Ahmed F. Abdel-Magied

Rare Earth Ions Adsorption onto Graphene Oxide Nanosheets

ABSTRACT Graphene oxide (GO) was synthesized and used as a coagulant of rare earth elements (REEs) from aqueous solution. Stability and adsorption capacities were exhibited for target REEs such as La(III), Nd(III), Gd(III), and Y(III). The parameters influencing the adsorption capacity of the target species including contact time, pH, initial concentration, and temperature were optimized. The adsorption kinetics and thermodynamics were studied. The method showed quantitative recovery (99%) upon desorption using HNO3 acid (0.1 M) after a short contact time (15 min).

Diastereomeric control of enantioselectivity: evidence for metal cluster catalysis

Enantioselective hydrogenation of tiglic acid effected by diastereomers of the general formula [(μ-H)2Ru3(μ3-S)(CO)7(μ-P-P*)] (P-P* = chiral Walphos diphosphine ligand) strongly supports catalysis by intact Ru3 clusters. A catalytic mechanism involving Ru3 clusters has been established by DFT calculations.

Ultrasound-Mediated Three-Component Reaction “On-Water” Protocol For the Synthesis of Novel Mono- and bis-1,3-Thiazin-4-one Derivatives

Green synthetic and catalyst-free strategy towards the synthesis of novel mono- and bis-1,3-thiazin-4-one scaffolds through a one pot, reaction of carbon disulfide, monoacetylenic esters and amines ...

Chemical and Photochemical Water Oxidation Mediated by an Efficient Single-Site Ruthenium Catalyst

Abstract Water oxidation is a fundamental step in artificial photosynthesis for solar fuels production. In this study, we report a single‐site Ru‐based water oxidation catalyst, housing a dicarboxylate‐benzimidazole ligand, that mediates both chemical and light‐driven oxidation of water efficiently under neutral conditions. The importance of the incorporation of the negatively charged ligand framework is manifested in the low redox potentials of the developed complex, which allows water oxidation to be driven by the mild one‐electron oxidant [Ru(bpy)3]3+ (bpy=2,2’‐bipyridine). Furthermore, combined experimental and DFT studies provide insight into the mechanistic details of the catalytic cycle.

Substituent Effects in Molecular Ruthenium Water Oxidation Catalysts Based on Amide Ligands

The production of clean and sustainable energy is considered as one of the most urgent issues for our society. Mastering the oxidation of water to dioxygen is essential for the production of solar fuels. A study of the influence of the substituents on the catalytic activity of a series of mononuclear Ru complexes (2 a–e) based on a tetradentate ligand framework is presented. At neutral pH, using [Ru(bpy)3](PF6)3 (bpy=2,2’‐bipyridine) as the terminal oxidant, a good correlation between the turnover frequency (TOF) and the Hammett σmeta parameters was obtained. Additionally, a general pathway for the deactivation of Ru‐based catalysts 2 a–e during the catalytic oxidation of water through poisoning by carbon monoxide was demonstrated. These results highlight the importance of ligand design for fine‐tuning the catalytic activity of water oxidation catalysts.

Catalyst–solvent interactions in a dinuclear Ru-based water oxidation catalyst

Photocatalytic water oxidation represents a key process in conversion of solar energy into fuels and can be facilitated by the use of molecular transition metal-based catalysts. A novel straightforward approach for covalent linking of the catalytic units to other moieties is demonstrated by preparation of a dinuclear complex containing two [Ru(pdc)(pic)3]-derived units (pdc = 2,6-pyridinedicarboxylate, pic = 4-picoline). The activity of this complex towards chemical and photochemical oxidation of water was evaluated and a detailed insight is given into the interactions between the catalyst and acetonitrile, a common co-solvent employed to increase solubility of water oxidation catalysts. The solvent-induced transformations were studied by electrochemical and spectroscopic techniques and the relevant quantitative parameters were extracted.

Incorporation of strontium and europium in crystals of α-calcium isosaccharinate

The final repository for short-lived, low and intermediate level radioactive waste in Sweden is built to act as a passive repository. Already within a few years after closure water will penetrate the repository and conditions of high alkalinity (pH 10.5-13.5) and low temperature (< 7 °C) will prevail. The mobility of radionuclides in the repository is dependent on the radionuclides distribution between solid and liquid phases. In the present work the incorporation of strontium (II) and europium (III) in α-calcium isosaccharinate (ISA) under alkaline conditions (pH ∼10) at 5 °C and 50 °C have been studied. The results show that strontium and europium are incorporated into α-Ca(ISA)2 when crystallized both at 5 °C and 50 °C. Europium is incorporated to a greater extent than strontium. The highest incorporation of europium and strontium at 5 °C rendered the phase compositions Ca0.986Eu0.014(ISA)2 (2.4% of Eu(ISA)3 by mass) and Ca0.98Sr0.02(ISA)2 (2.2% of Sr(ISA)2 by mass). XPS spectra show that both trivalent and divalent Eu coexist in the Eu incorporated samples. Strontium ions were found to retard the elongated growth of the Ca(ISA)2 crystals. The incorporation of Sr2+ and Eu3+ into the solid phase of Ca(ISA)2 is expected to contribute to a decreased mobility of these ions in the repository.

An eco-compatible access to diversified bisoxazolone and bisimidazole derivatives

An efficient, straight-forward and eco-friendly synthetic strategy for the assembly of novel bisoxazolones via a four-component, sequential reaction of dialdehydes, glycine, benzoyl chloride and ac ...

[μ-Bis(diphenyl-phosphan-yl-κP)methane]-deca-carbonyl-tri-μ-hydrido-trirhenium(I)(3 Re-Re) dichloromethane solvate.

In the title compound, [Re3(μ-H)3(C25H22P2)(CO)10]·CH2Cl2, the three Re atoms form a triangle bearing ten terminal carbonyl groups and three edge-bridging hydrides. The bis(diphenylphosphanyl)methane ligand bridges two Re atoms. Neglecting the Re—Re interactions, each Re atom is in a slightly distorted octahedral coordination environment. The dichloromethane solvent molecule is disordered over two sets of sites with fixed occupancies of 0.6 and 0.4.