Controlled synthesis and photoluminescence properties of ZnS nanowires and nanoribbons

Rapid synthesis of wurtzite ZnS nanowires and nanoribbons has been achieved by a simple thermal evaporation of ZnS powder onto Si substrate in the presence of Au catalyst. A vapor-liquid-solid process is proposed for the formation of the ZnS nanostructures. The flow rate of the inert carrier Ar gas along with the temperature play an important role in defining the morphology of the ZnS nanostructures. The morphological change of the ZnS nanostructures and their growth sequence were studied through scanning electron microscopy. Room-temperature photoluminescence measurements showed intense blue emission at approximately 398 nm from both the nanowires and the nanoribbons.     

Synthesis,structural and biochemical aspects of titanocene and zirconocene chelates of acetylferrocenyl thiosemicarbazones

The reactions of bis(cyclopentadienyl)titanium(IV)/zirconium(IV) dichloride with a new class of organometallic thiosemicarbazones (LH), derived by condensing acetylferrocene with substituted thiosemicarbazides, have been studied and two types of bimetallic products, viz. [Cp₂M(L)Cl] (M = Ti or Zr) and [CpZr(L)₃], have been isolated. On the basis of various physicochemical and spectral studies, five- and seven-coordinate structures have been assigned to these derivatives, respectively. Attempts have been made to establish a correlation between biological activity and the structures of the products.     

Synthesis,spectroscopic and thermal studies on ruthenium(III), rhodium(III) and iridium(III) complexes with hydrazones derived from 2,6-diacetylpyridine and different aromatic hydrazides

Summary The reactions of MCl₃·3H₂O (M=Ru, Rh or Ir) with hydrazones have been studied by three different methods and complexes of the types [M(LH₂)(H₂O)₂]Cl₃, [M(L)Cl(H₂O)] and [M(LH₂)Cl₂]Cl·H₂O have been isolated. Tentative structural conclusions are drawn for these products based upon elemental analysis, electrical conductance, magnetic moment, and i.r. and¹H n.m.r. data. The thermal stability and mode of decomposition for the complexes have been studied by t.g.a., d.t.g. and d.s.c. techniques.     

Synthesis and physico-chemical and biological studies on ruthenium (III) complexes with Schiff bases derived from aminocarboxylic acids

Summary Ruthenium(III) complexes of types [Ru(L)₃], [Ru(L)Cl(H₂O)₂], [Ru(L)Cl₂]_n, [Ru(L)Cl(H₂O)]_n(LH =Schiff bases derived from anthranilic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde orm-hydroxyacetophenone; LH₂=Schiff bases derived from anthranilic acid and salicylaldehyde oro-hydroxyacetophenone; LH=Schiff bases derived fromp-aminobenzoic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde orm-hydroxyacetophenone; LH₂=Schiff bases derived fromp-aminobenzoic acid and salicylaldehyde oro-hydroxyacetophenone) have been synthesized and characterized on the basis of elemental analyses, conductance, magnetic moment and spectral (electronic, i.r. and¹H n.m.r.) data. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of crystal field theory and various parameters have been evaluated. On the basis of the electronic spectra, an octahedral geometry has been established for all these complexes except [Ru(L)Cl₂]_n. The complexes [Ru(L)Cl₂]_n are pentacoordinate and a trigonal-bipyramidal environment, D_3h, is suggested for the ruthenium(III) ion. The thermal behaviour of these complexes has also been studied by t.g., d.t.g and d.s.c techniques. Heats of reaction for the decomposition steps were calculated from the d.s.c. curves. The antifungal and antiviral activities of the complexes with Schiff bases derived from anthranilic acid were also investigated.     

An Anthracene-Based Metal-Organic Framework for Selective Photo-Reduction of Carbon Dioxide to Formic Acid Coupled with Water Oxidation

A Zr-based metal-organic framework has been synthesized and employed as a catalyst for photochemical carbon dioxide reduction coupled with water oxidation. The catalyst shows significant carbon dioxide reduction property with concomitant water oxidation. The catalyst has broad visible light as well as UV light absorption property, which is further confirmed from electronic absorption spectroscopy. Formic acid was the only reduced product from carbon dioxide with a turn-over frequency (TOF) of 0.69 h⁻¹ in addition to oxygen, which was produced with a TOF of 0.54 h⁻¹. No external photosensitizer is used and the ligand itself acts as the light harvester. The efficient and selective photochemical carbon dioxide reduction to formic acid with concomitant water oxidation using Zr-based MOF as catalyst is thus demonstrated here.     

High Activity and Selective Fischer–Tropsch Catalysts for Use in a Microchannel Reactor

Each process configuration for practicing the Fischer–Tropsch synthesis places demands particular to that configuration on the catalyst to be used. We discuss how a particular catalyst, prepared by the OMX (organic matrix combustion) method, when used in conjunction with the Velocys microchannel reactor system, results in a very stable, high performance Fischer–Tropsch synthesis system. With the ability to remove heat far more effectively than a conventional reactor system, this microchannel reactor requires a catalyst with much higher volumetric reactive site density. Further, with such a high volumetric reaction rate, mass transfer effects will be important in both the observed activity and selectivity of the operating catalyst. Nevertheless, the catalyst prepared using the OMX method exhibits an apparent turnover frequency which is considerably higher than reported for other catalysts in the literature. In addition to high activity, an economically useful catalyst must exhibit a stable, high selectivity for liquid products and be able to recover near-fresh performance using a regeneration approach which can be carried out with the catalyst in-place. An example of such a stable, multiply regenerated catalyst is given. Finally, further development has focused on a catalyst with even higher C₅₊ selectivity.     

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.     

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.