Iron Acetylacetonate Research Articles

Supramolecular Surface Functionalization of Iron Oxide Nanoparticles with α-Cyclodextrin-Based Cationic Star Polymer for Magnetically-Enhanced Gene Delivery.

Supramolecular polymers formed through host–guest complexation have inspired many interesting developments of functional materials for biological and biomedical applications. Here, we report a novel design of a non-viral gene delivery system composed of a cationic star polymer forming supramolecular complexes with the surface oleyl groups of superparamagnetic iron oxide nanoparticles (SPIONs), for magnetically enhanced delivery of DNA into mammalian cells. The cationic star polymer was synthesized by grafting multiple oligoethylenimine (OEI) chains onto an α-cyclodextrin (α-CD) core. The SPIONs were synthesized from iron(III) acetylacetonate and stabilized by hydrophobic oleic acid and oleylamine in hexane, which were characterized in terms of their size, structure, morphology, and magnetic properties. The synthesized magnetic particles were found to be superparamagnetic, making them a suitable ferrofluid for biological applications. In order to change the hydrophobic surface of the SPIONs to a hydrophilic surface with functionalities for plasmid DNA (pDNA) binding and gene delivery, a non-traditional but simple supramolecular surface modification process was used. The α-CD-OEI cationic star polymer was dissolved in water and then mixed with the SPIONs stabilized in hexane. The SPIONs were “pulled” into the water phase through the formation of supramolecular host–guest inclusion complexes between the α-CD unit and the oleyl surface of the SPIONs, while the surface of the SPIONs was changed to OEI cationic polymers. The α-CD-OEI-SPION complex could effectively bind and condense pDNA to form α-CD-OEI-SPION/pDNA polyplex nanoparticles at the size of ca. 200 nm suitable for delivery of genes into cells through endocytosis. The cytotoxicity of the α-CD-OEI-SPION complex was also found to be lower than high-molecular-weight polyethylenimine, which was widely studied previously as a standard non-viral gene vector. When gene transfection was carried out in the presence of an external magnetic field, the α-CD-OEI-SPION/pDNA polyplex nanoparticles greatly increased the gene transfection efficiency by nearly tenfold. Therefore, the study has demonstrated a facile two-in-one method to make the SPIONs water-soluble as well as functionalized for enhanced magnetofection.

Adsorptive stripping voltammetric determination of carbofuran in herbs on chromatographic sorbent modified electrode

• Novel carbon-containing modified electrode was developed for carbofuran determination. • Carbon ink containing chromatographic sorbent, polyethylene glycol, and iron acetylacetonate was used. • The practical applicability of the novel electrode was verified on determination of carbofuran in herbs. The determination of carbofuran (CBF) in herbs (wild chamomile and Saint-John's-wort) was developed using a carbon-containing electrode (CCE) modified with carbon ink (CI) containing chromatographic sorbent (CS) based on chromaton (Ch), polyethylene glycol (PEG), and iron acetylacetonate (Fe(AA) 3 ). The surface morphology of the Ch/PEG/Fe(AA) 3 /CI/CCE was investigated by scanning electron microscopy (SEM) in backscattered-electron (BSE) mode and by electrochemical impedance spectroscopy (EIS). Electrochemically inactive CBF was converted to an electrochemically active phenolic analogue CBFP by an alkaline hydrolysis. The electrochemical behavior of CBFP at Ch/PEG/Fe(AA) 3 /CI/CCE was studied by cyclic voltammetry (CV) in a phosphate buffer solution (PBS) pH 6.86 in the potential range from −0.4 to 1.2 V. Under the optimal experimental conditions, linear concentration dependences in the concentration range from 0.25 to 10 µmol·L −1 were obtained by linear scan voltammetry in the first derivative mode (LSVFD) with limit of detection ( LOD ) 0.08 µmol·L −1 . The proposed Ch/PEG/Fe(AA) 3 /CI/CCE demonstrated good sensitivity and selectivity for the determination of CBF after its conversion to CBFP. The use of sorbents as modifying agents of electrodes for the determination of carbamate pesticides opens up the possibilities for “green” electroanalytical chemistry.

Hydrogen/Halogen Exchange of Phosphines for the Rapid Formation of Cyclopolyphosphines.

The hydrogen/halogen exchange of phosphines has been exploited to establish a truly useable substrate scope and straightforward methodology for the formation of cyclopolyphosphines. Starting from a single dichlorophosphine, a sacrificial proton "donor phosphine" makes the rapid, mild synthesis of cyclopolyphosphines possible: reactions are complete within 10 min at room temperature. Novel (aryl)cyclopentaphosphines (ArP)5 have been formed in good conversion, with the crystal structures presented. The use of catalytic quantities of iron(III) acetylacetonate provides significant improvements in conversion in the context of diphosphine (Ar2P)2 and alkyl-substituted cyclotetra- or cyclopentaphosphine ((AlkylP)n, where n = 4 or 5) formation. Both iron-free and iron-mediated reactions show high levels of selectivity for one specific ring size. Finally, investigations into the reactivity of Fe(acac)3 suggest that the iron species is acting as a sink for the hydrochloric acid byproduct of the reaction.

Conversion of a polysilazane‐modified cellulose‐based paper into a C/SiFe(N,C)O ceramic paper via thermal ammonolysis

AbstractCellulose‐based paper samples were surface‐modified by a polymeric single‐source precursor prepared from perhydropolysilazane (PHPS) and iron(III)acetylacetonate (Fe(acac)3) and ammonolyzed at 500°C, 700°C, 900°C, and 1000°C, leading to C/SiFe(N,C)O‐based ceramic papers with in situ‐generated hierarchical micro/nano‐morphology. As reference, cellulose‐free samples were prepared under the same conditions. Upon thermal treatment, the microstructure evolutions of the resulting ceramic paper and the reference sample were comparatively investigated. Scanning electron microscopy (SEM) showed that for all temperatures, the ceramic papers exhibit the same morphology as the template, however, with noticeable shrinkage and curling, particularly evident at higher temperatures. X‐ray diffraction (XRD) measurements of the reference samples and the ceramic papers showed a similar crystallization behavior and phase evolution in both materials. In the ceramic paper, the crystallization process seems to occur at a later time. The results provide a comprehensive understanding of the investigated C/SiFe(N,C)O‐based ceramic system. It was shown that use of the cellulose‐based paper template has the benefit of retaining the microstructure and furthermore, apart from transforming the cellulose fibers into turbostratic carbon, does not change the phase evolution during the polymer‐to‐ceramic transformation, allowing at the same time the manufacturing of novel morphologically complex parts by a convenient one‐pot synthesis approach.

Effects of precursors on the phase, magnetic and photocatalytic properties of nano Fe2O3 synthesized by low temperature calcination

By calcining ferric acetylacetonate (Fe(ACAC)3), Fe(NO3)3·9H2O and FeCl3·6H2O in air at 300 °C for 5 h, maghemite (γ-Fe2O3) nanoparticles, hematite (α-Fe2O3) nanoparticles and α-Fe2O3 nanoflakes were synthesized, respectively. The γ-Fe2O3 nanoparticles demonstrated far stronger magnetism (remanent magnetization (Mr) = 9.9 emu/g) than α-Fe2O3 nanoparticles (Mr = 0.06 emu/g) and nanoflakes (Mr = 0.13 emu/g) at room temperature. For photocatalytic reduction of aqueous Cr(VI) in the presence of visible-light and citric acid, the performance of different Fe2O3 samples was found to be in the order of α-Fe2O3 from FeCl3·6H2O > γ-Fe2O3 from Fe(ACAC)3 > hydrothermally synthesized α-Fe2O3 nanorods > α-Fe2O3 from Fe(NO3)3·9H2O > hydrothermally synthesized α-Fe2O3 nanoparticles. This work reveals the decisive role of precursors in the phase, magnetic and photocatalytic properties of low temperature calcination-synthesized Fe2O3. The phase-tunable synthesis of nano Fe2O3 by low temperature calcination of easily available precursors is simple, cost-effective and practical for large scale industrial production.

Polymer‐derived FexSiy/SiC@SiOC ceramic nanocomposites with tunable microwave absorption behavior

AbstractIron‐containing PSO precursors (FePSO) were synthesized by modification of polysiloxane with different amounts of ferric acetylacetonate [Fe(acac)3], then porous SiFeCO ceramics were successfully prepared by subsequent pyrolysis. The chemical modification and ceramization process of PFSO precursors were studied by FT‐IR and TGA measurements. XRD patterns imply that the SiC crystalline can be easily observed when PFSO was exposed to 1200℃ in nitrogen atmosphere, while pure PSO exhibited broad diffraction peaks of SiC at 1500℃, meaning that the grain coarsening of SiC was accelerated by adding iron. The crystallization behavior of ferric silicide (FexSiy) is complex due to the variation of iron content in feed and annealing temperature, and FexSiy/SiC@SiOC nanocomposites were produced after annealing. Because of the in‐situ formation of SiC, FexSiy, and carbon strips in nanocomposites, PFSO‐derived ceramics demonstrate enhanced microwave absorption performance. The best effective absorption bandwidth (<−10 dB) and the minimum reflection loss are 2.6 GHz and −38 dB, respectively, which are achieved in the sample PFSO‐3–1300℃. FexSiy/SiC@SiOC nanocomposites synthesized in this work exhibit potential application in the field of electromagnetic interference, the carbon content and the crystallization behavior of FexSiy are the critical factors for the performance optimization.

Observation of Surface Ligands-Controlled Etching of Palladium Nanocrystals.

Selective adsorption of ligands on nanocrystal surfaces can affect oxidative etching. Here, we report the etching of palladium nanocrystals imaged using liquid cell transmission electron microscopy. The adsorption of surface ligands (i.e., iron acetylacetonate and its derivatives) and their role as inhibitor molecules on the etching process were investigated. Our observations revealed that the etching was dominated by the interplay between palladium facets and ligands and that the etching exhibited different pathways at different concentrations of ligands. At a low concentration of iron acetylacetonate (0.1 mM), rapid etching primarily at {100} facets led to a concave structure. At a high concentration (1.0 mM), the etch rate was decreased owing to a protective film of iron acetylacetonate on the {100} facets and a round nanoparticle was achieved. Ab initio calculations showed that the differences in adsorption energy of inhibitor molecules on palladium facets were responsible for the etching behavior.

Self-healing epoxy coating synthesis by embedment of metal 2-methyl imidazole and acetylacetonate complexes with microcapsules

The restoration of mechanical properties is desired for creating the self-healing coatings with no corrosion capabilities. The encapsulation of epoxy resins is limited by various factors in urea and melamine formaldehyde microcapsules. An improved method was developed, where epoxy resin was encapsulated by individual wrapping of poly(melamine-formaldehyde) and poly(urea-formaldehyde) shell around emulsified epoxy droplets via oil-in-water emulsion polymerization method. The synthesized materials were characterized analytically. The curing of the epoxy was achieved by adding the [Ni/Co(2-MI)6].2NO3 as a latent hardener and iron acetylacetonate [Fe(acac)3] as a latent accelerator. Isothermal and non-isothermal differential scanning calorimetric analysis revealed lower curing temperature (Tonset = 116 °C) and lower activation energies (Ea ≈ 69–75 kJ/mol). The addition of microcapsules and complexes did not adversely alter the flexural strength and flexural modulus of the epoxy coatings. The adhesion strength of neat coating decreased from 6310.8 ± 31 to 4720.9 ± 60 kPa and percent healing increased from 50.83 to 67.45% in the presence of acetylacetonate complex at 10 wt% of microcapsules.

Chitosan as capping agent in a robust one-pot procedure for a magnetic catalyst synthesis

Here, we report a one-pot solvothermal method for the development of magnetically recoverable catalysts with Ru or Ag nanoparticles (NPs) capped by chitosan (CS), a derivative of natural chitin. The formation of iron oxide NPs was carried out in situ in the presence of CS and iron acetylacetonate in boiling triethyleneglycol (TEG) due to CS solubilization in warm TEG. Coordination with Ru or Ag species and the NP formation take place in the same reaction solution, eliminating intermediate steps. In optimal conditions the method developed allows stabilization of 2.2 nm monodisperse Ru NPs (containing both Ru0 and Ru4+ species) that are evenly distributed through the catalyst, while for Ag NPs, this stabilizing medium is inferior, leading to exceptionally large Ag nanocrystals. Catalytic testing of CS-Ru magnetically recoverable catalysts in the reduction of 4-nitrophenol to 4-aminophenol with excess NaBH4 revealed that the catalyst with 2.2 nm Ru NPs exhibits the highest catalytic activity compared to samples with larger Ru NPs (2.9–3.2 nm). Moreover, this catalyst displayed extraordinary shelf-life in the aqueous solution (up to ten months) and excellent reusability in ten consecutive reactions with easy magnetic separation at each step which were assigned to its conformational rigidity at a constant pH. These characteristics as well as favorable environmental factors of the catalyst fabrication, make it promising for nitroarene reduction.

Visible light active Fe-Pr co-doped TiO2 for water pollutants degradation

Fe–Pr co-doped TiO2 photocatalysts are synthetized by sol–gel method using titanium tetraisopropoxide, praseodymium nitrate and iron acetylacetonate as precursors of titania, praseodymium and iron, respectively. The chemical-physical properties of all prepared samples are analysed by X-ray diffraction (XRD), Raman spectroscopy, UV–vis diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence (PL) spectroscopy and N2 adsorption at −196 °C. XRD patterns show the main peaks of anatase phase in all photocatalysts and evidence that Fe and Pr ions are effectively introduced into the TiO2 lattice. UV–vis DRS spectra indicate the reduction of the band gap value of Fe-Pr co-doped TiO2 with respect to TiO2 and Pr-doped TiO2 thank to co-doping of TiO2 with Pr and Fe ions. The photocatalytic performances of all prepared samples are investigated for the degradation of Acid Orange 7 azo dye (AO7) and also of phenol under visible light irradiation. Photocatalytic efficiency obtained using Fe–Pr co-doped TiO2 markedly increases compared to un-doped TiO2, Pr-doped TiO2 and Fe-doped TiO2 photocatalysts. Fe-Pr co-doped TiO2 prepared with 8.5 mg of praseodymium nitrate gave the best photocatalytic activity. The enhanced photocatalytic activity should be associated with the simultaneous doping of TiO2 with Pr3+ and Fe3+ ions that induces a marked decrease of band gap value together with an enhanced generation of oxygen vacancies, which can trap electrons, and therefore reducing their recombination with photogenerated positive holes. Indeed, using the optimized Fe-Pr co-doped TiO2, the dye discoloration and mineralization is about 87 and 80 %, respectively, after 60 min of LEDs visible light irradiation, underlining the best performances of the optimized Fe–Pr co-doped TiO2 in terms of treatment time. Finally, the optimized Fe-Pr co-doped TiO2 is tested for visible light degradation of phenol in aqueous solution, confirming the absence of possible sensitization phenomena of photocatalyst surface by the AO7 dye.

Coating of Wood with Fe2O3-Decorated Carbon Nanotubes by One-Step Combustion for Efficient Solar Steam Generation.

As the global water shortage becomes increasingly serious, it is highly imperative to develop efficient, renewable, and large-scale water purification devices. Herein, an efficient solar-driven water purification device of wood coated with Fe2O3 nanoparticle-decorated carbon nanotubes (Fe2O3/CNT) is fabricated in only a few seconds by one-step combustion of ferric acetylacetonate in an ambient environment. The thin layer of the Fe2O3/CNT hybrid coated on the upper surface of the wood serves as a solar-light absorber for converting solar energy to thermal energy, while the thermally insulating wood layer with vertically aligned channels endows the device with rapid water upward transport and localizes the generated heat inside the Fe2O3/CNT layer for solar-driven water evaporation. As a result, the wood/Fe2O3/CNT device achieves a high water steam generation capability of 1.42 kg m-2 h-1 along with an excellent evaporation efficiency of 87.2% under 1 sun irradiation, higher than most of the wood-based solar-driven water evaporation device reported. This device is also efficient in the purification of seawaters and wastewaters. This work demonstrates a rapid and facile methodology for large-scale fabrication of wood/Fe2O3/CNT devices for efficient solar-driven water purification.

O-Heterocycle Synthesis via Intramolecular C-H Alkoxylation Catalyzed by Iron Acetylacetonate.

Intramolecular alkoxylation of C-H bonds can rapidly introduce structural and functional group complexities into seemingly simple or inert precursors. The transformation is particularly important due to the ubiquitous presence of tetrahydrofuran (THF) motifs as fundamental building blocks in a wide range of pharmaceuticals, agrochemicals, and natural products. Despite the various synthetic methodologies known for generating functionalized THFs, most show limited functional group tolerance and lack demonstration for the preparation of spiro or fused bi- and tricyclic ether units prevalent in molecules for pharmacological purposes. Herein we report an intramolecular C-H alkoxylation to furnish oxacycles from easily prepared α-diazo-β-ketoesters using commercially available iron acetylacetonate (Fe(acac)2) as a catalyst. The reaction is proposed to proceed through the formation of a vinylic carboradical arising from N2 extrusion, which mediates a proximal H-atom abstraction followed by a rapid C-O bond forming radical recombination step. The radical mechanism is probed using an isotopic labeling study (vinyl C-D incorporation), ring opening of a radical clock substrate, and Hammett analysis and is further corroborated by density functional theory (DFT) calculations. Heightened reactivity is observed for electron-rich C-H bonds (tertiary, ethereal), while greater catalyst loadings or elevated reaction temperatures are required to fully convert substrates with benzylic, secondary, and primary C-H bonds. The transformation is highly functional group tolerant and operates under mild reaction conditions to provide rapid access to complex structures such as spiro and fused bi-/tricyclic O-heterocycles from readily available precursors.

Polychelates Based on Magnesium, Aluminum, Iron, Zirconium, and Vanadyl Acetylacetonates - Synthesis, Structure and Properties

The formation of polymeric acetylacetonates of magnesium, aluminum, iron, zirconium, and vanadyl under conditions of mechanochemical activation with subsequent condensation in boiling toluene has been investigated. The obtained compounds have been studied by the methods of gel chromatography, X-ray diffractometry, and positron annihilation and IR spectroscopy. Aluminum chelates have been studied by means of NMR spectroscopy. It has been demonstrated that the mechanochemical activation with subsequent boiling in toluene results in the formation of polymeric chelates, mostly those of iron, zirconium and, to a smaller degree, chelates of aluminum, magnesium, and vanadyl. The molecular weight of soluble high-molecular fractions is in the range 3000–5000 Da. The layered polymer structure has been revealed. Cross-section areas of polymer chains and volumes of coherent scattering regions have been calculated from the diffractometry data. The morphology of polymers consisting of spherical particles of sizes in the range 100–700 nm has been investigated. Based on the data of positron annihilation spectroscopy (PAS), density, and nitrogen low-temperature adsorption, the dependence of the chelate stability on the specific polarizing potential has been determined. A fractal structure of solid-state polychelates has been revealed.

Fabrication of Antiswelling Loose Nanofiltration Membranes via a "Selective-Etching-Induced Reinforcing" Strategy for Bioseparation.

With diverse selectivity, higher permeance, and good antifouling property, loose polyamide nanofiltration (NF) membranes can be potentially deployed in various bioseparation applications. However, the loose NF membrane with a low crosslinking degree generally suffers from the alkali-induced pore swelling during chemical cleaning, resulting in degradation of separation performance with time. In this work, we conceive a novel strategy to tailor the separating layer through alkaline post-etching following the interfacial polymerization process, where piperazine and tannic acid (TA) were used as water-phase monomers, and trimesoyl chloride (TMC) and ferric acetylacetonate were employed as organic monomers in n-hexane. Thereinto, the polyester network formed by TA and TMC was selectively etched by alkaline treatment, thus obtaining a loose NF membrane, whose structure and performance could be facilely tailored by controlling the TA ratio and the etching pH. As a result, the well-designed loose NF membrane exhibited higher flux, better selectivity, and more stable separation performance in a long-term filtration of diluted cane molasses. Interestingly, the obtained loose NF membrane showed excellent antiswelling ability during alkaline cleaning because of network locking induced by Fe3+ chelation, decrease in the carboxyl proportion (more hydroxyl generation due to the ester bond hydrolysis), and enhanced interface interaction between the separation layer and the sublayer attributed to catechol adhesion effect. Therefore, such a "selective-etching-induced reinforcing" strategy could endow the polyamide NF membrane with both loose and antiswelling separation layer in a reliable and scalable way, which provides a new perspective for preparing highly selective and stable NF membrane for resource recovery.

Enhanced electromagnetic wave absorption performance of SiCN(Fe) fibers by in-situ generated Fe3Si and CNTs

The SiCN(Fe) fibers with excellent one-dimensional microstructure and electromagnetic wave (EMW) absorption performance were synthesized by combining polymer-derived ceramics (PDCs) method and electrospinning. The in-situ generation of Fe3Si and CNTs by adding ferric acetylacetonate (FA) into the raw materials effectively improved the dielectric properties, magnetic properties and the impedance matching performance of the SiCN(Fe) fibers. The EMW absorption performance of SiCN(Fe) fibers were mainly based on dipole polarization loss, interface polarization loss and eddy current loss. The RLmin value of SiCN(Fe) fibers reached −47.64 dB at 1.38 mm and the effective absorption band (EAB, RL ≤ −10 dB) reached 4.28 GHz (13.72–18 GHz, 1.35 mm).

Three-dimensional fast elemental mapping by soft X-ray dual-energy focal stacks imaging.

The three-dimensional (3D) dual-energy focal stacks (FS) imaging method has been developed to quickly obtain the spatial distribution of an element of interest in a sample; it is a combination of the 3D FS imaging method and two-dimensional (2D) dual-energy contrast imaging based on scanning transmission soft X-ray microscopy (STXM). A simulation was firstly performed to verify the feasibility of the 3D elemental reconstruction method. Then, a sample of composite nanofibers, polystyrene doped with ferric acetylacetonate [Fe(acac)3], was further investigated to quickly reveal the spatial distribution of Fe(acac)3 in the sample. Furthermore, the data acquisition time was less than that for STXM nanotomography under similar resolution conditions and did not require any complicated sample preparation. The novel approach of 3D dual-energy FS imaging, which allows fast 3D elemental mapping, is expected to provide invaluable information for biomedicine and materials science.

Microwave‐Assisted Solvothermal Controlled Synthesis of Fe‐Co Composite Material

AbstractSyntheses of cobalt‐iron oxide composites starting from cobalt acetate and iron acetylacetonate are carried out by microwave‐assisted solvothermal process, using ethylene glycol as the solvent and (polyvinylpyrrolidone) PVP, as the stabilizer. Indeed, the reaction mechanism in the presence of ethylene glycol is well understood with the role of PVP being the inhibitor of nanoparticle growth. However, the control of the morphology of the synthetized nanoparticles is still a great challenge. Herein, it is demonstrated that by adding amines to the reaction mixture, it is possible to control the morphology of the prepared bimetallic cobalt‐iron materials. Thus, different Fe‐Co oxide micro‐particles are synthetized by an innovative microwave‐assisted solvothermal synthesis, which allows to considerably reduce reaction time from 12 h to 15 min, with respect to conventional methods. The procedure is optimized by varying several parameters, such as amount of PVP, in the presence or in the absence of amines, reaction temperature. The dark brown powders of the product are characterized by scanning electron microscopy, infrared spectroscopy, and thermal analysis, confirming the beneficial effect of the presence of the amine on the morphology of the obtained composites. These results open a new scenario for further studies on the possibility to control the morphology of composite materials.

Synthesis, characterization, thermal stability, electrochemical behavior, and antioxidant activity of new oxovanadium(iv) and iron(ii) tetradentate Schiff base complexes

Two new tetradentate oxovanadium(IV) and iron(II) Schiff base complexes have been prepared by the interaction of vanadyl(IV) and iron(III) acetylacetonate with the ligand obtained from the reaction of ethylenediamine and 5′-(N-methyl-N-phenylaminomethyl)-2′-hydroxyacetophenone in methanol. These complexes have been characterized by means of different spectroscopic techniques such as UV–visible, FT-IR, mass spectrometry, and elemental analysis. In addition, thermogravimetric (TG) and differential thermogavemetric analysis (DTG) have been utilized to investigate the thermal stability of these complexes. Results showed that both Schiff base complexes decompose in five consecutive stages, and a mechanism has been proposed for each stage of thermal decomposition. Thermogravimetric analysis has been carried out using four different heating rates of 5, 10, 15, and 20 °C min−1, and the kinetic parameters of these complexes have been calculated using the Kissinger method. Cyclic voltammetry has been employed to examine the electrochemical behavior of the two synthesized complexes in dimethyl sulfoxide (DMSO) at a glassy carbon electrode. Each of these complexes displayed one quasi-reversible single electron transfer peak near 0.255 V vs. saturated calomel electrode (SCE) for the V(V)–V(IV) couple and near −0.690 V vs. SCE for the Fe(III)–Fe(II) redox couples, respectively. Finally, the antioxidant activity of the newly prepared complexes has been investigated using the 2,2-diphenyl-1-picrylhydrazyle (DPPH) free radical scavenging assay. Results revealed that the oxovanadium Schiff base complex exhibits good antioxidant activity.

Versatile Surface Functionalization of Water-Dispersible Iron Oxide Nanoparticles with Precisely Controlled Sizes.

The synthesis of highly water-dispersible iron oxide nanoparticles with surface functional groups and precisely controlled sizes is essential for biomedical application. In this paper, we report a one-pot strategy for versatile surface functionalization. The iron oxide nanoparticles are first synthesized by thermal decomposition of iron(III) acetylacetonate (Fe(acac)3) in diethylene glycol (DEG), and their surfaces are modified by adding the surface ligands at the end of the reaction. The size of iron oxide nanoparticles can be precisely controlled in nanometer scale by continuous growth. This facile synthesis method enables the surface modification with different coating materials such as dopamine (DOPA), polyethylene glycol with thiol end group (thiol-PEG), and poly(acrylic acid) (PAA) onto the iron oxide nanoparticles, introducing new surface functionalities for future biomedical application. From transmission electron microscopy (TEM) and X-ray diffraction (XRD), the morphology and crystal structure are not changed during surface functionalization. The attachment of surface ligands is studied by Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). The surface functional groups are confirmed by X-ray Photoelectron Spectroscopy (XPS). In correlation with the change of hydrodynamic size, PAA coated nanoparticles are found to exhibit outstanding stability in aqueous solution. Furthermore, we demonstrate that the functional groups are available for conjugating with other molecules such as fluorescent dye, showing potential biological applications. Lastly, the magnetic resonance phantom studies demonstrate that iron oxide nanoparticles with PAA coating can be used as T1 and T2 dual-modality contrast agents. Both r1 and r2 relaxivities significantly increase after surface functionalization with PAA, indicating improved sensitivity.

A modified graphitic carbon nitride (MCN)/Fe3O4 composite as a super electromagnetic wave absorber

The nitrogen content of g-C3N4 was reduced by magnesium thermal reduction to obtain porous C (MCN), and MCN was combined with Fe3O4 particles by decomposition of ferric acetylacetonate.