Computer-Generated High-Valent Iron-Oxo and Manganese-Oxo Species with Polyoxometalate Ligands: How do they Compare with the Iron-Oxo Active Species of Heme Enzymes?

2004 ◽  
Vol 116 (42) ◽  
pp. 5779-5783 ◽  
Author(s):  
Samu�l P. de Visser ◽  
Devesh Kumar ◽  
Ronny Neumann ◽  
Sason Shaik
Keyword(s):  
Active Species ◽  
Heme Enzymes ◽  
High Valent

scholarly journals High-Valent Iron-Oxo Complexes as Dominant Species to Eliminate Pharmaceuticals and Chloride-Containing Intermediates by the Activation of Peroxymonosulfate Under Visible Irradiation

2019 ◽  
Vol 150 (5) ◽  
pp. 1355-1367 ◽  
Author(s):  
Zhexin Zhu ◽  
Wangyang Lu ◽  
Tiefeng Xu ◽  
Nan Li ◽  
Gangqiang Wang ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ultra Performance Liquid Chromatography ◽  
Active Species ◽  
Ionization Mass ◽  
High Definition ◽  
Pyridine Ligands ◽  
Photocatalytic System ◽  
High Valent ◽  
Oxidation Efficiency ◽  
Chlorine Ion

Abstract Generally, the sulfate (SO4·−) and hydroxyl (HO·) radicals are the dominant active species in most catalytic oxidation processes with peroxymonosulfate (PMS). However, the existence of various natural organic and inorganic matters in aquatic environments might influence the oxidation efficiency of these radicals, and/or form more toxic and refractory intermediates than the parent, especially in chlorine-ion-containing conditions. Here, we constructed a novel visible-light catalytic system with PMS based on iron hexadecachlorophthalocyanine-poly (4-vinylpyridine)/polyacrylonitrile nanofibers through pyridine ligands to generate high-valent iron-oxo (Fe(IV)=O) species as the main active species. The coordination structure was characterized by UV–Vis diffuse reflection, X-ray photoelectron spectroscopy, etc. The high-valent iron-oxo generation from peroxysulfate O–O bond heterolytic cleavage was proved by high-definition electrospray ionization mass spectrometer. Ultra-performance liquid chromatography coupled with high-definition mass spectrometry showed that the photocatalytic system was efficient for the degradation of carbamazepine and the chlorinated intermediates by iron-oxo active species in chlorine-ion-containing conditions. Graphic Abstract

scholarly journals SBA-15 Anchored Metal Containing Catalysts in the Oxidative Desulfurization Process

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 984 ◽  
Author(s):  
Marcello Crucianelli ◽  
Bruno Mattia Bizzarri ◽  
Raffaele Saladino
Keyword(s):  
Selective Adsorption ◽  
High Surface ◽  
High Surface Area ◽  
Oxidative Desulfurization ◽  
Active Species ◽  
Organometallic Complexes ◽  
Alternative Methods ◽  
Metal Species ◽  
Desulfurization Process ◽  
High Valent

Recalcitrant sulfur compounds are common impurities in crude oil. During combustion they produce SOx derivatives that are able to affect the atmospheric ozone layer, increasing the formation of acid rains, and reducing the life of the engine due to corrosion. In the last twenty years, many efforts have been devoted to develop conventional hydrodesulfurization (HDS) procedures, as well as alternative methods, such as selective adsorption, bio-desulfurization, oxidative desulfurization (ODS) under extractive conditions (ECODS), and others. Among them, the oxidative procedures have been usually accomplished by the use of toxic stoichiometric oxidants, namely potassium permanganate, sodium bromate and carboxylic and sulfonic peracids. As an alternative, increasing interest is devoted to selective and economical procedures based upon catalytic methods. Heterogeneous catalysis is of relevance in industrial ODS processes, since it reduces the leaching of active species and favors the recovery and reuse of the catalyst for successive transformations. The heterogenization of different types of high-valent metal transition-based organometallic complexes, able to promote the activation of stoichiometric benign oxidants like peroxides, can be achieved using various solid supports. Many successful cases have been frequently associated with the use of mesoporous silicas that have the advantage of easy surface modification by reaction with organosilanes, facilitating the immobilization of homogeneous catalysts. In this manuscript the application of SBA-15 as efficient support for different active metal species, able to promote the catalytic ODS of either model or real fuels is reviewed, highlighting its beneficial properties such as high surface area, narrow pore size distribution and tunable pore diameter dimensions. Related to this topic, the most relevant advances recently published, will be discussed and critically described.

Mechanisms of N-Demethylations Catalyzed by High-Valent Species of Heme Enzymes:  Novel Use of Isotope Effects and Direct Observation of Intermediates

1998 ◽  
Vol 120 (41) ◽  
pp. 10762-10763 ◽  
Author(s):  
Yoshio Goto ◽  
Yoshihito Watanabe ◽  
Shunichi Fukuzumi ◽  
Jeffrey P. Jones ◽  
Joseph P. Dinnocenzo
Keyword(s):  
Direct Observation ◽  
Isotope Effects ◽  
Heme Enzymes ◽  
High Valent

Mechanisms of Sulfoxidation Catalyzed by High-Valent Intermediates of Heme Enzymes:  Electron-Transfer vs Oxygen-Transfer Mechanism

1999 ◽  
Vol 121 (41) ◽  
pp. 9497-9502 ◽  
Author(s):  
Yoshio Goto ◽  
Toshitaka Matsui ◽  
Shin-ichi Ozaki ◽  
Yoshihito Watanabe ◽  
Shunichi Fukuzumi
Keyword(s):  
Electron Transfer ◽  
Oxygen Transfer ◽  
Transfer Mechanism ◽  
Heme Enzymes ◽  
High Valent

Invasive species in the flora of Ukraine. I. The group of highly active species

Geo&Bio ◽  
2019 ◽  
Vol 2019 (17) ◽  
pp. 116-135 ◽  
Author(s):  
Vira V. Protopopova ◽  
◽  
Myroslav Shevera
Keyword(s):  
Invasive Species ◽  
Active Species ◽  
Highly Active

Kinetic Control of Interpenetration in Fe-Biphenyl-4,4′-dicarboxylate MOFs by Coordination and Oxidation Modulation

2018 ◽  
Author(s):  
Dominic Bara ◽  
Claire Wilson ◽  
Max Mörtel ◽  
Marat M. Khusniyarov ◽  
ben slater ◽  
...  
Keyword(s):  
Self Assembly ◽  
Surface Areas ◽  
Metal Precursors ◽  
Additional Coordination ◽  
Fine Control ◽  
Multiple Alternative ◽  
Metal Organic ◽  
Dft Simulations ◽  
High Valent ◽  
And Control

Phase control in the self-assembly of metal-organic frameworks (MOFs) – materials wherein organic ligands connect metal ions or clusters into network solids with potential porosity – is often a case of trial and error. Judicious control over a number of synthetic variables is required to select for the desired topology and control features such as interpenetration and defectivity, which have significant impact on physical properties and application. Herein, we present a comprehensive investigation of self-assembly in the Fe-biphenyl-4,4'-dicarboxylate system, demonstrating that coordination modulation, the addition of competing ligands into solvothermal syntheses, can reliably tune between the kinetic product, non-interpenetrated MIL-88D(Fe), and the thermodynamic product, two-fold interpenetrated MIL-126(Fe). DFT simulations reveal that correlated disorder of the terminal anions on the metal clusters in the interpentrated phase results in H-bonding between adjacent nets and is the thermodynamic driving force for its formation. Coordination modulation slows self-assembly and therefore selects the thermodynamic product MIL-126(Fe), while offering fine control over defectivity, inducing mesoporosity, but electron microscopy shows the MIL-88D(Fe) phase persists in many samples despite not being evident in diffraction experiments, suggesting its presence accounts for the lower than predicted surface areas reported for samples to date. Interpenetration control is also demonstrated by utilizing the 2,2'-bipyridine-5,5'-dicarboxylate linker; DFT simulations show that it is energetically prohibitive for it to adopt the twisted conformation required to form the interpenetrated phase, and are confirmed by experimental data, although multiple alternative phases are identified due to additional coordination of the Fe cations to the N-donors of the ligand. Finally, we introduce oxidation modulation – the concept of using metal precursors in a different oxidation state to that found in the final MOF – as a further protocol to kinetically control self-assembly. Combining coordination and oxidation modulation allows the synthesis of pristine MIL-126(Fe) with BET surface areas close to the predicted maximum capacity for the first time, suggesting that combining the two may be a powerful methodology for the controlled self-assembly of high-valent MOFs.<br><br>

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