Intercalation chemistry of aluminium dihydrogentriphosphate with weak bases and polymerization of aniline between its layers

Weak bases such as 2-aminopyridine, 4-aminopyridine,o-phenylenediamine,p-phenylenediamine and aniline were intercalated into aluminium dihydrogentriphosphate (ADHP) using ultrasonic wave irradiation. The interlayer spacing of ADHP increased from 8.1 Å to 12.4–20.0 Å. From the values of the layer expansions and host/guest ratios, bilayer or monolayer structures were considered. Chemical oxidation of the aniline resulted in the formation of polyaniline in the ADHP layers.Author for correspondence.     

New Layered Double Hydroxide, Zn–Ti LDH : Preparation and Intercalation Reactions

The layered double hydroxide (LDH) well known for its abilityto intercalate anionic compounds has been prepared conventionallyonly with bivalent and trivalent cations. In this study, Zn–Ti LDH consisting of bivalent and tetravalent cations was prepared, andreacted with organic monocarboxylic, dicarboxylic and aromatic acidsat high or room temperature. XRD patterns of the prepared LDH(Zn–Ti-CO₃) showed that interlayer spacing of the LDH was 0.67 nm. The value was small compared to the usual LDH (Zn–Al–CO₃)of 0.76 nm in the case of carbonate anion as the guest. Also, DTA,TG and DTG analysis indicated that the electrostatic force betweenthe layers and carbonate anions increased where the carbonate anionsin Zn–Ti LDH decomposed at 255 °C while those inZn–Al–CO₃ decomposed at 230–240 °C.     

Intercalation of dodecyl sulfate into layered double hydroxides

The intercalation of sodium dodecyl sulfate and exchange of dodecyl sulfate anion into layered double hydroxides has been examined by means of X-ray diffraction, infrared and thermogravimetric procedures. Three types of derivatives were obtained having mean interlayer spacings of 26 Å, 36 Å and 47 Å, respectively. These interlayer distances did not correlate with the amount of organic incorporated between the layers but, as shown by computer simulations, depended upon the orientation of the chains within the interlamellar space. In several reactions both intercalation of neutral sodium dodecyl sulfate as well as exchange of the dodecyl anion took place. Attempts to remove the alkyl sulfate chains with dilute acid resulted in dissolution of the more basic metals producing non-stoichiometric layered products.     

X-Ray Diffraction Studies of Sol-Gel Derived ORMOSILs Based on Combinations of Tetramethoxysilane and Trimethoxysilane

ORMOSILs have been prepared in the series TMOSx·MTMS(100 – x) (where TMOS is tetramethoxysilane; MTMS is methyltrimethoxysilane; x is mol% silane with respect to total silane for 0 x 100) by means of acid catalyzed, sol-gel processing. After drying at 60°C, small bulk samples were obtained of excellent optical clarity. Powder X-ray diffraction (XRD) patterns, in the range of 5 to 60°2, were compared with that of fused silica. All the prepared samples were amorphous. Fused silica exhibits one broad peak, d2 centered at d-spacing 4.12 Å. For the TMOS100 silica xerogel, the analogous broad peak had shifted slightly, to be centered at 3.88 Å; and remained in about the same position as x was decreased for the series TMOSx·MTMS(100 – x). In addition, a second, broad peak, d1, was observed for the ORMOSIL series centered at the d-spacing 8.7 Å for MTMS100 (i.e., x = 0) and increasing smoothly as x was increased, reaching 11.3 Å for x = 70, and >11.3 Å for x > 70. The intensity of d1 was found to have trebled, relative to the intensity of d2, on increasing the organic character of the matrix from TMOS70·MTMS30 to MTMS100.The d2 peak appearing at about 4 Å for both fused silica and the ORMOSILs is assumed to be associated with the spacing between silicon atoms connected by means of an oxygen bridge. The Si–O–Si angle for silica xerogels is known to depend upon the nature of the sol-gel processing and is bigger than that of fused silica.The d1 peak may be associated with the spacing between silicons attached to methyl groups and indicative of channels of methyl groups in the structure. Alternatively, the d1 peak may have its origin in a preferred, discrete structural unit in the matrix for instance cubane based on a octameric silicon arrangement.     

Methotrexate intercalated ZnAl-layered double hydroxide

The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 Å in pristine LDH to 21.3 Å in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion.     

Investigation of the local structure of nanosized CdS crystals stabilized with glutathione by the radial distribution function method

For stabilized nanoparticles of cadmium sulfide, a highly resolved radial distribution function was derived from the dispersion curve of synchrotron radiation ( = 0.08824 Å). The nanoparticle core has dimensions of 15 Å–20 Å and consists of Cd and S atoms in a 1:1 ratio. In the inner part of the nanoparticle, these atoms have a random tetrahedral coordination similar to that in crystalline CdS. Half of all core S atoms belong to the ligands and are coordinated by the surface Cd atoms. In contrast to the inner S atoms, these S atoms each binds two or three Cd atoms, forming a CdSCd bond angle of 100°, which is smaller than the tetrahedral angle. The Cd-S bond lengths are similar for both types of sulfur and vary within 2.52 Å–2.53 Å. The spatial arrangement of the Cd and S atoms beyond the first coordination sphere is significantly different from that of bulk CdS, which may be caused by perturbations induced by the surface S atoms.Original Russian Text Copyright © 2004 by V. I. Korsunskii, R. Neder, K. Hradil, J. Neuefeind, K. Barglik-Chory, and G. MüllerTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 452–461, May–June 2004.     

An Optical Chemical Sensor Based on Swellable Dicarboxylate Functionalized Polymer Microspheres for pH Copper and Calcium Determination

An optical chemical sensor based on polymer swelling and shrinking has been studied by way of optical transmission. Polyvinylbenzyl chloride cross-linked with divinylbenzene and derivatized as the dicarboxylate was dispersed as microspheres in a hydrogel membrane. The absorbance was measured vs. the wavelength upon exposing the modified membrane to solutions of varying pH (3.0–9.0). At low pH (3.0), the absorbance had the highest value (1.34), while the absorbance decreased significantly (1.10) when the pH was increased to 9.0, indicating polymer swelling.The modified membrane was also used for sensing metal ions, in particular calcium and copper. Complex formation with the dicarboxylate functionality caused the polymer to shrink. This resulted in an increase in absorbance for a concentration ranging from 1.0×10^–3 to 4.0×10^–3M.     

A New Organic-Inorganic Hybrid Nanocomposite, BEDT-TTF Intercalated into Layered FePS3

A new inorganic–organic hybrid compound, Fe_0.76PS₃(BEDT-TTF)_0.48 (BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene), has been synthesized by the reaction of the pre-intercalate Fe_0.90PS₃(Phen)_0.41 (phen=1,10-phenanthroline) with (BEDT-TTF)₂I_x. The powder X-ray diffraction (XRD) results show that the expansion of the lattice spacing (Δ d) is about 4.0 Å compared with the pristine FePS₃, indicating that the molecular ring plane of the guest is parallel to the layer of the host. The infrared spectrum of the intercalate shows the existence of BEDT-TTF as a guest between the interlayer region of the layered FePS₃. The room-temperature electrical conductivity of the compressed pellet of Fe_0.76PS₃(BEDT-TTF)_0.48 is about 10⁻⁷ S/cm, which is in the same order of magnitude as that of the pristine FePS₃(10⁻⁷ S/cm). The magnetic properties measured with a SQUID-magnetometer indicate that Fe_0.76PS₃(BEDT-TTF)_0.48 exhibits the paramagnetism from 120 to 300 K and Curie-Weiss Law was obeyed above 140 K, but a strong antiferromagnetic phase transition occurs at T_N of 100 K.     

Spectrographic a.c. spark method for the estimation of yttrium in rare earth mixtures

Summary The spectrographic estimation of yttrium in rare earth mixtures was achieved within a concentration range of 1–90% by means of the a.c. spark method using a large quartz spectrograph. The sample was mixed with ceria and zinc oxide in the ratio 212. The Y lines 2414.68 Å and 2856.36 Å were used as analytical lines for the ranges of 1–15% and 10–90%, respectively. The Ce line at 2603.65 Å served as internal standard line. The standard deviation was 2–5%.

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Spektrographische Bestimmung von Yttrium in Gemischen Seltener Erden mit Hilfe der Wechselstrom-Funken-methode

Zusammenfassung Yttrium konnte im Konzentrationsbereich von 1–90% mit einem großen Quarzspektrographen bestimmt werden. Die Probe wird mit Cerdioxid und Zinkoxid im Verhältnis 212 gemischt. Als Analysenlinie dient die Y-Linie 2414,68 Å (1–15%) bzw. 2856,36 Å (10–90%). Als innere Standardlinie wird die Ce-Linie 2603,65 Å verwendet. Die Standardabweichung betrug 2–5%.

     

Synthesis and Structure of Tin(II) Hexafluorozirconate

The crystal structure of SnZrF₆ is determined. The compound is synthesized by slow crystallization from a melted mixture of SnF₂ and ZrF₄ (2 : 1). The crystals are monoclinic: a = 6.6119(5), b = 5.2503(5), c = 6.9929(6) Å, = 114.239(4)°, space group P2/n, Z = 2. The structure is layered. The layers are formed from the chains of edge-sharing, eight-vertex zirconium polyhedra and Sn²⁺ cations. The Zr–F and Sn–F bond lengths in the layer vary from 2.309(1) to 2.269(1) Å and from 2.186(1) to 2.361(1) Å, respectively. The layers are linked by intermolecular Sn–F bonds with lengths of 2.868(1) and 2.871(1) Å.     

硫代硫酸根插层水滑石的层间限域反应

将无机阴离子硫代硫酸根(S2O23-)限域在锌铝水滑石(LDH)层间,并研究了其在水滑石层板限域空间内被铁氰根(Fe(CN)63-)氧化的反应过程.通过X射线衍射(XRD)和傅里叶变换红外(FTIR)光谱仪对反应的中间产物和最终产物进行的表征发现,氧化产物连四硫酸根(S4O62-)进入到溶液中,还原产物亚铁氰根(Fe(CN)64-)则保留在水滑石层间.进一步系统研究了该反应的动力学过程,考察了硫代硫酸根插层水滑石用量、铁氰化钾浓度和温度对反应的影响.结果表明该氧化还原反应符合球体内扩散模型.根据温度对反应速率影响,得出了该反应的表观活化能为24.6kJ.mol-1,比相同条件下溶液中反应活化能降低了约13.7kJ.mol-1.采用分子动力学(MD)模拟计算了水分子含量对硫代硫酸根插层水滑石层间距大小的影响.计算表明:在水溶液环境中,水滑石微反应器的尺寸在特定方向具有可调控性.根据实验表征和理论计算对该层间反应的机理进行了探讨.因此,该类层状材料可以作为一种新型纳米级微反应器应用于调控化学反应.     

Fourier Transform Infrared Spectra of Naphthalene Disulfonates between Layers of Mg and Al double Hydroxide: Intercalation by Means of Coprecipitation and Direct Observation of Coordination from the Interlayer Anion to the Metal Cation in the Layer

A Mg/Al-layered double hydroxide with interlayernaphthalene-2,6-disulfonate having a basal spacing of1.68 nm was prepared by means of the coprecipitationmethod. The results of powder X-ray diffractionare compared with those of other intercalates whichhave interlayer naphthalene disulfonates. Fouriertransform infrared spectra of the LDH intercalatedcompounds reveal that the organic molecules located inthe interlayer region are stable. Coordinationfrom the oxygen atom in the –SO₃ ^- group of the interlayer molecules to the metal cation in the layeris observed.     

高层间距氧化铝柱层状钛酸盐的制备和表征

层往化合物因其具有独特的大分子吸附和催化等性能而受到人们的高度重视．至今，人们对层柱粘土和四价金属磷酸盐的制备和表征已作了比较详细和深入的研究k一句，但对一系列以八面体骨架结构为基；出的层状金属氧化物的“插x化学”（intercalationcheAnstry）的研究相对较少，且大部分。作都局限在用有机胺来支撑此类层状金属氧化物［‘－’］由于层间的有机物不耐高温，此类层柱材料在各方面（尤其是催化方面）的应用就受到了很大的限制．合成高热稳定性和大层间距的层柱金属氧化物一直是该领域的研究重。点之一．同层状粘土不同，这类层…     

(N,N, N′, N′-tetramethylethylenediammonium)Cu2X6 (X=Cl,Br): crystal structure and magnetic interactions

Summary The crystal structures of (Me₄enH₂)Cu₂Cl₆ and (Me₄enH₂)Cu₂Br₆ have been determined. The triclinic crystals contain chains of symmetrically bibridged [Cu₂X₆]^2– dimers. Within the dimers the Cu–X distances average 2.299 Å (Cl) and 2.408 Å (Br) and the Cu–X–Cu angles are 96.4(1)^o (Cl) and 95.7(1)^o (Br). Longer Cu–X bonds, 2.679(1)Å (Cl) and 2.761(3)Å (Br), link dimers together into infinite chains via asymmetrical bridges. The bridging angles for the asymmetric bridge are 92.2(1)^o (Cl) and 89.4(1)^o (Br). Magnetic susceptibility data for both compounds are indicative of antiferromagnetic coupling. Analyses of the data yields J/k=–23(1)K (Cl) and –82(2)K (Br) for the interdimer coupling and J/k=–5(1)K (Cl) and –4(1)K (Br). The intradimer coupling for the chloride is in accord with magneto-structure relations deduced for similar salts. Similarly, the increased antiferromagnetic contribution upon substitution of Cl by Br follows trends previously observed.     

In situ polymerization of the 4-vinylbenzenesulfonic anion in Ni-Al-layered double hydroxide and its molecular dynamic simulation

This paper describes a systematic study on the thermal polymerization of both pristine 4-vinylbenzenesulfonic anion (VBS) and intercalated VBS in the two-dimensional (2D) gallery of Ni-Al layered double hydroxide (VBS/Ni-Al-LDH), by virtue of combining experimental and theoretical investigations. In situ FT-IR, in situ high-temperature X-ray diffraction (HT-XRD), UV-vis absorption spectroscopy, TG-DTA and elemental analysis were used to study the polymerization process, and it was found that the polymerization of VBS/Ni-Al-LDH occurs at ca. 150-170 degrees C, at least 40 degrees C lower than that of the pristine VBS, indicating that the layered structure of LDH is favorable for thermal polymerization of VBS. Therefore, this layered inorganic material may have potential application as a "molecular reactor" for enhancing the efficiency of polymerization reaction. Furthermore, the sheet-like polymerization product was obtained with the LDHs lamella as template. For better understanding the structure and arrangement of intercalated VBS and the polymerization product between the layers of Ni-Al-LDH, molecular dynamics (MD) simulation method was employed. The simulation results of hydration energies show that there are two relatively stable stages upon the increase of the number of interlayer water molecules. VBS molecules exhibit a tendency from tilted to vertical orientation with respect to the layers as the interlayer water content increases. Compared with the experimental results, the calculated interlayer spacing is more severely affected by interlayer water content. Finally, a typical tetramer product of VBS intercalated LDH was studied and the simulated equilibrium interlayer spacing is consistent with the experimental result of in situ HT-XRD. Based on the combination of experimental and theoretical studies on the interlayer polymerization system, the aim of this work is to deeply investigate the differences in thermal polymerization process between pristine monomers and intercalated ones in the gallery of LDHs, and to give detailed information of the arrangement and swelling behavior of guest molecules confined between the sheets of host layers.     

Crystal and molecular structure of the simple cation-radical salt ethylenedithiopropylenedithiotetrathiafulvalene trichloromercurate (EPT)HgCl3

The new cation-radical salt (EPT)HgCl₃ is prepared. Its structure and electrical conductivity are studied. The crystal structure of (EPT)HgCl₃ contains (EPT)⁺ in the chair conformation and trigonal planar HgCl₃ ^– packed into organic and inorganic layers alternating along thea axis. Shortened intermolecular contacts join HgCl₃ ^– into infinite chains along the c axis (Hg...Cl, 3.289 and 3.387 Å), form stacks (S...S, 3.536 and 3.597 Å) and layers (S...S, 3.427–3.498 Å) of EPT⁺ cation-radicals, and create cation-anion interactions between neighboring layers in the crystal (Cl...S, 3.396–3.521 Å, Cl...C, 3.360 Å). The configuration of the bonds around Hg in HgCl₃ ^– is distorted trigonal planar: Hg-Cl, 2.342(3)–2.449(3) Å, Cl-Hg-Cl, 110.7(1)–137.4(1). The Hg atom lies out of the plane of the Cl atoms by 0.015 Å. The conductivity of (EPT)HgCl₃ at 20°C is ₃₀₀ 5·10^–2 (·cm)^–1. The dependence of conductivity on temperature is semiconducting in nature.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2055–2061, September, 1991.     

Synthesis and Characterization of Poly(ethylene terephthalate)/Modified Lithium‐Aluminum‐Layered Double Hydroxide Nanocomposites Prepared Using In‐situ Polymerization

Layered double hydroxides are a type of layered stacked compound, which can be intercalated with organic‐molecule modifiers. An ion‐exchange process for layered double hydroxide (LDH) was used to intercalate water‐soluble sulfanilic acid salt (SAS) and dimethyl 5‐sulfoisopthalate (DMSI) into lithium aluminum layered double hydroxides (LiAl LDHs). In this work, a hydrothermal process was used to modify LiAl LDHs, and the modified LiAl LDHs were treated with either SAS or DMSI through an ion‐exchange process and were then intercalated using bis‐hydroxyethylene terephthalate (BHET). The results indicate that the modified LiAl LDHs improved the interlayer compatibility between the PET and LiAl LDH layers; thus, enabling the oligomer molecules to more easily enter the gallery of the LiAl LDH layers so that polymer chains could be included between the LDH layers during polymerization of the matrix. The better barrier, mechanical properties, and thermal stability of these new types of PET nanocomposites are discussed.     

Synthesis and Structure of Tetraphenylantimony γ-Alkylacetylacetonates

Tetraphenylantimony -ethylacetylacetonate and -allylacetylacetonate were synthesized by reacting pentaphenylantimony with -ethylacetylacetone or -allylacetylacetone in toluene. Their structures were determined by X-ray diffraction analysis. The coordination polyhedron of the antimony atom is a distorted octahedron. In the tetraphenylantimony -ethylacetylacetonate, the Sb–C bond lengths vary in the 2.156(2)–2.170(1) Å range, the SbOC(1)C(2)C(1")O" heterocycle is symmetric, and the Sb–O and O–C distances are 2.201(1) and 1.284(2) Å, respectively. In the tetraphenylantimony -allylacetylacetonate, the Sb–C bond lengths vary in the 2.159(1)–2.167(1) Å range and the Sb–O(1,2) distances are 2.234(1) and 2.191(1) Å.     

Stimuli-responsive hybrid materials: breathing in magnetic layered double hydroxides induced by a thermoresponsive molecule

A hybrid magnetic multilayer material of micrometric size, with highly crystalline hexagonal crystals consisting of CoAl–LDH ferromagnetic layers intercalated with thermoresponsive 4-(4-anilinophenylazo)benzenesulfonate (AO5) molecules diluted (ratio 9 : 1) with a flexible sodium dodecylsulphate (SDS) surfactant has been obtained. The resulting material exhibits thermochromism attributable to the isomerization between the azo (prevalent at room temperature) and the hydrazone (favoured at higher temperatures) tautomers, leading to a thermomechanical response. In fact, these crystals exhibited thermally induced motion triggering remarkable changes in the crystal morphology and volume. In situ variable temperature XRD of these thin hybrids shows that the reversible change into the two tautomers is reflected in a shift of the position of the diffraction peaks at high temperatures towards lower interlayer spacing for the hydrazone form, as well as a broadening of the peaks reflecting lower crystallinity and ordering due to non-uniform spacing between the layers. These structural variations between room temperature (basal spacing (BS) = 25.91 Å) and 100 °C (BS = 25.05 Å) are also reflected in the magnetic properties of the layered double hydroxide (LDH) due to the variation of the magnetic coupling between the layers. Overall, our study constitutes one of the few examples showing fully reversible thermo-responsive breathing in a 2D hybrid material. In addition, the magnetic response of the hybrid can be modulated due to the thermotropism of the organic component that, by influencing the distance and in-plane correlation of the inorganic LDH, modulates the magnetism of the CoAl–LDH sheets in a certain range.     

Intercalation of porphyrin (TMPyP) and copper-porphyrin into γ-zirconium phosphate

Water-soluble ,,,-tetrakis(4-N-methylpyridyl)porphine(TMPyP) was directly intercalated into -zirconium phosphate (-ZrP) with expansion of the interlayer distance from 12.3 to a maximum of 17.2 Å, indicating parallel orientation of porphyrin to the layer of -ZrP. Diffuse reflectance spectra of the intercalate shows that the porphyrin is protonated in the interlayer space. Uptake of Cu²⁺ ions into the porphyrin intercalate takes place with further increase in the interlayer distance. It was observed that TMPyP metalated Cu²⁺ in -ZrP. Copper porphyrin can also be taken up quite easily and an interlayer spacing of 18.6 Å is attained.