Composition,structure, and morphology of nanostructured aluminosilicates

The data on synthesizing nanosized potassium aluminosilicates (PAS) with a ratio of Si/Al of 1–5 obtained in the KOH–Al₂(SO₄)₃ · 18H₂O–SiO₂ · nH₂O–H₂O multicomponent system have been presented. Their composition, morphology, and IR and NMR spectra have been studied.     

Cu(II) and Zn(II)-Pyridine-2,3-Dicarboxylate Complexes with 2-Methylimidazole: Syntheses, Crystal Structures, Spectroscopic and Thermal Analyses

Two new Cu(II) and Zn(II)-pyridine-2,3-dicarboxylate (pydc) complexes with 2-methylimidazole (2-Meim), [Cu(pydc)(2-Meim)₃]·H₂O (1) and {[Zn(μ-pydc)(H₂O)(2-Meim)]·H₂O}_n (2) have been synthesized and characterized by elemental, spectral (IR and UV–Vis.) and thermal analyses. The molecular structures of mononuclear (1) and polynuclear (2) complexes have been determined by the single crystal X-ray diffraction. Compound 1 crystallizes in the triclinic P ? 1 space group, while compound 2 crystallizes in the monoclinic P2₁/c space group. The pyridine-2,3-dicarboxylate ligand acts in two different coordination modes; namely, bidentate-(N,O) for 1 and μ-tridentate-(N,O,O) for 2, the latter displaying a 1D polynuclear structure. The crystal packing of the complexes exhibit 3D supramolecular frameworks including channels by C–H···π, π···π, and N–H···O interactions. Water molecules occupy the channels by O–H···O hydrogen bonds.     

Synthesis, Crystal Structure, Spectroscopic and Thermal Properties of a Novel Complex of Hydantoin-5-acetic acid with Co(II)

The complex, tetraaqua bis(hydantoin-5-acetato) cobalt(II) was synthesized by the reaction of hydantoin-5-acetic acid and CoCl₂·6H₂O presence of NaHCO₃. The structure of the complex was determined by X-Ray single crystal data the thermal analyses, FT–IR and magnetic susceptibility data are also presented. The monoclinic crystal of the title compound, [Co(C₅H₅N₂O₄)₂(H₂O)₄], lie across centers of inversion in space group P21/c. The complex features a distorted octahedral [CoO₆] coordination with hydantoin-5-acetato and water ligands. The hydantoin-5-acetato anion is bonded to the cobalt(II) ion via its deprotonated carboxylic acid O atom. The complex molecules show three dimensional supramolecular networks by O–H···O and N–H···O interactions.     

An expedient synthesis of methyl vinyl sulfide from dimethyl disulfide and acetylene

Dimethyl disulfide reacts with acetylene under atmospheric pressure in basic reductive systems MOH (M=Na, K)–N₂H₄?·?H₂O–N-methylpyrrolidone and Na₂S?·?9H₂O–N₂H₄?·?H₂O–N-methylpyrrolidone to form methyl vinyl sulfide in up to 79% yield.     

Synthesis,crystal structure and desulfurization properties of zig-zag 1D coordination polymer of copper(II) containing 4-methoxybenzoic acid ligand

ABSTRACT

Combustion of fuels containing organosulfur compounds has resulted in the emission of sulfur oxides (SO_x) into the atmosphere, therefore, causing serious environmental and health hazards. Herein, slightly distorted octahedral zig-zag 1D coordination polymer of copper(II) [Cu(4-mba)₂(H₂O)₃] was synthesized by reacting copper sulfate pentahydrate with a carboxylate-containing ligand (H-4mba?=?4-methoxybenzoic acid) and employed for sulfur compound uptake. The ligand coordinates to the copper(II) atom via two pairs of deprotonated ligating atoms (carboxylate oxygens) and two water molecules. Structural characterization also reveals that interplay of O–H···O, N–H···O, C-H···O and C–H···π interactions between lattice and coordinated water and ligands significantly contribute to the crystal packing leading to the formation and strengthening of three-dimensional supramolecular assembly. The complex, [Cu(4-mba)₂(H₂O)₃], show potential for desulfurization of fuel with an observed adsorption capacity of 9.6?mg/g at 32°C for 6?h. DFT calculations further revealed a transfer of electron sulfur-containing compounds and the complex, [Cu(4-mba)₂(H₂O)₃], thus leading to a stronger pi–pi interaction.     

Water sorption on composites “LiBr in a porous carbon”

Water sorption equilibrium of LiBr confined to pores of a mesoporous synthetic carbon Sibunit and a macroporous expanded graphite (samples SWS-2C and SWS-2EG, respectively) was studied. Isobars of water sorption on these composites are measured at vapor pressure 6–81 mbar and temperature 30–145 °C. The type of sorption equilibrium for the two composites appears to be quite different. The isobars for SWS-2EG have a plateau corresponding to one molecule of H₂O adsorbed by one molecule of LiBr, which indicates the formation of crystalline hydrate LiBr·H₂O inside pores with a monovariant type of equilibrium. At lower temperatures, the equilibrium becomes divariant that is typical for LiBr–water solutions. On the contrary, the water sorption equilibrium for SWS-2C is divariant over the whole temperature and pressure range which means that no crystalline hydrates are formed inside Sibunit pores. In our opinion, this distinction results from differences in a pore structure of the host carbons. The composite sorption capacity can reach 0.6–1.1 g H₂O per 1 g of the dry sorbent at relative humidity 70%. The advanced sorption capacity makes the sorbents promising for gas drying, thermal storage of energy and other applications.     

Sorption of phosphine by activated carbon cloth and the effects of impregnation with silver and copper nitrates and the presence of water

The interaction of PH₃ and H₂O vapour with an activated carbon cloth before and after impregnation with AgNO₃ and Cu(NO₃)₂ · 3H₂O has been studied, as well as the systems PH₃ + AgNO₃ and PH₃ + Cu(NO₃)₂ · 3H₂O. PH₃ sorption isotherms at 25°C, determined gravimetrically in the range 0–25 Torr before and after impregnation with the salts, showed that raw cloth had a strong affinity for PH₃. Impregnation enhanced the sorption capacity of the cloth above a certain pressure limit, which depended on the metal content, but apparently reduced it below this. All isotherms exhibited sorption-desorption hysteresis, with the loops failing to close as the pressure approached zero, while a second sorption run on raw cloth was reversible. Impregnation also increased the amount of sorbate retained under vaccum. A Dubinin-Astakhov relationship was followed by some of the sorption data. With bulk salts on exposure to PH₃ at 25°C, linear plots of weight loss against equilibrium gas pressure indicated chemical reaction. H₂O vapour adsorption isotherms at 25°C measured gravimetrically up to relative pressures of 0.8 on raw cloth were of BET Type V with a marked hysteresis loop. Impregnation with AgNO₃ had little effect on the isotherm shape, except at low pressure where a small second hysteresis loop appeared, which failed to close as the pressure approached zero. With a mixture of H₂O and PH₃, gravimetric studies showed that the sorption capacity of AgNO₃ impregnated cloth for PH₃ was markedly reduced by the presence of H₂O. Gas infrared studies showed N₂O present when AgNO₃ impregnated cloth interacted with PH₃; the presence of H₂O markedly reduced the amount of N₂O. No infraredactive species were detected when raw cloth was exposed to PH₃, while N₂O and NO were produced when bulk AgNO₃ and Cu(NO₃)₂ · 3H₂O were exposed to PH₃. SEM with ED X-ray analysis showed nodular growth of virtually pure Ag together with AgNO₃ on the surface of AgNO₃ impregnated cloth. After exposure to PH₃, P was largely confined to areas away from the nodules. XPS showed a layer of AgNO₃ together with some metallic Ag on AgNO₃ impregnated cloth. After exposure to PH₃, the formation of at least two P compounds, one airsensitive, was indicated, irrespective of the purity of the gas.     

Synthesis,Characterization and Fluorescence Properties of Poly(styrene-co-n-caprylamide maleic acid) and Its Europium(III) and Terbium(III) Complexes

Copolymer of poly(styrene-co-n-caprylamide maleic acid) (PSCMA, defined as HL) and its lanthanide complexes Ln(L)₃·6H₂O (Ln = Eu and Tb) had been synthesized and characterized by elemental analysis, X-ray diffraction, Fourier transform infrared spectra, UV-spectrophotometer and thermal analysis (TG–DTA). The fluorescence properties of the HL ligand and the Ln(L)₃·6H₂O complexes in the solid state were investigated. At room temperature, the HL ligand had a strong broad emission band at 410–575 nm (λmax = 458 nm) under excitation at 380 nm, while the respective characteristic emission of Eu(III) and Tb(III) ions was observed in Ln(L)₃·6H₂O complexes. This demonstrated that the HL ligand in the extra-framework channels succeeded in sensitizing Eu(III) and Tb(III) ions emission. Compared with the Eu(L)₃·6H₂O complex, the fluorescence intensity of the Tb(L)₃·6H₂O complex was much stronger. This indicated that the lowest excited triplet state energy level of HL matched well with the excited state energy level of Tb(III). With the increase of the Ln(III) ions content below 15 wt%, the fluorescence intensity increased monotonically. All the Ln(L)₃·6H₂O complexes exhibited high quantum yield, long fluorescence lifetime and good thermal stability.     

A novel three-dimensional 3d–4f heterometallic coordination polymer with unique (3,4)-connected topology and helical units: Synthesis,crystal structure and photoluminescence property

One new three-dimensional 3d–4f heterometallic coordination polymer, namely, {[EuZn₂(imdc)₂(C₂O₄)_0.5(H₂O)₄]·2H₂O}_n (1) (H₃imdc = imidazole-4,5-dicarboxylic acid), has been successfully synthesized by the hydrothermal reactions of Eu₂O₃, Zn(NO₃)₂·6H₂O, H₃imdc, H₂C₂O₄·2H₂O and H₂O. Single-crystal X-ray diffraction analysis reveals that complex 1 possesses 3D heterometallic framework containing 2D layer based on L–Zn2–L (L = imdc) helical chains and L–EuZn1–L chains. Complex 1 exhibits unprecedented (3,4)-connected four-nodal topology with Schläfli symbol (6·7·8) (6·7·9) (6·7²·8²·10) (7·8²). Moreover, the photoluminescence property of 1 was investigated in the solid-state at room temperature.     

Four New Metal–Organic Supramolecular Networks Based on Aromatic Acid and Flexible Bis(imidazole) Ligand: Synthesis,Structures and Luminescent Properties

Four new metal–organic supramolecular networks, namely, [Zn(H₂pdc)₂(H₂O)₂]·2H₂O·bbi (1), {[Cd(Hpdc)₂]·2H₂O₂·H₂bbi}_n (2), [Zn(BA)₂(bbi)]_n (3), and {[Cd(BA)₂(bbi)]·H₂O}_n (4) (H₃pdc = 3,5-pyrazoledicarboxylic acid, HBA = 3-hydroxybenzoic acid and bbi = 1,1′-(1,4-butanediyl)bis(imidazole)) have been synthesized under hydrothermal conditions and characterized by IR spectra, elemental analyses, and single-crystal X-ray diffraction analyses. Compound 1 possesses zero-dimensional (0D) structure, which is finally extended into a two-dimensional (2D) supramolecular network via O–H···O and C–H···O hydrogen bonds. Complex 2 displays a 2D network structure built from Cd²⁺ atoms interconnected by Hpdc^2? ligands. The adjacent networks are further assembled into three-dimensional (3D) supramolecular structure through O–H···O hydrogen bonds. Compounds 3 and 4 show similar one-dimensional (1D) chains, in which four-coordinated Zn(II) atoms and six-coordinated Cd(II) atoms are bridged by bbi ligands. Through O–H···O and C-H···O hydrogen bonding interactions, the 1D chains are further packed into 2D and 3D supramolecular frameworks for 3 and 4, respectively. Obviously, the structural differences among compelxes 1–4 are attributed to the different central metal atoms and organic ligands. In addition, compounds 1–4 exhibit blue fluorescent emission in the solid state at room temperature.     

Molecular switching of nickel(ΙΙ) complexes using a hemilabile N,N′-bis(β-carbamoylethyl)1,2-diaminocyclohexane ligand

The reaction of NiCl₂·6H₂O with one equivalent hemilabile diaminodiamide ligand N,N′-bis(β-carbamoylethyl)1,2-diaminocyclohexane (1) gave a pale blue compound [Ni(C₁₂H₂₄N₄O₂)(H₂O)₂]₂·3H₂O·4Cl (2). With more than one equivalent ligands, 2 was transformed to a yellow species [Ni(C₁₂H₂₂N₄O₂)]·3H₂O (3) by the Ni–O to Ni–N bond rearrangement at two amide sites of the complex. The color change could be described as a pH dependent isomerization of the ligand. The results presented could be useful in the design of new Ni(II)-based switching materials.     

Production of nano zinc borate (4ZnO·B2O3·H2O) and its effect on PVC

In this study, nano sized zinc borate powder with a formula of 4ZnO·B₂O₃·H₂O was synthesized using 2ZnO·3B₂O₃·3.0–3.5H₂O as a starting chemical which was produced using a wet chemical method. After dissolving 2ZnO·3B₂O₃·3.0–3.5H₂O in an ammonia solution, the clear solution was boiled until a white powder formed. The resultant powder was characterized with XRD, FTIR, TGA and TEM. XRD, FTIR and TGA results proved that the powder was belonged to the 4ZnO·B₂O₃·H₂O. Nano composites of 4ZnO·B₂O₃·H₂O–polyvinylchloride (PVC) were produced by injection moulding by adding 1 and 5 wt% zinc borate powders into PVC to enhance its flame retardancy. Limiting oxygen index (LOI) of virgin PVC increased from 41% to 47% and 54% for the 1 and 5 wt% zinc borate added PVC, respectively. Nano zinc borate addition into the PVC does not have considerable negative effect on the mechanical properties of zinc borate–PVC composites even at high amounts of 5 wt%.     

c-BN color change with bonded water added into the h-BN–Mg system

Cubic boron nitride (c-BN) crystals were synthesized in conditions of high temperature and high pressure (HTHP) when different kinds of bonded water were respectively added into the system of h-BN–Mg. All bonded water used in this work could reduce the temperature of growing c-BN compared to that in the system of h-BN–Mg. The c-BN color could change from black to yellow when certain amounts of bonded water, such as NiSO₄·6H₂O and CuSO₄·5H₂O, Mg(OH)_2, were added. However, c-BN color remained black no matter how much bonded water, such as NiCl₂·6H₂O, CuCl₂·2H₂O, and SnCl₂·2H₂O, was added. The bonded water can be classified into Chlorine-containing bonded water (Cl-BW) and Chlorine-free bonded water (ClF-BW) according to their different characters and effects on the synthesized c-BN color.     

SPECTRAL STUDIES AND EQUILIBRIUM ANALYSIS OF THE DIDODECYLNAPHTHALENE SULFONIC ACID,DICYCL0HEXAN0-18-CR0WN-6, Sr2+EXTRACTION SYSTEM

The species and equilibria present in the synergistic extraction system for strontium, composed of didodecylnaphthalene sulfonic acid (HDDNS) and dicyclohexano-18-crown-6 (DC18C6) in CCI⁴, have been studied by IR and proton NMR spectroscopies, vapor pressure osmometry (VPO), and Karl Fischer (KF) titrations. With the aid of least-squares computer methods to fit the IR and VPO results, a series of proposed equilibria and associated equilibrium constants have been shown to adequately account for all of the observed behavior. The sulfonic acid and the salt of the acid alone in CCI⁴solution form the micellar species (HDDNS·xH₂O) ₁₁(× is in the range 7-8) and (Sr(DDNS)₂· 11 H₂O) ₆respectively. The sulfonic acid alone, under conditions of intermediate loadings with Sr²⁺, yields the predominant species (Sr(DDNS) ₂)₃(HDDNS) ₅·×H₂O. When alone in solution, DC18C6 is a monomer, but it forms adducts with the free sulfonic acid and its strontium salt, yielding the respective product species (HDDNS) ₇·DC18C6· ×H₂O and Sr(DC18C6)(DDNS)₂· 2H₂O. An excess of HDDNS or Sr(DDNS)₂in the presence of Sr(DC18C6)(DDNS) ₂2H₂O yields predominantly Sr(DC18C6)(DDNS)₂(HDDNS)₂· ×H₂O and (Sr(DC18C6)(DDNS)₂) ₂(Sr(DDNS)₂) ₃3' · ×H₂O respectively.     

Sol-Gel Synthesis,Thermal Behavior of Nanopowders and Chemical Stability of La<Subscript>1 – <Emphasis Type="Italic">x</Emphasis></Subscript>Ho<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>PO<Subscript>4</Subscript> Ceramic Matrices

Nanosized powders of orthophosphates in the LaPO₄–HoPO₄–H₂O system have been synthesized to determine the mutual solubility of LaPO₄ · nH₂O and HoPO₄ · nH₂O initial components and to obtain ceramic matrices by sintering them. Formation of hexagonal, monoclinic or tetragonal solid solutions was revealed, and their limits and thermal stability were determined. A series of limited hexagonal LaPO₄ · nH₂O-based solid solutions was observed within the 0 ≤ x ≤ 0.6 concentration range up to 600°C. Further they transformed to monoclinic LaPO₄-based form within the 0 ≤ x ≤ 0.3 concentration range. Solubility of LaPO₄ · nH₂O and LaPO₄ in tetragonal HoPO₄(· nH₂O) is lower (≤10 mol %). Specific surface area of La_1–xHo_xPO₄ · nH₂O powders was in the range of 90.5–165.0 m²/g depending on x. Leaching rate of La³⁺ and Ho³⁺ from La_1–xHo_xPO₄ matrices in nitric acid solution (pH 1–2) was determined to be 10^–5–10^–2 g/(cm² day) for both ions.     

Two cobalt(II) coordination polymers based on carboxylate ligand: Preparation,crystal structures and magnetic properties

Two new coordination polymers, [Co₂(L)_1.5(OH)(H₂O)₂]·2H₂O (1) and [CoL(bpp)] (2) (H₂L = 2,5-dibenzoylterephthalic acid and bpp = 1,3-bis(4-pyridyl)propane), have been synthesized and characterized by elemental analyses, IR spectra, and thermogravimetric analyses. Their structures were determined by single crystal X-ray diffraction analyses. Complex 1 exhibits a 3D framework assembled from tetra-nuclear cobalt-oxygen bridged by carboxylic O atoms with a (4¹²·6³) topology. Complex 2 possesses a 2D layered structure which extends into a 3D architecture via C–H···π interaction between propane proton and the phenyl ring or pyridine ring of an adjacent sheets. Furthermore, the magnetic properties of them are discussed.     

Synthesis,Crystal Structure,Electrochemical and Catalytic Properties of Hybrid Polyoxomolybdate Clusters-Based Terbium Complex

The inorganic–organic compound based on polyoxomolybdate [Tb(C₂H₆SO)₈][PMo₁₂ O₄₀]·2C₂H₆SO·½H₂O (I) has been isolated and structurally characterized by single-crystal X-ray molecular structure, IR spectra, thermogravimetric analysis and cyclic voltammetry measurements. The catalytic activities of (I) were also tested. The title compound crystallizes in monoclinic crystal system with C2/c space group. In the crystal, the polyoxidometalate anions are arranged in chains parallel to the [010] direction. The complex cations are located between these layers and linked to the neighbouring anions via weak C–H?O hydrogen bonding interactions leading to the formation of three dimensional network structure. Their catalytic activity toward organic dye is quite sizeable since the target removal is about 68% in the presence of the system POM-Tb/H₂O₂ after 120 min.     

Two kinds of cobalt–based coordination polymers with excellent catalytic ability for the selective oxidation of cis-cyclooctene

Two kinds of cobalt–based coordination polymers {[Co(dsd)(H₂O)₄]·4,4′-bpy}(1) and {[Co(dsd)(H₂O)₄]·H₂O} (2) with the chain structure possess excellent catalytic ability for the selective oxidation of cis-cyclooctene.     

24-Membered octanuclear manganese metalladiazamacrocycle

The novel macrocyclic octanuclear manganese(III) 24-metallacrown-8 [Mn₈(C₉₆N₁₆O₂₄H₁₀₄)₆(DMF)₇(H₂O)·3DMF·4.5H₂O (1), has been self-assembly synthesized and characterized. The pentadentate ligand is N-isobutyryl-5-methylsalicylhydrazide (H₃ibumshz). The supramolecular complex assumes a nearly planar cyclic structure with succession of eight structural moieties of the type [Mn(III)–N–N₈ and measure ～22.74 Å in outer diameters. The chiralities of the manganese centers on the metalladiazamacrocycle occur in alternating ···ΔΛΔΛ··· configurations. The title 24-metallacrown-8 has no crystallographic centrosymmetry. The magnetic property of the title 24-metallacrown-8 exhibits a weak antiferromagnetic exchange interaction.     

Phosphoric acid-modified magnesium oxychloride: Study of water stability,kinetics, and pair distribution function

Magnesium oxychloride (MOC) excels in performance applications due to inherent structural strength, fire retardant properties, and numerous other attributes. To avoid the slow degradation of MOC when exposed to water, phosphoric acid is usually added, effectively increasing retention of structural properties (water stability). While this is an effective method, it is poorly understood. Additions of 2.5 wt.% and above had positive impacts on the water stability, preserving ~50 wt.% crystalline MOC after water stability tests. Phosphoric acid addition also impacted the reaction kinetics, increasing the activation energy of curing from 72.2 to 87.6-95.2 kJ/mol. Using synchrotron X-ray scattering and pair distribution function analysis, we identified an unreported amorphous phase formed when phosphoric acid is added; this phase contains structural motifs related to MgHPO₄·3H₂O (newberyte), Mg₂P₂O₇·3.5H₂O (magnesium pyrophosphate), and amorphous MOC phase. The short-range order of the samples show a prominent peak at ~3.2 Å that grows with increasing acid addition, believed to be a combination of newberyte (~3.4 Å Mg–P), pyrophosphate (~3.25 Å Mg–P), and MOC (~3.15 Å Mg–Mg). We propose that the increased water stability observed is due to this combined amorphous phase, which retains the low water solubility properties of MgHPO₄·3H₂O and Mg₂P₂O₇·3.5H₂O, effectively protecting the MOC crystalline phase.