RESUMEN

The complex was prepared with preyssler polyoxoanion and transition metal (Mo), a cationic surfactant as a connector. It has tuneable physical and chemical potential which has been exploited to study novel properties. A new technique of shock wave impulses is also used on the Mo-PHP complex. Extensive use of cationic surfactants could impact accumulation in the environment set off the surfacing of bacterial resistance. Due to the electrostatic binding to bacterial surface, the hydrophobic parts of cationic surfactants tend to penetrate bacterial cell walls and may cause membrane lysis and bacteria death. The surfactant-supported and direct release of metal ions from P5W29Mo against bacterial resistance has been explained schematically. The dielectric study helps to understand the dissociation of cations that generate polarons and the hopping mechanism with neighbouring vacant atomic sites. Structural analysis confirms the formation of cationic surfactant incorporated polyoxoanion (Mo-PHP). A hexagonal shape-like structure for the PHP complex has been observed. The Mo-incorporated PHP complex was characterized using UV-visible (UV), Fourier Transform-infrared (IR), Raman spectra, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) techniques.

RESUMEN

The effects of glucose on the growth and surface properties of MoS2 with a nanosheet structure were investigated in detail. In the presence of glucose, the hydrothermal reaction of sodium molybdate and thiourea yields carbon-loaded MoS2 nanocomposites (C/MoS2). Compared with bare MoS2 nanosheets with more than six layers obtained in the absence of glucose and carbon spheres with a diameter of 500 nm prepared from the carbonization of glucose, C/MoS2 consists of one- or three-layered MoS2 and carbon spheres with a diameter less than 1 nm to give a large Brunauer-Emmett-Teller surface area (3-20 times larger than the individual materials). The surface characterizations reveal that both MoS2 and carbon spheres of C/MoS2 have a negative charge on the surface, suggesting that the previously reported explanation, in which the adsorption of MoS2 and/or molybdate ions on carbon spheres inhibits the growth and aggregation of MoS2, is not correct. Based on Fourier transform infrared and 1H NMR spectra, it is demonstrated that glucose acts as the hydrogen bond donor toward polyoxomolybdate species such as Mo8O264-, Mo7O246-, and MoO42- in the range of pH = 2-12. The intermolecular hydrogen bond not only inhibits the growth of both the (002) plane of MoS2 and carbon spheres, but also enables the formation of C-O-Mo bonds in the in situ generated C/MoS2. Compared with bare MoS2, C/MoS2 not only show a lower over-potential by 60 mV for the electrocatalytic evolution of hydrogen, but also has a larger mass specific capacitance by three times, due to the larger surface area and the interfacial interaction through the C-O-Mo bonds.

RESUMEN

A novel complex based on the Dawson-like [H3BiW18O60]6-, i.e. (C2H9N2)2[{Cu(C10H8N2)(C2H8N2)}2(H3BiW18O60)]·5.5H2O or (enH)2[{Cu(2,2'-bipy)(en)}2(µ4-H3BiW18O60)]·5.5H2O, (1), where enH is protonated ethane-1,2-diamine, 2,2'-bipy is 2,2'-bipyridine and en is ethane-1,2-diamine, has been synthesized hydrothermally and characterized by elemental analysis, single-crystal X-ray diffraction analysis, IR spectroscopy, powder XRD, and thermogravimetry and differential thermal analysis (TG-DTA). For (1), each [H3BiW18O60]6- anion acts as a tetradentate ligand connecting [Cu(2,2'-bipy)(en)]2+ fragments via two terminal and two bridging O atoms, forming a two-dimensional network structure. Along the a and c axes, polyoxometalate units are arranged in an AB…AB manner. The electrochemical behaviour of (1)-CPE (CPE is a carbon paste electrode) was investigated in 2 M H2SO4 solution by cyclic voltammetry (CV). The redox process of WVI/V takes place at E1/2 = -0.58 (I-I') and -0.37 V (II-II'), and at -0.04 V (III-III') for CuII/0. The magnetic properties of (1) were investigated in the range 2-300 K and indicated the existence of strong antiferromagnetic exchange interactions between the Cu2+ centres.

RESUMEN

We examined the positional isomerism and vanadium substitution on the 51V magic angle spinning NMR spectra of potassium salts of vanadium-substituted polyoxotungstates of the Wells-Dawson series. NMR parameters of this class of catalytically active polyoxotungstates effect of are reported. Multiple species, indicative of differences in the local environment at the substitution sites, are observed in solid-state NMR spectra of the di- and tri- substituted complexes in contrast to solution NMR spectra, where single average chemical shift was observed. The quadrupolar and chemical shift anisotropy parameters depend strongly on the position and the degree of the vanadium substitution into the oxoanion core establishing 51V SATRAS NMR spectroscopy as a sensitive probe of the local electronic environment in these catalytically active solids.

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