Iron Carbonyl Research Articles

Effect of multiple freeze‐thaw cycles on protein and lipid oxidation in rabbit meat

SummaryFrozen storage is chosen to be the preferred method in meat preservation. However, multiple freeze‐thaw (F‐T) cycles will occur during the transfers or distribution processes under poor cold‐chain conditions. This study investigated the effects of multiple freeze‐thaw (F‐T) cycles on water mobility, microstructure damage, protein oxidation and lipid oxidation in rabbit meat during seven F‐T cycles through 56 days. Scanning electron microscopy results indicated that the increase of F‐T cycles induced the rupture of endomysia and the increase of gaps between fibres. Low‐field nuclear magnetic resonance (LF‐NMR) results showed that the peak area of T21 and T22 decreased with increasing number of repeated F‐T cycles, indicating that immobile water shifted to free water, and free water mobility increased. During repeated freeze‐thaw process, the peroxide value, thiobarbituric acid‐reactive substances, non‐haem iron content and carbonyl groups of rabbit meat gradually increased, whereas haem content, haem iron content and sulfhydryl content of rabbit meat gradually decreased. In addition, the results of Fourier transform infrared, sodium dodecyl sulphate polyacrylamide gel electrophoresis, and intrinsic fluorescence spectroscopy indirectly proved that multiple F‐T cycles could cause α‐helix structure disruption, protein aggregation and degradation, and tryptophan oxidation of rabbit meat myofibrillar protein (MP). Overall, multiple repeated F‐T cycles changed moisture migration, damaged microstructure and promoted lipid and protein oxidation of rabbit meat.

Fluorine Migration from Carbon to Iron and Fluorine–Iron Dative Bonds in Octafluorocyclohexadiene Iron Carbonyl Chemistry

The geometries and energies of mononuclear and binuclear octafluorocyclohexadiene iron carbonyl derivatives have been studied using density functional theory. The lowest energy C6F8Fe(CO)3 tricarbonyl structure is the octafluoro-1,3-cyclohexadiene derivative known experimentally. Isomeric structures containing the other two possible C6F8 hexagon ligands lie at higher energies. Unprecedented oxidative addition involving fluorine migration from carbon to iron is theoretically predicted in the C6F8Fe(CO)4 tetracarbonyl systems to give low-energy C6F7Fe(CO)4F structures. A similar energetically favored fluorine migration, also from carbon to iron, converts the coordinatively unsaturated (η4-C6F8)Fe(CO)2 dicarbonyl complex to the coordinatively saturated heptafluorocyclohexadienyl complex (η5-C6F7)Fe(CO)2F. For C6F8Fe2(CO)8, trans isomers with two Fe(CO)4 moieties on opposite sides of the C6F8 ring coordinated to C═C bonds are the lowest energy structures. These are similar to the experimentally known hexafluorocyclopentadiene complex C5F6[Fe(CO)4]2. The corresponding cis isomers with the Fe(CO)4 moieties on the same size of the C6F8 ring are high-energy structures, possibly a consequence of the steric hindrance between the two closely spaced Fe(CO)4 moieties. The low-energy C6F8Fe2(CO)7 structures may be viewed as the substitution products of the experimentally known Fe2(CO)9, with the two carbonyl groups replaced by a terminal or bridging C6F8 ligand donating four electrons to one or both iron atoms of the central Fe2 unit. The low-energy singlet structures in the unsaturated C6F8Fe2(CO)6 system have C6F8 ligands donating electrons to the central Fe2 system not only through Fe–C bonds but also through F→Fe dative bonds involving fluorine lone pairs.

Pd-Catalysed carbonylative Suzuki–Miyaura cross-couplings using Fe(CO)5under mild conditions: generation of a highly active, recyclable and scalable ‘Pd–Fe’ nanocatalyst

Fe(CO)5delivers COin situfor carbonylative-Suzuki–Miyaura cross-coupling, leading to concomitant formation of catalytically competent Pd–Fe nanoparticles.

DFT Study on the Mechanism of Iron-Catalyzed Diazocarbonylation.

The mechanism of the carbonylation of diazomethane in the presence of iron–carbonyl–phosphine catalysts has been investigated by means of DFT calculations at the M06/def-TZVP//B97D3/def2-TZVP level of theory, in combination with the SMD solvation method. The reaction rate is determined by the formation of the coordinatively unsaturated doublet-state Fe(CO)3(P) precursor followed by the diazoalkane coordination and the N2 extrusion. The free energy of activation is predicted to be 18.5 and 28.2 kcal/mol for the PF3 and PPh3 containing systems, respectively. Thus, in the presence of less basic P-donor ligands with stronger -acceptor properties, a significant increase in the reaction rate can be expected. According to energy decomposition analysis combined with natural orbitals of chemical valence (EDA–NOCV) calculations, diazomethane in the Fe(CO)3(phosphine)(η1-CH2N2) adduct reveals a -donor–-acceptor type of coordination.

Preparation of Microwave Multi-Adsorbent Nanocomposites Based on Copper, Iron Carbonyl, Carbon Nanofiber, Graphite Nanoflake and Polypyrrole

The composites of Cu, Carbonyl iron (CI), carbon nanofiber (CNF), graphite nanoflake (GNF)/polypyrrole (PPy) and [(Cu-CI-CNF-GNF) 0.5-PAA]-PPy0.5 were synthesized via different methods by in-situ polymerization on the surface of nanoparticles (NPs) with core-shell structure. This paper describes a method for polyacrylic acid (PAA) coating of NPs in aqueous solution. Then PPy coating was performed by template polymerization on NPs-PAA. Morphology, magnetic and conductivity properties were observed via scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and four probe method, respectively. The microwave characterization of nanocomposite was evaluated through arch test based on a network analyzer. The PPy nanocomposites possessed the excellent microwave multi absorbers properties in 2-18 GHz. It was also found that nanocomposites with 50% w/w and light weight exhibit good microwave absorbing properties in 2-3 GHz and 5-14 GHz frequency, so can be used to cellphone, radio frequency and radar shielding.

Iron Carbonyl Complexes Containing N,C,S-Tridentate Ligands with Quinoline, Vinyl, and Benzenethiolate Units

Iron(III) carbonyl complexes of N,C,S-tridentate ligands containing quinoline-N, vinyl-C, and benzenethiolate-S donors were synthesized by three steps from quinolyl-substituted benzothiophenes via ...

Four iron(II) carbonyl complexes containing both pyridyl and halide ligands: Their synthesis, characterization, stability, and anticancer activity

Four iron(II) carbonyl complexes, fac‐[Fe (CO)3X2(py)] (X = I−, 1 and Br−, 3), fac‐[{Fe (CO)3X2}2(bipy)] (X = I−, 2 and Br−, 4), were facilely synthesized by reacting cis‐[Fe (CO)4X2] (X = I−, Br−) with pyridine (py) and 4,4′‐dipyridine (bipy) ligands, respectively, in good yields (70%~85%). These complexes were fully characterized, and the structures of Complexes 2 and 3 were crystallographically analyzed. In dimethyl sulfoxide, they decomposed rapidly to release carbon monoxide (CO), and in methanol, they showed better stability which allowed kinetically analyzing their decomposing behaviors. The self‐decomposing in methanol fitted first‐order kinetics with a half‐time ranging from several minutes to 1 h. Our results suggested that the ligand with great conjugation (bipy) and strong electron‐donating capability (iodide) could stabilize the iron(II) carbonyl complexes. The decomposition of the iodo complexes (1 and 2) involved the production of iodine radicals. MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide) assessments revealed that the efficacy against human bladder carcinoma cell line (RT112) is in the following trend: 1 > 2 > 3 > 4. The relatively strong efficacy of Complexes 1 and 2 is mainly contributed to the in situ generated iodine radicals. The combination of the cytotoxicity of the in situ generated radicals with the anticancer activity of CO as reported in literatures may lead to developing novel anticancer drugs with enhanced efficacy.

Direct Reductive Amination of Camphor Using Iron Pentacarbonyl as Stoichiometric Reducing Agent: Features and Limitations

The method of direct reductive amination of camphor and fenchone was proposed. The most effective reducing agent is iron carbonyl. No ligands or solvents are needed. The stereochemistry of the corresponding products was determined by HMBC, HSQC, and NOESY spectra. The limitations of the method were shown. The reaction of camphor with primary amines led to exclusively exo product, while the reaction of fenchone led to exclusively endo product. The reaction of camphor with cyclic secondary amines led to the mixture of endo and exo isomers.

DEMERCAPTANISION OF PETROL AND PETROL REFINARY PRODUCTS AS AN ENVIROMENT PROTECTION METHOD

This article studies the demercaptanision of petrol and petrol refinery products as an environment protection method. The reactions of sulfur, hydrogen sulfide and organosulfur compounds in oil and oil products with iron carbonyls were studied. Their reactivity was analyzed. A method was developed for the preparation of iron dodecacarbonyl based on the amine salt of undecacarbonyl hydridotriferrate followed by acidification. The results obtained can be the basis of the chemical technology for demercaptanization of oil and oil products as an environment protection method.

Investigation of the combustion of iron pentacarbonyl and the formation of key intermediates in iron oxide synthesis flames

The information of the gas phase kinetics are relevant for the development of detailed reaction mechanisms as well as for process design and control in flame synthesis. In this study, the decomposition of iron pentacarbonyl and the reaction pathways towards iron oxide clusters and particles in laminar H2/O2/Ar low-pressure synthesis flames are investigated. Gas-phase species are analyzed by photoionization and electron ionization mass spectrometry. The extraction of a representative sample from the particle-laden flow of a synthesis flame by an intrusive sampling technique for the analysis is challenging, because iron-intermediate species can condense easily. Cations can be extracted from the flame with a high efficient ion sampling technique that results in high sensitivity. Iron-containing cations provide evidence of the presence of key intermediates, e.g., Fe(OH)2, Fe(OH)3, Fe2O3, and larger Fe-O-clusters which are the dominant intermediates with respect to particle formation and need to be considered in future gas-phase reaction mechanisms.

Effect of Hydrophobic Iron Oxide Nanoparticles on the Properties of Oil-Based Drilling Fluid

AbstractLately, nanoparticles (NPs) have shown the potential to improve the performance of oil well fluids significantly. Several studies have reported the ability of NPs to produce improved properties of both water and oil-based drilling fluids. In this study, hydrophobic iron oxide NPs were synthesized by thermal decomposition of iron pentacarbonyl in an inert atmosphere, and its performance was tested in the oil-based drilling fluid with 90/10 oil-to-water ratio (base fluid). Oil-based drilling fluids treated with nanofluids were formulated by adding 0.5 wt% and 1.0 wt% iron oxide NPs in hexane solution to the base drilling fluid. The base fluid and the nanofluid-treated drilling fluids were evaluated by characterizing their rheological properties at different temperatures, viscoelastic properties, lubricity, filtrate loss, static and dynamic settling, and separation properties. Results showed that 0.5 wt% iron oxide dispersed in hexane reduced the high pressure high temperature (HPHT) filtrate loss by 70%, filter cake thickness by 55%, and the coefficient of friction by 39%. Moreover, the nanofluid based drilling fluid reduced the free oil layer caused by syneresis during aging at high temperature by 16.3% compared to the base fluid. This study has shown that hydrophobic iron oxide NPs have the potential to improve the properties of oil-based drilling fluid.

Determination of gas-phase absorption cross-sections of FeO in a shock tube using intracavity absorption spectroscopy near 611 nm

We report state-resolved absorption cross-section measurement and oscillator-strength evaluation of the gas-phase iron oxide (FeO) orange system near 611 nm. Intracavity absorption spectroscopy (ICAS) with a homemade broadband dye laser was applied for time-resolved measurements of absorption spectra of shock-activated mixtures of iron pentacarbonyl and carbon dioxide (diluted in argon), generating gas-phase FeO. The measurements were performed with a time resolution of 170 µs in the spectral range of 16,316–16,353 cm−1 that includes a large number of FeO absorption lines. Across the 8-cm diameter of the shock tube, ICAS leads to an effective absorption path length of 260 m. Absorption cross-section values of 0.5 × 10–18–4 × 10–18 cm2 were determined for temperatures around 2200 K and pressures of ∼1.3 bar. Pressure- and temperature-independent oscillator strengths for individual ro-vibronic transitions within the 611-nm band of FeO orange system are reported for the first time. These data are generally applicable for quantitative absorption measurements of flame studies of iron chemistry, where FeO plays a key role as intermediate species.

Iron carbonyl complexes of a rigid chelating dicarbene: A density functional theory study

The series of vegiR dicarbenes with a phenanthroline-like backbone synthesized by Kunz and co-workers provide rigid chelating bidentate ligands with carbon donor atoms. Such ligands can, in principle, replace two carbonyl groups in a metal carbonyl derivative leading to analogues of metal carbonyls but with weaker-field carbon-based ligands. Density functional theory has been used to investigate the structures and energetics of the iron carbonyl complexes (vegiMe)Fe(CO)n (n = 3, 2) and (vegiMe)Fe2(CO)n (n = 7, 6, 5) of the simplest such ligands with methyl substituents. Replacement of two carbonyl groups in Fe(CO)5 with one vegiMe ligand is predicted to give trigonal bipyramidal and tetragonal pyramidal isomers of the tricarbonyl (vegiMe)Fe(CO)3 having similar energies within ~2 kcal/mol suggesting a fluxional system. Removal of a carbonyl group from (vegiMe)Fe(CO)3 is predicted to give singlet and triplet (vegiMe)Fe(CO)2 dicarbonyl structures with similar energies having a hole in the coordination sphere for the “missing” carbonyl group. A quintet (vegiMe)Fe(CO)2 structure with tetrahedral FeC4 coordination is a higher energy isomer by ~10 kcal/mol. The three lowest energy (vegiMe)Fe2(CO)7 structures, obtained by replacing two carbonyl groups in Fe2(CO)9 with one vegiMe ligand, have the vegiMe ligand bridging a Fe–Fe single bond to form a six-membered Fe2CN2C ring. Isomeric (vegiMe)Fe2(CO)7 structures with the vegiMe ligand chelated to a single iron atom forming a five-membered FeC2N2 ring lie at least 10 kcal/mol above the lowest energy isomer. The lowest energy isomers of the unsaturated (vegiMe)Fe2(CO)n (n = 6, 5) are triplet and quintet spin state structures reflecting the lower field strength of the vegiR ligands relative to carbonyl groups.

A Stimulus-Responsive Polymer Composite Surface with Magnetic Field-Governed Wetting and Photocatalytic Properties.

With the increasing demand for liquid manipulation and microfluidic techniques, surfaces with real-time tunable wetting properties are becoming the focus of materials science researches. In this study, we present a simple preparation method for a 0.5–4 µm carbonyl iron (carbonyl Fe) loaded polydimethylsiloxane (PDMS)-based magnetic composite coating with magnetic field-tailored wetting properties. Moreover, the embedded 6.3–16.7 wt.% Ag-TiO2 plasmonic photocatalyst (d~50 nm) content provides additional visible light photoreactivity to the external stimuli-responsive composite grass surfaces, while the efficiency of this photocatalytic behavior also turned out to be dependent on the external magnetic field. The inclusion of the photocatalyst introduced hierarchical surface roughness to the micro-grass, resulting in the broadening of the achievable contact and sliding angle ranges. The photocatalyst-infused coatings are also capable of catching and releasing water droplets, which alongside their multifunctional (photocatalytic activity and tunable wetting characteristics) nature makes surfaces of this kind the novel sophisticated tools of liquid manipulation.

Experimental and numerical investigation of iron-doped flames: FeO formation and impact on flame temperature

Gas-phase iron compounds strongly affect the flame structure already at very low concentrations, which implies the control of combustion efficiency, pollution formation, and materials synthesis in flames. The impact of iron pentacarbonyl on low-pressure premixed flames was investigated experimentally and numerically for a broad range of equivalence ratios. The burner was operated in top-to-bottom orientation, causing a strong effect of buoyancy on the flow field, a configuration, also known as buoyancy-opposed flame. The application of ultra-sensitive broadband intracavity laser absorption diagnostics enabled path-integrated measurements of gas-phase FeO in the particle-laden flow. Spatially-resolved temperature distributions were measured via OH laser-induced fluorescence. The measurements were complemented by detailed simulations of the down-firing flame to determine the (one-dimensional) flow field on the centerline of the burner. The experimental findings were the basis for extension of existing reaction schemes for iron-doped flames and a new skeletal scheme was proposed. Measured temperatures and normalized FeO concentrations were used to validate both the detailed and the skeletal scheme. The results of the optimization and reduction procedure helped to improve the understanding of the structure of the iron-doped flame and the role of iron-cluster formation in the interaction mechanisms which cause the flame inhibition or promotion by iron-compounds.

An improved wideband three‐way waveguide power divider based on directional coupler for Ku band application

In this paper, a directional-coupler-based wideband three-way waveguide power divider is demonstrated. The proposed power divider consists of tapered rectangular waveguide, six-port directional coupler and iron pentacar-bonyl terminations. Its fractional bandwidth is 10.99% at 12.9 to 14.4 GHz. In addition, the return loss of all input and output ports is better than 20 dB and the isolation of the three output ports is more than 20 dB. Moreover, the insert loss is better than 5.19 dB including the power division ratio of 4.8 dB and the amplitude imbalance among the three output ports of less than ±0.4 dB. The experimental results agree well with the simulation ones, which indicates the validity of our method. With the above-mentioned characteristics, the proposed device can be widely used in Ku band communication systems.

Highly Stable Iron Carbonyl Complex Delivery Nanosystem for Improving Cancer Therapy.

Metal carbonyl complexes can readily liberate carbon monoxide (CO) in response to activation stimulus. However, applicability of metal carbonyl complexes is limited because they are unstable under natural ambient conditions of moisture and oxygen. Reported here is the rational design of an iron carbonyl complex delivery nanosystem for the improvement of cancer therapy. We demonstrated that iron pentacarbonyl (Fe(CO)5) can be encapsulated into the cavity of a Au nanocage under an oxygen-free atmosphere and then controllably form iron oxide on the surface of the Au nanocage under aerobic conditions. The formation of iron oxide efficiently avoids the leakage and oxidation of the caged Fe(CO)5. The resulting nanomaterial exhibits excellent safety, biocompatibility, and stability, which can be specifically activated under near-infrared (NIR) irradiation within the tumor environment to generate CO and iron. The released CO causes damage to mitochondria and subsequent initiation of autophagy. More importantly, during autophagy, the nanomaterial that contains iron and iron oxide can accumulate into the autolysosome and result in its destruction. The produced CO and iron show excellent synergistic effects in cancer cells.

Structural and electromagnetic properties of Fe2Co-multi-walled carbon nanotubes-polystyrene based composite

Here, we report on the synthesis, characterization, and electromagnetic properties of the composites based on Fe2Co alloy nanoparticles, multi-walled carbon nanotubes (MWCNTs), and polystyrene (PS). The absorbing electromagnetic characteristics of Fe2Co/MWCNT-PS composites in the frequency range of 1–18 GHz have been tuned by controlling their dielectric and magnetic properties. For this, Fe2Co/MWCNT hybrids with a controlled composition and particle size of the Fe2Co alloy have been obtained by thermal decomposition of iron and cobalt carbonyls on the surface of MWCNTs with subsequent production of Fe2Co/MWCNT-PS membranes by vacuum filtration. The optimization of the conditions of the Fe2Co alloy particles formation as well as the study of the structure and morphology of the hybrids and membranes based on them have been carried out using HRTEM, HAADF-STEM, SEM, XRD, and TPD. The effect of the calcination temperature on the evolution of the chemical composition, structure, size, and morphology of supported Fe2Co nanoparticles has been thoroughly studied. In order to enhance the shielding properties of the material, a multilayer composite structure has been proposed and optimized, consisting of five alternating layers of Fe2Co/MWCNT-PS membranes and dielectric layers (neat PS) localized on a metal surface. The simulation results show that the proposed five-layer material, consisting of three layers of Fe2Co/MWCNT-PS membranes with thickness of 0.1 mm and two layers of PS with thickness of 0.5 mm, shows the highest efficiency of electromagnetic interference shielding (−14.2 dB at 17.5 GHz) as compared to a similar composite consisting of MWCNT-PS membranes (−5.4 dB at 17.5 GHz). Such multilayer structure is cost-effective and lightweight, which makes it a perspective material for EMI shielding.

Redox Condensations of o-Nitrobenzaldehydes with Amines under Mild Conditions: Total Synthesis of the Vasicinone Family.

A total synthesis of the vasicinone family of natural products from bulk chemicals was developed. Reductive condensation of o-nitrobenzaldehydes with amines utilizing iron pentacarbonyl as a reducing agent followed by subsequent oxidation leads to a great variety of polycyclic nitrogen-containing heterocycles under mild conditions. Enantiomerically pure vasicinone, rutaecarpine, isaindigotone, and luotonin were synthesized from readily available starting materials like hydroxyproline, nitrobenzaldehyde, pyrrolidine, and piperidine in two to four operational steps without chromatography. The antifungal activity of all products was tested.

Magnetic and near-infrared derived heating characteristics of dimercaptosuccinic acid coated uniform Fe@Fe3O4 core\u2013shell nanoparticles

Among the number of hyperthermia materials, magnetic nanoparticles have received much attention. In this work, we studied the heating characteristics of uniform Fe@Fe3O4 core–shell nanoparticle under near-infrared laser irradiation and external AC magnetic field applying. The Fe@Fe3O4 core–shell nanoparticles were prepared by thermal decomposition of iron pentacarbonyl and followed by controlled oxidation. The prepared uniform particles were further coated with dimercaptosuccinic acid to make them well dispersed in water. Near-infrared derived photothermal study of solutions containing a different concentration of the core–shell nanoparticles was made by using 808 nm laser Source. Additionally, magnetic hyperthermia ability of the Fe@Fe3O4 nanoparticle at 150 kHz and various oersted (140–180 Oe) condition was systemically characterized. The Fe@Fe3O4 nanoparticles which exhibited effective photo and magnetic hyperthermia are expected to be used in biomedical application.