A novel inorganic–organic hybrid compound constructed from copper(II)-monosubstituted polyoxometalates and poly(amidoamine)

A novel inorganic–organic hybrid compound constructed from copper(II)-monosubstituted polyoxometalate Na₅PW₁₁Cu(H₂O)O₃₉ (PW₁₁Cu) and poly(amidoamine) (PAMAM) dendrimer was prepared at room temperature in an aqueous solution. The title compound PW₁₁Cu/PAMAM was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, indicating that the PW₁₁Cu was chemically anchored to PAMAM. The compound was first used as a bulk-modifier to fabricate a chemically modified carbon paste electrode (CPE) by direct mixing. The PW₁₁Cu/PAMAM bulk-modified CPE showed well-defined cyclic voltammograms with four redox couples in 0.2 M NaAc buffer solution and high electrocatalytic activity for the reduction of hydrogen peroxide and nitrite. Furthermore, the CPE revealed good stability due to the insolubility of the title compound and the interaction between PW₁₁Cu and PAMAM.     

A new organic–inorganic hybrid based on Mn–salen and decavanadate

An organic–inorganic hybrid based on Mn-salen and decavanadate, [NH₄]₂[Mn(salen)(H₂O)₂]₄[V₁₀O₂₈]?·?6H₂O (1) (salen?=?N,N′-ethylene-bis(salicylideneiminate)), has been synthesized by the strategy of secondary building units in mixed methanol–water solution and was structurally characterized by single-crystal X-ray diffraction, elemental analyses, IR, and UV-Vis. The [Mn(salen)(H₂O)₂]⁺ cations and water molecules are located in the interspaces among the polyoxoanions [V₁₀O₂₈]^6? forming a POM-based supramolecule. Compound 1 is the first example of metal-Schiff-base polyoxovanadates. The photocatalytic analysis, cyclic voltammetry, and electrocatalytic analysis of 1 have been investigated.     

A new organic–inorganic hybrid polyoxoniobate based on Lindqvist-type anion and nickel complex

A new organic–inorganic hybrid polyoxoniobate (H₂en)₂[Ni(en)₃][H₂Nb₆O₁₉] · 5.5H₂O (1) (en = ethylenediamine) has been synthesized by the diffusion method and structurally characterized by elemental analyses, infrared spectrum, ultraviolet (UV) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction, thermogravimetric (TG) analysis, and single-crystal X-ray diffraction. Crystal structure analysis reveals that 1 exhibits a 3-D supramolecular architecture constructed from Lindqvist-type [H₂Nb₆O₁₉]^6? polyoxoanions and [Ni(en)₃]²⁺ via hydrogen-bonding interactions. The XPS measurement indicates that the oxidation state of Ni is +2. TG curve of 1 exhibits two steps of weight loss. In situ UV spectra display that 1 can exist in large pH range in aqueous solution.     

New organic–inorganic hybrid structure based on paradodecatungstate clusters and imidazolium cations

An organic–inorganic hybrid material based on paradodecatungstate anions and imidazolium cations, Na₂(HIm)₈(H₂W₁₂O₄₂)·10H₂O (HIm: imidazolium), has been synthesized under mildly acidic conditions. This compound was characterized by single-crystal X-ray diffraction, IR and UV–visible spectroscopies, and thermogravimetric and differential thermal analyses. The compound crystallizes in the triclinic P-1 space group with a = 11.6945(8) Å, b = 12.4782(6) Å, c = 14.0952(9) Å, α = 106.041(3)°, β = 109.338(2)°, γ = 100.249(3)°, V = 1781.0(3) Å³, and Z = 2. The crystal structure exhibits an infinite 1D inorganic structure built from [H₂W₁₂O₄₂]^10? clusters and sodium cations; adjacent chains are further joined up by hydrogen-bonding interactions between protonated imidazole cations, water molecules, and polyoxoanions, to form a 3D supramolecular architecture.     

Organic–inorganic hybrids based on polyoxometalates and copper coordination complexes

Two new hybrids based on Keggin polyoxometalates have been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, TG analysis, and single-crystal X-ray diffraction. The crystal structure analyses reveal that complex 1 has an infinite 1D chain structure, constructed from [Cu(2,2′-bpy)(4,4′-bpy)(H₂O)] fragments and [H₂PMo₁₁VO₄₀]^2? building blocks. Complex 2 has a 2D molecular ladder structure, with a basic structural unit composed of one bis(µ-OH) dicopper(II) [Cu₂(OH)₂(H₂O)₂(4,4′-bpy)₃] fragment, one [HPMo₁₂O₄₀], and four water molecules. The [Cu₂(OH)₂(H₂O)₂(4,4′-bpy)₃] units connect alternately to form edge rails. The [HPMo₁₂O₄₀] clusters act as rungs of the ladder, linking pairs of Cu atoms from the two adjacent edge rails. The electrochemical behavior of the complexes in modified carbon paste electrodes and their electrocatalytic reduction of nitrite were investigated.     

Three organic–inorganic hybrid complexes based on the Wells–Dawson polyoxoanion

Three new organic–inorganic hybrid complexes based on the Wells–Dawson polyoxoanion, namely (H₂bpp)[Ni₂(bpp)₂(H₂O)₄(P₂W₁₈O₆₂)]·H₂O 1, [Cu₆(Hbpy)₆(bpy)₃(P₂W₁₈O₆₂)₂]·2H₂O 2 and (Him)₅[Cu(im)₂(P₂W₁₈O₆₂)]·4H₂O 3 [bpp = 1,3-bis (4-pyridyl) propane, bpy = 4,4′-bipyridine, im = imidazole] have been synthesized and characterized. Complex 1 exhibits a three-dimensional (6, 3)-connected framework with anatase topology constructed from [α-P₂W₁₈O₆₂]⁶⁻ clusters and [Ni(bpp)]²⁺ fragments. Each [α-P₂W₁₈O₆₂]⁶⁻ anion links to six nickel atoms through six terminal oxygen atoms from four polar and two equatorial WO₆ octahedra, which shows a novel coordination mode of a Wells–Dawson cluster with a transition-metal atom. Complex 2 displays an interesting one-dimensional double-chain structure built from [α-P₂W₁₈O₆₂]⁶⁻ clusters and [Cu₂(bpy)(Hbpy)₂]²⁺ fragments. To our knowledge, complex 2 represents the first double-chain organic–inorganic hybrid complex based on a Wells–Dawson-type cluster. Complex 3 possesses a one-dimensional zigzag chain structure constructed from [α-P₂W₁₈O₆₂]⁶⁻ anions and [Cu(im)₂]⁺ units through weak Cu···O interactions.     

Responsive microstructures on organic–inorganic hybrid films

Micro-periodic structures exhibiting shape memory have been fabricated on organic–inorganic hybrid films. The microscale structures are obtained by forming wrinkles via buckling of the stiff surface layer. The surface-modified layers are obtained by surface photopolymerization or by oxidation of the hybrid films. The microscale structures are spontaneously formed by the shrinkage of the underlayer via gelation. The surface microstructures on titania- or silica-based films with hydrophilic swellable polymers exhibit a humidity response, i.e., a shape memory effect. This is observed when the surface microstructure disappears and is subsequently recovered with cyclic variation of the surrounding humidity. Micro-rolls are also fabricated by the selective swelling of surface-modified layers.     

Hydrothermal synthesis and structures of organic–inorganic hybrid solids based on arsenic-vanadate building blocks

Four novel organic–inorganic hybrid arsenic-vanadate complexes, [Cu(phen)][(As^VO₄)(V^V ₃O₇)(H₂O)] (1), [Cu(en)₂]₂[As₈V₁₄O₄₂(H₂O)]?·?2.5H₂O (2), [M(1,10-phen)₃]₂[As₈V₁₄O₄₂(H₂O)_0.5]?·?0.5H₂O (M?=?Mn, 3, Cd, 4) (1,10-phen?=?1,10-phenanthroline) have been hydrothermally synthesized for the first time and characterized by elemental analyses, XPS spectra, EPR spectra, IR spectra, TG analyses and single crystal X-ray diffraction. The structure of compound 1 consists of arsenic vanadate ribbons coordinated by the [Cu(phen)]²⁺ complex, while compounds 2 to 4 possess a spherical [As₈ ^IIIV₁₄ ^IVO₄₂]^4? cage with H₂O molecules encapsulated. The unexpected preparation 1 and the synthesis of compounds 2 to 4 on the basis of same polyoxoanion structures show that the pH value of the reaction plays a crucial role in controlling the basic architectures.     

Elastic organic–inorganic hybrid aerogels and xerogels

Novel aerogels and xerogels with methylsilsesquioxane (MSQ, CH₃SiO_1.5) networks have been prepared by a modified sol–gel process using surfactant and urea as a phase-separation inhibitor and as an accelerator for the condensation reaction, respectively. Optimized aerogels dried under a supercritical condition not only showed the similar properties as conventional pure silica aerogels such as high transparency and porosity etc, but also demonstrated outstanding mechanical strength against compression; the aerogel drastically shrank upon loading and then recovered when unloaded, which is called a “spring-back” behavior. On ambient pressure drying, the wet gel also exhibited the similar response against compression stress originated from the capillary pressure, and thus xerogels with the comparative structure and properties to those of corresponding aerogels have also been obtained. This unusual mechanical behavior is attributed to the trifunctional flexible networks of MSQ, low silanol concentration which prevents the irreversible shrinkage, and high concentration of a hydrophobic methyl group directly attached to every silicon atom which helps re-expansion after the temporal shrinkage.     

Assembly of two novel inorganic–organic hybrid solids based on 3-(aminomethyl)pyridine ligand

Two new inorganic–organic hybrids, (Hampy)Zn₂(PO₄) (HPO₃) (1) and (ampy)Zn₂(HPO₃)₂ (2), where ampy = 3-(aminomethyl)pyridine, have been solvothermally prepared and structurally characterized. Compound 1 exhibits an unusual two-dimensional layer structure, which possesses a central 4.8² zincophosphate sheet wrapped by infinite zincophosphite chains. Left- and right-handed helical chains participate in the formation of the zincophosphate layer. Compound 2 features a three-dimensional pillared-layer structure, in which two-dimensional Zn^II(HPO₃) inorganic sheets were cross-linked by ampy ligands. The simultaneous occurrence of zinc-amine helical chains in 2 is unique and, to the best of our knowledge, firstly encountered in phosphite/phosphate hybrid materials. Different coordination modes and roles of the same ampy ligand were observed in the formation of the hybrid structures.     

Hydrothermal syntheses and structural characterization of two organic–inorganic hybrid compounds based on Lindqvist polyanions

Two organic–inorganic hybrid polyoxometalates {[V₂W₄O₁₉{Cu(2,2′-bipy)₂}₂] · (4,4′-bipy)} _n (1) and [Co(2,2′-bipy)₃][W₆O₁₉] · H₂O (2) (2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine), constructed by Lindqvist polyanions and transition metal coordination cations, have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, UV spectra, thermogravimetric (TG) analyses, X-ray photoelectron spectroscopy (XPS), and single- crystal X-ray diffraction. Compound 1 is a neutral molecule and consists of a di-V^V substituted Lindqvist-type polyanion [V₂W₄O₁₉]^4?, two supporting copper cations [Cu(2,2′-bipy)₂]²⁺ and one free 4,4′-bipy. Neutral molecules of 1 are extended to a 2-D grid-like network by π–π stacking interactions between pyridine groups. The molecular structure of 2 contains one [W₆O₁₉]^2? cluster polyanion and a [Co(2,2′-bipy)₃]²⁺. Inductively coupled plasma (ICP) analysis and XPS spectrum of 1 prove the presence of V^V. TG curves of 1 and 2 indicate two weight loss steps.     

Luminescent organic–inorganic hybrid materials based on lanthanide containing ionic liquids and sylilated β-diketone

In this work, we report the luminescent organic–inorganic hybrid materials prepared by hydrolysis and condensation of sylilated β-diketone under acid conditions in the presence of carboxyl-functionalized ionic liquid in which Eu³⁺ ions are coordinated to the oxygen atoms of carboxylate groups from the ionic liquids. The obtained materials were characterized with FT-IR, TG and photoluminescence spectroscopy. FT-IR spectra imply that Eu³⁺ ions are still coordinated to the ionic liquid in the hybrid materials. Excitation and emission spectra demonstrate that the energy transfer occurs from the β-diketone molecules covalently bonded with silica to Eu³⁺ ions. The Eu³⁺ (⁵D₀) quantum efficiency value of the hybrid materials has been estimated based on the emission spectrum and the value of lifetime. A large value of ratio (16.44) between the intensities of the ⁵D₀→⁷F₂ and ⁵D₀→⁷F₁ transition and high value of ⁵D₀ quantum efficiency (51.01%) are obtained.     

TEOS/HDTMS inorganic–organic hybrid compound used for stone protection

Inorganic–organic hybrid crack-free xerogels were obtained by using a surfactant n-octylamine as a catalyst containing tetraethoxyorthosilicate (TEOS) and hexadecyltrimethoxysilane as an additive. We studied the effect of gelling time and sol pH on n-octylamine concentration. The organic modification was confirmed by infrared spectroscopic studies, and the hydrophobicity of the coating was tested by the contact angle measurements. The stone surface morphology of sample treated with hybrid sol was characterized. The results show the hybrid gel network exhibits a larger pore size than the gel containing exclusively the silica from TEOS. After the limestone’s surface was modified by hybrid sol, the contact angle of limestone increased from 58° to 123°. The protective performance evaluated by its ability to resist acid rain reveals that the protective effects are satisfied.     

Thermal and optical properties of novel polyurea/silica organic–inorganic hybrid materials

Current optical polymeric materials for advanced fiber laser development are susceptible to degradation due to the heat generated in high power usage. A suitable replacement light stripping material was explored to overcome this problem by examining optical and physical properties such as transmission/absorption, refractive index, thermal conductivity, and thermal stability. The synthesis and characterization of two new polyurea/silica ORMOSILs (ORganically MOdified SILicates) suitable for high temperature (up to 300 °C) optical applications are reported herein. A one-pot, room temperature synthesis is based upon commercially available bis-isocyanates and an amino-silane. These materials exhibit the combined traits of both glass and polymer by displaying optical clarity over a wide range of wavelengths stretching from the edge of the UV (250 nm) to well into the NIR (2,000 nm), refractive indices in the visible spectrum (n = 1.50–1.63), thermal conductivities of 0.26 ± 0.09 W/mK (ORMOSIL-A) and 0.27 ± 0.07 W/mK (ORMOSIL-B), and thermal stabilities up to 300 °C. The hybrid materials were found to be easily processed into films but thick casts (>2 mm) were subject to increased rates of cracking and longer curing times. Although this is typical of sol–gel chemistries, the organic constituents of ORMOSILs reduce this effect as compared to purely inorganic sol–gels. The effect of thermal aging on the materials’ properties will also be presented as well as a comparison of these materials and the current state of the art light stripping material.     

Research progress on hybrid organic–inorganic perovskites for photo-applications

Hybrid organic–inorganic perovskite materials have attracted significant attention of most researchers in recently years, which is ascribed to the superior photoelectric properties, such as the suitable band gaps for harvesting sunlight, and exhibit high optical adsorption, high charge-carrier lifetimes and long diffusion lengths. The photodetectors, light-emitting diodes, solar cells and photocatalysts represent the remarkable applications for the hybrid organic–inorganic perovskite materials. Herein, we review the recent progress of hybrid organic–inorganic perovskite-based photodetectors, light-emitting diodes, solar cells and photocatalysts. The challenges and outlook for the hybrid organic–inorganic perovskite-based photodetectors, light-emitting diodes, solar cells and photocatalysts are considered.     

Optical filters and resonant cavities based on di-ureasil organic–inorganic hybrids

Sol–gel derived poly(oxyethylene)/siloxane organic–inorganic di-ureasil hybrids containing different amounts (20–60% mol) of methacrylic acid (McOH) modified zirconium oxo-clusters (Zr-OMc) were processed as thin films and transparent and shape controlled monoliths. Laser direct writing was used to create channel waveguides, Bragg gratings, Fabry–Perot cavities and optical filters. The resulting Fabry–Perot optical cavity displays a free spectral range of 16.55 GHz and a fringe intensity contrast of 5.35 dB. Optical rejection values between 6.7 and 10.4 dB were obtained by varying the amount of the Zr-OMc oxo-clusters.     

Preparation and characterization of inorganic–organic hybrid proton exchange membranes based on phosphorylated PVA and PEG-grafted silica particles

We reported proton-conducting membranes with novel microstructure based on partially phosphorylated poly(vinyl alcohol) (P-PVA) and polyethylene glycol (PEG) grafted silica (PEG-SiO₂) particles. The PEG-SiO₂ particles were synthesized through acid catalyzed hydrolysis and condensation reactions. The membranes were characterized for their mechanical, structural, morphological, and electrical properties by employing tensile test, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), impedance analyzer, respectively. In these membranes, P-PVA acts as the proton source and PEG act as the proton solvent. The PEG-riched phases in the hybrid membrane form continuous ionic conducting pathways and subsequently give high ionic conductivity. The results suggest that the obtained membrane shows good thermal stability, excellent mechanical property and high ionic conductivity, and the low-cost hybrid membrane can be a promising candidate for intermediate temperature fuel cell systems.