Anion receptor functions of lanthanide tris(beta-diketonate) complexes: naked eye detection and ion-selective electrode determination of Cl- anion

Lanthanide tris(fluorinated beta-diketonates) acted as effective receptors of Cl- anion in luminescence sensing and ion-selective electrode systems via highly coordinated complexation.     

1D and 2D NMR studies of N-vinylcarbazole/butyl methacrylate copolymers

Copolymers containing N-vinylcarbazole (V) and butyl methacrylate (B) units of different compositions were synthesized and their compositions were determined from quantitative ¹³C{¹H} NMR spectroscopy. The reactivity ratios of the comonomers were estimated using the Kelen-Tudos and non-linear error in variable methods. The complete spectral assignment in terms of compositional and configurational sequences of the overlapping ¹H and ¹³C{¹H} spectra of the copolymers were done with the help of distortionless enhancement by polarization transfer, 2D heteronuclear single quantum correlation and total correlated spectroscopy experiments.     

Thermal analysis of lithium tris (malonato) ferrate(III) tetrahydrate

Thermal decomposition of lithium tris (malonato) ferrate (III) tetrahydrate i.e. Li₃[Fe(CH₂C₂O₄)₃].4H₂O has been studied in the temperature range of 353–873 K in static air atmosphere using Mössbauer, infrared spectroscopy and nonisothermal techniques (TG-DTG-DTA). The anhydrous complex decomposed into ferric oxide of varying particle sizes and alkali metal malonates/carbonates in succesive stages. Fimally a solid state reaction between -Fe₂O₃ and alkali metal carbonate gives fine particles of lithium ferrite (LiFeO₂) at a temperature lower than for oxalate precursor and for ceramic method.     

Facile one-step synthesis of N-α-Boc-1-alkyl-l-histidines

N-α-Boc-l-Histidine upon direct τ(N-1) ring alkylation with various alkyl halides in the presence of sodium hydride in DMF or CH₃CN easily afforded N-α-Boc-1-alkyl-l-histidines 2a-f. The reaction works equally well in either DMF or CH₃CN as solvent, however, CH₃CN is preferred due to ease of reaction work-up.     

Solid state photodecomposition of alkaline earth tris/malonato/ferrates/III/

Solid state photolysis of alkaline earth tris/malonato/ferrates/III/, i.e., M₃[Fe(CH₂C₂O₄)₃]₂.xH₂O /M=Mg, Ca, Sr, Ba/ has been investigated employing Mössbauer, infrared and reflectance spectroscopic techniques. The complexes were irradiated for 400 h using a medium pressure mercury vapour lamp of 250 Watts. Photoreduction led to the formation of M[Fe^II(CH₂C₂O₄)₂(H₂O)₂]. The extent of photoreduction showed the following order: Ca>Sr>Mg>Ba. The results have been compared with those of analogous alkaline earth tris/oxalato/ferrates/III/.     

A mercury(II) ion-selective electrode based on neutral salicylaldehyde thiosemicarbazone

A new ion-selective PVC membrane electrode based on salicylaldehyde thiosemicarbazone as an ionophore is developed successfully as sensor for mercury(II) ions. The electrode shows excellent potentiometric response characteristics and displays a linear log[Hg²⁺] versus EMF response over a wide concentration range of 1.778×10⁻⁶-1.0×10⁻¹ M with Nernstian slope of 29 mV per decade with the detection limit of 1.0×10⁻⁶ M. The response time of the electrode is less than 30 s and the membrane electrode operates well in the pH range of 1.0-3.0. The lifetime of the sensor is about 2 months. The electrode shows better selectivity towards Hg²⁺ ions in comparison with the alkali, alkaline and some heavy metal ions; most of these metal ions do not show significant interference (K^Pot_Hg,M values of the order of 10⁻³-10⁻⁴). The present sensor showed comparable or even better performance vis-à-vis similar PVC based ion-selective electrodes reported in literature. The sensor was also applied as an indicator electrode for potentiometric titration of Hg²⁺ions with I⁻ and Cr₂O₇²⁻.     

Cu-assisted C–N bond formations in six-membered N-heterocycle synthesis

Abstract

One of the highly emerging and important aspect of organic chemistry is the metal-catalyzed synthesis of the heterocycles. The methodologies used earlier for its synthesis were less approachable to the organic chemist because of their high cost, highly specified instrumentation and inconvenient methods. For both the stereoselective and regioselective synthesis of six-membered nitrogen-containing heterocycles, cyclic reactions that are Cu-catalyzed have known to be very efficient. The presented review covers the varied applications of Cu as a catalyst and its importance in the formation of six-membered nitrogen-containing heterocycles. The fascinating research that has been done in this area is also enclosed in this review.     

Unlike surfactant–polymer interactions of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate with water-soluble polymers

Single and mixed micelle formation by sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS) and their mixtures in pure water and in the presence of water-soluble polymers such as Synperonic 85 (triblock polymer, TBP), hydroxypropylcellulose (HPC), and carboxymethylcellulose sodium salt (CMC) were studied with the help of conductivity, pyrene fluorescence, cyclic voltammetry, and viscosity measurements. Conductivity measurements showed a single aggregation process for pure surfactants and their mixtures both in pure water as well as in the presence of water-soluble polymers. Triple breaks corresponding to two aggregation processes for SDS, SDBS, and their mixture in the presence of TBP were observed from fluorescence measurements. The first one demonstrated the critical aggregation process due to the adsorption of surfactant monomers on TBP macromolecule. The second one was attributed to the participation of surfactant–polymer aggregates formed at the first one, in the micelle formation process. The aggregation number ( N _agg) of single and mixed micelles and diffusion coefficient ( D) of electroactive probe were computed from the fluorescence and cyclic voltammetry measurements, respectively. Both parameters, along with the viscosity results, indicated stronger SDS–polymer interactions in comparison to SDBS–polymer interactions. Mixed surfactant–polymer interactions showed compensating effects of both pure surfactants. The nature of mixed micelles was found to be ideal in all cases, as evaluated by applying the regular solution and Motomura's approximations.     

Designing,antifungal and structure activity relationship studies of Azomethines and β-lactam derivatives of aza heterocyclic amines

The present investigation deals with the synthesis of seven azomethine derivatives 1–7 of aza heterocyclic amines by carrying out condensation reaction of them with veratraldehyde followed by cyclizing the CHN moiety in synthesized azomethines of 4-amino-1,2,4-triazole and 4-amino antipyrine to yield β lactam derivatives 8–9. The chemical constituents in the synthesized compounds were confirmed by UV, IR, 1H NMR, ¹³C NMR, and elemental analysis. In vitro antifungal activity of all the synthesized products was done against four pathogenic maize fungal strains i.e. Fusarium verticillioides, Macrophomina phaseolina, Rhizoctonia solani, and Dreschlera maydis. It was found that azomethine derivative having 4-amino-1,2,4-triazole ring was as effective as standard carbendazim 50 WP against R. solani and may be considered as promising antifungal agent; therefore further modifications may be done in its structure to get better drug candidate in future.     

Kinetics and mechanism of the oxidation of DL-methionine bybis(2,2′-bipyridyl)copper(II) permanganate

Summary The oxidation ofDL-methionine (MT) bybis(2,2-bipyridyl)copper(II) permanganate (BBCP) to the corresponding sulphoxide is first order in BBCP. Michaelis-Menten-type kinetics were observed with respect to MT. The formation constant of the intermediate complex and the rate constant for its decomposition were evaluated. The thermodynamic and activation parameters were also evaluated. The reaction is catalysed by H⁺ but 2,2-bipyridine does not affect the reaction rate. A mechanism is proposed.