Iron Sulfide Clusters Research Articles

Preparation of Iron-Based Sulfides and Their Applications in Biomedical Fields.

Recently, iron-based sulfides, including iron sulfide minerals and biological iron sulfide clusters, have attracted widespread interest, owing to their excellent biocompatibility and multi-functionality in biomedical applications. As such, controlled synthesized iron sulfide nanomaterials with elaborate designs, enhanced functionality and unique electronic structures show numerous advantages. Furthermore, iron sulfide clusters produced through biological metabolism are thought to possess magnetic properties and play a crucial role in balancing the concentration of iron in cells, thereby affecting ferroptosis processes. The electrons in the Fenton reaction constantly transfer between Fe2+ and Fe3+, participating in the production and reaction process of reactive oxygen species (ROS). This mechanism is considered to confer advantages in various biomedical fields such as the antibacterial field, tumor treatment, biosensing and the treatment of neurodegenerative diseases. Thus, we aim to systematically introduce recent advances in common iron-based sulfides.

Iron sulfide clusters for annulation of 2-nitrobenzonitriles and benzylamines toward synthesis of 2-aryl-4-quinazolinones

A method for coupling of benzylamines and 2-nitrobenzonitriles is herein reported. Reactions proceeded in the presence of FeCl3, elemental sulfur, urea, DABCO (1,4-diazabicyclo[2.2.2]octane) base, and DMF solvent. The conditions were compatible with both electron-donating and electron-withdrawing substituents. This tactic appears to be the first method to use a first-row transition metal to promote the synthesis of 2-aryl-4-quinazolinones from commercially available 2-nitrobenzonitriles.

Bacterium-Sculpted Porphyrin-Protein-Iron Sulfide Clusters for Distinction and Inhibition of Staphylococcus aureus.

Microbe-catalyzed surface modification is a promising method for the production of special targeting nanomaterials. A bacterium-selective material can be obtained by investigating the microbe-catalyzed mineralization of proteins. Herein, a novel method was fabricated for the biosynthesis of FeS-decorated porphyrin-protein clusters (P-CA@BE) via E. coli (Escherichia coli)-catalyzed bio-Fe(III) reduction and bio-sulfidation of porphyrin (P), caffeic acid (CA), and protein [bovine serum albumin (BSA)] assemblies. The assembly (P-CA@BSA) was identified by spectroscopic methods. Next, the P-CA@BSA assembly was transferred into FeS-decorated porphyrin-protein clusters (P-CA@BE) catalyzed by E. coli. There are partial β-folding proteins in P-CA@BE, which selectively recognize S. aureus (Staphylococcus aureus) and show different antibacterial properties against E. coli and S. aureus. Results demonstrate that the E. coli-catalyzed mineralization of the porphyrin-protein assembly is an effective method for the biosynthesis of S. aureus-sensitive metal-protein clusters.

The hyperthermophilic archaeon Pyrococcus furiosus utilizes environmental iron sulfide cluster complexes as an iron source.

Iron is an essential nutrient for almost all known organisms, but in aerobic, neutral pH environments, it is present primarily as precipitated oxyhydroxide minerals. In contrast, in anaerobic environments, iron can exist in its ferrous form (Fe2+) and remain soluble. In sulfide-rich, anaerobic environments, Fe2+ and sulfide react to form iron sulfide cluster complexes of the form FexSx (FeSaq), which further condense to form the mineral mackinawite, which itself is partly soluble. However, the ability of microorganisms to utilize iron sulfide as an iron source is not known. Here, we show that the anaerobic, hyperthermophilic archaeon Pyrococcus furiosus can directly assimilate the iron in dissolved iron sulfide cluster complexes (FeSaq) without further dissolution to Fe2+. Growth is only inhibited in the presence of a Fe2+-specific chelator. The FeSaq that is utilized can be formed either by reaction of chelated Fe2+ with sulfide or dissolved from mackinawite. Pyrococcus furiosus can utilize FeSaq larger than 3.5kDa, or Fe40S40, and may actively aid in the dissolution of mackinawite to the assimilated FeSaq. A model for iron sulfide assimilation from an insoluble mineral is proposed.

Structural and Electronic Rearrangements in Fe2S2, Fe3S4, and Fe4S4 Atomic Clusters under the Attack of NO, CO, and O2.

We report results, based on density functional theory-generalized gradient approximation calculations, that shed light on how NO, CO, and O2 interact with Fe2S2, Fe3S4, and Fe4S4 clusters and how they modify their structural and electronic properties. The interest in these small iron sulfide clusters comes from the fact that they are at the protein cores and that elucidating fundamental aspects of their interaction with those light molecules which are known to modify their functionality may help in understanding complex behaviors in biological systems. CO and NO are found to bind molecularly, leading to moderate relaxations in the clusters, but nevertheless to changes in the spin-polarized electronic structure and related properties. In contrast, dissociative chemisorption of O2 is much more stable than molecular adsorption, giving rise to significant structural distortions, particularly in Fe4S4 that splits into two Fe2S2 subclusters. As a consequence, oxygen tends to strongly reduce the spin polarization in Fe and to weaken the Fe-Fe interaction inducing antiparallel couplings that, in the case of Fe4S4, clearly arise from indirect Fe-Fe exchange coupling mediated by O. The three molecules (particularly CO) enhance the stability of the iron-sulfur clusters. This increase is noticeably more pronounced for Fe2S2 than for the other iron-sulfur clusters of different compositions, a result that correlates with the fact that in recent experiments of CO reaction with FemSm (m = 1-4), the Fe2S2CO product results as a prominent one.

Unexpected Product of the Reaction of Iron(II) Dichloroclathrochelate with the [Fe2(μ-S)2(CO)6]2– Cluster Dianion: Synthesis and X-ray Diffraction Structure of the First Cage Complex with Thiol Groups Inherently Bonded to a Macrobicyclic Framework

An attempt to prepare a hybrid clusteroclathrochelate by nucleophilic substitution of iron(II) dichloroclathrochelate by substitution of its chlorine atoms with the [Fe2(μ-S)2(CO)6]2– cluster dianion as a nucleophilic agent generated in situ by the reduction of Fe2(μ-S2)(CO)6 with lithium triethylborohydride unexpectedly gave the macrobicyclic complex with two inherent thiol groups as the single clathrochelate product. Obviously, the initial iron-sulfide cluster underwent a complete decomposition during the reaction, thus acting only as a source of HS– and S2– anions. The composition and the structure of the complex obtained were confirmed by elemental analysis, MALDI-TOF mass spectrometry, 1H and 13C{1H} NMR spectroscopy, and single crystal X-ray diffraction (CIF file CCDC 1585112). The encapsulated iron(II) ion is located at the centre of its FeN6 coordination polyhedron possessing the geometry intermediate between a trigonal prism (the distortion angle φ = 0°) and a trigonal antiprism (φ = 60°) with φ ≈ 25°; the height of this polyhedron is 2.33 A. The presence of two thiol groups in the vicinal positions of the same ribbed moiety of the macrobicyclic molecule substantially affects the crystal packing of the molecular crystal containing clathrochelate dimers formed by four hydrogen bonds of two types (i.e., two S–H···O and two S–H···N bonds). The obtained cage complex and its deprotonated forms seem to be promising cis-disulfide bridging or chelating ligand synthons for the synthesis of new types of polynuclear complexes and coordination polymers as well.

Electron Transfer between Electrically Conductive Minerals and Quinones.

Long-distance electron transfer in marine environments couples physically separated redox half-reactions, impacting biogeochemical cycles of iron, sulfur and carbon. Bacterial bio-electrochemical systems that facilitate electron transfer via conductive filaments or across man-made electrodes are well-known, but the impact of abiotic currents across naturally occurring conductive and semiconductive minerals is poorly understood. In this paper I use cyclic voltammetry to explore electron transfer between electrodes made of common iron minerals (magnetite, hematite, pyrite, pyrrhotite, mackinawite, and greigite), and hydroquinones—a class of organic molecules found in carbon-rich sediments. Of all tested minerals, only pyrite and magnetite showed an increase in electric current in the presence of organic molecules, with pyrite showing excellent electrocatalytic performance. Pyrite electrodes performed better than commercially available glassy carbon electrodes and showed higher peak currents, lower overpotential values and a smaller separation between oxidation and reduction peaks for each tested quinone. Hydroquinone oxidation on pyrite surfaces was reversible, diffusion controlled, and stable over a large number of potential cycles. Given the ubiquity of both pyrite and quinones, abiotic electron transfer between minerals and organic molecules is likely widespread in Nature and may contribute to several different phenomena, including anaerobic respiration of a wide variety of microorganisms in temporally anoxic zones or in the proximity of hydrothermal vent chimneys, as well as quinone cycling and the propagation of anoxic zones in organic rich waters. Finally, interactions between pyrite and quinones make use of electrochemical gradients that have been suggested as an important source of energy for the origins of life on Earth. Ubiquinones and iron sulfide clusters are common redox cofactors found in electron transport chains across all domains of life and interactions between quinones and pyrite might have been an early analog of these ubiquitous systems.

Synthesis, Characterization, and Nitrogenase-Relevant Reactions of an Iron Sulfide Complex with a Bridging Hydride.

The FeMoco of nitrogenase is an iron–sulfur cluster with exceptional bond-reducing abilities. ENDOR studies have suggested that E4, the state that binds and reduces N2, contains bridging hydrides as part of the active-site iron-sulfide cluster. However, there are no examples of any isolable iron-sulfide cluster with a hydride, which would test the feasibility of such a species. Here, we describe a diiron sulfide hydride complex that is prepared using a mild method involving C–S cleavage of added thiolate. Its reactions with nitrogenase substrates show that the hydride can act as a base or nucleophile and that reduction can cause the iron atoms to bind N2. These results add experimental support to hydride-based pathways for nitrogenase.

New Iron–Sulfur Clusters Help Hydrogenases Tolerate Oxygen

One S less: recent crystallographic studies have revealed a new, oxygen-tolerant kind of iron-sulfide cluster [4Fe-3S], which contains only three rather than four sulfur atoms in its cage (see picture; yellow=S, red=Fe, blue=N, green=cysteine). It is proposed that the cluster's ability to transfer multiple electrons increases the oxygen tolerance by enabling the enzyme to reduce O(2) rapidly, converting the dioxygen into harmless water before it can damage the protein.

Wheel‐Shaped Lanthanide Iron Sulfide Clusters

Wheel‐Shaped Lanthanide Iron Sulfide Clusters

A new synthetic route to iron-sulfide clusters modeling the active site of nitrogenase

A new synthetic route to iron-sulfide clusters modeling the active site of nitrogenase

The Alkaline Solution to the Emergence of Life: Energy, Entropy and Early Evolution

The Earth agglomerates and heats. Convection cells within the planetary interior expedite the cooling process. Volcanoes evolve steam, carbon dioxide, sulfur dioxide and pyrophosphate. An acidulous Hadean ocean condenses from the carbon dioxide atmosphere. Dusts and stratospheric sulfurous smogs absorb a proportion of the Sun's rays. The cooled ocean leaks into the stressed crust and also convects. High temperature acid springs, coupled to magmatic plumes and spreading centers, emit iron, manganese, zinc, cobalt and nickel ions to the ocean. Away from the spreading centers cooler alkaline spring waters emanate from the ocean floor. These bear hydrogen, formate, ammonia, hydrosulfide and minor methane thiol. The thermal potential begins to be dissipated but the chemical potential is dammed. The exhaling alkaline solutions are frustrated in their further attempt to mix thoroughly with their oceanic source by the spontaneous precipitation of biomorphic barriers of colloidal iron compounds and other minerals. It is here we surmise that organic molecules are synthesized, filtered, concentrated and adsorbed, while acetate and methane--separate products of the precursor to the reductive acetyl-coenzyme-A pathway-are exhaled as waste. Reactions in mineral compartments produce acetate, amino acids, and the components of nucleosides. Short peptides, condensed from the simple amino acids, sequester 'ready-made' iron sulfide clusters to form protoferredoxins, and also bind phosphates. Nucleotides are assembled from amino acids, simple phosphates carbon dioxide and ribose phosphate upon nanocrystalline mineral surfaces. The side chains of particular amino acids register to fitting nucleotide triplet clefts. Keyed in, the amino acids are polymerized, through acid-base catalysis, to alpha chains. Peptides, the tenuous outer-most filaments of the nanocrysts, continually peel away from bound RNA. The polymers are concentrated at cooler regions of the mineral compartments through thermophoresis. RNA is reproduced through a convective polymerase chain reaction operating between 40 and 100 degrees C. The coded peptides produce true ferredoxins, the ubiquitous proteins with the longest evolutionary pedigree. They take over the role of catalyst and electron transfer agent from the iron sulfides. Other iron-nickel sulfide clusters, sequestered now by cysteine residues as CO-dehydrogenase and acetyl-coenzyme-A synthase, promote further chemosynthesis and support the hatchery--the electrochemical reactor--from which they sprang. Reactions and interactions fall into step as further pathways are negotiated. This hydrothermal circuitry offers a continuous supply of material and chemical energy, as well as electricity and proticity at a potential appropriate for the onset of life in the dark, a rapidly emerging kinetic structure born to persist, evolve and generate entropy while the sun shines.

Reaction of Fe 2S 2+ with C 2H 2 studied with a radiofrequency ion trap/time-of-flight mass spectrometer

The reactivity of iron sulfide cluster ions with acetylene has been studied in a radiofrequency ion trap with a time-of-flight mass spectrometer. A newly built set-up is described in detail. The cluster ions are produced by laser ablation and stored in the ion trap for about one second to react with acetylene. The product ions as well as the remaining parent cluster ions are analyzed with the time-of-flight mass spectrometer. The Fe 2S 2 + cluster ion reacts efficiently with C 2H 2 and forms Fe 2S 2(C 2H 2) n + ( n⪕4). The structure of Fe 2S 2 + is discussed on the basis of the favorable attachment of two or four C 2H 2 molecules.