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.     

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.     

Preparation of Aryl‐Substituted E‐Homoallylic Bromides from Cyclopropylcarbinol and PBr3

An expeditious synthesis of aryl substituted E‐homoallylic bromides has been accomplished by the cleavage of cyclopropylcarbinols with phosphorus tribromide.     

Noncovalent Intermolecular Interaction in Cofacially Stacked 24π Antiaromatic Hexaphyrin Dimer

π–π Stacking is omnipresent not only in nature but in a wide variety of practical fields applied to our lives. Because of its importance in a performance of natural and artificial systems, such as light harvesting system and working layer in device, many researchers have put intensive effort into identifying its underlying nature. However, for the case of π–π stacked systems composed of antiaromatic units, the understanding of the fundamental mechanisms is still unclear. Herein, we synthesized a new type of planar β,β’-phenylene-bridged hexaphyrin (1.0.1.0.1.0), referred as naphthorosarin which possesses the 24π-electron conjugated pathway. Especially, the corresponding antiaromatic porphyrinoid shows the unique property to form dimeric species adopting the face-to-face geometry which is unprecedented in cases of known annulated naphthorosarins. In order to elucidate the intriguing properties derived from the stacked dimer, the current study focuses on the experimental support to rationalize the observed π–π interactions between the two subunits.     

Ru(II)‐based antineoplastic: A “wingtip” N‐heterocyclic carbene facilitates access to a new class of organometallics that are cytotoxic to common cancer cell lines

The syntheses, structures, and chemotherapeutic activities of Ag(I)‐, Au(I)‐, and Ru(II)‐complexes ligated to a novel N‐heterocyclic carbene ligand, 2‐(4‐nitrophenyl)imidazo[1,5‐a]pyridin‐2‐ylidene ( 1 ), are described. The corresponding complexes, [Ag( 1 )₂][PF₆], [Au( 1 )₂][PF₆] ( 3 ), and [Ru( 1 )(p‐cymene)Cl][PF₆] ( 4 ), were prepared using convenient transmetallation chemistry and characterized using a range of spectroscopic and analytical techniques. X‐ray crystallography revealed that complexes 2 and 3 adopted linear structures whereas 4 exhibited a prototypical “piano‐stool”‐like geometry; the structural assignments were further supported by DFT calculations. A series of in vitro studies revealed that while the aforementioned Ag(I), Au(I) and Ru(II) complexes exhibited significant cytotoxicities against the human colon adenocarcinoma (HCT 116), lung cancer (A549), and breast cancer (MCF7) cell lines, the Ru derivative was most prominent.     

Ultrafast Excited State Relaxation Dynamics of New Fuchsine- a Triphenylmethane Derivative Dye

An all-inclusive investigation of the ultrafast excited state relaxation dynamics of a triphenylmethane derivative molecule, New Fuchsine (NF), using a combined approach of density functional theory (DFT), femtosecond transient absorption spectroscopy (fs-TAS), and photoluminescence spectroscopy is presented in this work. The DFT calculations confirmed the formation of twisted molecular structure in the excited state of NF in ethanol solution with bond rotation of ≈86°. TAS measurements of NF solution exhibited ultrafast ground state-recovery pathway via a conical intersection confirming an ultrafast structural reorientation. On the contrary, TAS measurements of NF thin-film exhibited a longer excited-state lifetime suggesting a hindered molecular twisted state formed as an intermediate step. Photophysical kinetic models are proposed to globally fit the fs-TAS data establishing the twisted intramolecular charge transfer (TICT) state mediated ground state recovery for NF in solution and thin film, respectively. Temperature-dependent photoluminescence study of NF film provided a clear insight into the effect of rotational motion of phenyl rings in NF molecules over the TICT mediated emission.