Structural characterization of rare intramolecularly (1,4-Te?N) bonded diorganotellurides and their monomeric complexes with mercury(II) halides: Metal assisted C-H?X (Hg) interactions leading to supramolecular architecture

Monomeric tellurides 4-RC₆H₄(SB)Te [SB = 2-(4,4′-NO₂C₆H₄CHNC₆H₃-Me); R = H, 1a; Me, 1b; OMe, 1c], which incidentally represent the first example of a telluride with 1,4-Te?N intramolecular interaction, have been prepared and characterized by solution and solid-state ¹²⁵Te NMR, ¹³C NMR and X-ray crystallography. Interplay of weak C-H?O and C-H?π interactions in the crystal lattice of 1b and 1c are responsible for the formation of supramolecular motifs. These tellurides undergo expected oxidative addition reactions with halogens and interhalogens and also interact coordinatively with mercury(II) halides to give 1:2 complexes, HgX₂[4-RC₆H₄(SB)Te]₂ (X = Cl, R = H, 2a; Me, 2b; OMe, 2c and X = Br, R = H, 3a; Me, 3b; and OMe, 3c) with no sign of Te-C bond cleavage, as has been reported for some 1,5-Te?N(O) intramolecularly bonded tellurides. The complexes 2a and 3c are the first structurally characterized monomeric 1:2 adducts of mercury(II) halides with Te ligands. The 1,4-Te?N intramolecular interactions in the solid-state are retained in the complexes highlighting simultaneously the Lewis acid and base character of the Te(II) atom. Packing of molecules in the crystal lattice of 2a and 3c reveals that non-covalent C-H?Cl/Br interactions involving metal-bound halogen atoms possess significant directionality and in combination with coordinative covalent interactions may be of potential use in creating inorganic supramolecular synthons.     

Thermoelastic stability analysis of laminated composite plates: An analytical approach

The paper presents Chebyshev series based analytical solutions for the postbuckling response of the moderately thick laminated composite rectangular plates with and without elastic foundations. The plate is assumed to be subjected to in-plane mechanical, thermal and thermomechanical loadings. In-plane mechanical loading consists of uniaxial, biaxial, shear loadings and their combinations. The temperature induced loading is due to either uniform temperature or a linearly varying temperature across the thickness. The mathematical formulation is based on higher order shear deformation theory (HSDT) and von-Karman nonlinear kinematics. The elastic foundation is modeled as shear deformable with cubic nonlinearity. The thermal and mechanical properties of the composites are assumed to be temperature dependent. The quadratic extrapolation technique is used for linearization and fast converging finite double Chebyshev series is used for spatial discretization of the governing nonlinear equations of equilibrium. The effects of plate parameters and foundation parameters on buckling and postbuckling response of the plate are presented.     

Effect of gamma irradiation on transport of charge carriers in Cu nanowires

In this paper, we report the effect of gamma ray photons on the electrical conductivity of 100 nm Cu nanowires prepared by the technique of electrodeposition using track-etched membranes. Different fluences of photons have been used to observe the effect and in each case of post-irradiation, electrical conductivity is found to increase in a linear manner with increase in applied potential difference; however the rate of increase of conductivity is different in different cases of radiation fluence. Grain boundary scattering is of significance for the post-irradiation parabolic nature of the I–V characteristics (IVC), which are of a linear pattern following Ohm’s law before irradiation. Increase or decrease in the number of charge carriers during their transport through the nanowires is the result of two competitive processes—specular and diffusive scattering of charge carriers (electrons) from grain boundaries, which are itself a region of high resistance rather than inter-grain regions. The results have been discussed in light of the Mayadas and Shatzkes (MS) model with a slight modification for irradiated nanowires.     

Composite Polymer Nanoparticles via Transitional Phase Inversion Emulsification and Polymerisation

Summary: A new route was employed to produce composite polymer nanoparticles. First, a model polymer (a low molecular-weight polyisobutene) was dissolved in a model monomer (styrene) and then the solution was emulsified in water containing a pair of nonionic surfactants via a transitional phase inversion route. After phase inversion, which produced an oil-in-water miniemulsion, polymerisation of the vinyl monomer gave composite polymer particles. Low temperature emulsification was not practical because the inverted oil-in-water emulsions reinverted to water-in-oil emulsions upon raising the temperature to the reaction temperature. Miniemulsions prepared at the reaction temperature with low monomer content in the oil phase showed good stabilty in the course of polymerisation and produced latexes with a particle size similar to the size of drops in the initial miniemulsions.     

Theoretical Study of the Effects of Templated Materials on Aggregate Formation

Summary: We have conducted Monte Carlo simulations to investigate a greatly simplified model for a blend composed of templated materials (polymers or monomers), smaller reacting particles and solvents on a two‐dimensional lattice. In the simulations, we compute the mean chain conformation of flexible templated polymers, and the distribution of the number of adjacent reacting particles aligned along the same axis to rationalize how templated materials affect the physical aggregation of smaller particles in a blend. We first examine the effects of the effective interactions between templated materials and smaller reacting particles. For repulsive interactions, flexible templated polymers tend to contract to reduce repulsions arising from smaller reacting particles, but for attractive interactions, mean chain dimension increases to maximize attraction. When templated material composition is increased, the conformational deformation of templated polymers becomes more pronounced. Moreover, in the presence of attractive interactions, reacting particles are more dispersed in the blend. In contrast, repulsive interactions increase the probability of aggregation of reacting particles. Also, our findings show that templated monomers (without chain connectivity) interact with reacting particles more effectively than with templated polymers due to the greater interacting area per monomer, which enhances the dispersion and segregation of reacting particles in the blend due to the attractive and repulsive interaction, respectively. In addition, as templated material composition is increased, the probability of forming a larger aggregate decreases. This simple model allows us to elucidate the role of templated materials on the physical aggregation of smaller particles in a blend.

Probability distribution P(m) of finding m adjacent reacting particles along the same axis in the presence of templated polymers (open symbols) and templated monomers (solid symbols) for different monomer‐reacting particle ratio, 1:3 (□/▪), 1:1 (○/•) and 3:1 (▵/▴):.     

Synthesis and characterization of 4‐vinyl pyridine‐grafted Teflon‐PFA film for water technologies

To get highly reactive polymeric materials for selective studies of enzyme immobilization, water purification, separation, and enrichment technologies, we attempted to graft 4‐vinyl pyridine (4‐VP) onto Teflon‐PFA by simultaneous γ‐ray initiation. The resulting graft copolymers were quaternized by treatment with some alkylating agents. Optimum conditions for grafting were evaluated through the variation of the total dose of radiation, the amount of water, and the monomer concentration. The effect of the solvent composition (H₂O/MeOH) was also studied. In the presence of MeOH, grafting occurred less often and was nonselective as 4‐VP was incorporated on both sides in comparison with highly selective grafting in an aqueous medium. The percentages of the grafting, total conversion, and grafting efficiency and the rates of the polymerization, grafting, and homopolymerization were also evaluated. Some other monomers such as methacrylic acid, methyl methacrylate, maleic acid, acrylonitrile, and vinyl imidazole were not incorporated onto the backbone film under the optimum grafting reaction conditions evaluated for the grafting of 4‐VP. Although some grafting occurred, the graft yield was too low to be considered of any significance. The grafted films were quaternized with benzyl chloride, and quaternized and unquaternized films were used for the immobilization of lipase. The former showed high activity with lipase and has potential for development as a bioreactor. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4506–4518, 2000     

λ-Shaped mesogens based on chalconyl ester core having variable side chain: Synthesis and characterisation

In present study, we have synthesized two newly chalconyl-ester core LCs having variable side chain and fixed disubstituted butoxy group at another terminal end. All this compounds were well characterized by elemental analysis, FT-IR, ¹H NMR. The mesomorphic properties of these compounds were observed by optical polarized light microscopy (POM) and also confirmed by using differential scanning calorimetry (DSC) and X-ray diffraction pattern (XRD). Detailed XRD investigation endorses the presence of the nematic phase in higher angle region and SmC phase in lower angle region. In addition, it is found that all the prepared materials display enantiotropic LCs phases except first four members in series-1 and first member in series-2. Thermal stability of SmC and nematic phase of series-1 is higher as compare to series-2. To get more insights, the DFT based HOMO, LUMO studies are carried out which supports intramolecular charge transfer interactions and stability in this class of mesogens.     

Spectroscopy vs. Electrochemistry: Catalyst Layer Thickness Effects on Operando/In Situ Measurements

In recent years, operando/in situ X-ray absorption spectroscopy (XAS) has become an important tool in the electrocatalysis community. However, the high catalyst loadings often required to acquire XA-spectra with a satisfactory signal-to-noise ratio frequently imply the use of thick catalyst layers (CLs) with large ion- and mass-transport limitations. To shed light on the impact of this variable on the spectro-electrochemical results, in this study we investigate Pd-hydride formation in carbon-supported Pd-nanoparticles (Pd/C) and an unsupported Pd-aerogel with similar Pd surface areas but drastically different morphologies and electrode packing densities. Our in situ XAS and rotating disk electrode (RDE) measurements with different loadings unveil that the CL-thickness largely determines the hydride formation trends inferred from spectro-electrochemical experiments, therewith calling for the minimization of the CL-thickness in such experiments and the use of complementary thin-film control measurements.     

Sonocatalytic degradation of methylene blue using spindle shaped cerium oxide nanoparticles

Journal of Solid State Electrochemistry - The industrial revolution has raised major concern of environmental pollution, due to excess release of hazardous chemical, dyes, etc. into water bodies....