Lack of Linear Free Energy Relationships in the p-Toluenesulfonic Acid Mediated Chromium(VI) Oxidation of Organic Sulfides

Summary.  The oxidation of methylphenyl sulfide by imidazolium dichromate in acetonitrile mediated by p-toluenesulfonic acid is first order in IDC and TsOH and zero order in MeSPh in the concentration range studied. The IDC oxidation of 14 para-, meta-, and ortho-substituted phenylmethylsulfides at 20–45°C conforms to the isokinetic relationship but not to any of the linear free energy relationships; the isokinetic temperature lies within the experimental temperature range. Received April 18, 2000. Accepted (revised) July 12, 2000     

Linear free energy relationships in the chromium(VI) oxidation of sulfides in acetonitrile

The oxidation of 14 para-, meta-, and ortho-substituted phenyl methyl sulfides with isonicotinium dichromate in acetonitrile, brought out by p-toluenesulfonic acid, follows a common mechanism, conforms to the isokinetic relationship but not to any of the linear free energy relationships; the isokinetic temperature lies in the experimental temperature range.     

Kinetic Studies on the Oxidation of Organic Sulfides with Percarbonate in Acetic Acid

Oxidation of organic sulfides by anhydrous H₂O₂using percarbonate in glacial acetic acid is a second order reaction and is independent of the acidity of the medium. The oxidation conforms to the isokinetic and Hammett relationships.     

Substituent effect on nano TiO2‐ and ZnO‐catalyzed phenol photodegradation rates

Photodegradation of phenol on TiO₂ P25 Degussa, TiO₂ Hombikat, TiO₂ anatase, and ZnO nanoparticles exhibits identical photokinetic behavior. The degradation rates of 15 ortho‐, meta‐ and para‐ substituted phenols on the four semiconductor nanocrystals do not conform to the electronic effect of the substituents but show some common features. While the orthosubstituents slow down the reaction, nitro and hydroxyl groups enhance the same. The effects are rationalized. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 275–283, 2009     

Photosensitization of Imidazole Derivative by ZnO Nanoparticle

A sensitive imidazole based fluorescent sensor like 4, 5-diphenyl-2(E)-styryl-1H-imidazole, for ZnO has been designed and synthesized via simple steps. The absorption, fluorescence, SEM, EDX and IR studies indicate that imidazole derivative is bound on the surface of ZnO semiconductor. Based on photo-induced electron transfer (PET) mechanism, fluorescent enhancement has been explained and apparent binding constant has been calculated. Ligand adsorption on ZnO nanoparticle lowers of the HOMO and LUMO energy levels of imidazole derivative and the chemical affinity between the nitrogen atom of the imidazole and zinc ion on the surface of the nano oxide may be a reason for strong adsorption of the ligand on nanoparticle. The electron injection from photo excited imidazole derivative to the ZnO conduction band (S(*)→S(+) + e (CB) (-) ) accounts for the enhanced fluorescence.     

Formation of Peracetic Acid upon Aging of Perborate in Acetic Acid. Kinetics of the Oxidation of S-Phenylmercaptoacetic Acids

Summary.  Upon aging, perborate in glacial acetic acid generates peracetic acid and thus oxidizes S-phenylmercaptoacetic acid rapidly. Perborate dissolved in ethylene glycol, however, does not show the aging effect, and the corresponding oxidation proceeds smoothly. The oxidation is of second order and not acid catalyzed. Boric acid and borate do not influence the oxidation. In the smooth oxidation, is the reactive species. The oxidation of some para-substituted S-phenylmercaptoacetic acids conforms to the Exner relationship, indicating operation of a common mechanism. Also, the oxidation obeys the Hammett equation with a negative reaction constant. However, the oxidation of p-nitro-S-phenylmercaptoacetic acid follows a different kinetic pathway. Received March 15, 2000. Accepted (revised) May 3, 2000     

Study of interfacial charge transfer in nanosemiconductor–molecule composites

Interaction of sol–gel synthesized Ce–Ag‐codoped ZnO (CSZO) nanocrystals with (E)‐1‐(naphthalen‐1‐yl)‐2‐styryl‐1H‐phenanthro[9,10‐d]imidazole has been analysed. The synthesized nanocrystals and their composites with naphthyl styryl phenanthrimidazole have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X‐ray spectroscopy, X‐ray diffractometry, X‐ray photoelectron spectroscopy (XPS) lifetime and Fourier transform infrared spectroscopy and cyclic voltammetry. XPS shows doped silver and cerium in Ag⁰ and Ce⁴⁺ states, respectively_. SEM and TEM images of CSZO nanoparticles show that they appear to be 3D trapezoid and cocoon‐like shape. The selected area electron diffraction pattern supports the nanocrystalline character of the synthesized material. The percentages of doping of cerium and silver in CSZO are 0.54 (at.) and 0.34 (at.), respectively. From the energy levels of the materials used in the imidazole–CSZO composite, the dominant CT direction has been analysed. Theoretical investigation shows that the binding energy and energy gap of the imidazole composites are highly dependent on the nature of the silver oxide cluster and that charge transfer in the imidazole–Ag₄O₄ composite is faster than the same in other composites. Molecular docking technique has also been carried out to understand the imidazole–DNA interactions. Copyright © 2016 John Wiley & Sons, Ltd.     

Total synthesis of 4,5,7a,8-tetrahydro-1,2-dimethoxyphenanthro[10,1-bc]-azepin-6(7H)-one: A photochemical approach

The total synthesis of a novel benzazepine, 4,5,7a,8-tetrahydro-1,2-dimethoxyphenanthro[10,1-bc]azepin-6(7H)-one is described. Of crucial importance to the preparation of this material was a regiospecific Beckmann rearrangement reaction and the development of an aryl-aryl linkage by a photochemically induced coupling. Details of successful and attempted methodology are reported.