Synthesis,structural characterization and biological studies of neodymium(III) and samarium(III) complexes with mercaptotriazole Schiff bases

A series of neodymium(III) and samarium(III) complexes of type [Ln(L)Cl(H₂O)₃] have been synthesized with Schiff bases (LH₂) derived from 3‐(phenyl/substituted phenyl)‐4‐amino‐5‐mercapto‐1,2,4‐triazoles and isatin. The structures of the complexes were established using elemental analysis, molar conductivities, magnetic moments, infrared, NMR (¹H, ¹³C) and UV–visible spectra, X‐ray diffraction and mass spectrometry. The thermal behaviour of these compounds under non‐isothermal conditions was investigated using thermogravimetry and differential thermogravimetry. The intermediates obtained at the end of various thermal decomposition steps were identified from elemental analysis and infrared spectral studies. All the ligands and their complexes were also screened for their antibacterial activity against Staphylococcus aureus and Bacillus subtilis and antifungal activity against Aspergillus niger, Aspergillus flavus and Colletotrichum capsici. The screening results were correlated with the structural features of the compounds. Copyright © 2015 John Wiley & Sons, Ltd.     

Crystallographic and microstructural aspects of the superconductor YBa2Cu3O7-y —an overview

Crystal structures and structural inhomogeneities observed in YBa₂Cu₃O_7-y are reviewed. It is brought out that a proper understanding of the nature of the structural inhomogeneities is essential for exploiting the technological potential of this material. The need for an adequate characterization of specimens used for experiments is emphasized. Practical implications of the ferroelastic nature of the material are discussed.     

Synthesis,Structures, and Fungitoxicity of Novel Organophosphorus Compounds

Abstract

A series of biologically active organophosphorus compounds have been synthesized by the reactions of O,O-diethylchlorophosphate with Schiff bases derived from 5-(phenyl/substituted phenyl)-2-hydrazino-1,3,4-oxadiazole and salicylaldehyde/2-hydroxyacetophenone. The compounds have been characterized on the basis of analyses and spectral (IR, ¹H, ¹³C NMR) data. Fungicidal activities of these derivatives against Colletotrichum falcatum, Fusarium oxysporum, and Curvularia pallescence have been evaluated. All compounds showed moderate to significant antifungal activity.     

Macroscopic recognition of iodide by polymer appended calix[4]amidocrown resin

ABSTRACT

The current study reveals the synthesis of polymer appended Calix[4]amidocrown-5 with specific binding affinity for iodide at ppm-level. The low detection limits are observed via UV-vis and fluorescence spectroscopy. The time-dependent solution and solid-state ¹²⁷I NMR studies with 18.8 and 19 ppm shifts, indicate a strong sensing nature of resin towards iodide ion. A significant reduction in surface area and pore volume with higher thermostability of resin after iodide uptake indicated iodide inclusion in the amidocrown cavity. The mechanism of iodide sensing may be governed by noncovalent interactions of NH and OH protons present in amidocrown and phenyl ring as observed in terms of emission enhancement in fluorescence spectroscopy. The binding affinity and stoichiometric determinations are determined by Benesi-Hildebrand and Jobs plots, respectively.     

Molecular Modeling and 3D-QSAR Studies in 2-Aziridinyl-and 2,3-Bis(Aziridinyl)-1,4-Naphthoquinonyl Sulfonate and Acylate Derivatives as Potential Antimalarial Agents

Abstract

Malaria is still continuing to be one of the most dreadful diseases of the tropical countries particularly due to the development of resistance to the existing antimalarials. From observed, antimalarial activity of 2-aziridinyl- and 2,3-bis(aziridinyl)-1,4-naphthoquinonyl sulfonate and acylate derivatives acting through redox cycling mechanism, molecular modeling and three dimensional-quantitative structure activity relationship (3D-QSAR) studies have been carried out on a set of 63 compounds to identify important pharmacophors. Among several 3D-QSAR models generated, three models with correlation coefficient r > 0.82, match > 0.60 and chance = 0.00 have shown two common biophoric sites: one being the oxygen atom at position 1 of the naphthoquinone ring in terms of π-population, charge and electron donating ability while the second being the center of the phenyl ring in terms of its 6π-electrons. In addition to these sites, the models also share two common secondary sites: one positively contributing H-acceptor site while the second site contributing negatively in terms of steric refractivity. All these models showed good agreement between the experimental, calculated and predicted antimalarial activities.     

Experimental study and performance evaluation of various cook stove models based on energy and exergy analysis

This article presents the experimental study and comparative performance evaluation of four types of cook stoves using energy and exergy analysis. Analysis of four different types of cook stove models viz. Envirofit, Mangla, Harsha and Vikram were selected and the water boiling test has been carried out. The suitable biomass available from the local market was prepared in the proper size as described in the Bureau of Indian Standards (BIS) and has been used as the fuel for cook stove in this experimental study. The aluminium pots of proper capacity as per BIS standard have been used for different cook stoves. The data from the experiments was collected and evaluated for the energy and exergy efficiencies for different models. Based on the data analysis it is found that the exergy efficiency is much lower than that of the energy efficiency for all the four models. It is also found that the both the efficiencies of Envirofit model are found to be higher than those of other models studied here.     

A Convenient Synthetic Entry Into 2,2-Diorganyl-5,6-Diaryl-1,3,4,2-Dioxaza Silacyclohexene Derivatives VIA Dianion Cyclisation: Sequential One-Pot Cyclosylation

In a convenient one-pot sequence, treatment of bezoin and p-anisoin oximes with sodium hydride in dry THF in 1:2 molar ratio generates 1,5-dianion, which upon subsequent addition of diorganodichlorosilane yields 1,3,4,2-dioxazasilacyclohexene derivatives in good yields. In general, very often a salt elimination route is used for the synthesis of the title compounds.     

Cyclizations of Some Terminally Substituted a,c-Biladienes

Several examples of 1′,8′-disubstituted a,c-biladiene salt cyclizations, using copper(II) or iodine/bromine in hot o-dichlorobenzene, to give meso-substituted porphyrins are described.     

An Efficient Synthesis of Coumestans-A Probable Biogenetic Approach

A probable biogenetic type synthesis of coumestans by coupling in-situ generated o-quinones by mushroom tyrosinase oxidation of catechol and 4-hydroxy coumarins is reported.     

Surface modification of semiconductor photoelectrodes for better photoelectrochemical performance

The present paper describes the modification and solar hydrogen production studies employing a new semiconductor-septum (SC-SEP) photoelectrode ns-TiO₂/In₂O₃ based photoelectrochemical solar cell. The current-voltage characteristics of the above SC-SEP cell revealed that an enhancement in short-circuit current (I_SC) up to three times (5 ～ 14.6 mA cm^?2). The optimum hydrogen production rate was found to be 11.8 lh^?1 m^?2 for 5M H₂SO₄ and with a further increase in H₂SO₄ concentration, the hydrogen production rate was found to be invariant. In yet another part of our study instead of using new SC-SEP solar cell design, we used another new oxide material form such as ns-TiO₂/WO₃. The ns-TiO₂/WO₃ exhibited a high photocurrent and photo-voltage of 15.6 mA cm^?2, 960 mV, respectively. The ns-TiO₂/WO₃ electrode exhibited a higher hydrogen gas evolution rate of 13.8 lh^?1 m^?2. Evidences and arguments are put forward to show that, whereas for the bare ns-TiO₂ electrode, the improvement in the performance of this photo-electrode compared with its original form was due to the higher quantum yield. In the case of ns-TiO₂/In₂O₃ and ns-TiO₂/WO₃ photo-electrodes, the improvement is due to the improved spectral response resulting from decrease of energy band gap.