Layered Organic-inorganic Hybrid Research Articles

Out-of-plane polarization in a layered manganese chloride hybrid

We investigate possible mechanisms to induce electric polarization in layered organic-inorganic hybrids. Specifically, we investigate the structural phase transitions of PEA2MnCl4 (PEA = phenethylamine) using temperature dependent single-crystal X-ray diffraction analysis, including the symmetry analysis of the observed space groups. Our results show that PEA2MnCl4 transforms from a high-temperature centrosymmetric structure with space group I4/mmm to a low-temperature polar Pca21 phase via an intermediate phase with polar space group Aea2. We study the mechanism responsible for the I4/mmm to Aea2 polar phase transition and find that it is different from previously proposed mechanisms in similar systems. The transition is governed by the opening of a small dihedral angle between the phenyl ring planes of two adjacent PEA molecules, which consequently become crystallographically inequivalent in the Aea2 phase. This molecular rotation induces a significant difference in the lengths of the ethylammonium tails of the two molecules, which coordinate the inorganic layer asymmetrically and are consequently involved in different hydrogen bonding patterns. Consequently, the negatively charged chlorine octahedron that coordinates the Mn2+ cation deforms. This deformation moves the Mn2+ off-center along the out-of-plane-axis, contributing to the polar nature of the structure. Notably, the polar axis is out-of-plane with respect to the inorganic sheets. This is in contrast to other layered organic-inorganic hybrids as well as conventional layered perovskites, such as the Aurivillius phases, where in-plane polarization is observed. Our findings add to the understanding of possible mechanisms that can induce ferroelectric behavior in layered organic-inorganic hybrids.

Dielectric phase transition triggered by the order–disorder transformation of cyclopropylamine in a layered organic–inorganic halide perovskite

We used cyclopropylamine to construct a new layered inorganic–organic hybrid phase transition compound, which undergoes a solid-state phase transition around 273 K induced by the order–disorder transformation of organic moiety.

2D Porous Carbons prepared from Layered Organic-Inorganic Hybrids and their Use as Oxygen-Reduction Electrocatalysts.

2D porous carbon nanomaterials have attracted tremendous attention in different disciplines especially for electrochemical catalysis. The significant advantage of such 2D materials is that nearly all their surfaces are exposed to the electrolyte and can take part in the electrochemical reaction. Here, a versatile active-salt-templating strategy to efficiently synthesize 2D porous carbon nanosheets from layered organic-inorganic hybrids is presented. The resulting heteroatom-doped carbon nanosheets (NFe/CNs) exhibit exceptional performance for the oxygen-reduction reaction and in Zn-air battery electrodes. The activity of the best catalyst within a series of NFe/CNs exceeds the performance of conventional carbon-supported Pt catalysts in terms of onset potential (0.930 vs 0.915 V of Pt/C), half-wave potential (0.859 vs 0.816 V of Pt/C), long-time stability, and methanol tolerance. Also, when applied as a cathode catalyst in a zinc-air battery the NFe/CNs presented here outperform commercial Pt/C catalysts.

Synthesis and characterization of layered perovskite-type organic-inorganic hybrids (C n H2n+1NH3)2(CH3NH3) m-1Pb m I3m+1 (n=5–10, m=1, 2)

Layered organic-inorganic hybrids (CnH2n+1NH3)2(CH3NH3)m-1PbmI3m+1 containing monolayer (m=1) and bilayer (m=2) perovsikte were synthesized by reactions in solution. The influences of the reactant ratio, solvent, reaction temperature, and reaction time on the structures of the products were investigated. The structures and the properties of the hybrids were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet and visible (UV) absorption spectroscopy. The XRD patterns and the SEM images demonstrate that the pure bilayer perovskite hybrids are obtained. The UV-vis spectra indicate that the number of the inorganic perovskite layer (m) has greater impact on the band gap than the number of the carbon atoms (n). The band gap of bilayer hybrids (around 1.9 eV) is significantly less than that of monolayer hybrids (around 2.2 eV).

Efficient Removal and Recovery of Uranium by a Layered Organic–Inorganic Hybrid Thiostannate

Uranium is important in the nuclear fuel cycle both as an energy source and as radioactive waste. It is of vital importance to recover uranium from nuclear waste solutions for further treatment and disposal. Herein we present the first chalcogenide example, (Me2NH2)1.33(Me3NH)0.67Sn3S7·1.25H2O (FJSM-SnS), in which organic amine cations can be used for selective UO2(2+) ion-exchange. The UO2(2+)-exchange kinetics perfectly conforms to pseudo-second-order reaction, which is observed for the first time in a chalcogenide ion-exchanger. This reveals the chemical adsorption process and its ion-exchange mechanism. FJSM-SnS has excellent pH stability in both strongly acidic and basic environments (pH = 2.1-11), with a maximum uranium-exchange capacity of 338.43 mg/g. It can efficiently capture UO2(2+) ions in the presence of high concentrations of Na(+), Ca(2+), or HCO3(-) (the highest distribution coefficient Kd value reached 4.28 × 10(4) mL/g). The material is also very effective in removing of trace levels of U in the presence of excess Na(+) (the relative amounts of U removed are close to 100%). The UO2(2+)···S(2-) interactions are the basis for the high selectivity. Importantly, the uranyl ion in the exchanged products could be easily eluted with an environmentally friendly method, by treating the UO2(2+)-laden materials with a concentrated KCl solution. These advantages coupled with the very high loading capacity, low cost, environmentally friendly nature, and facile synthesis make FJSM-SnS a new promising remediation material for removal of radioactive U from nuclear waste solutions.

(Invited) Atomically Thin Two-Dimensional Organic-Inorganic Hybrid Perovskites

Intense research efforts have focused on two-dimensional (2D) materials in the last decade. Layered organic-inorganic hybrid perovskites, which were discovered more than 20 years ago and have proved to be promising semiconductor materials, have not been made into atomically thin sheets and investigated so far. In this talk, we report the solution-phase growth of single and few unit-cell-thick single crystalline 2D hybrid perovskites of (C4H9NH3)2PbBr4 with well-defined square shape and large size. In contrast to other 2D materials, the hybrid perovskite sheets exhibit an unusual structural relaxation, and this structural change leads to a band gap shift compared to the bulk crystal. The high quality 2D crystals exhibit efficient photoluminescence, and color tuning could be achieved by changing sheet thickness as well as composition via the synthesis of related materials. This study opens up the possibility of fundamental research into the synthesis and properties of atomically thin 2D hybrid perovskites, and introduces a new family of 2D semiconductors for nanoscale optoelectronic devices.

Distinctive excitonic recombination in solution-processed layered organic–inorganic hybrid two-dimensional perovskites

Solution-grown two-dimensional (C6H5C2H4NH3)2PbI4 perovskites show three distinctive excitonic emissions.

Layered hybrid perovskites with micropores created by alkylammonium functional silsesquioxane interlayers.

Layered organic-inorganic hybrid perovskites that consist of metal halides and organic interlayers are a class of low-dimensional materials. Here, we report the fabrication of layered hybrid perovskites using metal halides and silsesquioxane with a cage-like structure. We used a silsesquioxane as an interlayer to produce a rigid structure and improve the functionality of perovskite layers. Propylammonium-functionalized silsesquioxane and metal halide salts (CuCl2, PdCl2, PbCl2, and MnCl2) were self-assembled to form rigid layered perovskite structures with high crystallinity. The rigid silsesquioxane structure produces micropores between the perovskite layers that can potentially be filled with different molecules to tune the dielectric constants of the interlayers. The obtained silsesquioxane-metal halide hybrid perovskites exhibit some characteristic properties of layered perovskites including magnetic ordering (CuCl4(2-) and MnCl4(2-)) and excitonic absorption/emission (PbCl4(2-)). Our results indicate that inserting silsesquioxane interlayers into hybrid perovskites retains and enhances the low-dimensional properties of the materials.

Pb(en)0.5][B5O8(OH)]: A New Bilayered Organic–Inorganic Hybrid Lead Borate Built by B5O8(OH) Cluster Units

A new layered organic–inorganic hybrid lead borate [Pb(en)0.5][B5O8(OH)] (1, en = ethylenediamine), has been hydro(solvo)thermally synthesized and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, FT-IR spectroscopy and thermogravimetric analysis, respectively. Compound 1 crystallizes in triclinic system space group P-1 (No. 2), a = 6.6537(6) A, b = 6.7157(6) A, c = 10.6911(9) A, α = 99.015(7)°, β = 93.657(7)°, γ = 118.915(9)°, V = 407.59(6) A3, Z = 2. The structure consists of two infinite borate layers constructed from [B5O8(OH)]2− cluster building units, then two such layers are further connected by the linear [Pb2(en)]4+ complex linkers to form the novel bilayer structure.

Synthesis and Luminescent Properties of Blue-Emitting Hydrotalcite-Like Compound for NUV Light-Emitting Diodes

Layered organic-inorganic hybrid nanocomposite material with the hydrotalcite-like structure, containing Mg (II),Zn (II) and Al (III) in the layers, and salicylate ions in the interlayer, have been prepared by a simple coprecipitation method (MgAlZn-sal-HTlc). Fluorescence spectrum, XRD and TG were used to characterize the properties of the sample. Additionally, A LED device was fabricated by coating MgAlZn-sal-HTlc onto InGaN-based LED chip. The device emits bright blue light. All the results indicate that blue-emitting fluorescent hydrotalcite-like compound can act as blue components in the fabrication of white LED.

Low-frequency Raman study of the ferroelectric phase transition in a layeredCuCl4-based organic-inorganic hybrid

The ferroelectric phase transition at ${T}_{C}=340\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ in (${{\mathrm{C}}_{6}{\mathrm{H}}_{5}{\mathrm{CH}}_{2}{\mathrm{CH}}_{2}{\mathrm{NH}}_{3}{)}_{2}\mathrm{CuCl}}_{4}$ is studied by means of temperature-dependent low-frequency Raman scattering, focusing on the coupling of a low-energy librational mode to the order parameter of the transition. Analysis of the symmetry and characteristics of this mode links the dipolar order to the tilt angle of the organic cations. The thermal evolution of the Raman spectrum demonstrates the displacive component of the phase transition in combination with order-disorder phenomena and the importance of the organic-inorganic interplay to the physical properties of the compound. The ferroelectric properties investigated here can be generalized to the family of layered organic-inorganic hybrids.

Layered inorganic–organic hybrid material based on reduced graphene oxide and α-Ni(OH)2 for high performance supercapacitor electrodes

New method for the synthesis of a stacked layered rGO/α-Ni(OH)2 hybrid material with superior supercapacitive performance is demonstrated.

Aluminum-1,4-cyclohexanedicarboxylates: High-Throughput and Temperature-Dependent in Situ EDXRD Studies

The system AlCl3·6H2O/cis-H2CDC/trans-H2CDC/solvent was systematically investigated with high-throughput methods to study the influence of the two 1,4-cyclohexanedicarboxylate isomers (cis- and trans-H2CDC) as flexible aliphatic linker molecules on the formation of new crystalline compounds. Using the cis-isomer, the layered inorganic-organic hybrid compound [Al(OH)(cis-CDC)] (1) is formed. The use of trans-H2CDC leads to the microporous MOF [Al(OH)(trans-CDC)]·H2O (2) denoted CAU-13. Its framework is related to the well-known MIL-53, which was previously described for trivalent cations and rigid terephthalate linker molecules. The crystal structures of 1 and 2 were derived from powder X-ray diffraction data. Temperature-dependent in situ energy dispersive X-ray diffraction (EDXRD) experiments for the synthesis of 2 were carried out at HASYLAB, DESY, Hamburg. The kinetic analysis, applying the Gualtieri model to the experimental data, revealed Arrhenius activation energies of 76 kJ/mol for both the nucleation and the growth process. These values do not differ much from the activation energies reported for MOFs with aromatic rigid linker molecules.

White-light hydrotalcite-like compound emission from the incorporation of red-, green-, and blue-emitting metal complexes

A white-light hydrotalcite-like compound (Eu/Tb/Zn-HTlc) fabricated from Eu, Tb, and Zn complexes co-doped into magnesium-aluminum hydrotalcite (MgAl-LDH) was prepared by a simple one-pot chemical method. The structural and luminescent properties of Eu/Tb/Zn-HTlc were investigated. Excited by 370 nm UV light, the simultaneous emission bands of this single-matrix material are located in the red, green, and blue regions, combined to give a pure white emission (CIE x = 0.346 and y = 0.3339). This research represents a new strategy for designing layered organic-inorganic hybrid materials for LED-pumped white light.

Layered inorganic–organic hybrid with talc-like structure for cation removal at the solid/liquid interface

A new silylating agent N-((3-(3-(trimethoxysilyl)propylthio)propanamido)methyl)acrylamide synthesized from the reaction of N,N-methylenebisacrylamide and 3-mercaptopropyltrimethoxysilane yielded layered inorganic–organic talc-like magnesium phyllosilicate through the sol–gel process. Elemental analysis data based on sulfur demonstrated incorporation of 2.70mmolg−1 of organic moiety inside the lamellar cavities and the X-ray diffraction patterns confirmed the talc-like structure with a basal distance of 2.11nm. Infrared spectroscopy, 13C and 29Si NMR in the solid state are in agreement with the presence of organic chains covalently bonded to the inorganic lamellar framework, as also supported by the presence of Tn silicon species. Nitrogen, oxygen and sulfur basic centers sorb divalent lead, copper and cobalt cations with maximum capacity of 5.30, 3.82 and 1.60mmolg−1. The thermodynamic data for cation/basic center interactions at the solid/liquid interface were determined through calorimetric titration with exothermic enthalpy, negative Gibbs energy and positive entropy, as expected for spontaneous and favorable reaction conditions.

Synthesis and characterization of layered perovskite-type organic-inorganic hybrids (R-NH3)2(CH3NH3)Pb2I7

Layered organic-inorganic hybrids containing bilayer perovsikte (R-NH3)2(CH3NH3)Pb2I7 (where R=C12H25,C6H5C2H4) were synthesized by reactions in solution. The influences of the solvents and the reactant ratio on the structures of the products were investigated. The structures and the properties of the hybrids were characterized using X-ray diffraction (XRD) and ultraviolet and visible (UV) adsorption spectra. For comparing with the bilayer perovskite hybrids in structure and band gap magnitude, the hybrids containing monolayer perovskite (R-NH3)2PbI4 were also synthesized and characterized. The results demonstrate that the thickness of inorganic layer has obvious effect on the tunneling magnitude of the band gap but the organic part can be micro actuator of band gap.

Synthesis, crystal structure and spectroscopic investigations of a new tetrachloridozincate NH3(C6H4)2NH3ZnCl4

Chemical preparation, crystal structure and spectroscopic investigation are given for a new layered organic-inorganic hybrid, 4,4'-biphenylenediammonuim tetrachloridozincate. This compound is triclinic P1̄ with the following unit-cell parameters: a = 6.4052(1) Å, b = 9.5026(2) Å, c = 14.5807(4) Å, α = 100.547(2)°, β = 92.101(1)°, γ = 109.032(2)°, Z = 2, and V = 820.34(3) Å3. The crystal structure has been solved and refined to R1 = 0.031 and wR2 = 0.104 using 4733 independent reflections. The structure of this compound consists of inorganic layers built by isolated ZnCl42− tetrahedral. The organic entities, located between these layers, perform 3D cohesion through N-H…Cl hydrogen bonds. The vibrational properties of this compound were studied using IR absorption. The observed bands were identified by comparison with the vibrational modes and frequencies observed in similar compounds.

The effect of microwave-assisted synthesis on the physico-chemical properties of pamoate-intercalated layered double hydroxide

Layered organic-inorganic hybrid nanocomposite was prepared by inserting the pamoate anion (PA) between Zn and Al layered double hydroxide (LDH) using co-precipitation method. The ageing process was done by two different methods; conventional oil bath and microwave-assisted method at various ageing times, from 15 to 60 min. As a result of successful intercalation of PA anion into Zn–Al LDH lamella, the expansion of the interlayer spacing from 8.9 to 18.1 A was observed in the powder X-ray diffractogram of the (ZAP) nanocomposite. Percentage of PA intercalated between the LDH was higher in the nanocomposite material aged using microwave irradiation (ZAPM) compared to conventional oil bath method (ZAP). The BET surface areas of ZAPM15 and ZAPM30 were in the range of 100–106 m2/g, which were higher compared to ZAP, 90 m2/g. In general, the microwave-assisted method has improved the physico-chemical properties of the nanocomposite material with shorter ageing time of 30 min compared to 18 h ageing time by con...

Synthesis and Electrochemical Performances of Electroactive Nano Layered Organic-Inorganic Perovskite Containing Trivalent Iron Ion

A steady layered organic-inorganic perovskite hybrid containing Fe3+ was prepared in the air with phenosafranine as organic sheets, the Fe(CN)63- as inorganic sheets. We utilized the Fe(CN)63- as inorganic sheets of perovskite hybrids, which may help to stabilize the unusual metal-deficient layered structures. The results of X-ray diffractometry (XRD) and scanning electron microscopy (SEM) show that the hybrid is typical layered perovskite structure. The hybrid was mixed with paraffin to form a hybrid paste for the hybrid paste electrode. Electrochemical characteristics of carbon paste electrode (CPE) modified by hybrid were investigated with cyclic voltammetry. The modified electrode can accelerate the electron-transfer to improve the electrochemical reaction reversibility and be use for the determination of chemicals. The interactions between sodium nitrite (NaNO2), sodium bromide (NaBr), hydroxylammonium chloride (NH2OH·HCl), hydroquinone (C6H6O2) with hybrid were studied. The modified electrode exhibits good electrochemical activity. The hybrid can be used as electrochemical materials.

The effect of substitution of zinc with aluminium in the brucite-like layers on the physicochemical properties of zinc-aluminium-layered double hydroxide-pamoate nanocomposite

Layered organic–inorganic hybrid materials of Zn-Al-layered double hydroxide (LDH)-pamoate nanocomposite (ZAPR) were prepared using various initial Zn/Al molar ratios (Ri) from 8:1 to 2:1 which gave initial values of A3+/(Zn2+ + Al3+) mole fractions, (xi) from 0.11 to 0.33. The Al3+ mole fractions in the resulting nanocomposite material (xf) were greater than xi and the difference between xi and xf was found to be a constant value of 0.03. The increase in the xf values will increase the Al3+ content in the interlayer spaces of layered double hydroxide and therefore increases the charge density of the inorganic brucite-like layers and give stronger electrostatic attraction between the excess positive charge of Al3+ and the negative charge of the interlayer pamoate anion and hence decreases the d value of the material. However, the BET surface area of the resulting materials will decreases when the xf is increased. This shows that the mole fraction of Zn2+ replaced by Al3+ in the inorganic brucite-like layer plays an important role in controlling the physicochemical properties of the resulting material, which is particularly useful in determining tailor-made property required in the designed material.