Colchiceine as an extractive indicator in the determination of copper(II)

Colchiceine, a new extractive indicator, is satisfactorily used in the determination of copper(II). A highly sensitive greenish yellow complex is formed with copper, which is extractable into chloroform. The results are comparable in sensitivity and selectivity with those of its precursors.     

Identification of mixed states using electron spectroscopy

X-ray photoelectron spectroscopy (XPS) is a highly surface sensitive technique and is used in identification of oxidation states in catalysts at various stages. Copper, silver and platinum based catalysts are widely used in petrochemical industries. Our attempts at characterization have revealed that elements in these catalysts are normally present then one stae. It is terefore essential to identify their in more chemical as well as oxidation states. Such identification combined with quantitative analysis of data is helpful in correlating catalyst performance. Examples of mixed state identification are presented.IPCL Communication No. 266     

Absence of neutron emission during interaction of deuterium with metal at low energies

Technique and instrumentation to detect reliably, multiplicity of neutrons emitted in sharp bursts (≤100 μs) has been developed where a burst of as low as 15 neutrons and continuous emission of ⋍10⁻¹ neutron/s may be detected. Using this technique, attempts were made to detect neutron emission from various experiments in which anomalous nuclear effects (or what is commonly referred to as cold fusion) may be expected to occur. No neutrons, above our detection threshold, were detected in the recent series of experiments.     

Xanthate anions in salts of biscyclopentadienylzirconium(IV) chelates

A series of [Cp ₂ZrL]⁺[ROCS₂]^? complexes whereL is the conjugate base of acetylacetone, benzoylacetone or 8-hydroxyquinoline andR=Me,Et ori-Pr have been synthesised in aqueous medium by the reaction of [Cp ₂ZrL]⁺Cl^? withROCS ₂ ^? K⁺. Various physico-chemical studies carried out for these complexes indicate that all the complexes are 1:1 electrolytes in which the ligandL is bidentate, consequently there is a tetrahedral coordination about the zirconium atom.     

Fabrication of a metal nanoparticles and polymer nanofibers composite material by an in situ chemical synthetic route

This work demonstrated a facile route for the synthesis of poly(3,5-dimethyl aniline) nanofibers by polymerization of 3,5-dimethyl aniline using Pd-acetate as the oxidant. The reduction of Pd ion is accompanied by oxidative polymerization of 3,5-dimethyl aniline, leading to a metal-polymer composite material. Palladium nanoparticles (approximately 2 nm) are uniformly distributed throughout the polymer that makes the composite material a unique morphology. The resultant composite material was characterized by means of different techniques. IR and Raman spectra provide the information on the chemical structure of the polymer. TEM images show the morphology of the polymer and size of the metal particles.     

Time Resolved Fluorescence and Energy Transfer Analysis of Nd<Superscript>3+</Superscript>–Yb<Superscript>3+</Superscript>–Er<Superscript>3+</Superscript> Triply-Doped Ba–Al-Metaphosphate Glasses for an Eye Safe Emission (1.54 μm)

This paper reports on the preparation and systematic analysis of energy transfer mechanisms in Nd³⁺–Yb³⁺–Er³⁺ co-doped new series of barium-alumino-metaphosphate glasses. The time resolved fluorescence of Nd³⁺ in triply doped Ba–Al-metaphosphate glasses have revealed that, Yb³⁺ ions could function as quite efficient bridge for an energy transfer between Nd³⁺ and Er³⁺ ions. As a result, a fourfold emission enhancement at 1.54 μm of Er³⁺ ions has been achieved through an excitation of ⁴F_5/2 level of Nd³⁺ at 806 nm for the glass having 3 mol% Yb³⁺ with an energy transfer efficiency reaching up to 94%. Decay of donor (Nd³⁺) ion fluorescence has been analyzed based on theoretical models such as direct energy transfer model (Inokuti–Hirayama) and migration assisted energy transfer models (Burshtein’s hopping and Yokota–Tanimoto’s diffusion). The corresponding energy transfer parameters have been evaluated and discussed. Primarily, electrostatic dipole–dipole (s ~ 6) interactions are found to be responsible for the occurrence of energy transfer process in theses glasses.     

A parameter uniform difference scheme for parabolic partial differential equation with a retarded argument

The paper deals with the analysis of a non-stationary parabolic partial differential equation with a time delay. The highest order derivative term is affected by the small parameter. This is precisely the case when the magnitude of the convective term becomes much larger compare to that of diffusion term. The solution of problem exhibits steep gradients in the narrow intervals of space and short interval of times. In these cases a dissipative loss turned out to be more complex. Even for the one spatial dimension and one temporal variable, not all difference scheme can capture these steep variation. Although the analysis is restricted to the model in one space dimension, the technique and comparison principles developed should prove useful in assessing the merits of numerical solution of other nonlinear model equations too.     

One-pot facile synthesis,crystal structure and antifungal activity of 1,2,3-triazoles bridged with amine-amide functionalities

A library of twenty five 1,2,3-triazoles bridged with amine-amide functionalities have been synthesized from reaction of N-substituted(prop-2-yn-1-yl)amines (2a–2e), 2-bromo-N-arylacetamides (4a–4e) and sodium azide through copper(I)-catalyzed alkyne-azide cycloaddition. The synthesized compounds were characterized by using FTIR, ¹H NMR, ¹³C NMR, and HRMS techniques. The structures of synthesized 5a (CCDC 1569245) and 5h (CCDC 1569249) were also confirmed by X-ray crystallography. Antifungal evaluation of newly synthesized triazoles was carried out against – Candida albicans and Aspergillus niger. Biological screening of synthesized 1,2,3-triazoles revealed moderate to good antifungal activity against tested strains.     

Porosity Switching in Polymorphic Porous Organic Cages with Exceptional Chemical Stability

Porous solids that can be switched between different forms with distinct physical properties are appealing candidates for separation, catalysis, and host–guest chemistry. In this regard, porous organic cages (POCs) are of profound interest because of their solution‐state accessibility. However, the application of POCs is limited by poor chemical stability. Synthesis of an exceptionally stable imine‐linked (4+6) porous organic cage ( TpOMe‐CDA ) is reported using 2,4,6‐trimethoxy‐1,3,5‐triformyl benzene (TpOMe) as a precursor aldehyde. Introduction of the ‐OMe functional group to the aldehyde creates significant steric and hydrophobic characteristics in the environment around the imine bonds that protects the cage molecules from hydrolysis in the presence of acids or bases. The electronic effect of the ‐OMe group also plays an important role in enhancing the stability of the reported POCs. As a consequence, TpOMe‐CDA reveals exceptional chemical stability in neutral, acidic and basic conditions, even in 12 m NaOH. Interestingly, TpOMe‐CDA exists in three different porous and non‐porous polymorphic forms (α, β, and γ) with respect to differences in crystallographic packing and the orientation of the flexible methoxy groups. All of the polymorphs retain their crystallinity even after treatment with acids and bases. All the polymorphs of TpOMe‐CDA differ significantly in their properties as well as morphology and could be reversibly switched in the presence of an external stimulus.