Degradation of monuron in aqueous solution by ionizing radiation

In this study ionizing radiation induced degradation of monuron was investigated by γradiolysis. γ-radiolysis is one of the Advanced Oxidation processes (AOPs) which is very effective method for the degradation of organic water pollutants. The end-products and transient intermediates were studied in order to describe the degradation mechanism. The main reaction is OH● addition to the aromatic ring forming hydroxyl-cyclohexadienyl type radicals. In addition to this radical, aminyl and phenoxyl radicals have also some contribution to the degradation. Monuron as a halogenated compound is sensitive to the hydrated electron attack. Due to the oxidation, chemical oxygen demand and total organic carbon content decreases during irradiatin treatment. The efficiency of oxidation is high compared to other aromatics. Both, OH● and eaq take part in the dehalogenation reactions

Iron(III) Complexes with Meridional Ligands as Functional Models of Intradiol-Cleaving Catechol Dioxygenases

Six dichloroiron­(III) complexes of 1,3-bis­(2′-arylimino)­isoindoline (BAIH) with various N-donor aryl groups have been characterized by spectroscopy (infrared, UV–vis), electrochemistry (cyclic voltammetry), microanalysis, and in two cases X-ray crystallography. The structurally characterized Fe^IIICl₂(L^<i>n</i>) complexes (<i>n</i> = 3, L³ = 1,3-bis­(2′-thiazolylimino)­isoindoline and <i>n</i> = 5, L⁵ = 1,3-bis­(4-methyl-2′-piridylimino)­isoindoline) are five-coordinate, trigonal bipyramidal with the isoindoline ligands occupying the two axial and one equatorial positions meridionally. These compounds served as precursors for catechol dioxygenase models that were formed in solution upon addition of 3,5-di-<i>tert</i>-butylcatechol (H₂DBC) and excess triethylamine. These adducts react with dioxygen in <i>N</i>,<i>N</i>-dimethylformamide, and the analysis of the products by chromatography and mass spectrometry showed high intradiol over extradiol selectivity (the intradiol/extradiol product ratios varied between 46.5 and 6.5). Kinetic measurements were performed by following the change in the intensity of the catecholate to iron ligand-to-metal charge transfer (LMCT) band, the energy of which is influenced by the isoindolinate-ligand (827–960 nm). In combination with electrochemical investigations the kinetic studies revealed an inverse trend between reaction rates and oxidation potentials associated with the coordinated DBC^2–. On the basis of these results, a substrate activation mechanism is suggested for this system in which the geometry of the peroxide-bridged intermediate may be of key importance in regioselectivity

Chromophores, Fluorophores and Robust Ancillary Ligands for Molecular Catalysts: 1,3-Bis(2-pyridylimino)isoindolines

Since the first report in the early 1950s, 1,3-bis(2-pyridylimino)isoindolines (BPIs) have found widespread applications in organic, inorganic and materials chemistry. This microreview focuses on recent progress towards chiral BPI derivatives as ligands for enantioselective catalysis as well as developments in the use of BPI complexes in materials science, focusing on luminescent and birefringent materials