Coordinate Covalent Research Articles

The impact of growth stimulators and retardants on the utilization of reserve lipids by sunflower seedlings

Using growth stimulators and anti-gibberillin preparations of different chemical compounds, we created different pressures in the coordinate covalent bond systems during germination of sunflower seeds. Using gibberellin and treptolem growth stimulators and Paclobutrazol and Chlormequat-Chlorid anti-gibberillin preparations is an efficient method of reconstructing coordinate covalent bond during the germination of seeds of oil-bearing crops. It allows determination of the role of the hormone factor in the utilization of reserve lipids over the heterotrophic phase of plant development. Blocking the synthesis of gibberellins by retardants caused decrease in activity of lipase, hydrolysis of reserve lipids and the meristem, which resulted in decrease in the energy of germination. Compared to the control, the impact of gibberellin increased the content of butyric acid, and the impact of Paclobutrazol reduced the content of butyric acid. Linoleic acid showed exactly the opposite changes. In relation to the control, a significant increase in the content of non-saturated linoleic acid was observed in both variants of the experiment. Gibberellic acid stimulated and Paclobutrazol slowed the usage of free higher fatty acids for the process of morphogenesis.

Organic free decavanadate based materials: Inorganic linkers to obtain extended structures

Decavanadate based extended structures containing compounds [{Na3(H2O)8(μ2-H2O)6Ag2}HV10O28]n·6nH2O (1), [Co(H2O)6]n[{Na2(H2O)6(μ2-H2O)4Co(H2O)2}V10O28]n·4nH2O (2) and [Zn(H2O)6]n[{Na2(H2O)6(μ2-H2O)4Zn(H2O)2}V10O28]n·4nH2O (3) have been synthesized from respective aqueous solutions of sodium metavanadate. Compounds 1, 2 and 3 crystallize in a triclinic space group P-1. Compound 1 is a three-dimensional inorganic solid, whereas compounds 2 and 3 are isomorphous one-dimensional inorganic polymers. In the crystal structure of compound 1, the silver (I) cation is coordinated to the terminal oxygen as well as bridging oxygen atoms of decavanadate anion and it is also connected to bridging oxygen atom of trimeric sodium aqua cluster cation. In the crystals of compound 2, one hexa-hydrated cobalt cation is present as a counter cation and one “di-sodium cobalt aqua-complex” cation is supported on the [V10O28]6– cluster anion by coordinate covalent bond. Compound 3 is isomorphous with compound 2, with Zn2+ present (in compound 3) in the place of Co2+ (in compound 2). Compounds 1, 2 and 3 are characterized by routine elemental analyses, FT-IR spectroscopy and unambiguously by single crystal X-ray crystallography. In the crystal structure of compound 1, an unusual silver dimer is observed.

Liquid Chromatography Tandem Mass Spectrometry and Nuclear Magnetic Resonance Spectroscopy of Magnesium (II) Gluconate Solution

Magnesium gluconate is a classical pharmaceutical compound used as a source of magnesium for the prevention and treatment of hypomagnesemia. To the best of our knowledge, a robust and reliable liquid chromatography tandem mass spectrometry technique has not yet been reported for the qualitative and quantitative analysis of magnesium gluconate. This study describes the method development for the LC–ESI–MS/MS analysis of magnesium gluconate using three different reversed-phase HPLC conditions (Method I–III) with comprehensive fragmentation pattern and the structural characterization by NMR spectroscopy. The LC–MS and NMR data were found in accordance with the structure of magnesium gluconate. When magnesium gluconate was dissolved in the acetonitrile and water–methanol solutions, it exists in situ in three different forms: magnesium gluconate itself, gluconic acid, and magnesium gluconate chelate with gluconic acid by a coordinate covalent bond. Method I exhibited pseudo-molecular ion peaks with more magnesium gluconate chelates with gluconic acid, while method II showed an adduct of magnesium gluconate with the solvent along with the molecular ion peak. There was no pseudo-molecular ion peaks found in method III. Thus, method III was found to be the more accurate, robust and reliable LC–MS method for the qualitative and quantitative analysis, structural characterization, and could also be suitable for the pharmacokinetic study of magnesium gluconate. The detailed fragmentation analysis might be useful for the structural characterization of unknown divalent organometallics.

Nature of metal-dependent assemblies of four coordination polymers based on imidazole substitute isophthalate ligand: Syntheses and crystal structures

Four novel coordination polymers with distinct different structures, {[CdL(H2O)]·0.5H2O}n (1), {[ZnL(H2O)]·H2O}n (2), {[CoL(H2O)2]·2H2O}n (3), and {[NiL(H2O)2]·2H2O}n (4) (L=5-(1-H-imidazole-1-yl)isophthalate) have been synthesized by the reaction of different transition metal cations with a rigid bi-functional ligand L. 1 possesses three-dimensional (3D) network framework, in which Cd(II) center is six coordinated by four L ligands and one aqua molecule. In compound 2, Zn(II) center adopts tetrahedral geometry and coordinated by three L ligands and one aqua molecule. 2 displays a [-AB-(H2O)n-AB-(H2O)n-] fashion 3D supramolecular network, in which A and B are two types of 2D covalent coordination layers. 3 and 4 are isostructural, metal center is six coordinated by three L ligands and two aqua molecules, and the 2D coordination layers construct the 3D supramolecular network with 1D rectangular channels via OH⋯O hydrogen bonds. The structural variation depends on the nature of metal cations. Solid-state luminescent for compounds 1–2 and magnetic properties for compounds 3–4 have been investigated.

On-surface synthesis of covalent coordination polymers on micrometer scale

On-surface synthesis under ultrahigh vacuum provides a promising strategy to control matter at the atomic level, with important implications for the design of new two-dimensional materials having remarkable electronic, magnetic, or catalytic properties. This strategy must address the problem of limited extension of the domains due to the irreversible nature of covalent bonds, which prevents the ripening of defects. We show here that extended materials can be produced by a controlled co-deposition process. In particular, co-deposition of quinoid zwitterion molecules with iron atoms on a Ag(111) surface held at 570 K allows the formation of micrometer-sized domains based on covalent coordination bonds. This work opens up the construction of micrometer-scale single-layer covalent coordination materials under vacuum conditions.

Two supramolecular complexes based on polyoxometalates and Co-EDTA units via covalent connection or non-covalent interaction

Two new 3D network organic-inorganic hybrid supramolecular complexes {[Na6(CoEDTA)2(H2O)13]·(H2SiW12O40)·xH2O}n (1) and [CoH4EDTA(H2O)]2(SiW12O40)·15H2O (2) (H4EDTA=Ethylenediamine tetraacetic acid) have been successfully synthesized by solution method, and characterized by infrared spectrum (IR), thermogravimetric-differential thermal analysis (TG-DTA), cyclic voltammetry (CV) and single−crystal X-ray diffraction (XRD). Both of the complexes are the supramolecules, but with different liking mode, they are two representative models of supramolecule. complex (1) is a 3D infinite network supramolecular coordination polymer with a rare multi-metal sturcture of sodium-cobalt-containing, which is mainly linked through coordinate-covalent bonds. While complex (2) is normal supramolecule, which linked by non-covalent interactions, such as H-bonding interaction, electrostatic interaction and van der waals force. Both of complex (1) and (2) exhibit good catalytic activities for catalytic oxidation of methanol, when the initial concentration of methanol is 3.0gm−3, flow rate is 10mLmin−1, and the quality of catalyst is 0.2g, for complex (1) and complex (2) the maximum elimination rates of methanol are 85% (150°C) and 92% (120°C), respectively.

Proximity-Directed Labeling Reveals a New Rapamycin-Induced Heterodimer of FKBP25 and FRB in Live Cells.

Mammalian target of rapamycin (mTOR) signaling is a core pathway in cellular metabolism, and control of the mTOR pathway by rapamycin shows potential for the treatment of metabolic diseases. In this study, we employed a new proximity biotin-labeling method using promiscuous biotin ligase (pBirA) to identify unknown elements in the rapamycin-induced interactome on the FK506-rapamycin binding (FRB) domain in living cells. FKBP25 showed the strongest biotin labeling by FRB–pBirA in the presence of rapamycin. Immunoprecipitation and immunofluorescence experiments confirmed that endogenous FKBP25 has a rapamycin-induced physical interaction with the FRB domain. Furthermore, the crystal structure of the ternary complex of FRB–rapamycin–FKBP25 was determined at 1.67-Å resolution. In this crystal structure we found that the conformational changes of FRB generate a hole where there is a methionine-rich space, and covalent metalloid coordination was observed at C2085 of FRB located at the bottom of the hole. Our results imply that FKBP25 might have a unique physiological role related to metallomics in mTOR signaling.

Structure modification and covalence variation induced by cation substitution in pure nitride Ca-α-sialon phosphor

Cation substitution is a useful method to modify the structure and luminescence properties of nitridosilicate phosphors. The crystal structure of pure nitride Ca-α-sialon with the composition Ca1.3+0.5xAl2.8+xSi9.2⿿xN16:Eu0.1 is changed by cation substitution (Al3+⿿Si4+). Smooth changes of lattice parameters with x indicate that Al3+ ions have been effectively incorporated into the Ca1.4Al2.8Si9.2N16 lattice. Although the replacement of Si4+ by Al3+ expands the lattice volume, the covalent coordination environment for Eu2+ becomes stronger. Eventually, the emission exhibits a red-shift. Owing to the increase of the crystallinity with Al3+ introducing, the emission intensity of the phosphors increases by 49%. The modified structure results in a strong covalence of Eu-N and an improvement of the thermal quenching.

Pfizer to acquire Anacor

Just a month after abandoning its merger with Allergan, Pfizer will pay roughly $5.2 billion to acquire Anacor Pharmaceuticals, a biotech firm that specializes in developing boron-containing small-molecule therapeutics. Anacor already has one approved drug, the antifungal Kerydin, but the centerpiece of the acquisition is crisaborole, a topical treatment for eczema that is currently under FDA review. Because a novel eczema treatment has not been approved in more than 15 years, crisaborole could deliver peak annual sales of $2 billion or more, Pfizer says. It expects FDA to give crisaborole the green light by January. Founded in 2002, Anacor seeks to take advantage of boron’s empty p orbital, which can form coordinate covalent bonds, a feature that stabilizes a drug’s interaction with its target. For Pfizer, the deal is its first after its attempt to buy Allergan for $160 billion. Pfizer dropped the merger last month after an unfavorable tax

In-silico bonding schemes to encode chemical bonds involving sharing of electrons in molecular structures

Encoding of covalent and coordinate covalent bonds in molecular structures using ground state valence electronic configuration is achieved. The bonding due to electron sharing in the molecular structures is described with five fundamental bonding categories viz. uPair–uPair, lPair–uPair, uPair–lPair, vPair–lPair, and lPair–lPair. The involvement of lone pair electrons and the vacant electron orbitals in chemical bonding are explained with bonding schemes namely “target vacant promotion”, “source vacant promotion”, “target pairing promotion”, “source pairing promotion”, “source cation promotion”, “source pairing double bond”, “target vacant occupation”, and “double pairing promotion” schemes. The bonding schemes are verified with a chemical structure editor. The bonding in the structures like ylides, PCl5, SF6, IF7, N-Oxides, BF4−, AlCl4− etc. are explained and encoded unambiguously. The encoding of bonding in the structures of various organic compounds, transition metals compounds, coordination complexes and metal carbonyls is accomplished.

Study on the behavior of sulfur in hydrolysis process of titanyl sulfate solution

The existing forms of sulfur in hydrolysis process of titanyl sulfate solution were studied. Also the effects of sulfur on crystal structure, crystallite size and crystal phase transition of the hydrated titanium dioxide(TiO2·H2O) and titanium dioxide (TiO2) were conducted. The analysis and methods of thermogravimetric-differential scanning calorimet (TG-DSC), energy dispersive spectrometer (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV–Vis diffuse reflectance spectra and Raman spectroscopy were employed to characterize. The results indicated that the sulfur was present in the form of SO42− ions in the hydrolysate of titanyl sulfate solution, and a portion of SO42− ions were combined on the surface of hydrated titanium dioxide by chemical adsorption in the forms of inorganic chelating bidentate coordination and covalent sulfate coordination, the residual SO42− ions were adsorbed on the surface of hydrated titanium dioxide by physical adsorption. The chemical adsorption of SO42− ions were conducive to the formation and stabilization of anatase, which changed the crystal structure, and hindered the transformation of the anatase into rutile. The results of Raman spectroscopy showed that the sulfur was dissociated in the forms of SO42− and HSO4− ions during the hydrolysis of titanyl sulfate solution. The characteristic peak at 1004 cm−1 corresponding to a new complex has been observed, which was composed of SO42− and hydrated titanium complex ions through the bonding on the surface. In basis of the above experimental results, the hydrolysis process of titanyl sulfate solution was illustrated from the microstructure with 3D atlas.

Physico-Chemical Characterization, Opto Electronic Investigation and Vibrational Analysis on Coordinate Covalent Complex; Bis (Thiourea) Nickel Bromide (BTNB) Using Experimental and Computational Tools

In this work, a thorough spectroscopic investigation is made on the molecule; Bis (thiourea) Nickel Bromide (BTNB) by recording FT-IR, FT-Raman and UV Visible spectra. The computational calculations were carried out by HF and DFT methods with 6-31++G(d, p) and 6-311++G(d, p) basis sets and the optimized geometrical parameters, vibrational fundamentals, natural bond orbitals, Frontier molecular orbital energies and NMR chemical shift have been calculated and presented in the table. The cause of change of physical and chemical properties by coordination covalent bond between metal and organic atoms has been discussed in detail. Hence, the Non Linear Optical properties of the present molecule have been studied by calculating average Polarizability and diagonal hyperpolarizability. The enhancements of physical and chemical properties of the coordination complex due to the Vander Waals bond have been interpreted. The thermodynamical parameters were calculated and these values are obtained from NIST thermodynamical program. The variation of specific heat capacity, entropy and enthalpy with respect to different temperature are displayed in the graph and are discussed. A new semiorganic nonlinear optical crystal of Bis (thiourea) Nickel Bromide (BTNB) was grown successfully by slow evaporation technique using water as solvent. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. Vibrational spectrum is recorded to determine symmetries of molecular vibrations. The recording of Optical absorbance spectrum revealed that this crystal has good transparency in the visible region. The nonlinear nature of the present crystal has been confirmed by the SHG test. The BTNB crystal was analyzed by a differential thermal analysis and thermo gravimetric analysis (DTA-TGA) to obtain its thermal stability. Vickers micro-hardness test has done on the crystal and this shows that the crystal has greater physical strength.

配位結合型の硫黄およびリンを含む官能基の開裂に対するマスシフト則の適用

配位結合型の硫黄およびリンを含む官能基の開裂に対するマスシフト則の適用

Controllable Grain Morphology of Perovskite Absorber Film by Molecular Self-Assembly toward Efficient Solar Cell Exceeding 17%

The highly developed crystallization process with respect to perovskite thin films is favorable for efficient solar cells. Here, an innovative intermolecular self-assembly approach was employed to retard the crystallization of PbI2 in dimethylformamide (DMF) by additional solvent of dimethyl sulfoxide (DMSO), which was proved to be capable of coordinating with PbI2 by coordinate covalent bond. The obtained PbI2(DMSO)x (0 ≤ x ≤ 1.86) complexes tend to be closely packed by means of intermolecular self-assembly. Afterward, an intramolecular exchange of DMSO with CH3NH3I (MAI) enabled the complexes to deform their shape and finally to reorganize to be an ultraflat and dense thin film of CH3NH3PbI3. The controllable grain morphology of perovskite thin film allows obtaining a power conversion efficiency (PCE) above 17% and a stabilized power output above 16% within 240 s by controlling DMSO species in the complex-precursor system (CPS). The present study gives a reproductive and facile strategy toward high quality of perovskite thin films and efficient solar cells.

Facile One-Step Synthesis of Nitrogen-Doped Carbon Nanofibers for the Removal of Potentially Toxic Metals from Water

Nitrogen-doped carbon nanofibers (N-CNFs) were prepared in a one-step method. N-CNFs were grown on an activated carbon fiber (ACF) substrate using catalytic chemical vapor deposition. Acetonitrile served as the single source of carbon and nitrogen. An approximately 10-fold increase of N-content, relative to the ACF substrate, was achieved in the densely and uniformly grown N-CNFs/ACFs. The prepared material, used as adsorbents for cadmium (Cd) and lead (Pb) in water, exhibited a significantly large adsorption capacity of approximately 161 ± 5 and 88 ± 3 mg/g for Cd and Pb, respectively, attributed to the lone pair of electrons in N atoms, which facilitated the formation of coordinate covalent bonds with the metal ions. The one-step method of preparing the N-enriched multiscale web of carbon micronanofibers in this study is simple, and the prepared material may be used as an efficient adsorbent for the removal of toxic metal ions from wastewater.

Structure, Characterization and Photocatalytic Activity of a Series of Well-Established Covalent Heterojunction Coordination Polymers

Six novel coordination polymers {Co(HCOO)2(4,4′-bipy)}n (1), {[Ni(4,4′-bipy)(OH)2(H2O)2]·suc·2H2O}n (2), {Ni(HCOO)2(4,4′-bipy)}n (3), {Zn(HCOO)2(4,4′-bipy)}n (4), {Cu(HCOO)2(4,4′-bipy)}n (5) and {[Cu(ox)(2,2′-bipy)]·2H2O}n (6) (suc succinic acid, ox oxalic cid) based on pyridine derivatives and carboxylates as ligands were designed and synthesized. The coordination polymers were characterized by elemental analysis, IR and UV–Vis spectra, powder X-ray diffraction, the thermo gravimetric analyses and single-crystal diffraction analysis. The structure analysis showed that the central metal atoms in coordination polymers 1, 2, 3, 4 and 6 all were six-coordination modes, forming distorted octahedron geometries. Cu atom in the coordination polymer 5 was four-coordination mode, forming square planar coordination geometry. While in the coordination polymers 1, 3 and 4, two metal centers were connected by bridging coordination fashions of formic acid ligand, forming a three-dimensional network structure, and in the coordination polymer 6, the two metal centers were connected by bridging coordination fashions of oxalic acid ligand, forming one-dimensional chain. In addition, the photocatalytic activity of a series of covalent heterojunction coordination polymers was studied.

Porous solids arising from synergistic and competing modes of assembly: combining coordination chemistry and covalent bond formation.

Design and synthesis of porous solids employing both reversible coordination chemistry and reversible covalent bond formation is described. The combination of two different linkage modes in a single material presents a link between two distinct classes of porous materials as exemplified by metal-organic frameworks (MOFs) and covalent organic frameworks (COFs). This strategy, in addition to being a compelling material-discovery method, also offers a platform for developing a fundamental understanding of the factors influencing the competing modes of assembly. We also demonstrate that even temporary formation of reversible connections between components may be leveraged to make new phases thus offering design routes to polymorphic frameworks. Moreover, this approach has the striking potential of providing a rich landscape of structurally complex materials from commercially available or readily accessible feedstocks.

Porous Solids Arising from Synergistic and Competing Modes of Assembly: Combining Coordination Chemistry and Covalent Bond Formation

AbstractDesign and synthesis of porous solids employing both reversible coordination chemistry and reversible covalent bond formation is described. The combination of two different linkage modes in a single material presents a link between two distinct classes of porous materials as exemplified by metal–organic frameworks (MOFs) and covalent organic frameworks (COFs). This strategy, in addition to being a compelling material‐discovery method, also offers a platform for developing a fundamental understanding of the factors influencing the competing modes of assembly. We also demonstrate that even temporary formation of reversible connections between components may be leveraged to make new phases thus offering design routes to polymorphic frameworks. Moreover, this approach has the striking potential of providing a rich landscape of structurally complex materials from commercially available or readily accessible feedstocks.

Directional supracolloidal self-assembly via dynamic covalent bonds and metal coordination.

An emerging strategy towards the sophistication of supramolecular nanomaterials is the use of supracolloidal self-assembly, in which micelles or colloids are used as building blocks. Binding directionality can produce nanostructures with attractive properties. Herein, we present a new directional supracolloidal self-assembly by virtue of dynamic covalent bonds and metal coordination in water. Conjugation of a ligand precursor to a water-soluble block copolymer through dynamic covalent bonds leads to the dehydration and micellization of the functionalized polymer. Reversible reaction facilitates the permeation of metal ions into core-shell interfaces. Conversely, metal-coordination promotes reaction over the interfaces. Cu(ii)-coordination occurs overwhelmingly inside each isolated micelle. However, Zn(ii)-coordination induced a directional self-assembly whose nanostructures evolve stepwise from nanorods, nanowires, necklaces, and finally to supracolloidal networks scaling-up to several tens of micrometres. Post-reactions of simultaneous dynamic covalent bond conversion and Zn(ii)-coordination over the core-shell interfaces endow these supracolloidal networks with a huge specific surface area for hydrophobic dative metal centres accessible to substrates in water. Water-soluble shells play important roles in directional supracolloidal assembly and in the stabilization of nanostructures. Thus the directional self-assembly provides a versatile platform to produce metallo-hybridized nanomaterials that are promising as enzyme-inspired aqueous catalysts.

Evidence for halogen bond covalency in acyclic and interlocked halogen-bonding receptor anion recognition.

The synthesis and anion binding properties of novel halogen-bonding (XB) bis-iodotriazole-pyridinium-containing acyclic and [2]catenane anion host systems are described. The XB acyclic receptor displays selectivity for acetate over halides with enhanced anion recognition properties compared to the analogous hydrogen-bonding (HB) acyclic receptor. A reversal in halide selectivity is observed in the XB [2]catenane, in comparison to the acyclic XB receptor, due to the interlocked host’s unique three-dimensional binding cavity, and no binding is observed for oxoanions. Notable halide anion association constant values determined for the [2]catenane in competitive organic–aqueous solvent mixtures demonstrate considerable enhancement of anion recognition as compared to the HB catenane analogue. X-ray crystallographic analysis of a series of halide catenane complexes reveal strong XB interactions in the solid state. These interactions were studied using Cl and Br K-edge X-ray Absorption Spectroscopy (XAS) indicating intense pre-edge features characteristic of charge transfer from the halide to its bonding partner (σAX←X–* ← X1s), and providing a direct measure of the degree of covalency in the halogen bond(s). The data reveal that the degree of covalency is similar to that which is observed in transition metal coordinate covalent bonds. These results are supported by DFT results, which correlate well with the experimental data.