Solvation effects on hole mobility in the poly G/Poly C duplex

Theoretical calculations of solvation contribution to hole energy in a polynucleotide chain give very low hole mobility values at zero temperature, μ < 10⁻³ cm²/(V s). We calculated hole mobility at physiological temperature for the Poly G/Poly C DNA duplex, which gave substantially larger mobility values. Mobility over the temperature range 20–400 K was calculated. Taking stacking interaction into account substantially increased hole mobility.     

Reactions of/n\pi ^{\rlap{--} x} / and/\pi \pi ^{\rlap{--} x} / states of triplet acetophenone with hydroperoxide moleculesstates of triplet acetophenone with hydroperoxide molecules

The photochemical interaction of triplet acetophenone /^TRO/ with α-phenyl ethyl hydroperoxide /HROOH/ has been studied in CCl₄ and CH₃CN. In CCl₄ only the \(/n\pi /^{\rlap{--} x}\) state of^TRO is active abstracting hydrogen from HROOH molecules. In CH₃CN both hydrogen abstraction and homolysis of HROOH take place, that is both \(/n\pi /^{\rlap{--} x}\) and \(/\pi \pi /^{\rlap{--} x}\) states of triplet RO play active role.     

Hole polarons in poly(G)-poly(C) and poly(A)-poly(T) DNA molecules

The polaron might play an important role in the process of charge migration through duplex DNA stack. In the present work, we investigate properties of hole polarons in DNA molecules containing identical base pairs, such as poly(G)-poly(C) and poly(A)-poly(T), An extended tight-binding model (extended Su-Schrieffer-Heeger model), which involves the effect of an electric field in the direction of DNA stack, will be introduced. The transfer integral and electron-phonon coupling parameters in this model are obtained according to ab initio calculation for different base pair dimers. Calculations reveal that the polaron in poly(A)-poly(T) has a wider shape and a higher mobility under a specific electric field than that in poly(G)-poly(C) DNA stack.     

High-resolution STM imaging of novel poly(G)-poly(C) DNA molecules

High-resolution scanning tunneling microscopy (STM) imaging of single double-stranded poly(G)-poly(C) DNA molecules, made by a novel synthesis method, shows the molecules morphology. The STM images reveal a periodic structure of approximately 4 nm, seen as repeating "bulbs" along the molecules. These "bulbs" are associated with the molecule helix (the major grooves). "Nicks", two per 100 nm on the average, are observed along the DNA as well. The STM measurements were supported by a morphological statistics of the DNA molecule groove length and apparent height relative to the surface.     

Pyramidal lead sulfide crystallites with high energy {113} facets

A new, generic method to exercise control over the shape of crystallites is reported. Crystals of PbS are grown in the unusual form of pyramids at the water-toluene interface. The pyramids are single crystalline and adopt a unique growth habit (slow growth along [113] direction). The pyramids are exclusive products of the reaction and are obtained in the form of a monolayered film spread across the fluid interface. The origins of the growth habit and assembly lie in phenomena unique to the liquid-liquid interface. The dimensions of the pyramidal base can be controllably varied in the range 575-1260 nm. Crystallites of other forms such as rods and spheres can be obtained by varying the properties of the fluid interface.     

Infrared Spectroscopy of \hbox {CH}_4/\hbox {N}_{2} and \hbox {C}_{2}\hbox {H}_{m}/\hbox {N}_{2} ({m = 2, 4, 6}) Gas Mixtures in a Dielectric Barrier Discharge

Fourier transform infrared spectroscopy of \(\hbox {CH}_{4}/\hbox {N}_{2}\) and \(\hbox {C}_{2}\hbox {H}_{m}/\hbox {N}_2\) ( \(m = 2, 4, 6\) ) gas mixtures in a medium pressure (300 mbar) dielectric barrier discharge was performed. Consumption of the initial gas and formation of other hydrocarbon and of nitrogen-containing HCN and \(\hbox {NH}_{3}\) molecules was observed. \(\hbox {NH}_{3}\) formation was further confirmed by laser absorption measurements. The experimental result for \(\hbox {NH}_{3}\) is at variance with simulation results.     

The {001} facets-dependent high photoactivity of BiOCl nanosheets

BiOCl nanosheets (BiOCl NSs) were synthesized by hydrolyzing a hierarchical flowerlike molecular precursor (Bi(n)(Tu)(x)Cl(3n), Tu = thiourea). High photoactivity of {001} facets of BiOCl NSs was observed, and the mechanism was discussed.     

Rb{Pr6C2}I12, an Iodide with a 13‐Electron Isolated Octahedral {Pr6C2} Cluster

Rb{Pr₆(C)₂}I₁₂ was obtained from a mixture of RbI, PrI₃, Pr and C as black single crystals at elevated temperatures. The black crystals are triclinic, (no. 2), a = 960.1(2), b = 957.0(2), c = 1003.4(2) pm, α = 71.74(2), β = 70.69(2), γ = 72.38(2)°, V = 805.6(3) 10⁶ pm³, Z = 1; R₁ = 0.0868 for all 2749 measured independent reflections. Rb{Pr₆(C)₂}I₁₂ contains {Pr₆(C₂)} clusters isolated from each other, surrounded by twelve edge‐bridging and six terminal ligands. The [{Pr₆(C)₂}Iⁱ₁₂I^a₆]^? units are connected via i‐a/a‐i bridges according to {Pr₆C₂}Iⁱ_6/1I^i‐a_6/2I^a‐i_6/2 with rubidium ions occupying twelve‐coordinate interstices.     

Interfacial synthesis of pyramidal lead sulfide crystallites with high energy {331} facets

Single crystals of PbS in the form pyramids with a high proportion of high energy {331} faces are obtained by the use of a novel reaction technique at the interface of water and toluene. The pyramids spontaneously form a monolayer spread across the entire water-toluene interface. The influence of deposition parameters such as temperature, solution concentration, reaction time on the nature and properties of interfacial films are studied. In addition, the effect of solvo-static parameters such as column height and interfacial area are investigated. The obtained films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM).     

Synthesis and Properties of Complexes with Unusual {MnIII4} and {MnII4} Cages

Two types of manganese complexes with [Mn₄] cores featuring the unusual distorted cube topology are presented, the first of which comprises new modifications of the reported complex [Mn^III₄(sao)₄(saoH)₄]·3CHCl₃: [Mn₄(sao)₄(saoH)₄]·1.32(C₄H₁₀O)·0.43(CH₄O) ( 1a ) and [Mn(sao)₄(saoH)₄]·0.5(CH₄O)·0.5(C₂H₃N) ( 1b ) sao = salicylaldoxime. The second, 0.55[Mn₄Cl₄(C₁₂H₉N₂O)₄(CH₃OH)₂(H₂O)₂]·0.45[Mn₄Cl₄(C₁₂H₉N₂O)₄(CH₃OH)₄] ( 2 ), is the first reported case of a {Mn^II₄} core of this topology besides known {Mn^III₄} compounds. Differences between the {Mn^II₄} and {Mn^III₄} situation are discussed, and so far overlooked differences in magnetic properties between different {Mn^III₄} compounds are pointed out.     

Synthesis of micro-sized titanium dioxide nanosheets wholly exposed with high-energy {001} and {100} facets

A new synthetic strategy was developed to prepare large-sized well-defined anatase TiO(2) nanosheets wholly dominated with thermodynamically unfavorable high-reactive {001} and {100} facets, which has a percentage of 98.7% and 1.3%, respectively. The as-prepared anatase TiO(2) nanosheets show a well-faceted morphology and have a large size in length (ca. 4.14 μm). The formation mechanism of the anatase TiO(2) nanosheets was also analyzed and investigated.     

Extraordinary atomic mobility of Au{111} at 80 Kelvin: effect of styrene adsorption

We describe how the presence of styrene, a weakly adsorbed molecule, dramatically restructures the Au{111} surface at temperatures as low as 80 K. The restructuring manifests itself both in mobility of step-edge atoms, as well as changes in the position of the herringbone reconstruction over time. These effects are explained in terms of the preferential adsorption sites of styrene allowing it to assist in atom detachment from step edges, as well as lowering of the energetic barrier for movement of the herringbone reconstruction. This work has important consequences for studies in which Au is used as a support for or as an electrical contact to molecules.     

Structures and formation of \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 4}} {\rm H}_{{\rm 8}} } \right]_{}^{_.^ + } $\end{document} ions

Several \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 4}} {\rm H}_{{\rm\ 8}} } \right]_{}^{_.^ + } $\end{document} ion isomers yield characteristic and distinguishable collisional activation spectra: \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm 1-butene} } \right]_{}^{_.^ + } $\end{document} and/or \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm 2-butene} } \right]_{}^{_.^ + } $\end{document} (a-b), \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm isobutene} } \right]_{}^{_.^ + } $\end{document} (c) and [cyclobutane]⁺ (e), while the collisional activation spectrum of \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm methylcyclopropane} } \right]_{}^{_.^ + } $\end{document} (d) could also arise from a combination of a-b and c. Although ready isomerization may occur for \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 4}} {\rm H}_{{\rm 8}} } \right]_{}^{_.^ + } $\end{document} ions of higher internal energy, such as d or e → a, b, and/or c, the isomeric product ions identified from many precursors are consistent with previously postulated rearrangement mechanisms. 1,4-Eliminations of HX occur in 1-alkanols and, in part, 1-buthanethiol and 1-bromobutane. The collisional activation data are consistent with a substantial proportion of 1,3-elimination in 1- and 2-chlorobutane, although 1,2-elimination may also occur in the latter, and the formation of the methylcycloprpane ion from n-butyl vinyl ether and from n-butyl formate. Surprisingly, cyclohexane yields the \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm linear butene} } \right]_{}^{_.^ + } $\end{document} ions a-b, not \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm cyclobutane} } \right]_{}^{_.^ + } $\end{document}, e.     

Gas phase isomerization of \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 10}} {\rm H}_{{\rm 14}} } \right]_{}^{_.^ + } $\end{document} ions generated from adamantanoid compounds

\documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 10}} {\rm H}_{{\rm 14}} } \right]_{}^{_.^ + } $\end{document} ions have been generated from a number of adamantanoid compounds, both by ionization and ionization followed-by fragmentation. Metastable ion abundance ratios of competitive reactions indicate the decomposition of these ions from common structures in all cases.     

Facile synthesis and structure elucidation of metal-organic frameworks with {ZnCa} and {Zn2Ca} metal cores

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13C{1H} single frequency off-resonance decoupling of secondary carbons

¹³C{¹H} single frequency off-resonance decoupled spectra of secondary carbons with two chemically non-equivalent protons are analysed theoretically and experimentally. By a careful analysis of the frequencies of all six transitions all spectral parameters, including the geminal proton-proton coupling constant, can be determined very accurately.