Oxovanadium complex as potential nucleic acid binder

DNA binding study of a vanadium(V) complex, Oxo-chloro-bis-N-phenylbenzohydroxamto-vanadium(V), derived from N-phenylbenzohydroxamic acid(PBHA) form a violet color complex with vanadium (V) in presence of hydrochloric acid is performed using absorption, fluorescence and viscometric techniques. The binding parameters of the PBHA-V(V) complex using calf thymus DNA (ct-DNA) and torula yeast RNA (t-RNA) have been determined. The complex shows the ability of cooperatively minor groove binding with ct-DNA as indicated by remarkable hyperchromicity and a blue shift of the absorption spectra. Quenching of metal complex calculation was carried out with Stern-Volmer equation and K_sv was found to be 2.32 ± 0.18 × 10⁴ M^?1, while in the case of t-RNA, enhancement is observed and that means the compound was not able to displace the Ethidium Bromide(EB)-t-RNA complex. Molecular docking was also applied to predict the mode of interaction of the hydroxamic acid with ct-DNA and t-RNA. DNA binding results of the complex are compared with those of the parent ligand.     

Rheology of particle suspensions in viscoelastic media. Wood flour-polypropylene melt

The dynamic mechanical behavior of suspensions of wood flour in polypropylene (PP) melts was investigated at varying filler concentrations. The main observed features were related to the viscoelastic nature of the polymer and to the filler aggregation, where the process of formation and destruction of particle clusters is governed by the polymer chain dynamics. The effect of the wood flour particles at low and large deformations was analyzed. The sample containing a wood flour concentration of 50% (by weight) showed a solid like behavior at low frequencies and was identified as the sample closer to a liquid-solid transition (LST). The values of the Newtonian viscosity obtained from sinusoidal oscillations at low frequencies were related to the concentration of filler in the suspensions. Moreover, a filler concentration scaling was found, that allows to obtain a master curve using the neat polymer as the reference and from which it is possible to calculate the dynamic mechanical behavior of all the suspensions. Apparently, for this system, the relaxation mechanisms of the neat polymer are not changed by the presence of the filler. However, the corresponding relaxation times are increased as a function of the filler concentration.     

A Unique Fluoride Nanocontainer: Porous Molecular Capsules Can Accommodate an Unusually High Number of “Rather Labile” Fluoride Anions

The present work refers to the challenging issue of fluoride anion recognition/binding in water by taking advantage of the unique possibilities offered by the porous molecular nanocontainers of the {Mo₁₃₂} Keplerate type allowing the study of a variety of new phenomena. Reaction of the highly reactive carbonate‐type capsule with aqueous HF results in the release of carbon dioxide and integration of an unprecedentedly large number of fluoride anions—partly as coordinated ligands at both the pentagonal units and the linkers, partly as a disordered water/fluoride assembly inside the cavity. The internal assembly and some of the fluoride ligands are easily released, which provides interesting options for future studies regarding coordination chemistry and catalysis under confined conditions.     

非晶态硅酸盐介观团粒结构模型及其参数

非晶态硅酸盐是典型的近程有序,远程无序的准稳定态体系,采用分数维理论与X射线小角散射(SAXS)、拉曼光谱(RS)、透射电子显微镜(TEM)等分析技术相结合,对高温熔融法和溶胶凝胶法合成的CaO-Al2O3-SiO2及Na2O-Al2O3-SiO2系列低维非晶硅酸盐试样进行了网络分数维、微粒微孔分数维、网络自相似比、回旋半径、微孔体积百分率、团粒尺度和微孔尺度等介观参数群的定量测定及研究,获得了低温硅酸盐凝胶、高温硅酸盐熔体(仿岩浆熔体)之淬火玻璃相均具有纳米级(几个nm至几十nm)统计性自相似团粒结构的结论,进而建立了介观团粒结构模型,揭示了该结构模型内各介观参数与其宏观参量的相关性,从而为非晶硅酸盐提供了一整套介观定量结构参数,确定了岩浆熔体是准稳定的、可演变的分数维体系,对探索自然界岩浆的地球化学特征以及低维复合材料结构性能的改进具有重要的理论和实用意义.     

An Anionic Ring Locked into an Anionic Axle: A Metastable Rotaxane with Chemically Activated Electrostatic Stoppers

The use of the electrostatic stoppers concept in the field of mechanically interlocked molecules is reported; these stoppers are chemically sensitive end groups on a linear guest molecule that allows for the conversion of a pseudo-rotaxane species into a rotaxane complex by a change in the medium acidity. The chemical stimulus causes the appearance of negative charges on both ends of the linear component, passing from cationic to anionic, and causing a significant ring-to-axle electrostatic repulsion. This phenomenon has two different and simultaneous effects: 1) destabilizes the complex as a consequence of confining an anionic ring into an anionic axle, and 2) increases the dissociation energy barrier, thus impeding ring extrusion. This newly formed metastable rotaxane species is resistant to solvent and temperature effects and performs as a two-state degenerated molecular shuttle in solution.     

1H and 13C spectral assignment of substituted 5H-[1,3]thiazolo[2,3-b]quinazolin-5-one and 12H-[1,3]benzothiazolo[2,3-b] quinazolin-12-one

(1)H and (13)C spectroscopic data for 5H-[1,3]thiazolo[2,3-b]quinazolin-5-one and 12H-[1,3]benzothiazolo[2,3-b]quinazolin-12-one derivatives were fully assigned by combination of one- and two-dimensional experiments (DEPT, HMBC and HMQC). Both heterocyclic systems show similar spectroscopic properties with some remarkable differences.     

Structured elastomeric submillimeter films displaying magneto and piezo resistivity

Structured elastomer films (100–150 µm) presenting piezo and magneto resistance are described. The films are composites of filler particles, which are both electrically conductive and magnetic, dispersed in an elastomeric matrix. The particles consist of magnetite (6 nm) grouped in silver‐coated aggregates (Fe₃O₄@Ag). The matrix is styrene–butadiene rubber (SBR) in which diethylene glycol (DEG) is added. The particles, SBR and DEG, are dispersed in toluene and then placed between two rare earth magnets. Formation of pseudo‐chains (needles) of inorganic material aligned in the direction of the magnetic field is obtained after solvent evaporation. The addition of DEG is substantial to obtain an electrically conductive material. The electrical conductivity is anisotropic and increases when applying normal stresses and/or magnetic fields in the direction of the needles. The elastomers, particles, and needless were characterized by XRD, SEM, EDS, FTIR, DSC, TGA, VSM, profilometry, and stress–strain analysis. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 574–586