Coordination Entities Research Articles

Cobalt-based coordination polymers as heterogeneous catalysts for activating Oxone to degrade organic contaminants in water: A comparative study

While Co represents the most efficient metal for activating Oxone to degrade organic contaminants, it is still highly desired to develop reusable and easy-to-recover heterogeneous Co-based catalysts. As chemistry of metal coordination compounds advances, a special class of organometallic polymers, so-called “coordination polymers” (CPs), has been developed. CPs contain repeated and cross-linked coordination entities to afford hierarchical structures with evenly-distributed Co moieties, making CPs attractive for activating Oxone. In this study, three CoCPs are particularly developed for the first time as heterogeneous catalysts to activate Oxone. Specifically, three organic ligands, including cyanuric acid (CA), trithiocyanuric acid (TTA), and pyridinedicarboxylic acid (PDA), were employed to investigate the effect of ligand on physical and chemical properties of the resulting CoCPs. More importantly, their catalytic activities for activating Oxone are compared and studied through investigating their distinct characteristics. As decolorization of Acid Red (AR) is employed as a model test for evaluating Oxone activation, these CoCPs outperform conventional Co3O4 nanoparticles (NPs) for activating Oxone. Among these CoCPs, CoCA exhibits the highest catalytic activity, followed by CoTTA and CoPDA, because CoCA possesses a much higher surface area and pore volume as well as a higher fraction of Co content. These CoCPs also remain effective under weakly acidic and basic as well as saline conditions for activating Oxone to decolorize AR. CoCPs are reusable to activate Oxone over multiple cycles and maintained regeneration efficiencies >90%. These features validate that CoCPs can be promising alterative catalysts for activating Oxone to degrade organic contaminants.

Evaluation of the stereoselectivity for titanium(IV)-based coordination entities induced by the enantiopure diphenylethene-1,2-diamine ligand

This article describes the formation of neutral TiO4N2-based coordination entities where the titanium centers are coordinated by oxygenated ligands incorporating one or two biphenolato units, i.e. L1 and L2 respectively. In these systems, the sixfold coordination spheres of each metallic center are completed by the enantiopure bidentate diphenylethene-1,2-diamine compound, abbreviated as dpeda. A solvent dependent diastereomeric ratio is evaluated by 1H NMR for the monomeric [Ti(L1)2((1R,2R)-dpeda)] or [Ti(L1)2((1S,2S)-dpeda)] (abbreviated as [R-Ti] or [S-Ti] respectively) complexes. The highest diastereomeric ratio for [Ti(L1)2(dpeda)] is obtained in chloroform (2 : 1). Energy calculation and circular dichroism spectra simulation, obtained by DFT, permit to assign the configuration of the stereoisomer formed in excess. The (1R,2R)-(+)-dpeda privileges the Δ form and (1S,2S)-(–)-dpeda the Λ form of the [Ti(L1)2(dpeda)] stereoisomers. The helicates formulated as [Ti2(L2)2((1S,2S)-dpeda)2] and [Ti2(L2)2(1R,2R)-dpeda)2] (abbreviated as [S-Ti2] or [R-Ti2] respectively) are obtained by following a multi-component self-assembly approach. In this case, the diastereomeric ratios evaluated by 1H NMR are much lower compared to those determined for the monomeric species, and a privileged P and M configuration for the [Ti2(L2)2(1R,2R)-dpeda)2] helicate and the [Ti2(L2)2((1S,2S)-dpeda)2] helicate respectively is assigned through theoretical calculations. Overall, this article describes a strategy to favour handedness in a helicate system where the chiral control is originated from a ligand that is not inscribed within the helical framework of the architecture.

Europium metal-organic framework for selective and sensitive detection of doxycycline based on fluorescence enhancement

Metal-organic framework is an extended coordination compound with repeating coordination entities and voids, which shows potential applications in gas storage, separation, catalysis, and etc. This work reports the synthesis of a new functional metal-organic framework of pyromellitic acid and europium, and its application in fluorescence sensing of doxycycline, a broad-spectrum polyketide antibiotic on the basis of fluorescence turn-on method. The metal-organic framework was initially non-fluorescent, however, with the addition of doxycycline, the system exhibited significant fluorescence enhancement at 526 nm and 617 nm, where both fluorescence intensities showed good linear correlations with the doxycycline concentration, suggesting the possibility for direct two-channel detection without any sensitization materials such as metal particles or surface-modified quantum dots. More interestingly, the unique fluorescence response of the system could discriminate doxycycline from other tetracycline antibiotics with high selectivity, and a limit of detection (LOD) was estimated to be 47 nM. It has been further demonstrated that the material has been successfully applied as sensing materials for selective determination of doxycycline in real samples of fish and urine.

{FeNO}7 -Type Halogenido Nitrosyl Ferrates: Syntheses, Bonding, and Photoinduced Linkage Isomerism.

Mononitrosyl-iron compounds (MNICs) of the Enemark-Feltham {FeNO}7 type can be divided into a doublet (S=1/2) and a quartet (S=3/2) spin variant. The latter relies on weak-field co-ligands such as amine carboxylates. Aqua-only co-ligation appears to exist in the long-known "brown-ring" [Fe(H2 O)5 (NO)]2+ cation, which was prepared originally from ferrous salts and NO in sulfuric acid. A chloride variant of this species, the green [FeCl3 (NO)]- ion, was first prepared analoguosly by using hydrochloric instead of sulfuric acid. As a tetrahedral species, it is the simple prototype of sulfur-bonded {FeNO}7 (S=3/2) MNICs of biological significance. Although it has been investigated for more than a century, neither clean preparative routes nor reliable structural parameters were available for the [FeCl3 (NO)]- ion and related species such as the [FeCl2 (NO)2 ]- ion, a prototypical dinitrosyliron species (a "DNIC"). In this work, both issues have been resolved. In addition, we report on a computational study on the ground- and excited-state properties including an assignment of the chromophoric transitions. Photoinduced metastable isomers were characterised in a combined experimental and computational approach that resulted in the confirmation of a single photoinduced linkage isomer of the paramagnetic nitrosyl-metal coordination entity.

Lignin Based Molecular Materials – a Zinc Vanillate with a Hydrogen Bonded 4‐ and 8‐connected Net with a New Topology

AbstractVanillic acid, C8H8O4, is a possible product from a future biorefinery with lignin as raw material. Two coordination compounds with this ligand in two different protonation states were prepared: 1 [Zn(C8H7O4)2(H2O)2] and 2 [Co2(C8H6O4)2(H2O)6] ⋅ 2H2O. Both compounds form extended 3D structures with strong hydrogen bonds. A high symmetry 8‐ and 4‐connected network topology, jus, is found in 1. The dinuclear coordination entity in 2 hints at a potentially useful SBU for MOF synthesis from lignin based bridging ligands.

Crystal structure and Hirshfeld surface analysis of bis (2-(2-(1H-benzo[d]imidazol-2-yl)hydrazono)propan-1-ol) nickel(II) chloride

Abstract The present work describes the crystal structure and Hirshfeld surface analysis of a transition metal coordination complex, bis (2-(2-(1H-benzo[d]imidazol-2-yl)hydrazono)propan-1-ol) nickel(II) chloride.Recrystallization of the title complex from aqueous methanol has crystallized the complex in monoclinic crystal system with P21/c space group. The asymmetric unit of the complex has two monomeric distorted octahedral coordination entities, along with four chloride anions and seven water molecules as crystallization solvent. The ring puckering analysis, intramolecular hydrogen and halogen bonding interactions and the C H⋯π and π–π interactions of the complex are explored. Further, the Hirshfeld surface analysisis carried out to reveal the nature and contributions of individual intermolecular interactions and the importance of the C H⋯π and π–π interactions in the crystal packing.

Synthesis and Complexing Ability of Hyperbranched Polyester Polyols Containing Carboxylic Acid Fragments

New hyperbranched polyester polycarboxylic acids containing terminal propanoic and acrylic acid fragments have been synthesized. According to the IR spectral data, the complexation of polydentate hyperbranched polyester polycarboxylic acids with Co(II), Ni(II), and Cu(II) ions involves chelation and bidentate bridging coordination by the terminal carboxy groups. All Co(II), Ni(II), and Cu(II) complexes with the obtained polyester polypropanoic acids are characterized by octahedral geometry of the coordination entity (MO6). The Co(II), Ni(II), and Cu(II) complexes with polyester polyacrylic acids have tetrahedral configuration of the coordination entity (MO4).

A new mechanism for remedial action schemes design in a multi-area power system considering competitive participation of multiple electricity market players

Unlike to common protective devices that are used for protection of power system equipment, Special Protection System (SPS) means an automated protective system which detects abnormal and predetermined conditions of the power system and applies preplanned corrective actions in order to maintain system integrity. The SPS is widely used in a restructured environment because it is known as a rapid and low cost alternative for network expansion to increase the transfer capability. Although the economic motivations and technical aspects of SPS are proposed in some references, the economic design of an SPS in a restructured environment has received less attention. In this paper, an economic-based method is presented to design remedial action schemes in a Multi-Area Power System (MAPS) with presence of Multiple Electricity Markets (MEM). The innovations of the proposed method are twofold: on one hand, the protection schemes are updated after each electricity market clearing that increases its performance because of the proximity to real time conditions. On the other hand, these remedial actions are designed economically in an environment with several independent Market Operators (MOs) through the interaction with a central coordinator entity. The proposed method is applied on a three-area test system and its results are presented by further explanation of its technical and economic advantages.

Data Connectivity and Smart Group Formation in Wi-Fi Direct Multi-Group Networks

Users of device-to-device (D2D) communication need efficient content discovery mechanisms to steer their requests toward the node in their neighborhood that is most likely to satisfy them. The problem is further compounded by the lack of a central coordination entity as well as by the inherent mobility of devices, which leads to volatile topologies. In this paper, we first discuss group-based communication among non-rooted Android devices using Wi-Fi direct, a protocol recently standardized by the Wi-Fi alliance. We propose intra- and inter-group communication methodologies, which we validate through a simple testbed where content-centric routing is used. Next, we address the autonomous formation of groups with the goal of achieving efficient device resource utilization as well as full connectivity. Finally, we evaluate the performance of our group formation procedure both in simulation and in a real testbed involving Android devices in different topologies.

Synthesis, structure and catalytic activities of nickel(II) complexes bearing N4 tetradentate Schiff base ligand

Two new nickel(II) complexes [Ni(L)Cl2] (1) and [Ni(L)(NCS)2] (2) of a neutral tetradentate mono-condensed Schiff base ligand, 3-(2-(2-aminoethylamino)ethylimino)butan-2-one oxime (L) have been synthesized and characterized using different physicochemical techniques e.g. elemental analyses, spectroscopic (IR, Electronic, NMR) methods, conductivity and molecular measurements. The crystal structure of complex (2) has been determined by using single crystal X-ray diffraction method and it suggests a distorted octahedral geometry around nickel(II) having a NiN6 coordinating atmosphere. The non-coordinated OH group on the ligand L remain engaged in H-bonding interactions with the S end of the coordinated thiocyanate moiety. These H-bonding interactions lead to OS separations of 3.132 Å and play prominent role in crystal packing. It is observed that the mononuclear units are glued together with such OH…S interactions and finally results in an 1D supramolecular sheet-like arrangement. DFT/TDDFT based theoretical calculations were also performed on the ligand and the complexes aiming at the accomplishment of idea regarding their optimized geometry, electronic transitions and the molecular energy levels. Finally the catalytic behavior of the complexes for oxidation of styrene has also been carried out. A variety of reaction conditions like the effect of solvent, effect of temperature and time as well as the effect of ratio of substrate to oxidant were thoroughly studied to judge the catalytic efficiency of the Ni(II) coordination entity.

Synthesis and Characterization of Zn(II) Complexes of 2-(7-Bromo-2-oxo-5-phenyl-2,3-dihydro-1H-1,4-benzodiazepin-1-yl)acetohydrazide and Its Condensation Products with Pyruvic Acid and Isatin

The systems ZnCl2–2-(7-bromo-2-oxo-5-phenyl-2,3-dihydro-1H-1,4-benzodiazepin-1-yl)acetohydrazide (Hydr)–propan-2-ol, ZnCl2–Hydr–pyruvic acid (HPv), and Zn(CH3COO)2–Hydr–isatin(HIz)–propan-2-ol were studied. Optimal synthesis conditions were determined, and the complexes [Zn(Hydr)2Cl2], [Zn(HydrHPv)2Cl2], and [Zn(HydrIz)2] were isolated. The complexes were characterized by elemental analysis, thermogravimetry, IR spectroscopy, and mass spectrometry. The electrical conductivities of the complexes were measured. The local environment of the central atom in the coordination entity was determined by X-ray absorption spectroscopy.

Hyperbranched polyester poly[3-(morpholin-4-yl)propionates] and their copper(II) complexes

Novel polydentate ligands on the basis of second- and third-generation hyperbranched polyesters containing terminal poly[3-(morpholin-4-yl)propionate] groups and their 6 : 1 and 13 : 1 polynuclear copper(II) complexes were synthesized. The degree of functionalization of the polyesters with morpholine increases in going from the second (56%) to third generation (68%). According to IR and electronic spectroscopy data, each coordination entity in the complexes is an isolated paramagnetic center of the formula CuN2O2Solv2 (Solv = H2O, DMSO).

Synthesis, spectral analysis, stability constants, antioxidant and biological activities of Co (II), Ni (II) and Cu (II) mixed ligand complexes of nicotinamide, theophylline and thiocyanate

In the present study, transition metal complexes or coordination entities with metal precursors such as Co (II), Ni (II) and Cu (II) of mixed ligands namely, nicotinamide (NA), theophylline (TP) and KSCN in water were synthesized under refluxing conditions. The optimization of the reactions to obtain the composition of complexes was performed. The structural elucidation of the complexes was undertaken by using physico-chemical and spectroscopic methods (UV/Vis, FT-IR, Mass and XRD) and thermal analysis. The spectral measurements of mixed ligands with the Co (II), Ni (II) and Cu (II) complexes are compared with each other in determining which atoms of the ligand are coordinated to the metal ion. Based on spectral and magnetic moment measurements, all the coordination entities were identified as in distorted octahedral structure and have the form [M(NA)2 (TP)2(SCN)2]·xH2O. In addition, K (stability constant) and ΔG (Gibbs free energy) values were calculated by using the Babko and Stanley & Turner's methods. Antioxidant, antibacterial and antifungal activities of the complexes were studied.

Coordination entities of a pyrene-based iminopyridine ligand: Structural and photophysical properties

A pyrene-based iminopyridine ligand L has been prepared and displays the absorption and emission properties expected for pyrene-based derivatives in solution. Ligand L, as well as two neutral and one monocationic coordination entities, respectively formulated as [ZnLCl2] 1, [ReLCl(CO)3] 3 and [CuL2](BF4) 2, have been crystallized and analyzed by single crystal X-ray diffraction analysis. The corresponding crystal structures indicate the formation of supramolecular architectures generated by offset π⋯π stacking between pyrene fragments and strong C–H⋯π interactions in coordination entity 1. For the cationic coordination entity 2, the crystal packing reveals the presence of C–H⋯F and C–H⋯π interactions and numerous C–H⋯π contacts interconnecting the molecules into a 3D network. As for coordination entity 3, hydrogen bonding and π⋯π stacking link the molecules in a three dimensional manner. Zinc(II) and copper(I) coordination entities have also been studied through isothermal titration calorimetry, which indicate a strong binding and a different stoichiometry for both coordination entities. Photophysical studies of the ligand and corresponding coordination entities show a monomer type pyrene emission and a higher fluorescence quantum yield for the zinc coordination entity 1 as compared with copper 2 and rhenium 3 coordination entities.

Structure, Physicochemical and Biological Properties of an Aqua (2,2′,2′′‐Nitrilotriacetato)‐oxidovanadium(IV) Salt with 4‐Methylpyridinium Cation

The crystal structure of a nitrilotriacetate (nta) oxidovanadium(IV) salt with 4‐methylpyridinium cation, [4‐Me(Py)H]+, of [4‐Me(Py)H][VO(nta)(H2O)] stoichiometry was determined. The complex comprises a discrete mononuclear [VO(nta)(H2O)]– coordination entity that can be rarely found among other known compounds containing nitrilotriacetate oxidovanadium(IV) moieties. The complex was characterized by spectroscopic (IR and EPR) methods, magnetic measurements, and thermogravimetry (TG‐FTIR). The stability of the title compound in aqueous solutions was investigated by using the potentiometric titration method. Furthermore, spectrophotometric (UV/Vis) studies have revealed that the compound is capable to scavenge the superoxide free radicals (O2•–) as well as stable organic radicals i.e. 2,2′‐azinobis(3‐ethylbenzothiazoline‐6 sulfonic acid) cation radical (ABTS+•) and 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH•). Finally, biological properties of the complex studied were investigated in relation to its cytoprotective activity against the oxidative damage generated exogenously by using hydrogen peroxide in the HT22 hippocampal neuronal cell line (the MTT assay). Additionally, the biological action of the compound towards two human osteosarcoma HOS and MG‐63 cell lines (the MTT and BrdU tests) as well as the untransformed human osteoblast hFOB 1.19 cell line was tested.

Desenvolvimento regional e cooperação entre empresas - instituições: o caso dos Arranjos Produtivos Locais de Tecnologia da Informação do Paraná

Este trabalho avalia as aglomerações produtivas de Tecnologia da Informação das Regiões Metropolitanas de Curitiba, Londrina e Maringá, seguindo as especificidades do SNI - Sistema Nacional de Inovação - em sua abordagem em nível mesoeconômico. Analisam-se as relações de cooperação entre as firmas, com organizações e instituições e, conjuntamente, a compradores-fornecedores e a formação de suas competências técnicas por meio das relações com entidades e associações de apoio e coordenação. Conclui-se que essas relações tendem a gerar externalidades positivas entre firmas-regiões (economias externas), tanto incidentais (inconscientemente) quanto planejadas (buscadas pelas empresas), as quais ocorrem por força da proximidade geográfica ou de suas especializações setoriais.

New Socio-technical Devices to Improve Coordination in Healthcare in France

In the specific context of the Healthcare coordination between medical, socio medical and social organizations of the ambulatory field in France, we propose to examine some tracks with the perspective offered by new ways of sharing information. First we explain our researchers’ position and the methodology used. Then after reviewing different models of coordination entities, we intend to clarify the role played by such organizations acting as interface between hospitals and ambulatory services. We will then address the issue of Information and Communication Technologies (ICT) that contribute to support and improve the healthcare coordination. Through the evolution observed with the convergence between organizational models of coordination and technological devices, we will try to highlight the way of producing and sharing information on healthcare platforms for care coordination. As an illustration of the value created by the new socio-technical devices, we will have a glimpse at the current innovative trend in healthcare coordination in France.

Supramolecular Cd(II) complexes with (E)-N,N′-bis(2-pyridyl)iminoisoindoline (2-pyimiso): synthesis, X-ray structures, Hirshfeld surface analyses, and DFT study of [CdX2(2-pyimiso)2] (X = Cl or NCS)

The paucity of coordination entities bearing (E)-N,N′-bis(heteroaryl)iminoisoindolines has prompted us to investigate coordination modes and supramolecular features of (E)-N,N′-bis(2-pyridyl)iminoisoindoline (2-pyimiso), a versatile iminobis(pyridyl) ligand. In this article we report the synthesis, spectroscopic characterization and crystal structure analysis of two Cd(II) : 2-pyimiso (1 : 2) bis-adducts, [CdX2(2-pyimiso)2] [X = Cl (1) or NCS (2)]. Our X-ray structural results reveal that 1 exhibits distorted tetrahedral coordination (four-coordinate geometry index τ4 = 0.92), whereas 2 displays six-coordinate Cd(II) and two four-membered chelate rings (bite angles = 52.5°), each comprising one Cd–Npy [2.247(2) Å] bond and one Cd⋯Nimine [2.809(21) Å] secondary interaction. Remarkably, in 2 each 2-pyimiso unit binds to Cd(II) according to an unusual bidentate coordination. The contributions of the Cd–N and Cd–Cl bond valences to the total metal valence for both 1 and 2 have been evaluated to confirm the coordination modes of 2-pyimiso, which can be interpreted in terms of Jørgensen’s principle of symbiosis. X-ray structure and Hirshfeld surface analyses have shown that the crystal structure of 1 is determined by two perpendicular 1-D chains formed by weak hydrogen bonds along the a- and c-axes, whereas the supramolecular architecture of 2 exhibits 2-D sheets parallel to the ab-plane interconnected by C–H⋯π interactions along the c-axis. A vibrational analysis of both products has been conducted at the DFT B3LYP-D3/LACV3P** level of calculation.

Absorption and luminescence spectra of 5-aryl-3-methyl-1,2,4-oxadiazoles and their chelate complexes with Zinc(II) and copper(II)

5-(2-Hydroxyphenyl)-3-methyl-1,2,4-oxadiazole and its O-methyl and O-acyl derivatives, as well as zinc(II) and copper(II) chelates, were synthesized. All these compounds showed luminescence with the emission maxima ranging from λ = 332 to 490 nm, but only 5-(2-methoxyphenyl)- and 5-(2-acetoxyphenyl)-3-methyl-1,2,4-oxadiazoles and zinc(II) complex of 5-(2-hydroxyphenyl)-3-methyl-1,2,4-oxadiazole were characterized by high luminescence quantum yield (φ = 0.308–0.452, 0.089–0.153, and 0.115–0.334, respectively). Stable conformers of 5-(2-hydroxyphenyl)-3-methyl-1,2,4-oxadiazole with different structures of the coordination entity were identified by DFT quantum chemical calculations.

Synthesis, crystal structures, and characterization of a new substituted 1,2,4-triazole and its two Co(II)/Mn(II) complexes

A new triazole-substituted ligand H2L (H2Trza = 3-amino-1H-1,2,4-triazole-5-acetate) and its two new isomorphic compounds [M(HTrza)2(H2O)2] ∙ 2H2O (Co(I) and Mn(II)) have been synthesized and characterized structurally. Their X-ray crystal structures (CIF files CCDC nos. 906893 for I and 906892 for II) show that H2L belongs to a tetragonal system; space group P43 with a = b = 5.0445(13), c = 27.054(10) A; Z = 4. Complex I belongs to a monoclinic system; space group P21/n with a = 7.6543(8), b = 7.3453(8), c = 13.6283(14) A; β = 91.5990(10)°, Z = 2. Complex II belongs to a triclinic system; space group with a = 6.8550(15), b = 8.0630(18), c = 15.173(4) A; α = 84.794(4)°, β = 79.005(3)°, γ = 73.779(4)°, Z = 2. X-ray analysis demonstrates that compound H2L is found to contain a H2Trza and a lattic water molecule; complexes I and II are discrete mononuclear species. The central Co(II) and Mn(II) atoms exhibit octahedral coordinations, type 4 + 2. In two compounds, the coordination entities are further organized via hydrogenbonding interactions to generate uniform supramolecular networks. Thermal stabilities of two compounds were examined by thermogravimetric analysis.