Oxygen binding to sulfur in nitrosylated iron--thiolate complexes: relevance to the Fe-containing nitrile hydratases

Iron-nitrosyl complex containing S-bonded monosulfinate [PPN][(NO)Fe(S,SO2-C6H4)(S,S-C6H4)] (3) has been isolated from sulfur oxygenation of complex [PPN][(NO)Fe(S,S-C6H4)2] (2) which is obtained from addition of NO molecule to [PPN][(C4H8O)Fe(S,S-C6H4)2] (1) in organic solvents. This result reveals that binding of NO to the iron center promotes sulfur oxygenation of iron dithiolates by dioxygen and stabilizes the S-bonded sulfinate iron species. Analysis of the bond angles for complexes 2 and 3 reveals that iron is best described as existing in a distorted trigonal bipyramidal coordination environment surrounded by one NO, three thiolates, and one sulfinate in complex 3, whereas the distorted square pyramidal geometry is adopted in complex 2. Complex 3 further reacts in organic solvents with molecular oxygen in the presence of [PPN][NO2] to produce the dinuclear bis(sulfinate) complex [PPN]2[(NO)Fe(SO2,SO2-C6H4)(S,S-C6H4)]2 (4). Complex 3 showed reaction with PPh3 in THF/CH2Cl2 to yield complex 2 and Ph3PO. Upon photolysis of CH2Cl2 solution of complex 3 under N2 purge at ambient temperature, the UV-vis and IR spectra consistent with the formation of complex 2 demonstrate that complex 2 and 3 are photochemically interconvertible. Obviously, complex 3 is thermally quite stable but is photochemically active toward [O] release. Also described are the X-ray crystal structures of 3 and 4.     

Size controlled synthesis of ZnO nanoparticles via electric field assisted continuous spray pyrolysis (EACoSP) reactor

ZnO nanoparticles were synthesized by the continuous spray pyrolysis technique (CoSP) and the effect of applied voltage across the spray nozzle and an annular ground electrode during spray has been studied. X-ray diffraction and transmission electron microscopy studies showed that the product has (hexagonal) wurtzite structure with the average particle size decreasing from 18.5?nm to 12.9?nm in the presence of a high DC voltage (1?kV). The higher value of the absorption peak for the nanoparticles synthesized without voltage is supportive of this behavior. The films deposited by spin coating using these nanoparticles can be used for a variety of applications, particularly as photoelectrodes for dye-sensitized solar cells.     

Electrochemical parameters of aluminum oxide film in situ during anodization of aluminum by white light-optical interferometry

Optical Review - Both Fabry–Pérot interferometry and the DC electrochemical method have been simultaneously used for the first time to measure in situ the anodic current density (J) of...     

Convergence to agreement and the role of public information

When states of the world are normally distributed, the sequential exchange and revision of beliefs converges to agreement in finitely many rounds of communication. Public information may reduce the information shared by individuals after the revision of beliefs.     

Accessing C2-Functionalized 1,3-(Benz)azoles through Transition Metal-Catalyzed C−H Activation

The skeletal presence of 1,3-azoles in a variety of bioactive natural products, pharmacophores, and organic materials demands the derivatization of such heteroarenes regioselectively. Plenty of cross-coupling as well as cyclocondensation reactions have been performed to build up these skeletons but remained commercially unrealizable. A couple of severe drawbacks are faced by these traditional protocols that require a more straightforward strategy to obviate them. Transition metal-catalyzed C−H functionalization has emerged as a superior alternative in that context. 1,3-Azoles and their benzo counterparts have been extensively functionalized exploiting both noble and earth-abundant transition metals. Lately, C-2 functionalization have gained much traction due to the ease of attaining high regioselectivity and installation of synthetically manipulative functionalities. This critical review presents a bird‘s eye view of all major C-2 functionalization of (benz)azoles catalyzed by a diverse set of metals performed over the past 15 years.     

The k-essence scalar field in the context of Supernova Ia observations

We study a framework where the hypothesis of a minimum length in space-time is complemented with the notion of reference frame invariance. It turns out natural to interpret the action of the obtained reference frame transformations in the context of doubly special relativity. As a consequence of this formalism we find interesting connections between the minimum length properties and the modified velocity-energy relation for ultra-relativistic particles. For example, we can predict the ratio between the minimum lengths in space and time using the results from OPERA on superluminal neutrinos.     

Fate of an accretion disc around a black hole when both the viscosity and dark energy is in effect

This paper deals with the viscous accretion flow of a modified Chaplygin gas towards a black hole as the central gravitating object. A modified Chaplygin gas is a particular type of dark energy model which mimics of radiation era to phantom era depending on the different values of its parameters. We compare the dark energy accretion with the flow of adiabatic gas. An accretion disc flowing around a black hole is an example of a transonic flow. To construct the model, we consider three components of the Navier–Stokes equation, the equation of continuity and the modified Chaplygin gas equation of state. As a transonic flow passes through the sonic point, the velocity gradient being apparently singular there, it gives rise to two flow branches: one in-falling, the accretion and the other outgoing, the wind. We show that the wind curve is stronger and the wind speed reaches that of light at a finite distance from the black hole when dark energy is considered. Besides, if we increase the viscosity, the accretion disc is shortened in radius. These two processes acting together make the system deviate much from the adiabatic accretion case. It shows a weakening process for the accretion procedure by the work of the viscous system influencing both the angular momentum transport and the repulsive force of the modified Chaplygin gas.