3D-QSAR and molecular docking were applied to predict inhibitory activity of 196 compounds towards poly-(ADP-riboso)-polymerase-1 (PARP). Proportion of experimentally active ligands was higher among compounds with good rankings from both methods (57%) compared to compounds scored as inactive by at least one method (40% for docking-active, QSAR-inactive compounds).
A new organic-inorganic hybrid material composed of O-D bromobismuthate anions and bis(4-cyano-1-pyridino)pentane cations was synthesized and characterized. The replacement of Br with I resulted in a decrease in the optical band gap from 2.88 eV for (C17H18N4)(2)Bi2Br10 to 1.59 eV for (C17H18N4)BiI5. Thus, (C17H18N4)BiI5 can be proposed as a candidate material for solid state solar cells.
Carbon monoxide as an example of reducing agent, in contrast to classical reducing agents (hydrogen and metal hydrides), can provide very high atom precision for reductive addition of substrates with various functional groups. This enables synthesis of new compounds with unique structures and properties.
Investigation of charge delocalization (redistribution) in a SpnF-catalyzed reaction that proceeds through overlapping Diels–Alder and bis-pericyclic mechanisms has shown that it is better represented as a nonpolar cycloaddition rather than a cationic rearrangement.
The investigation of antibacterial activity of three-finger cobra cytotoxins towards Gram-negative and Gram-positive bacteria showed no activity against the former species, whereas M. luteus was found most susceptible to cytotoxins. A correlation was revealed between this activity and hydrophobicity of the toxins (HTL scores), total charge and its distribution over the toxin molecule: the absence of Glu-16 residue and the presence of positively charged residues (Lys30/His31) in the tip of the loop 2
Triallylborane-mediated thermal trans/cis-isomerization of α-allylated azaheterocycles is a unique stereoselective transformation providing straightforward access to important heterocycles. The main experimental features of this process, namely, thermodynamically controlled isomer ratio, 1,3-allylic strain as a driving force and regioselectivity are quantitatively described by quantum chemical calculations at B3LYP/6-31+G(d,p)/PCM(DMSO) level of theory.
2(5)-Substituted 4-hydroxy-3,4-diphenylcyclopent-2-en-1-ones easily react with 2.5 molar excess of maleic anhydride to give 1(4)-substituted 7,8-diphenylbicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydrides containing alkyl groups at bridgehead of the bicycle. The stereochemistry of the obtained bicyclic bis-anhydrides was determined to be syn-syn.
The hydrogenation of diphenylacetylene (DPA) on palladium–silver catalysts with a single-atom structure was investigated. It has been shown experimentally that the reaction rate of alkene to alkane hydrogenation is substantially lower than the rate of DPA semi-hydrogenation. The kinetic barriers of all stages of hydrogenation were calculated by the DFT method.
According to the UV-VIS spectroscopic data, preferential solvation in binary solvents results in the formation of less stable ion pairs MQ(+)I(-) as compared to those in individual solvents.
A combination of the common quantum mechanics based transition state theory and exhaustive conformational search for the modeling of difficult reactions with hundreds of competing transition states is proposed. This approach is applied to study all transition state conformations of a reaction occurring in the catechol O-methyltransferase (COMT) active site in the absence of a major part of the enzyme, and the results are compared to the recent QM/MM modeling of this reaction within the enzyme. The main points of the method are (i) constraining of forming bonds upon conformer generation and (ii) preliminary constrained optimizations of located conformations to minima using a quantum mechanical method. Importantly, this methodology is applicable to the quantum mechanical part in QM/MM calculations and can reduce demand for large sampling in difficult cases.
A new perfluorinated sulfocationic polymer and a membrane based thereon have been produced using the thermally initiated high-pressure polymerization. The proton conductivity of obtained material is higher than that of commercial Nafion membranes and reaches 57 mS cm–1 at 21 C and 114 mS cm–1 at 79 C.
A new organic-inorganic hybrid material containing bromo-bismuthate anions and bis(1-pyridino)hexane cations was synthesized and characterized. The reaction between (C-16/H22N2)(2)Bi2Br10 and HBr in the presence of HI vapor afforded (C16H22N2)(3)(BiBr6)2 as the main product and (C16H22N2)(3)(BiBr6)(BiBr7I) as a by-product containing the BrIBr- anion coordinated
The task of choosing a reliable density functional (DFT) approximation remains one of the most puzzling ones in quantum chemical modeling and materials simulations. Since DFT functionals are in general not systematically improvable, benchmarking them on specifically designed test sets is the usual way for identifying a method best suited for a particular purpose. To get an answer from a bunch of numbers, statistical analysis should be applied. In this article the possibilities and pitfalls of statistical error analysis are discussed, taking as an example the ranking of approximate functionals by the accuracy of their self-consistent electron densities, which were recently shown to have worsened in the last decade.
The relationship between crystal structures of three isomeric aminopyridinium iodobismuthates containing one-dimensional [(BiI4)n]n− anions, acidity of aminopyridinium cations and optical properties was revealed
The ion associates [Fe(CN)(6)](4-), M+, [Cu edta](2-), which are observed in the UV-VIS spectra of K-4[Fe(CN)(6)] + Na-2[Cu edta] solutions as an absorption band at 500 nm, contain alkali metal cations, and they are more stable in water-organic solutions than in aqueous solutions.