Copper(II) complexes of thioarylazo-pentanedione: Structures,magnetism, redox properties and correlation with DFT calculations

Copper(II) complexes of 3-((2-(alkylthio)phenylazo)-2,4-pentanedione, tridentate O, N, S donor ligands, are described in this work. Chloride bridged copper(II) polymers (1) and thiocyanato bridged copper(II) dimmers (2) are characterized by a single crystal X-ray diffraction study. The complexes show antiferromagnetic interactions, with J = −0.5 ± 0.1 cm⁻¹ (1a) and −25.8 ± 0.5 cm⁻¹ (2b), which implies stronger coupling in the –SCN-bridging compound. The spectra, redox and magnetism are explained by DFT studies.     

A Comparative Study of Nucleon Structure in Light-Front Quark Models in AdS/QCD

We present a comparative study of nucleon structure such as electromagnetic form factors, transverse charge and magnetization densities in three different models within AdS/QCD framework.     

Experimental observation of dust circulation in unmagnetized cogenerated dusty plasma

The vortex motion of a dust cloud was experimentally observed in unmagnetized cogenerated dusty plasma in different experimental parameters. Particle image velocimetry analysis demonstrated that several vortex zones exist in the dust cloud at relatively low pressures (0.06 mbar (or 6 Pa)–0.08 mbar (or 8 Pa)) and low discharge voltages (peak‐to‐peak voltage 540–560 V), whereas in relatively high pressure (0.4 mbar (or 40 Pa)–0.7 mbar (or 70 Pa)) and high discharge voltage (peak‐to‐peak voltage 690–740 V), dust vortices formed in dense dust cloud with background plasma fluctuation.     

A study on the electronic effect of <Emphasis Type="Italic">para</Emphasis> substituents in the aryloxy ring of the hydrazone ligands on the vanadium centre in a family of mixed-ligand [V<Superscript>V</Superscript>O(ONO)(OO)] complexes

[V^IVO(acac)₂] reacts with the methanolic solutions of tridentate dibasic ONO donor hydrazone ligands derived from the condensation of benzoyl hydrazine with either 2-hydroxyacetophenone (H₂L¹) or its para-substituted derivatives (H₂L^2–4) (general abbreviation H₂L), in the presence of vanillin (Hvan) in equimolar ratio under aerobic conditions generating the mixed-ligand oxovanadium(V) complexes of the type [V^VO(L)(van)], (1)–(4) in good yield. All the complexes are diamagnetic and exhibit only ligand-to-metal charge transfer (l.m.c.t.) band near 510 nm in addition to intra-ligand (π → π*) transition band near 330 nm in CH₂Cl₂ solution. ¹H-n.m.r. spectra of the complexes in CDCl₃ solution indicate the presence of two isomeric forms [(1A), (1B); (2A), (2B); (3A), (3B) and (4A), (4B)] in different ratios, which is explained by the interchange of the two binding sites of van⁻ motif between its coordinated equatorial and axial positions. Complexes display two quasi-reversible one electron reduction peaks near +0.10 V and near +0.30 V versus s.c.e. in CH₂Cl₂ solution which are attributed to the successive reduction of V^V→ V^IV and the V^IV→ V^III motifs, respectively. λ_max (for l.m.c.t. transition), and the two reduction potential values (E _1/2)^I (average of the first step anodic and first step cathodic peak potentials) and (E _1/2)^II (average of the second step anodic and second step cathodic peak potentials) of the complexes, are found to be linearly related to the Hammett constants (σ) of the substituents in the aryloxy ring of the hydrazone ligands. λ_max, (E _1/2)^I and (E _1/2)^II values show large dependence: dλ_max/dσ = 37.29 nm, d(E _1/2)^I/dσ = 0.21 V and d(E _1/2)^II/dσ = 0.21 V, respectively, on σ.     

Synthesis and characterization of a polymer-anchored palladium(II) Schiff base complex and its catalytic efficiency in phosphine-free Sonogashira coupling reactions

A polymer-anchored Pd(II) Schiff base complex has been synthesized by reacting a polymeric amine with 2-pyridinecarboxaldehyde to get the polymer-anchored Schiff base, which was then reacted with palladium acetate. The catalyst was characterized by physicochemical and spectroscopic methods. It shows excellent catalytic activity in the Sonogashira coupling of phenylacetylene with aryl halides using triethylamine as a base and copper iodide as a co-catalyst in water under open air at 70 °C. We have also studied the effects of base and solvent on the coupling reaction. Sonogashira reactions of phenylacetylene with a variety of functionalized aryl halides were performed under the optimized reaction conditions. This catalyst gives excellent yields without the use of phosphine ligands. Further experiments showed that the catalyst can be used five times without much loss in the catalytic activity.     

Synthesis,characterization and catalytic activities of a reusable polymer-anchored palladium(II) complex: effective catalytic hydrogenation of various organic substrates

A poly(3,6-dibenzaldimino N-vinyl carbazole) Pd(II) complex has been synthesized and characterized by physicochemical and spectroscopic techniques. The complex was found to be highly active toward hydrogenation reactions of various organic substrates under atmospheric pressure at ambient temperature. A tentative reaction mechanism is proposed on the basis of kinetic studies and isolation of reactive intermediates. The catalyst shows good conversion rates, thermal stability and recyclability.     

Micellar Effect on Chromium(VI) Oxidation of Ethanol and Propan-1-ol in Aqueous Acid Media

Cetylpyridinium chloride (CPC) inhibits the Cr(VI) oxidation of ethanol and propan-1-ol while sodium dodecyl sulfate (SDS) catalyzes the title reactions. At higher values of the [surfactant], the rate attains a limiting value. The micellar effect has been explained by considering the preferential partitioning of the reactants in terms of the suggested mechanism. Applicability of the Menger-Portnoy model and Piszkiewicz model to explain the observed micellar effect has been examined. This revised version was published online in June 2006 with corrections to the Cover Date.     

Two CdII/CoII‐Imidazolate Coordination Polymers: Syntheses,Crystal Structures,Stabilities, and Luminescent/Magnetic Properties

Cadmium(II) based 2D coordination polymer [Cd(L1)₂(DMF)₂] ( 1 ) (L1 = 4,5‐dicyano‐2‐methylimidazolate, DMF = N,N′‐dimethylformamide) and 2D cobalt(II)‐imidazolate framework [Co(L3)₄] ( 2 ) (L3 = 4,5‐diamide‐2‐ethoxyimidazolate) were synthesized under solvothermal reaction conditions. The materials were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X‐ray diffraction measurement (PXRD) and single‐crystal X‐ray diffraction. Compound 1 has hexacoordinate Cd^II ions and forms a zigzag chain‐like coordination polymer structure, whereas compound 2 exhibits a 2D square grid type structure. The thermal stability analysis reveals that 2 showed an exceptional thermal stability up to 360 °C. Also, 2 maintained its fully crystalline integrity in boiling water as confirmed by PXRD. The solid state luminescent property of 1 was not observed at room temperature. Compound 2 showed an independent high spin central Co^II atom.