ZnS/Fe2O3/Ag Ternary Nanocomposite Photocatalyst for the Degradation of Dyes Under Visible Light

Russian Journal of Physical Chemistry A - Recently the researchers have shown great interest on photocatalysis, especially in dyes degradation by nanocomposites under visible light. In this work,...     

Calix[4]arene-based ditopic receptors for simultaneous recognition of fluoride and cobalt(II) ions

A series of calix[4]arene based ditopic receptors possessing bipyridyl and hydrazone units have been synthesized and evaluated for ionic recognition. It has been observed that the synthesized derivatives function as allosteric receptors for simultaneous recognition of Co²⁺and F^? ions through non-covalent interactions. Significant bathochromic shifts in the UV–visible spectrum with a profound colour change promise their use to engineer novel applications.     

Synthesis of novel chromogenic azocalix[4]arenemonoquinones and their binding with alkali metal cations

Five new chromogenic azocalix[4]arenemonoquinones have been synthesized, characterized and examined for their interaction with alkali metal cations (Li⁺, Na⁺, K⁺, Rb⁺ and Cs⁺) by UV-visible spectroscopic and cyclic voltammetric techniques. It has been determined that 4a selectively exhibits a significant bathochromic shift in its UV-visible spectrum on interaction with potassium ion in comparison to its treatment with other alkali metal cations. The binding stoichiometry of 4a and potassium ion was established to be 1:1 with an association constant of 3.27 × 10⁴ M^?1. Cyclic voltammetric experiments in 4:1 dichloromethane-acetonitrile also revealed a significant anodic shift (ΔE _(1/1′) = 115 mV) of the original redox waves of 4a on interaction with potassium ion.     

Synthesis and electrochemical studies of charge-transfer complexes of thiazolidine-2,4-dione with σ and π acceptors

In the present work, we report the synthesis and characterization of novel charge-transfer complexes of thiazolidine-2,4-dione (TZD) with sigma acceptor (iodine) and pi acceptors (chloranil, dichlorodicyanoquinone, picric acid and duraquinone). We also evaluated their thermal and electrochemical properties and we conclude that these complexes are frequency dependent. Charge-transfer complex between thiazolidine-2,4-dione and iodine give best conductivity. In conclusion, complex with sigma acceptors are more conducting than with pi acceptors.     

Physicochemistry of interaction between the cationic polymer poly(diallyldimethylammonium chloride) and the anionic surfactants sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium N-dodecanoylsarcosinate in water and isopropyl alcohol-water media

The physicochemistry of interaction of the cationic polymer poly(diallyldimethylammonium chloride) (PDADMAC) with the anionic surfactants sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium N-dodecanoylsarcosinate was studied in detail using tensiometry, turbidimetry, calorimetry, viscometry, dynamic light scattering (DLS), and scanning electron microscopy (SEM). Fair interaction initially formed induced small micelles of the surfactants and later on produced free normal micelles in solution. The interaction process yielded coacervates that initially grew by aggregation in the aqueous medium and disintegrated into smaller species at higher surfactant concentration. The phenomena observed were affected by the presence of isopropyl alcohol (IP) in the medium. The hydrodynamic sizes of the dispersed polymer and its surfactant-interacted species were determined by DLS measurements. The surface morphologies of the solvent-removed PDADMAC and its surfactant-interacted complexes from water and IP-water media were examined by the SEM technique. The morphologies witnessed different patterns depending on the composition and the solvent environment. The head groups of the dodecyl chain containing surfactants made differences in the interaction process.     

Modifying metal nanoparticle placement on carbon supports using an aerosol-based process, with application to the environmental remediation of chlorinated hydrocarbons

A facile aerosol-based process (ABP) is developed to vary the placement of iron nanoparticles on the external surface of carbon microspheres or within the interior. This is accomplished through the competitive mechanisms of sucrose carbonization and the precipitation of soluble iron salts, in an aerosol droplet passing through a high temperature heating zone. At lower aerosolization temperatures, carbonization occurs first leading to iron salt precipitation on the external surface, while at higher temperatures interior placement occurs through concurrent iron salt precipitation and sucrose carbonization. The resulting composites are highly conducive to the reductive dechlorination of compounds such as trichloroethylene (TCE) as the carbon support is a strong adsorbent, and zerovalent iron effectively reduces TCE to innocuous gases such as ethane. Since both iron and carbon are widely used catalysts and catalyst supports, the simple process of modifying iron placement has significant potential applications in heterogeneous catalysis.     

高效可回收多相催化剂SiO_2-Cu_2O催化伯胺和仲胺苄基化反应(英文)

A mild,effective,and selective procedure is reported for the mono N-benzylation and N,N-dibenzylation of primary amines as well as mono N-benzylation of secondary amines using silicasupported copper(I) oxide in water.The silica-supported Cu2O was generated in situ by the reaction of Fehling solution and glucose at 100 °C onto activated silica.The catalyst was filtered,washed with water,and oven-dried,and was characterized by Fourier transform infrared spectroscopy,thermogravimetric analysis,scanning electron microscopy,transmission electron microscopy,and atomic absorption spectroscopy.The prepared Cu2O-SiO2 was found to be thermally stable up to 325 °C.The copper was uniformly distributed onto the surface of the silica,and the mean particle diameter was 7 nm.The catalyst served as a selective heterogenous catalyst for the N-benzylation of primary and secondary amines.The catalyst is recyclable and was used effectively upto fifth run without a significant loss of catalytic activity.Various reaction solvents including water,acetonitrile,and toluene were screened for N-benzylation of amines,and the success of the aqueous system highlights the low environmental impact of the procedure.     

Synthesis and characterization of a new lanthanide based MRI contrast agent,potential and versatile tracer for multimodal imaging

In the present work a modular pathway towards the synthesis of a new versatile MRI contrast agent is reported and its physico-chemical properties are described. Two different functional groups were attached on two arms of the gadolinium 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA) in order to get a platform able to bind one probe designed to target specific biological marker and a fluorescent molecule likely to be used for optical imaging. The nuclear magnetic relaxation dispersion (NMRD) profile, the oxygen-17 relaxometric NMR study and stability assessment versus transmetalation of the Gd-complex show that this new contrast agent has a relaxivity and transmetalation stability similar to Gd–DOTA.     

Level density of a bose gas and extreme value statistics

We establish a connection between the level density of a gas of noninteracting bosons and the theory of extreme value statistics. Depending on the exponent that characterizes the growth of the underlying single-particle spectrum, we show that at a given excitation energy the limiting distribution function for the number of excited particles follows the three universal distribution laws of extreme value statistics, namely, the Gumbel, Weibull, and Fréchet distributions. Implications of this result, as well as general properties of the level density at different energies, are discussed.