Preparation and electrical conductivity of organoheterobimetallic-maleonitriledithiolates

The new complexes [PhHg]₂[M(mnt)₂] [M = Ni^II, Cu^II, Zn^II or Pd^II; mnt^2– = 1,2-dicyano-1,2-ethylenedithiolate (maleonitriledithiolate)] have been characterized spectroscopically and magnetically and their solid phase conductivity measured. All compounds exhibit solid phase _rt in the 1.29 × 10^–12–5.68 × 10^–10 S cm^–1 range and semiconduct in the 313–383 K range.     

Triphenylene based copper ensemble for the detection of cyanide ions

The binding behavior of triphenylene based copper ensemble prepared in situ has been investigated toward various anions (F(-), Cl(-), Br(-), I(-), CH(3)COO(-), H(2)PO(4)(-), NO(3)(-), OH(-), ClO(4)(-), CN(-), CO(3)(-) and SO(4)(-)) by UV-vis and fluorescence spectroscopy. Among various anions tested, 1-Cu(2+) ensemble shows selective and sensitive response towards cyanide ions and responds to CN(-) ions even in the presence of bovine serum albumin and in blood serum milieu. Further, as practical application of compound 1, we utilized the TLC strips coated with THF solution of 1 for the solid state detection of copper and cyanide ions.     

Visual chiral recognition of mandelic acid and α-amino acid derivatives by enantioselective gel formation and precipitation

Novel chiral receptors based on l-phenylalanine and l-valine have been synthesized and their chiral recognition properties toward mandelic acid and N-tosyl α-amino acids are studied. The phenylalanine-based receptor undergoes enantioselective gel formation with R-mandelic acid and N-tosyl-d-valine, whereas the valine-linked receptor in their presence results in the formation of precipitates.     

InCl3‐Driven Regioselective Synthesis of Functionalized/Annulated Quinolines: Scope and Limitations

The efficient, regioselective synthesis of functionalized/annulated quinolines was achieved by the coupling of 2‐aminoaryl ketones with alkynes/active methylenes/α‐oxoketene dithioacetals promoted by InCl₃ in refluxing acetonitrile as well as under solvent‐free conditions in excellent yields. This transformation presumably proceeded through the hydroamination–hydroarylation of alkynes, and the Friedländer annulation of active methylene compounds and α‐oxoketene dithioacetals with 2‐aminoarylketones. In addition, simple reductive and oxidative cyclization of 2‐nitrobenzaldehyde and 2‐aminobenzylalcohol, respectively, afforded substituted quinolines. Systematic optimization of the reaction parameters allowed us to identify two‐component coupling (2CC) conditions that were tolerant of a wide range of functional groups, thereby providing densely functionalized/annulated quinolines. This approach tolerates the synthesis of various bioactive quinoline frameworks from the same 2‐aminoarylketones under mild conditions, thus making this strategy highly useful in diversity‐oriented synthesis (DOS). The scope and limitations of the alkyne‐, activated methylene‐, and α‐oxoketene dithioacetal components on the reaction were also investigated.     

Determination of aminoglycoside residues in kidney and honey samples by hydrophilic interaction chromatography‐tandem mass spectrometry

Two methods based on liquid chromatography–tandem mass spectrometry were developed for the determination of ten aminoglycosides (streptomycin, dihydrostreptomycin, spectinomycin, apramycin, paromomycin, kanamycin A, gentamycin C1, gentamycin C2/C2a, gentamycin C1a, and neomycin B) in kidney samples from food‐producing animals and in honey samples. The methods involved extraction with an aqueous solution (for the kidney samples) or sample dissolution in water (for the honey samples), solid‐phase extraction with a weak cation exchange cartridge and injection of the eluate into a liquid chromatography–tandem mass spectrometry system. A zwitterionic hydrophilic interaction chromatography column was used for separation of aminoglycosides and a triple quadrupole mass analyzer was used for detection. The methods were validated according to Decision 2002/657/EC. The limits of quantitation ranged from 2 to 125 μg/kg in honey and 25 to 264 μg/kg in the kidney samples. Interday precision (RSD%) ranged from 6 to 26% in honey and 2 to 21% in kidney. Trueness, expressed as the percentage of error, ranged from 7 to 20% in honey and 1 to 11% in kidney.     

Facile Synthesis of Imidazole Fused Fluoroquinolones

Studies on synthetic design of 7,8‐imidazole fused fluoroquinolones from 8‐amino‐6‐fluoro‐4‐hydroxy‐N‐methyl‐7‐(methyl amino)quinoline‐3‐carboxamide and ketones/carboxylic acids and their antibacterial activity.     

T-shaped non-symmetrical twin liquid crystalline compounds

New unconventional T-shaped non-symmetrical dimeric liquid crystalline compounds have been synthesised and their thermotropic properties studied on the hot-stage of a polarising microscope. These compounds consist of an azo-ester mesogenic unit with a range of terminal substituents (–CH₃, –OCH₃, –NO₂ or –Cl) at one end, interconnected by a flexible spacer (n?=?4, 5 or 10) via ether and ester linking units to a biphenyl moiety at the lateral hydroxyl position of the azo-ester. All the compounds were characterised using a combination of elemental analysis and standard spectroscopic methods. The compounds were found to exhibit enantiotropic nematic and smectic mesophases. The effect of different terminal substituents on mesomorphism is discussed.     

Enhanced dielectric and electro-optical properties of a newly synthesised ferroelectric liquid crystal material by doping gold nanoparticle-decorated multiwalled carbon nanotubes

In this article, a newly synthesised ferroelectric liquid crystal (FLC) material, namely LAHS 22, has been characterised. The characterisation of the FLC material has been performed using dielectric relaxation spectroscopy, differential scanning calorimetry and polarisation optical microscopy. We observed an enhancement in the dielectric and electro-optical properties of the FLC material by incorporating gold nanoparticles (GNPs)-decorated multiwalled carbon nanotubes (MWCNTs). The GNPs-decorated MWCNTs cause an increment in dielectric dispersion (up to kHz), absorption, spontaneous polarisation and rotational viscosity of the FLC material. The pure and GNPs-decorated MWCNTs doped FLC cells were analysed by means of various dielectric spectroscopic and optical measurements. The observed enhancement in the dielectric and electro-optical properties of the FLC material has also been studied with concentration of GNPs-decorated MWCNTs in FLC material. The GNPs-decorated MWCNTs/FLC composites are not only of fundamental importance, but also useful materials for device applications such as liquid crystal displays and memory devices.     

Accurate measurement of uranium isotope ratios in soil samples using thermal ionization mass spectrometry equipped with a warp energy filter

A chemical and mass-spectrometric procedure for uranium isotopic analysis using a thermal ionisation mass spectrometer equipped with a Wide Aperture Retardation Potential energy filter has been developed and applied to uranium isotopic measurements for various soil samples. Soil samples were digested using a microwave digestor. Uranium was isolated from soil samples by the chemical separation procedure based on the use of anion-exchange resin and UTEVA extraction chromatography column. The isotope ratios were measured for two certified reference materials by using a VG Sector 54-30 thermal ionisation mass spectrometer in dynamic mode with Faraday cup and Daly ion counting system. Replicates of standard reference materials showed excellent analytical agreement with established values supporting the reliability and accuracy of the method. Precision of the ²³⁵U/²³⁸U ratio was achieved by a correction factor of 0.22% amu as a function of ion-beam intensity with sample loads of around 250?ng of U. The resulting reproducibility for standards and soil samples was better than 0.2% at two standard deviations (SD). Uranium isotopic compositions have been determined in several reference soil samples such as Buffalo river sediment, NIST 2704, river sediment SRM 4350b and ocean sediment NIST-4357 and a Chernobyl soil sample. There was a significant deviation from the natural uranium in comparison with Chernobyl soil samples.     

Structural and optical characterization of Ag-doped TiO2 nanoparticles prepared by a sol–gel method

Undoped and silver-doped TiO₂ nanoparticles (Ti_1?x Ag _x O₂, where x?=?0.00?C0.10) were synthesized by a sol?Cgel method. The synthesized products were characterized by X-ray diffraction (XRD), particle size analyzer (PSA), scanning electron microscope (SEM), and UV?CVisible spectrophotometer. XRD pattern confirmed the tetragonal structure of synthesized samples. Average crystallite size of synthesized nanoparticles was determined from X-ray line broadening using the Debye?CScherrer formula. The crystallite size was varied from 8 to 33?nm as the calcination temperature was increased from 300 to 800?°C. The incorporation of 3 to 5% Ag⁺ in place of Ti⁴⁺ provoked a decrease in the size of nanocrystals as compared to undoped TiO₂. The SEM micrographs revealed the agglomerated spherical-like morphology of particles. SEM, PSA, and XRD measurements show that the particles size of the powder is in nanoscale. Optical absorption measurements indicated a red shift in the absorption band edge upon silver doping. Direct allowed band gap of undoped and Ag-doped TiO₂ nanoparticles measured by UV?CVis spectrometer were 3.00 and 2.80?eV, respectively, at 500?°C.