Reduction of CO in the presence of light excited-state hydride transfer reaction in a NADPH-inspired derivative.

The photo-catalytic reduction of CO into chemical feedstocks using solar energy has attracted vast interest in environmental science because of global warming. Based on our previous study on the CO complex with one of the benzimidazoline (BI) derivatives, we explore the photochemical reduction of CO in one of the benzimidazoline derivatives (1,3-dimethyl-5,6-diol-2,3-dihydro-1-benzimidazole) by quantum-chemical methods. Our results reveal that carbon dioxide can be reduced to formate (HCOO) by a hydride transfer reaction in the excited state of this complex of benzimidazoline derivative and CO.

Light-driven reduction of CO: thermodynamics and kinetics of hydride transfer reactions in benzimidazoline derivatives.

CO capture, conversion and storage belong to the holy grail of environmental science. We therefore explore an important photochemical hydride transfer reaction of benzimidazoline derivatives with CO in a polar solvent (dimethylsulfoxide) by quantum-chemical methods. While the excited electronic state undergoing hydride transfer to formate (HCOO) shows a higher reaction path barrier compared to the ground state, a charge-transfer can occur in the near-UV region with nearly barrierless access to the products involving a conical intersection between both electronic states.

Electronic properties of environmental pollutants and their mutagenic activity: Nitro derivatives of azaphenanthrenes.

The physico-chemical properties of nitroazaphenanthrene isomers: 4-nitro-9-azaphenanthrene (4-N-9-Aph), 5-nitro-9-azaphenanthrene (5-N-9-Aph), 6-nitro-4-azaphenanthrene (6-N-4-Aph), 8-nitro-1-azaphenanthrene (8-N-1-Aph), and 8-nitro-4-azaphenanthrene (8-N-4-Aph) have been investigated theoretically using Density Functional Theory (DFT) calculations. Equilibrium geometries, relative stability, ionization potentials, electron affinities, molecular electrostatic potentials, dipole moments, electric polarizabilities, and vibrational properties of these isomers are presented. Averaged O-N-C-C dihedral angle, dipole moment, polarizability, the summation of IR intensities (∑IIR) and the summation of Raman activities (∑ARaman) over all 3N-6 vibrational degrees of freedom are sensitive to the structure of isomers.

Two nitro derivatives of azabenzo[a]pyrene N-oxide: electronic properties and their relation to mutagenic activity.

The equilibrium geometries, relative energies, IR and Raman spectra, vertical ionization potentials (IP), vertical electron affinities (EA), dipole moments (μ), electronic dipole polarizabilities (α), and molecular electrostatic potentials (MEP) of two species that show very high mutagenicity, 1-nitro-6-azabenzo[a]pyrene N-oxide (1-N-6-ABPO) and 3-nitro-6-azabenzo[a]pyrene N-oxide (3-N-6-ABPO), are investigated by means of Density Functional Theory (DFT) using B3LYP functional with different basis sets. The 3-N-6-ABPO isomer was estimated to be much more mutagenic in Salmonella typhimurium tester strain TA98 (396,000 revertants/nmol) than 1-N-6-ABPO (36100 revertants/nmol) (Fukuhara et al., 1992).

Theoretical study of the molecular properties of dimethylanthracenes as properties for the prediction of their biodegradation and mutagenicity.

There is little information available on methyl derivatives of anthracene and their interaction with the enzymes of bacterial consortia that could be found in petroleum sludge. In this study a theoretical investigation of all dimethylanthracenes (DMA) isomers and their relation to biodegradation are presented. Equilibrium geometries, ionization potentials (IP), electronic affinities (EA), dipole moments and electronic dipole polarizabilities of DMA isomers calculated by Density Functional Theory (DFT) methods are reported.

The molecular properties of nitrobenzanthrone isomers and their mutagenic activities.

The mutagenic activity of five mono-substituted nitrobenzanthrones (NBA) has been determined in the Ames assay (Takamura-Enya et al., 2006). In the present study, a theoretical investigation of the electronic properties of all mono-substituted NBA isomers and their relation to mutagenic activity are presented.

The electronic properties of trimethylnaphthalenes as properties for the prediction of biodegradation rates: ab initio and DFT study.

There is little information on trimethylnaphthalenes (TMNs) which are constituents of diesel fuel and bitumen emissions. In this study, a theoretical investigation of the electronic properties of all trimethylnaphthalene (TMN) isomers and their relation to biodegradation are presented. Equilibrium geometries, ionization potentials (IPs), electron affinities (EAs), dipole moments and electronic dipole polarizabilities of TMN isomers calculated by ab initio and Density Functional Theory (DFT) methods are reported.

Assessment of arsenic and mercury contamination in the Tisa River sediments and industrial canal sediments (Danube alluvial formation), Serbia.

The purpose of this study was to examine the levels of As and Hg and mobility of these contaminants in the sediments of the River Tisa and canal sediments (alluvial formation of the Danube River, Serbia), in order to determine the degree to which the ecosystem is harmed by these pollutants. The sequential extraction procedure (modified Tessier method) was used to extract the metals from the sediments. Arsenic is extracted in the second, third and fifth fraction, with dominant extraction in the second fraction.

Water-soluble main ions in precipitation over the southeastern Adriatic region: chemical composition and long-range transport.

Background, Aim And Scope: Precipitation samples collected from 1995 to 2000 at meteorological station in the eastern outskirts of Herceg Novi (Montenegro) were analysed on Na(+), K(+), Mg(2+), Ca(2+), Cl(-), SO(4) (2-), NO(3)(-) and NH(4)(+). Four-day backward trajectory simulations were conducted during the precipitation period to investigate the regional transport of main ions and their deposition in the region of the southeastern Adriatic Sea. The air mass trajectories were classified into six trajectory categories by the origin and direction of their approach to Herceg Novi.

Evaluation of heavy metal contamination in sediments using the method of total digestion and determination of the binding forms-Tisa River Basin, Serbia.

This paper describes an approach for the evaluation of metal contamination in sediment, using the determination of binding forms of elements (sequential extraction method), the total element content (digestion method), as well as a comparison of the obtained results with the legislative limits of the EU. Results indicate that silicates are significant substrates for Ni and Cr, whereas Zn, Cd, Pb, and Cu were not dominantly bound to silicates. Mg is present in the form of carbonates and silicates; Fe is in the form of oxides, and Mn is in the form of Mn carbonate and oxides.

Trace elements as tracers of environmental pollution in the canal sediments (alluvial formation of the Danube River, Serbia).

The purpose of this study was to examine the levels of trace elements and to discuss the origin and mobility of these contaminants in the canal sediments (alluvial formation of the Danube River). The most significant fractions binding all of the studied elements were oxides and silicates. The high proportion of elements in the residual fraction and the generally low contents of extractable elements reflected the background geochemical conditions.

Assessment of heavy metal pollutants accumulation in the Tisza river sediments.

In this study we have worked on the evaluation of heavy metal contamination in the sediments taken from the Tisza River and its tributaries, and thereby used the sequential extraction method, geochemical normalization, the calculation of the enrichment factor (EF), and the methods of statistical analysis. The chemical fractionation of Ni, Cu, Zn, Cr, Pb, Fe, and Mn, carried out by using the modified Tessier method, points to different substrates and binding mechanisms of Cu, Zn and Pb in sediments of the tributaries and sediments of the Tisza River. The similarities in the distributions of Fe and Ni in all types of sediments are the result of geochemical similarity as well as of the fact that natural sources mainly affect the concentration levels of these elements.

Simultaneous production of pullulan and biosorption of metals by Aureobasidium pullulans strain CH-1 on peat hydrolysate.

It was demonstrated that during the growth of Aureobasidium pullulans strain CH-1 on the acid hydrolysate of peat from the Vlasina Lake, the content of metals (Cu, Fe, Zn, Mn, Pb, Cd, Ni and Cr) decreased due to biosorption. The reduction in the metal content was found to be in the range (%): 38.2-62.