Special pair dance and partner selection: elementary steps in proton transport in liquid water

Conditional and time-dependent radial distribution functions reveal the details of the water structure surrounding the hydronium during the proton mobility process. Using this methodology for classical multistate empirical valence bond (MS-EVB) and ab initio molecular dynamics trajectories, as well as quantal MS-EVB trajectories, we supply statistical proof that proton hops in liquid water occur by a transition from the H3O+[3H2O] Eigen-complex, via the H5O2+ Zundel-complex, to a H3O+[3H2O] centered on a neighboring water molecule. In the "resting period" before a transition, there is a distorted hydronium with one of its water ligands at a shorter distance and another at a longer distance than average. The identity of this "special partner" interchanges rapidly within the three first-shell water ligands. This is coupled to cleavage of an acceptor-type hydrogen bond. Just before the transition, a partner is selected by an additional translation of the H3O+ moiety in its direction, possibly enabled by loosening of donor-type hydrogen bonds on the opposite side. We monitor the transition in real time, showing how the average structure is converted to a distorted H5O2+ cation constituting the transitional complex for proton hopping between water molecules.     

Effect of X-radiation on lipid peroxidation and antioxidant systems in rats treated with saponin-containing compounds

The aim of this study was to investigate the effect of three saponin-containing plant species extracts (Aesculuc hippocastanum L. seed extract [AHE], Medicago sativa L. extract [MSE] and Spinacia oleracea L. extract [SOE]) on lipid peroxidation and on antioxidant systems in rats exposed to X-rays (XR). The rats were divided into three categories. The first category served as controls and received only a standard diet. The second category served as the radiation group and received 5 and 10 Gy XR dose. The third category (XR+extract-treated) received plant extracts (25.0 or 50.0 mg kg(-1) live weight) and 5 or 10 Gy XR dose. Blood samples were analyzed for their content of malondialdehyde (MDA), reduced glutathione (GSH), plasma vitamin C, beta-carotene and retinol. In animals receiving XR, the plasma MDA (P < 0.001) value significantly increased but the level of GSH (P < 0.01), vitamin C (P < 0.001), retinol and beta-carotene (P < 0.001) decreased significantly with increasing XR doses. In the XR+extract-treated groups, the concentrations of MDA increased significantly with increasing radiation but their concentrations decreased significantly with increasing extract concentrations. Plasma concentrations of GSH, beta-carotene, retinol and vitamin C in XR+extract-treated groups decreased significantly with increasing XR dose but their concentrations increased with increasing extract doses. Further, comparison of blood samples of XR+extract-treated groups with those from the control group showed that GSH, beta-carotene, retinol and vitamin C values increased significantly but that MDA values decreased significantly. The results showed that all extracts have enhanced the antioxidant status and decreased the incidence of free radical-induced lipid peroxidation in blood samples of rats exposed to XR. However, the antioxidant effect of AHE-administered animals was more effective than that of MSE- and SOE-administered whole-body XR rats. We conclude that the supplementation with saponin-containing extracts may serve to reinforce the antioxidant systems, thus having protective effect against cell damage by XR.     

Adducts of Cyclodiphosph(V)azenes: Synthesis and Structure

The reaction of Ph₂PCl and PhPCl₂ with bis(trimethylsilyl)sulfur diimide in the presence of GaCl₃ and AlCl₃ yields diadducts of the corresponding cyclodiphosph(V)azene: [Ph₂PN]₂·(GaCl₃)₂ ( 1 ), [Ph₂PN]₂·(AlCl₃)₂ ( 2 ), and [Ph(Cl)PN]₂·(AlCl₃)₂ ( 3 ). This reaction is triggered by Lewis acids, which catalyse the (CH₃)₃Si‐Cl and S₈ elimination. The structures of 1· 2 CH₂Cl₂, 2· 2 CH₂Cl₂ and 3 were determined by single crystal X‐ray studies ( 1 : triclinic, , a = 9.679(2) Å, b = 9.863(2) Å, c = 11.366(2) Å, α = 113.55(3)°; β = 99.59(3)°; γ = 106.67(3)°; V = 902.8(3) ų, Z = 1; 2 : triclinic, , a = 9.639(2) Å, b = 9.804(2) Å, c = 11.321(2) Å, α = 113.71(3)°; β = 99.44(3)°; γ = 106.70(3)°; V = 889.3(3) ų, Z = 1; 3 : orthorhombic, Pbca, a = 14.853(3) Å, b = 9.261(2) Å, c = 16.631(3) Å, V = 2287.7(8) ų, Z = 4.     

GaCl3-assisted cyclization reactions in hypersilyl(trimethylsilyl)aminodichlorophosphine

Hypersilyl(trimethylsilyl)aminodichlorophosphine, (hyp)N(SiMe3)PCl2, was treated with GaCl3, which resulted in the formation of an interesting novel bicycle, composed of a four-membered SiNP2 ring and a five-membered P2Ga2Cl ring. In the presence of Me3SiN3, the same reaction provided access to a cyclo-2-phospha-4-sila-1,3-diazenium tetrachlorogallate. The free chloro-cyclo-phosphasiladiazane was obtained by the addition of nucleophilic bases.     

Condensation of Indoline with Some 1,2‐ and 1,3‐Diketones

Bismuth nitrate catalyzed condensation reactions of indoline with 1,2‐ and 1,3‐diketones were investigated and were reported to proceed via different reaction pathways with the involvement of one or two of the carbonyl groups. While the reaction of indoline with cyclohexane‐1,3‐dione ( 4 ) gave solely condensation product, the reaction between the acetylacetone ( 5 ) and indoline provided N‐acetyl indoline as single products on retro‐aldol process. In contrast to 1,3‐diketones, the reaction with benzil ( 17 ) was performed under difficult conditions and proceeded to give secondary products.     

Random walks on stochastic hyperbolic half planar triangulations

We study the simple random walk on stochastic hyperbolic half planar triangulations constructed in (Angel and Ray, Ann Probab, in press). We show that almost surely the walker escapes the boundary of the map in positive speed and that the return probability to the starting point after n steps scales like © 2016 Wiley Periodicals, Inc. Random Struct. Alg., 49, 213–234, 2016     

The structure of the Mitchell order—I

We isolate here a wide class of well-founded orders called tame orders, and show that each such order of cardinality at most κ can be realized as the Mitchell order on a measurable cardinal κ, from a consistency assumption weaker than o(κ) = κ⁺.     

Electrochemistry, spectroscopy, and electrogenerated chemiluminescence of some star-shaped truxene-oligofluorene compounds

We report electrochemical studies, spectroscopy, and electrogenerated chemiluminescence (ECL) of four monodisperse star-shaped truxene core-oligofluorene compounds (T1-T4). All oligomers produced stable radical anions and radical cations and showed blue ECL by ion annihilation with an intensity that could be seen with the naked eye. ECL spectra showed that all ECL emissions were at the same position as the fluorescence emission, except for T1, the compound with the shortest fluorene arms that produced some longer wavelength emission in addition to that seen in the fluorescence spectrum. When tetra-n-butylammonium oxalate was used as a coreactant for T1, the emission was much weaker than that in ion annihilation with the same long-wavelength emission observed, making it unlikely that this emission can be ascribed to excimer formation. The ECL intensity of T4 was about 80% of the common blue ECL emitter, 9,10-diphenylanthracene (DPA), under similar conditions.     

An extension of a Bourgain-Lindenstrauss-Milman inequality

Let ‖⋅‖ be a norm on Rn. Averaging ‖(ε₁x₁,…,εnxn)‖ over all the n² choices of , we obtain an expression |||x||| which is an unconditional norm on Rn. Bourgain, Lindenstrauss and Milman [J. Bourgain, J. Lindenstrauss, V.D. Milman, Minkowski sums and symmetrizations, in: Geometric Aspects of Functional Analysis (1986/1987), Lecture Notes in Math., vol. 1317, Springer, Berlin, 1988, pp. 44-66] showed that, for a certain (large) constant η>1, one may average over ηn (random) choices of and obtain a norm that is isomorphic to |||⋅|||. We show that this is the case for any η>1.     

Structure and energetics of the hydronium hydration shells

Proton solvation and proton mobility are both subjects of great interest in chemistry and biology. Here we have studied the hydration shells of H3O+ at temperatures ranging from 260 to 340 K using the multistate empirical valence-bond methodology (MS-EVB2). We have calculated the radial distribution functions for the protonium and its solvation shells. Furthermore, we have determined the Gibbs energy and the enthalpy for hydrogen bonds donated or accepted by the first two solvation shells, in comparison to bulk water. We find systematic bond-energy differences that appear to agree with a recent IR study on proton hydration. Implications of our results to various proton mobility mechanisms are discussed.