Study of the Composition,Structure, and Sorption Properties of Nanostructured Aluminosilicates

Sorption properties of synthetic nanostructured potassium aluminosilicates with Si/Al ratios from 1 to 5 fabricated in a multicomponent system KOH–Al₂(SO₄)₃·18H₂O–SiO₂·nH₂O–H₂O under static sorption conditions at various temperatures and nitrate salt background have been investigated; the activation energy of cesium ions sorption has been evaluated.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

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%.     

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.     

Physical–chemical properties of nanopowders and ceramic samples of REE orthophosphates

A series of physical–chemical studies of a series of binary REE orthophosphate systems has been performed: LaPO₄–DyPO₄–H₂O, LaPO₄–YPO₄–H₂O, LaPO₄–LuPO₄–H₂O, YPO₄–LuPO₄–H₂O, and YPO₄–ScPO₄–H₂O. Nanopowders of Ln'_{1 ?x}Ln'_x PO₄ · nH₂O orthophosphates have been synthesized by the sol–gel method using direct and reverse precipitation techniques. Ceramic samples were produced from the nanopowders, and their physical–mechanical properties were determined depending on the thermal treatment temperature and duration. The ceramic samples’ thermal behavior has been investigated by the dilatometry method. The results have been compared depending on the technique of nanopowder synthesis.     

Three new coordination polymers based on 4-oxo-1(4H)quinolineacetate: Synthesis,structures and luminescent properties

Reactions of 4-oxo-1(4H)-quinolineacetic acid (Hoqa) and varied metal salts of Zn(II), Cd(II) and Ag(I) resulted in the formation of three new coordination polymers, namely, [Zn(oqa)₂]·H₂O (1), [Cd(bpy)(oqa)₂(H₂O)₂]·4H₂O (2) and [Ag(bpy)(oqa)]·2H₂O (3) (bpy = 4,4′-bipyridine). Complex 1 has a three-dimensional (3D) polymeric network with diamondoid topology; compounds 2–3 exhibit one-dimensional (1D) chain structure characteristics, which are further assembled through π–π stacking attractions and hydrogen bonds, forming the 3D supramolecular frameworks. In addition, the solid-state luminescent properties of the ligand Hoqa and complexes 1–2 have been investigated 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.     

Synthesis,structures, luminescent and magnetic properties of four coordination polymers based on biphenyl-2,4′,5-tricarboxylic acid and different N-donor ligands

Four new coordination polymers [Zn(HL)(bibp)]_n (1: H₃L = biphenyl-2,4′,5-tricarboxylic acid, bibp = 4,4′-bis(imidazolyl)biphenyl), [Co(HL)(bibp)]_n (2), [Co(HL)(bib)]_n·4nH₂O (3: bib = 1,4-bis(1-imidazoly)-benzene), [Co_1.5(L)(bib)_1.5(H₂O)]_n·3nH₂O (4), have been synthesized under solvo/hydrothermal conditions, and have been fully characterized by single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), IR spectra, elemental analysis and thermogravimetric analysis (TGA). Structural analyses reveal that both 1 and 2 display a 4-fold interpenetrated framework. Complex 3 possesses a 2D (4,4) network. Complex 4 exhibits a 3D framework with the point symbol of {3²·4·6⁷}₂{3²·6¹⁰·7²·8}. Moreover, photoluminescence properties of 1 and magnetic properties of 2–4 have also been studied in detail.     

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.     

Synthesis and Crystal Structures of a Lanthanum(III) 1D Polymer and a Mixed-Ligand Cerium(III) Binuclear Complex Derived from Pyridine-2,6-dicaboxylic Acid

Lanthanum(III) and cerium(III) complexes of pyridine-2,6-dicaboxylic acid (H₂Pydc) have been prepared and their crystal structures were determined by X-ray crystallography. The single crystal analysis reveals that the lanthanum(III) complex, 1 is polymeric consisting of {[La(Pydc)₂(H₂O)₂]·4H₂O} _n units linked through carboxylate oxygen atoms and exhibiting nine coordination number. Intermolecular O–H···O hydrogen bonds produce R ₁ ¹ (6), R ₄ ⁴ (16) and R ₄ ⁴ (20) rings, which lead to three-dimensional polymeric chains. The crystal structure of the cerium(III) complex, 2 [{Ce(Pydc)₃}{Ce(Pydc)(HO–CH₂CH₂–OH)(H₂O)₃}·6H₂O)] shows that the complex is a mixed-ligand binuclear system in which one cerium coordinated to three Pydc molecules, while the other cerium is bound to one Pydc, one oxygen atom of the other Pydc, one ethylene glycol and three water molecules. Each of the two Ce(III) ions is nine coordinated. Intermolecular O–H···O hydrogen bonds produce R ₂ ² (8) and R ₂ ² (20) rings, which lead to three-dimensional polymeric chains. The complexes were further investigated using elemental analysis, FTIR spectroscopy and thermogravimetric analysis.     

PLZT—Synthesis,sintering and ceramics microstructure

Producing of PLZT powders by original two-stage co-precipitation method from mixed solution of inorganic salts ZrOCl₂·8H₂O, TiCl₄, La(NO₃)₃·6H₂O, Pb(NO₃)₂, was carried out. The sequence of phases formed during PLZT synthesis has been studied by X-ray and DTA analysis. Ceramic samples were prepared by two-stage hot-pressing technology. Dielectric, ferroelectric and optical properties have been measured. Ceramic microstructures were studied by SEM with energy dispersive analytical capability (EDX). The fine-grained microstructure was quite uniform with the average grain size of 5–7 μm, without internal or grain boundary porosity. The optical transmittance of ceramic plates (thickness of 0.3 mm) measured at wavelength of 630 nm reached 67–69%.     

The effects of cold sintering parameters on the densification of Na2WO4 ceramics using Na2WO4·2H2O dry powders

Cold sintering process (CSP) combines transient liquid phase and/or external pressure to assist the densification of ceramics, the sintering mechanism of which is typically dominated by the “dissolution–precipitation” process. In this work, Na₂WO₄·2H₂O dry powders without liquid water have been used as the “liquid phase” to realize the densification of Na₂WO₄ ceramics. The effects of sintering parameters on the CSP of Na₂WO₄ ceramics using Na₂WO₄·2H₂O dry powders are systematically studied, including sintering temperature, external pressure, sintering process time and the amount of Na₂WO₄·2H₂O phase. It is found that the “liquid phase,” that is, Na₂WO₄·2H₂O is the key factor for controlling the CSP of Na₂WO₄ ceramics, and Na₂WO₄·2H₂O hydrate shows an advantage of homogeneous dispersion of liquid water. The sintering temperature affects the densification mechanism involved with plastic deformation and the “dissolution–precipitation,” external pressure accelerates the densification process, and enough sintering process time ensures the completion of CSP. Finally, the optimum cold sintering parameters of Na₂WO₄ ceramics by Na₂WO₄·2H₂O powders are obtained at 150°C and 240 MPa for 60 min with a pretreatment at 150°C for 30 min.