Coordination Environment Of Metal Ion Research Articles

Efficient and clean treatment of indium-bearing zinc ferrite: A new approach using a water-regulated deep eutectic solvent

Indium, a strategic key metal, is mainly recovered from zinc leaching residue. However, a challenging problem in the treatment of zinc leaching residue is how to efficiently and cleanly treat the poorly soluble phase, the indium-bearing zinc ferrite (IBZF). Here, we propose a novel strategy for the selective extraction of indium, zinc and iron from IBZF. By introducing water to regulate the coordination environment of a choline chloride-anhydrous oxalic acid based deep eutectic solvent (ChCl-Oxa based DES), efficient leaching and deep separation of indium, zinc and iron were achieved. Water, acting as both co-solvent and diluent, played a critical role in the whole process. The addition of a little water reduces the viscosity of the DES, thereby improving the leaching of indium, zinc and iron. Under specific leaching conditions (leaching temperature of 90 °C, liquid/solid ratio of 20:1 ml/g, molar ratio of ChCl:Oxa = 1:1, molar ratio of DES:H2O = 1:3 and reaction time of 3.5 h), the leaching efficiencies of indium, zinc and iron were 96.27 %, 95.55 % and 96.33 %, respectively. The subsequent addition of large amounts of water dilutes and dissociates the structure of the DES, facilitating the stepwise precipitation and deep separation of metal ions. The precipitation efficiency of zinc and iron reached 93.06 % and 98.07 %, respectively. Residual indium ions in the solution were effectively adsorbed by activated carbon, with a recovery efficiency of 75.7 % after five cycles of adsorption. The solution separated from the metal ions was well regenerated by evaporation and addition of Oxa. Our work represents a novel approach for the recycling and clean utilization of zinc leaching residue. And the regulation of the coordination environment of metal ions in DES is proved to have great potential in metal recycling.

Recent advances and future perspectives in MOF-derived single-atom catalysts and their application: a review

This article discusses the relationship between single-atom sites and the catalytic mechanism of functional MOFs which is related to the coordination environment of metal ions, and also summarizes the research progress of MOF-derived SACs in recent years.

Selective Extraction of Transition Metals from Spent LiNix Coy Mn1-x-y O2 Cathode via Regulation of Coordination Environment.

The complexity of chemical compounds in lithium-ion batteries (LIBs) results in great difficulties in the extraction of multiple transition metals, which have similar physicochemical characteristics. Here, we propose a novel strategy for selective extraction of nickel, cobalt, and manganese from spent LiNix Coy Mn1-x-y O2 (NCM) cathode through the regulation of coordination environment. Depending on adjusting the composition of ligand in transition metal complexes, a tandem leaching and separation system is designed and finally enables nickel, cobalt, and manganese to enrich in the form of NiO, Co3 O4 , and Mn3 O4 with high recovery yields of 99.1 %, 95.1 %, and 95.3 %, respectively. We further confirm that the combination of different transition metals with well-designed ligands is the key to good selectivity. Through our work, fine-tuning the coordination environment of metal ions is proved to have great prospects in the battery recycling industry.

Selective Extraction of Transition Metals from Spent LiNixCoyMn1−x−yO2 Cathode via Regulation of Coordination Environment

AbstractThe complexity of chemical compounds in lithium‐ion batteries (LIBs) results in great difficulties in the extraction of multiple transition metals, which have similar physicochemical characteristics. Here, we propose a novel strategy for selective extraction of nickel, cobalt, and manganese from spent LiNixCoyMn1−x−yO2 (NCM) cathode through the regulation of coordination environment. Depending on adjusting the composition of ligand in transition metal complexes, a tandem leaching and separation system is designed and finally enables nickel, cobalt, and manganese to enrich in the form of NiO, Co3O4, and Mn3O4 with high recovery yields of 99.1 %, 95.1 %, and 95.3 %, respectively. We further confirm that the combination of different transition metals with well‐designed ligands is the key to good selectivity. Through our work, fine‐tuning the coordination environment of metal ions is proved to have great prospects in the battery recycling industry.

“A spectroscopic picture paints 1000 words” mapping iron speciation in brain tissue with “full spectrum per pixel” X-ray absorption near-edge structure spectroscopy

Coordination chemistry enables a variety of vital functions in biological systems; however, characterising the chemical form of metal ions in cells and tissue is notoriously difficult. One technique that is gaining substantial momentum in this research area is X-ray absorption near-edge structure (XANES) spectroscopy. The XANES spectrum can be a rich source of information with respect to the coordination environment of metal ions. Further, XANES spectroscopy is compatible with microscopy mapping protocols as the spectra are recorded across a relatively narrow range of data points (typically 50–100). Although the potential of XANES spectroscopy to study metal ion coordination chemistry has long been known, data collection speed has only relatively recently reached the state in which maps can be collected with a full spectrum per pixel. The realisation of this capability now places XANES spectroscopic mapping among a suite of other spectroscopic imaging techniques, such as Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy, which are available to characterise biochemical composition, in situ within cells and tissue. Herein, we report a proof-of-concept application of XANES spectroscopic mapping to begin exploration of Fe speciation in brain tissue, which demonstrates the potential of this method for the biomedical sciences, and identifies important areas for consideration with respect to future protocol developments.

Synthesis, crystal structures and luminescence studies of zinc(II) and cadmium(II) complexes with 5-(1H-tetrazol-5-yl)nicotinic acid

Two coordination polymers (CPs) with novel tri-functional ligand, [Zn(H2O)(CH3OH)L]n (1) and [Cd(H2O)L]n (2), (H2L = 5-(1H-tetrazol-5-yl)nicotinic acid), have been synthesized and structurally characterized. Differently, 1 exhibits the 2D layer structure, while 2 exhibits the 3D structure due to the different connection modes between metal nodes and tri-functional ligand. The different coordination habit between metal ions and ligands must be responsible for the fabrication of versatile topologies. At room temperature, 1 exhibits an intense emission at around 367 nm, while 2 exhibits an intense emission at 358 nm. The different shift of the peak from free ligand, 1 and 2 must be assigned to the different configuration and π-bonding of L caused by the different coordination environments of metal ions.

Electrochemical studies of binary and ternary copper(II) complexes with α-factor analogues

Copper(II) binding properties of Saccharomyces cerevisiae pheromone (α-factor) analogues, namely WHWSKNR-am, FHWSKNR-am and WHFSKNR-am amino acid sequences, were studied using voltammetry techniques, fluorescence and UV–Vis spectroscopy. Despite the same 3N binding mode attributed to XHZ-type oligopeptides, the obtained results demonstrated high dependence of the electrochemical properties of their copper(II) complexes on the metal ion coordination environment. Changes triggered by ternary complex formation with imidazole molecule, leading to 4N structure formation, were also examined. The investigated derivatives underwent reduction and oxidation processes as well, however the coordination sphere affected mainly the anodic signal. Different electrochemical responses of α-factor analogues revealed significant influence of tryptophan residue position in a peptide sequence and indicated the complexity of ongoing redox processes. That stems from the presence of two different redox active centers and the possibility of the occurrence of multiple electrostatic interactions engaging charged groups, metal cation and indole moiety.

Crystal Chemistry of Zinc Quinaldinate Complexes with Pyridine-Based Ligands

Substitution of methanol in [Zn(quin)2(CH3OH)2] (quin− denotes an anionic form of quinoline-2-carboxylic acid, also known as quinaldinic acid) with pyridine (Py) or its substituted derivatives, 3,5-lutidine (3,5-Lut), nicotinamide (Nia), 3-hydroxypyridine (3-Py-OH), 3-hydroxymethylpyridine (3-Hmpy), 4-hydroxypyridine (4-Py-OH) and 4-hydroxymethylpyridine (4-Hmpy), afforded a series of novel heteroleptic complexes with compositions [Zn(quin)2(Py)2] (1), [Zn(quin)2(3,5-Lut)2] (2), [Zn(quin)2(Nia)2]·2CH3CN (3), [Zn(quin)2(3-Py-OH)2] (4), [Zn(quin)2(3-Hmpy)2] (5), [Zn(quin)2(4-Pyridone)] (6) (4-Pyridone = a keto tautomer of 4-hydroxypyridine), and [Zn(quin)2(4-Hmpy)2] (7). In all reactions, the {Zn(quin)2} structural fragment with quinaldinate ions bound in a bidentate chelating manner retained its structural integrity. With the exception of [Zn(quin)2(4-Pyridone)] (6), all complexes feature a six-numbered coordination environment of metal ion that may be described as a distorted octahedron. The arrangement of ligands is trans. The coordination sphere of zinc(II) in the 4-pyridone complex consists of only three ligands, two quinaldinates, and one secondary ligand. The metal ion thereby attains a five-numbered coordination environment that is best described as a distorted square-pyramid (τ parameter equals 0.39). The influence of substituents on the pyridine-based ligand over intermolecular interactions in the solid state is investigated. Since pyridine and 3,5-lutidine are not able to form hydrogen-bonding interactions, the solid state structures of their complexes, [Zn(quin)2(Py)2] (1) and [Zn(quin)2(3,5-Lut)2] (2), are governed by π···π stacking, C–H∙∙∙π, and C–H∙∙∙O intermolecular interactions. With other pyridine ligands possessing amide or hydroxyl functional groups, the connectivity patterns in the crystal structures of their complexes are governed by hydrogen bonding interactions. Thermal decomposition studies of novel complexes have shown the formation of zinc oxide as the end product.

Syntheses, crystallization and selective dye adsorption of three Co(II) coordination polymers via one-pot reaction

Three novel Co(II) coordination polymers, namely [Co(HL)(4,4′-bibp)]n (1), [Co(HL)(4,4′-bibp)]n (2) and {[Co2(L)(4,4′-bibp)2(H2O)3(HCOO)]·2H2O·HCOOH}n (3) (H3L=5-(2′′-carboxylphenoxy)isophthalic, 4,4′-bibp=4,4′-bis(imidazol-1-yl)biphenyl) were synthesized through one-pot reaction under co-crystallization conditions. These complexes were characterized by elemental analysis, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric (TG) analysis and single-crystal X-ray diffraction. Complexes 1 and 2 were supramolecular isomers with different 2D configurations. Complex 1 shows a sql 2D-network with a [Co(HL2−)]n single-strand helix chain and another [Co(4,4′-bibp)]n single-strand helix chain, which are further assembled into 3D supramolecular architectures through H-bonds and C–H⋯N bonds. While complex 2 exhibits another 2D-network with two different [Co(HL2−)]n helix chains (left and right) and one [Co(4,4′-bibp)]n zigzag chain, which further constructing a 3D supramolecular structure through H-bonds. Compared with 1 and 2, 3 also shows a sql 2D-network with a bigger channel which influenced by the coordination environment of metal ions. Furthermore, the selective dye adsorption studies indicate that complex 1 can highly and selectively adsorb Methyl Orange (MO) in a short time, and complex 2 shows a highly adsorption activity for Alizarin Red S (ARS) than Methyl Orange, and complex 3 can selectively adsorb Methyl Orange.

Modifying magnetic properties and dispersity of few-layer MoS2 particles by 3d metal carboxylate complexes

The interaction of MoS2 sheets produced by chemical exfoliation of LiMoS2 in liquid media with trinuclear metal carboxylate complexes of the general formula [M3(O2CR)6L3]n+ (M = Fe, Co; R = CH3, C(CH3)3, CH2N+(CH3)3; L = H2O or pyridine) was studied. The composition, structure and dispersity of the obtained materials as well as the distribution of magnetically active metal cations within their particles were analyzed on the basis of PXRD, SEM, TEM, HAADF-STEM, TGA-MS and magnetic measurements data. The interaction process was found to result in the displacement of the important part of carboxylate ligands from coordination environment of metal ions and formation of metal oxide-like nanoclusters. These nanoclusters are distributed within the surface of MoS2 sheet packets of the thickness of 4–6 nm, which are formed due to restacking of exfoliated MoS2. The metal complexes strongly influence sheet restacking, leading to a significantly lower (up to ∼ 1.5 times) thickness of the sulfide packets than in their absence. The metal atoms constituting oxide nanoclusters exhibit strong antiferromagnetic interactions.

Evolutionary implications of metal binding features in different species' prion protein: an inorganic point of view.

Prion disorders are a group of fatal neurodegenerative conditions of mammals. The key molecular event in the pathogenesis of such diseases is the conformational conversion of prion protein, PrPC, into a misfolded form rich in β-sheet structure, PrPSc, but the detailed mechanistic aspects of prion protein conversion remain enigmatic. There is uncertainty on the precise physiological function of PrPC in healthy individuals. Several evidences support the notion of its role in copper homeostasis. PrPC binds Cu2+ mainly through a domain composed by four to five repeats of eight amino acids. In addition to mammals, PrP homologues have also been identified in birds, reptiles, amphibians and fish. The globular domain of protein is retained in the different species, suggesting that the protein carries out an essential common function. However, the comparison of amino acid sequences indicates that prion protein has evolved differently in each vertebrate class. The primary sequences are strongly conserved in each group, but these exhibit a low similarity with those of mammals. The N-terminal domain of different prions shows tandem amino acid repeats with an increasing amount of histidine residues going from amphibians to mammals. The difference in the sequence affects the number of copper binding sites, the affinity and the coordination environment of metal ions, suggesting that the involvement of prion in metal homeostasis may be a specific characteristic of mammalian prion protein. In this review, we describe the similarities and the differences in the metal binding of different species’ prion protein, as revealed by studies carried out on the entire protein and related peptide fragments.

Back Cover: A Multispectroscopic Study of 3 d Orbitals in Cobalt Carboxylates: The High Sensitivity of 2p3d Resonant X-ray Emission Spectroscopy to the Ligand Field (Angew. Chem. Int. Ed. 4/2013)

3d transition-metal-ion coordination is crucial in many chemical processes and in the understanding of their reaction mechanisms. In their Communication on page 1170 ff. M. M. van Schooneveld, F. M. F. de Groot et al. show for cobalt(II) carboxylates that synchrotron-based 2p3d resonant X-ray emission spectroscopy (RXES) allows for a far more judicious determination of the metal-ion coordination environment than benchmark ultraviolet/visible (UV/Vis) and 2p X-ray absorption (XAS) spectroscopy do.

Applications of Time-Resolved Laser Fluorescence Spectroscopy to the Environmental Biogeochemistry of Actinides

Time-resolved laser fluorescence spectroscopy (TRLFS) is a useful means of identifying certain actinide species resulting from various biogeochemical processes. In general, TRLFS differentiates chemical species of a fluorescent metal ion through analysis of different excitation and emission spectra and decay lifetimes. Although this spectroscopic technique has largely been applied to the analysis of actinide and lanthanide ions having fluorescence decay lifetimes on the order of microseconds, such as UO , Cm, and Eu, continuing development of ultra-fast and cryogenic TRLFS systems offers the possibility to obtain speciation information on metal ions having room-temperature fluorescence decay lifetimes on the order of nanoseconds to picoseconds. The main advantage of TRLFS over other advanced spectroscopic techniques is the ability to determine in situ metal speciation at environmentally relevant micromolar to picomolar concentrations. In the context of environmental biogeochemistry, TRLFS has principally been applied to studies of (i) metal speciation in aqueous and solid phases and (ii) the coordination environment of metal ions sorbed to mineral and bacterial surfaces. In this review, the principles of TRLFS are described, and the literature reporting the application of this methodology to the speciation of actinides in systems of biogeochemical interest is assessed. Significant developments in TRLFS methodology and advanced data analysis are highlighted, and we outline how these developments have the potential to further our mechanistic understanding of actinide biogeochemistry.

ChemInform Abstract: Applications of Lanthanide Luminescence Spectroscopy to Solution Studies of Coordination Chemistry

Abstract Luminescence spectroscopy is an important technique for the study of the coordination chemistry of the lanthanide ions in both the solution and solid state. This article concentrates on applications aimed at elucidating the coordination structure in solution phase systems. Luminescence lifetime measurements which allow the examination of the metal ion coordination environment in a wide variety of ligand systems are discussed. In addition, recent developments in the use of Eu(III) 7 F 0 → 5 D 0 excitation spectroscopy are presented. In the final section, the application of luminescence techniques to the examination of ligand sensitized lanthanide luminescence is reviewed briefly.

Self-assembly, thermal stability and photoluminescence of two mixed-ligand silver(i) networks via 2D → 2D and 2D → 3D parallel interpenetration of (4,4) nets

Two mixed-ligand silver(I) coordination polymers (CPs) [Ag2(dmapym)2(suc)·H2O]n (1) and [Ag2(dmapym)2(bdc)·2H2O]n (2), (dmapym = 2-amino-4,6-dimethylpyrimidine, H2suc = succinic acid, H2bdc = 1,3-benzenedicarboxylic acid), were synthesized and characterized. The structure of 1 presents an argentophilic interaction enhanced 2-crossing [2]-catenane motif formed between pairs of parallel interpenetrating 2D 44-sql nets. For 2, as the dicarboxylate changes from flexible H2suc to rigid V-shaped H2bdc, each highly undulated 2D 44-sql net was penetrated in parallel by the two nearest neighbouring ones and thus the overall 2D → 3D network is formed. The geometries and flexibility of dicarboxylates influence the coordination environments of metal ions and arrangement of ligands and thus determine the structures of the CPs. The photoluminescent and thermal properties of 1 and 2 have also been investigated.

Structures and Energetics of Erbium Chloride Complexes in Aqueous Solution

A series of aqueous, constant ionic strength solutions containing 0.5 m Er is studied as a function of chloride/perchlorate ion concentration using high-energy X-ray scattering (HEXS) to probe the metal ion coordination environment. Perchlorate is seen to form an outer-sphere complex only in the end member (4.0 m perchlorate) of the series. Chloride ions are seen to bind as both inner- and outer-sphere complexes. A quantitative analysis of the scattering data is used to determine stability constants that depend on whether the complexation with chloride ions is assumed to add to or to replace the waters bound in the first coordination sphere. Published stability constants obtained from liquid-liquid extraction clarify the mechanism involved and, together with the HEXS data, present a consistent picture of the chemistry. The stability constants determined from the HEXS data, beta(1) = 0.38(8) and beta(2) = 0.014(9), are small, less than the available thermal energy in solution at room temperature. The combination of chemical separations and HEXS data for the analysis supports the argument that the complexes formed are real under the experimental conditions. Details of the structural correlations and interactions are discussed for applications including separations and environmental modeling.

Substituent effect on the assembly of coordination polymers containing isophthalic acid and its derivatives

Four coordination polymers [Zn4(H2O)(ip)4(py)6]n1, {[Zn2(hip)2(py)4]2·(py)}n2, [Zn(tbip)(py)2]n3 and [Mn(tbip)(py)2]n4 (H2ip = isophthalic acid, H2hip = 5-hydroxyisophthalic acid, H2tbip = 5-tert-butylisophthalic acid, py = pyridine), have been hydrothermally synthesized and characterized. The photoluminescent properties of 1–3 have also been investigated. For 1–3, as substituents change from H, OH to tert-butyl, the coordination numbers of Zn2+ ions decrease, and the dimensionalities of the structures of 1–3 decrease from 2D (4,4) net, 1D double stranded chain to 1D chain. For 3 and 4, as Mn2+ tends to have a higher coordination number as compared to Zn2+, the structure of 4 is a 2D (4,4) net while the structure of 3 is a 1D chain. The substituents on isophthalic acid influence the coordination environments of metal ions and the coordination modes of the carboxyls, and thus determine the structures of the coordination polymers. The coordination behavior of metal ions also affects the formation of the structures.

Prion Proteins Leading to Neurodegeneration

Prion diseases are fatal neurodegenerative disorders related to the conformational alteration of the prion protein (PrP C) into a pathogenic and protease-resistant isoform PrP(Sc). PrP(C) is a cell surface glycoprotein expressed mainly in the central nervous system and despite numerous efforts to elucidate its physiological role, the exact biological function remains unknown. Many lines of evidences indicate that prion is a copper binding protein and thus involved in the copper metabolism. Prion protein is not expressed only in mammals but also in other species such as birds, reptiles and fishes. However, it is noteworthy to point out that prion diseases are only observed in mammals while they seem to be spared to other species. The chicken prion protein (chPrP C) shares about 30% of identity in its primary sequence with mammal PrP C. Both types of proteins have an N-terminal domain endowed with tandem amino acid repeats (PHNPGY in the avian protein, PHGGGWQ in mammals), followed by a highly conserved hydrophobic core. Furthermore, NMR studies have highlighted a similar globular domain containing three alpha-helices, one short 3(10)-helix and a short antiparallel beta-sheet. Despite this structural similarity, it should be noted that the normal isoform of mammalian PrP C is totally degraded by proteinase K, while avian PrP C is not, thereby producing N-terminal domain peptide fragments stable to further proteolysis. Notably, the hexarepeat domain is considered essential for protein endocytosis, and it is supposed to be the analogous copper-binding octarepeat region of mammalian prion proteins. The number of copper binding sites, the affinity and the coordination environment of metal ions are still matter of discussion for both mammal and avian proteins. In this review, we summarize the similarities and the differences between mammalian and avian prion proteins, as revealed by studies carried out on the entire protein and related peptide fragments, using a range of experimental and computational approaches. In addition, we report the metal-driven conformational alteration, copper binding modes and the superoxide dismutase-like (SOD-like) activity of the related copper(II) complexes.

Synthesis, characterization and bioactivity of a new Fe(III) 18-metallacrown-6 and a new trinuclear linear Ni(II) complexes

A new trinuclear linear Ni(II) compound [Ni 3(H 2O) 2(DMA) 2(acshz) 2] · 2DMF (DMA = dimethylamine) ( 1) and a new Fe(III) 18-metallacrown-6 [Fe 6(acbshz) 6(DMF)(H 2O) 5] · 5DMF ( 2), with two similar pentadentate ligands, N-acryloyl-salicylhydrazide (H 3acshz) and N-acryloyl-5-bromosalicylhydrazide (H 3acbshz) have been synthesized and characterized by X-ray crystallography. In compound 1, three nickel ions arrange in a strictly linear structure, adjacent molecules are linked by intermolecular H bonds to form a 2D infinite wave-like structure. In compound 2, the ring of the metallacrown is consisted of six interlink [Fe–N–N] repeated units through hydrazide N–N group bridging. It is the first metallacrown that the coordination environments of metal ions in the cycle ring are different, and these differences make the two faces of the disc-shaped hexanuclear ring do not have opposite chiralities. The studies in solution integrity and stability of the metallacrown 2 show it is soluble and stable in DMF. UV–Vis titrations demonstrate the metallacrown 2 is stable in DMF even in the presence of excess metal ions. Antibacterial screening data indicate the two compounds all have antimicrobial activities against the tested microorganisms. The activities of metallacrown 2 are stronger than trinuclear compound 1.

Characterization of an Improved Extraction Chromatographic Material for the Separation and Preconcentration of Strontium from Acidic Media

:The determination of radiostrontium in biological and environmental samples generally requires its preliminary separation and preconcentration, both to remove radionuclides that may interfere with subsequent β-counting and to free it from the large quantities of inactive substances present (e.g., calcium). Extraction chromatography employing an inert support impregnated with a solution of a crown ether in an oxygenated, aliphatic solvent (e.g., 1-octanol) has previously been demonstrated to provide a simple and effective method for the isolation of strontium from a variety of samples for subsequent determination. In this work, it is shown that a chromatographic resin capable of retaining strontium efficiently and selectively from acidic media can be prepared simply by dispersing a crown ether alone on an appropriate support. This “solventless” resin is demonstrated to offer several advantages over its conventional analog, in particular, good physical stability, higher capacity, and improved metal ion retention. In addition, extended X-ray absorption tine structure measurements are shown to provide insight into the coordination environment of metal ions sorbed by the resin.