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.

A detailed analysis of the spin-crossover reaction of HS binding to heme and the six-coordinated FeP(Im)-HS porphyrin complex.

The potential energy surfaces of the HS binding to iron-porphyrin (FeP) with the imidazole (Im) ligand via intersystem crossings are investigated by using density functional theory. The minimum energy intersystem crossing point (MEISCP) between the quintet and triplet states (MEISCP) for the Fe(II)P(Im)-HS complex is located at a Fe-S distance of 3.39 Å with only 1.

Modeling the hydrogen sulfide binding to heme.

The binding of hydrogen sulfide to a model heme compound is investigated by coupled-cluster singles-doubles augmented by a perturbative triple excitations, CCSD(T), and density functional theory, DFT. The minimum energy path for the HS addition to an isolated heme center of the heme protein is evaluated by adopting as a model the heme compound FeP(Im) (P = porphyrin; Im = imidazole). The FeP(Im)-HS aduct is bound by 13.

Theoretical study of nitrodibenzofurans: A possible relationship between molecular properties and mutagenic activity.

In this study we present a theoretical investigation of the molecular properties of nitrodibenzofurans (NDFs) and dinitrodibenzofurans (DNDFs) and their relation to mutagenic activity. Equilibrium geometries, relative energies, vertical ionization potentials (IP), vertical electron activities (EA), electronic dipole polarizabilities, and dipole moments of all NDFs and three DNDFs calculated by Density Functional Theory (DFT) methods are reported. The Ziegler/Rauk Energy Decomposition Analysis (EDA) is employed for a direct estimate of the variations of the orbital interaction and steric repulsion terms corresponding to the nitro group and the oxygen of the central ring of NDFs.

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.

Ab initio quantum study of nonadiabatic S(1)-S(2) photodynamics of s-trans-butadiene.

The nonadiabatic photodynamics of s-trans-butadiene in its lowest singlet excited states is studied theoretically, using a fully quantal approach. The coupled 1Bu and 2Ag states are considered in the calculation, representing the lowest dipole-allowed electronic transition, and the dipole-forbidden state with substantial double-excitation character, respectively. Up to six nuclear degrees of freedom, including out-of-plane dihedral angles, are included.

The predicted spectrum and singlet-triplet interaction of the hypermetallic molecule SrOSr.

In accordance with previous studies in our group on Be, Mg, and Ca hypermetallic oxides, we find that SrOSr has a linear X̃1Σ(g)+ ground electronic state and a very low lying first excited ã3Σ(u)+ triplet electronic state. No gas-phase spectrum of this molecule has been assigned yet, and to encourage and assist in its discovery we present a complete ab initio simulation, with absolute intensities, of the infrared absorption spectrum for both electronic states. The three-dimensional potential energy surfaces and the electric dipole moment surfaces of the X̃1Σ(g)+ and ã3Σ(u)+ electronic states are calculated using a multireference configuration interaction (MRCISD) approach in combination with internally contracted multireference perturbation theory (RS2C) based on complete active space self-consistent field (CASSCF) wave functions applying a Sadlej pVTZ basis set for both O and Sr and the Stuttgart relativistic small-core effective core potential for Sr.

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.

The predicted spectrum of the hypermetallic molecule MgOMg.

The present study of MgOMg is a continuation of our theoretical work on Group 2 M(2)O hypermetallic oxides. Previous ab initio calculations have shown that MgOMg has a linear (1)Σ(g)+ ground electronic state and a very low lying first excited triplet electronic state that is also linear; the triplet state has (3)Σ(u)+ symmetry. No gas phase spectrum of this molecule has been assigned, and here we simulate the infrared absorption spectrum for both states.

Parallel alignment of water and aryl rings-crystallographic and theoretical evidence for the interaction.

Analysis of crystal structures from the Cambridge Structural Database (CSD) that involve close contact between water and aryl rings revealed the existance of conformations where the water molecule or one of its O-H bonds is parallel to the aromatic ring plane at distances typical for stacking interactions; attractive interaction energies obtained from ab initio calculations performed on model systems are significant (e.g.DeltaE(CCSD(T)) = -1.

Are chelate rings aromatic? Calculations of magnetic properties of acetylacetonato and o-benzoquinonediimine chelate rings.

The aromaticity of the chelate rings of acetylacetonato (acac) and o-benzoquinonediimine (bqdi) ligands was investigated theoretically by calculating nucleus-independent chemical shifts (NICS). The calculations were done for the complexes with various metals and various other ligands. The results show that acac chelate rings in none of the complexes satisfy this magnetic criterion for aromaticity.

Ab Initio Study of the Electronic Spectrum of B2H2.

The results of ab initio calculations of the potential curves for the torsional motion, symmetric H-B stretching, and B-B stretching in low-lying valence- and Rydberg-character triplet and singlet electronic states of B2H2 are reported. Particularly, the dissociation process B2H2 --> BH + BH out of various electronic states of B2H2 is studied. The nature of binding in B2H2 is discussed in terms of the composition of the electronic wavefunctions.

Ab Initio Study of the Electronic Spectrum of B2H2.

The present paper represents the first part of an extensive theoretical study on the electronic spectrum of B2H2. The results of ab initio calculations of the vertical spectrum and the trans- and cis-bending potential curves for the low-lying triplet and singlet electronic states are reported. Special attention is paid to the study of the interaction between valence- and Rydberg-type electronic species.

[Psychomotor development in children born with anoxia--perinatal risk factors].

In 1989 a control of psychomotor development was conducted in 318 children born with the Apgar score of 7 and less. The children controlled were of the age of 3 months to 6.5 years old.

[The effect of pH values and the method of delivery on intrapartum injuries in the neonate].

pH values of the blood taken intrapartally from the presenting part of fetus was analysed in 255 deliveries. The analysis comprised pH values of newborns born by Cesarean section in which pH values were determined from the blood of the umbilical cord, immediately after birth. The authors also analysed pH values in newborns born by vacuum extraction as well as in normal vaginal deliveries, and pH values were determined from the blood of the umbilical cord, immediately after birth.

[Urinary tract infection in patients with calculi].

The authors review a series of 2,475 cases of patients operated for renal calculi and select 843 files in which the bacteriological study was performed. E. coli is the most common organism (29.