Structural features of biologically active coordination compounds of vanillinsemicarbazone

Summary Complexes of vanillinsemicarbazone (VSC) with Mn^II, Fe^II, Co^II, Ni^II, Cu^II, Zn^II, Cd^II and Hg^II have been prepared and characterised by elemental analyses, molar conductance, magnetic susceptibility and spectral data. Probable structures for the complexes are suggested on the basis of their physico-chemical properties. The fungitoxicity of VSC and the isolated complexes have been tested on pathogenic fungi. On leave from the University of Mysore, India.     

A metal nanoparticle-based supramolecular approach for aqueous biphasic reactions

beta-cyclodextrin immobilized on Pd nanoparticles was successfully employed as an efficient phase-transfer catalyst in aqueous biphasic hydrogenation reactions.     

Complexometric determination of thallium(III) in pure solution,alloys, and complexes using semicarbazide hydrochloride as a releasing agent

A simple and accurate complexometric method is proposed for the determination of Tl(III) using semicarbazide hydrochloride as a releasing agent. In the presence of diverse metal ions, thallium is complexed first with a known excess of EDTA, and the surplus EDTA is then titrated with standard zinc sulfate at pH 5.0–6.0 (hexamine) using xylenol orange indicator. An excess of 5% aqueous neutral solution of semicarbazide hydrochloride is then added and the released EDTA is titrated against standard zinc sulfate solution. The method works well in the range 2–50 mg of Tl(III) with relative errors < 0.5%, standard deviations 0.05mg and coefficient of variation 0.4%. The method is applied for the determination of thallium content in complexes and alloy compositions     

Extractive spectrophotometric determination of molybdenum as a thiocyanate-2-acetylpyridinethiosemicarbazone complex

A new spectrophotometric method for the determination of molybdenum is based on the extraction of the orange red molybdenum thiocyanate-2-acetylpyridinethiosemicarbazone complex into chloroform from hydrochloric acid. The complex has an absorption maximum at 470 nm with a molar absorptivity of 1.7 × 10⁴ liters mol^?1 cm^?1. Beer's law is valid from 0.1 to 6.5 ppm of molybdenum. The equilibrium shift method indicated a 1:4:2 complex. The method has been used successfully for the determination of molybdenum in molybdenum steels.     

Comparative computational appraisal of supercritical CO2-based natural circulation loop: effect of heat-exchanger and isothermal wall

Journal of Thermal Analysis and Calorimetry - Natural circulation loop (NCL) is a geometrically simple heat transfer device in which fluid flow occurs due to density gradient of loop fluid, induced...     

Graphene and graphene oxide as effective adsorbents toward anionic and cationic dyes

In the present study, exfoliated graphene oxide (EGO) and reduced graphene oxide (rGO) have been used for the adsorption of various charged dyes such as methylene blue, methyl violet, rhodamine B, and orange G from aqueous solutions. EGO consists of single layer of graphite decorated with oxygen containing functional groups such as carboxyl, epoxy, ketone, and hydroxyl groups in its basal and edge planes. Consequently, the large negative charge density available in aqueous solutions helps in the effective adsorption of cationic dyes on EGO while the adsorption is negligible for anionic dyes. On the other hand, rGO that has high surface area does not possess as high a negative charge and is found to be very good adsorbent for anionic dyes. The adsorption process is followed using UV-Visible spectroscopy, while the material before and after adsorption has been characterized using physicochemical and spectroscopic techniques. Various isotherms have been used to fit the data, and kinetic parameters were evaluated. Raman and FT-IR spectroscopic data yield information on the interactions of dyes with the adsorbent.     

Palladium-catalyzed cross-coupling of aryl chlorides with alkenylboronic acids with low E/Z isomerization

Using a bulky electron-rich monodentate benzoferrocenyl phosphine as supporting ligand, an efficient protocol for stereoselective palladium-catalyzed Suzuki-Miyaura cross-coupling of aryl chlorides with alkenylboronic acids was uncovered. Using this protocol, both trans- and cis-alkenylboronic acids can be coupled with high stereoselectivity giving the corresponding vinylarenes in good to quantitative yields. Electron-poor and -rich aryl chlorides including highly hindered ones are all suitable substrates for the reaction.     

Structure and Properties of γ‐Brass‐Type Pt2Zn11—δ (0.2 < δ < 0.3)

The γ‐brass type phase Pt₂Zn_11—δ (0.2 < δ < 0.3) was prepared by reaction of the elements in evacuated silica ampoules. The structures of crystals grown in the presence of excess zinc or alternatively excess platinum were determined from single crystal X‐ray diffraction intensities and confirmed by Rietveld profile fits. Pt₂Zn_10.72(1) crystallizes in the space group I4¯3m, a = 908.55(4) pm, Z = 4. The structure refinement converged at R_F = 0.0302 for I_o > 2σ (I_o) for 293 symmetrically independent intensi ties and 19 variables. The structure consists of a 26 atom cluster which is comprised of four crystallographically distinct atoms. The atoms Zn(1), Pt(1), Zn(2) and Zn(3) form an inner tetrahedron IT, an outer tetrahedron OT, an octahedron OH, and a distorted cuboctahedron CO respectively. About 14 % of the Zn(1) sites are unoccupied. Pt₂Zn_10.73 melts at 1136(2) K. It is a moderate metallic conductor (ρ₂₉₈ = 0.2—0.9 mΩ cm) whose magnetic properties (χ_mol = —4.6 10^—10 to —5.4 10^—10 m³ mol^—1) are dominated by the core diamagnetism of its components.     

Multi-component synthesis of 2-amino-6-(alkylthio)pyridine-3,5-dicarbonitriles using Zn(II) and Cd(II) metal-organic frameworks (MOFs) under solvent-free conditions

Multi-component synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines has been developed by using the reaction of aldehydes, malononitrile, and thiophenols in the presence of a Zn(II) or a Cd(II) metal-organic framework (MOF) as the heterogeneous catalyst. This protocol tolerates different functional groups on the substrates and does not require the use of any organic solvent. Moreover, the Zn(II) and Cd(II) MOF catalysts can be recovered and reused for a number of runs without loss of activity.     

Extractive spectrophotometric determination of molybdenum(V) in molybdenum steels

An extraction spectrophotometric method has been developed for the determination of traces of molybdenum present in molybdenum steels which is based on the extraction of the orange-red molybdenum-thiocyanate-acetonethiosemicarbazone complex into chloroform from hydrochloric acid medium. The complex has an absorption maximum at 472 nm with a molar absorptivity of 1.9 × 10⁴ liters mol⁻¹ cm⁻¹. Beer's law is valid over the concentration range 0.1–9.5 ppm of molybdenum with an optimum concentration range of 0.4–9 ppm. The equilibrium shift method indicates 1:4:2 composition for molybdenumthiocyanate-acetonethiosemicarbazone complex. The effect of acidity, reagent concentrations, temperature, and interferences from various ions are reported.