Ferryl and Ferrate Species: Mössbauer Spectroscopy Investigation

High-valent iron species of oxidation states +4, +5, and +6, have been involved as intermediates in enzymatic reactions, in green organic synthesis, and in purification and disinfection of water. Many of these species have been synthesized to understand their role in different systems, which include ferryl complexes (oxoiron(IV) (Fe^IV=O), oxoiron(V) (Fe^V=O)), iron(IV / V / VI)-nitride complexes, and ferrates ((Fe^VIO₄^2–, Fe(VI), Fe^VO₄^3–, Fe(V), and Fe^IVO₄^4–, Fe(IV)). Ferryl and iron-nitride complexes have organic ligands surrounded at the iron center and are soluble in non-aqueous solvent. Comparatively, ferrate species are tetraoxyanions and are soluble in water. This paper presents Mössbauer spectroscopy as a tool to distinguish different oxidation states of iron and to gain information on the geometry and structure of high-valent iron complexes. Examples are given to demonstrate the application of Mössbauer spectroscopy in learning mechanisms of thermal decomposition of ferrates, encapsulation of heavy metals by ferrates, and oxidation of thiols by ferrates

Low temperature magnetic properties of iron bearing sulfides and their contribution to magnetism of cometary bodies

Peer reviewe

Catalytically active bovine serum amine oxidase bound to fluorescent and magnetically drivable nanoparticles

Novel superparamagnetic surface-active maghemite nanoparticles (SAMNs) characterized by a diameter of 10 ± 2 nm were modified with bovine serum amine oxidase, which used rhodamine B isothiocyanate (RITC) adduct as a fluorescent spacer-arm. A fluorescent and magnetically drivable adduct comprised of bovine serum copper-containing amine oxidase (SAMN–RITC–BSAO) that immobilized on the surface of specifically functionalized magnetic nanoparticles was developed. The multifunctional nanomaterial was characterized using transmission electron microscopy, infrared spectroscopy, mass spectrometry, and activity measurements. The results of this study demonstrated that bare magnetic nanoparticles form stable colloidal suspensions in aqueous solutions. The maximum binding capacity of bovine serum amine oxidase was approximately 6.4 mg g−1 nanoparticles. The immobilization procedure reduced the catalytic activity of the native enzyme to 30% ± 10% and the Michaelis constant was increased by a factor of 2. We suggest that the SAMN–RITC–BSAO complex, characterized by a specific activity of 0.81 IU g−1, could be used in the presence of polyamines to create a fluorescent magnetically drivable H2O2 and aldehydes-producing system. Selective tumor cell destruction is suggested as a potential future application of this system

Ultrathin hierarchical porous carbon nanosheets for high-performance supercapacitors and redox electrolyte energy storage

ICN2 is funding from the CERCA Programme/Generalitat de CatalunyaThe design of advanced high-energy-density supercapacitors requires the design of unique materials that combine hierarchical nanoporous structures with high surface area to facilitate ion transport and excellent electrolyte permeability. Here, shape-controlled 2D nanoporous carbon sheets (NPSs) with graphitic wall structure through the pyrolysis of metal-organic frameworks (MOFs) are developed. As a proof-of-concept application, the obtained NPSs are used as the electrode material for a supercapacitor. The carbon-sheet-based symmetric cell shows an ultrahigh Brunauer-Emmett-Teller (BET)-area-normalized capacitance of 21.4 µF cm (233 F g), exceeding other carbon-based supercapacitors. The addition of potassium iodide as redox-active species in a sulfuric acid (supporting electrolyte) leads to the ground-breaking enhancement in the energy density up to 90 Wh kg, which is higher than commercial aqueous rechargeable batteries, maintaining its superior power density. Thus, the new material provides a double profits strategy such as battery-level energy and capacitor-level power densit

Citrinin mycotoxin recognition and removal by naked magnetic nanoparticles

Citrinin is a nephrotoxic mycotoxin which can be synthesized by Monascus mold during the fermentation process in foods. Monascus, generally described as red mold, is a red-pigmented filamentous fungus attracting a great interest for the production of natural dyes and cholesterol-lowering statins. We individuated a specie of Monascus producing high amount of natural dyes. However, this high pigmentation was correlated with the production of citrinin. Peculiar magnetic nanoparticles, synthesized in-house and called \u201cSurface Active Maghemite Nanoparticles\u201d (SAMNs), are proposed as an efficient and reliable mean for citrinin removal from Monascus treated foods. The nanomaterial efficiency for citrinin binding was proved on Monascus suspensions, and SAMN@citrinin complex was characterized by M\u4e7ssbauer spectroscopy and magnetization measurements, showing that SAMNs resulted structurally and magnetically well conserved after citrinin binding. SAMNs are excellent and stable magnetic nano-carrier for toxin removal, which can be applied in food industry

Noncovalent Functionalization of Graphene and Graphene Oxide for Energy Materials, Biosensing, Catalytic, and Biomedical Applications

This Review focuses on noncovalent functionalization of graphene and graphene oxide with various species involving biomolecules, polymers, drugs, metals and metal oxide-based nanoparticles, quantum dots, magnetic nanostructures, other carbon allotropes (fullerenes, nanodiamonds, and carbon nanotubes), and graphene analogues (MoS2, WS2). A brief description of pi-pi interactions, van der Waals forces, ionic interactions, and hydrogen bonding allowing noncovalent modification of graphene and graphene oxide is first given. The main part of this Review is devoted, to tailored functionalization for applications in drug delivery, energy materials, solar cells, water splitting, biosensing, bioimaging, environmental, catalytic, photocatalytic, and biomedical technologies. A significant part of this Review explores the possibilities of graphene/graphene oxide-based 3D superstructures and their use in lithium-ion batteries. This Review ends with a look at challenges and future prospects of noncovalently modified graphene and graphene oxideope