode with toluene used as a dopant to enhance the ionization efficiency of non-polar PAHs. The on-column instrument …