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.     

Static and dynamic properties of KCN<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Cl<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>

An extended three-body force shell model (ETSM) has been applied to investigate the static and dynamic properties of KCN _x Cl_1−x for the compositionx = 0.56 and 1.0 at 300 K. The phonon dispersion curves computed by us are compared with the single crystal neutron diffraction data. The unusual features of these curves are the upward curvature seen in some of the acoustic branches. This is a result ofK-dependent softening of the phonon due to translation-rotation coupling. The transverse acoustic branch is more soft near the zone centre.     

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.     

Effect of microhydration on the atmospherically important metastable carbonyl sulfide anion: Structure,energetic, and infrared study

Structure, energetics, and vibrational frequency of the microhydrated carbonyl sulfide anion [OCS^?? (H₂O)_n (n = 1–6)] have been explored by the systematic ab initio study to have a comprehensive understanding about the hydration‐induced stabilization phenomenon of OCS^?. Water binds with the OCS^? in single hydrogen‐bonded (SHB) or double hydrogen‐bonded (DHB) fashion with O? H S and O? H O contacts. Maximum five water molecules can stay in a cyclic water network of these hydrated clusters forming interwater hydrogen bonding (IHB) with each other and out of this, maximum of two water molecules can bind directly to the OCS^? in (DHB) arrangement. The stabilization energy values of OCS^?? (H₂O)_n depict that ion–water interaction is significant up to four water molecules and beyond that OCS^? is stabilized by IHB between the water molecules. The CO stretching frequency of OCS^? gets red shifted, whereas CS stretching frequency gets blue shifted on hydration. Charge analysis of hydrated clusters of OCS^? indicates that negative charge moves toward oxygen from sulfur on hydration. © 2015 Wiley Periodicals, Inc.     

Phenanthroline-fluorescein molecular hybrid as a ratiometric and selective fluorescent chemosensor for Cu2+ via FRET strategy: synthesis,computational studies and in vitro applications

A FRET-based chemosensor L containing donor phenanthroline and acceptor fluorescein moiety was designed, synthesised and characterised for the ratiometric fluorescent detection of Cu²⁺ in organo-aqueous solution. Probe L showed high selectivity and excellent sensitivity towards Cu²⁺ ions by exhibiting both colorimetric and fluorometric changes due to opening of the spirolactum ring of fluorescein upon complexation with Cu²⁺. In presence of Cu²⁺ ions, probe L formed L-Cu²⁺ complex in 1:1 stoichiometric fashion which is established on the basis of Job’s plot and mass spectroscopy. We also performed DFT computational studies to know the binding nature and coordination feature of the complex. Furthermore, fluorescence imaging studies revealed that probe L was cell permeable and could be used to detect intracellular Cu²⁺ in living cells.     

A novel approach for the one-pot synthesis of linear and angular fused quinazolinones

A convenient and inexpensive one step methodology has been developed for the synthesis of linear and angular fused quinazolinones. The protocol, which uses amino heterocycles and o-bromo benzyl/naphthyl bromides as reactants, CuI as catalyst, Cs₂CO₃ as base, l-proline as ligand, and DMF as solvent, proceeds via nucleophilic aromatic substitution of the N-heteroaromatic cationic intermediate followed by in situ aerial oxidation at the benzylic position to the quinazolinone scaffold.     

Synthesis,characterization, and catalytic activity of a polymer-supported copper(II) complex with a thiosemicarbazone ligand

A thiosemicarbazone Cu(II) complex anchored to a polystyrene framework has been synthesized and characterized by analytical and spectroscopic techniques. The complex was found to be a highly active catalyst for the oxidation of various organic substrates including alkenes and alcohols using H₂O₂ as oxidant. The reaction conditions were optimized with respect to temperature, solvent, oxidant, catalyst amount, and substrate to peroxide ratio. The heterogeneous catalyst was reused five times without significant loss of activity. A comparison between the catalytic activities of this polymer-supported Cu(II) complex and its homogeneous analogue was carried out.     

Synthesis of polypyrrole nanoparticles and its grafting with silica gel for selective binding of chromium(VI)

Polypyrrole nanoparticles of desired structure have been synthesized through simple micelle technique. It is then grafted with functionalized silica gel to develop a novel organic-inorganic hybrid material. The role of dimethyl dichloro silane (coupling agent) in grafting is demonstrated. The nanoparticles are characterized by TEM, SEM and TGA. Grafting reactions are evaluated by spectral (FTIR) analysis and chemical test. The Cr(VI) binding behavior of the composite is studied in various pH of the medium. The selectivity in binding Cr(VI) is monitored. The metal ion adsorption capacity and surface area of the material are found to be 38 mg/g and 235 m²/g, respectively.     

Asymmetric stochastic localization in geometry controlled kinetics

We consider the motion of Brownian particles confined in a two-dimensional symmetric bilobal enclosure with uneven cross section. Varying cross section of the confinement results in an effective entropic potential in reduced dimension. By employing two external noise forces, one additive and another multiplicative along x direction, we demonstrate that a correlation between them causes a symmetry breaking of entropic stability, i.e., a difference in relative stability of two lobes. This leads to an asymmetric localization of population in the stationary state. A two-state model is proposed to explain the asymmetric localization of population due to entropic diffusion.