Efficient and reusable Cu (II)-metalated silica-based inorganic-organic hybrid catalyst for dye degradation

An efficient silica-based inorganic-organic hybrid was synthesized by using 3-(2-aminoethylamino)propyltrimethoxylsilane as linker and 2-Quinolinecarboxaldehyde for Schiff's base formation which was further coordinated by Cu (II) chloride. The hybrid was characterized by relevant techniques, i.e., FT-IR, DRUV-Vis, SEM, EDX, ICP-AES, TGA and EPR technique which support its formation. The synthesized hybrid material was successfully used as heterogeneous catalyst for degrading Reactive Black-5 (RB-5), a non-biodegradable diazo dye. The degradation mechanism follows advanced oxidation technique utilizing hydrogen peroxide as an environmentally amiable green oxidant; where the hybrid catalyst decomposes H₂O₂ to generate ·OH free radicals. Effects of dye concentration, H₂O₂ concentration and temperature variation on dye degradation process were studied and best reaction conditions for maximum degradation of RB-5 were also worked out. The catalyst showed 87% dye degradation in 130 ?min at best reaction conditions. Easy separation, reusability and efficient dye degradation ability of the catalyst are the motivating factors for the development of such hybrid material for solving critical environmental issues.     

8-羟基喹啉-5-磺酸构筑的有机-无机配位化合物的合成、结构和性质研究

在溶剂热条件下,以8-羟基喹啉-5-磺酸为配体,合成了两个新的有机-无机配位化合物Mn（QS）（H2O）（1）和Co（QS）（H2O）2（2）（H2QS=8-hydroxylquinoline-5-sulfonic acid）,并且对他们进行了单晶X-射线解析.其中化合物1是一个具有金红石拓扑的三维开放骨架结构,化合物2是一个三维超分子结构.我们对这些化合物进行了粉末X射线,红外光谱,差热热重,荧光光谱和磁学性质的研究.     

Synthesis,crystal structure and properties of inorganic-organic hybrid polymers based on 8-hydroxylquinoline-5-sulfonic acid

Two new inorganic-organic hybrid polymers, Mn(QS)(H2O) (1) and Co(QS)(H2O)2 (2) (H2QS=8-hydroxyl-quinoline-5-sulfonic acid), based on 8-hydroxylquinoline-5-sulfonate ligand, have been synthesized under solvothermal conditions and their structures were solved by single-crystal X-ray diffraction analysis. Compound 1 is a three-dimensional open framework with rutile topology structure, and compound 2 is a three-dimensional supramolecular structure. These compounds were characterized by powder XRD, infrared spe...     

Thermal stability and lifetime estimates of a high temperature epoxy by Tg reduction

Thermal degradation of a high temperature epoxy network is studied in terms glass transition temperature (T_g) reduction over a temperature window encompassing the T_g of the network. The T_g is shown to decrease as the network is thermally aged at elevated temperatures in air and in argon. The duration of the aging experiments is extended to long time such that the absolute T_g reduction approaches a long time reduction plateau. Degradation is dominated by non-oxidative pyrolysis with a small contribution from diffusion limited thermal oxidative degradation at the surface. A time–temperature superposition is constructed from the extent of T_g reduction of samples aged in air and the thermal shift factors are shown to have Arrhenius scaling behavior. An activation energy is extracted that agrees with previous activation energy measurements derived from other property measurements of the same network aged under similar conditions. The agreement of the activation energy with past results shows that T_g reduction is controlled by the same degradation mechanism and may be used as an observable for lifetime estimates when thermal degradation is pyrolytic in nature. The extent of T_g reduction is modeled with an autocatalytic rate expression and compared to previous property measurements to show the difference in sensitivity of observable material properties on degradation.     

An inorganic-organic compound with 1D honeycomb-like channels constructed from non-covalent linkage: synthesis and properties

An inorganic-organic hybrid compound {[Cu(phen)₃]₂PW₁₁VO₄₀ ·?2H₂O (1) has been hydrothermally prepared and structurally characterized by elemental analyses, IR, CV, TG, magnetic susceptibility measurements and single crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic space group C2/c with a =?27.232(2) Å, b =?25.351(2) Å, c =?16.2748 (4) Å, β?= 105.20°, V =?10842.3 ų, Z =?4, R₁ =?0.0490 and wR₂ =?0.1362. The structure of 1 exhibits a three-dimensional supramolecular network, formed by hydrogen-bonding and π–π stacking interactions. The three-dimensional network consists of one-dimensional honeycomb channels, which accommodate free water molecules. The size of the channel is 10.4 ×?10.4 Å. Electrochemistry of 1 shows it undergoes three one-electron reversible redox processes. Variable-temperature magnetic measurements show typical antiferromagnetic interactions in the 2–300 K temperature range.     

A novel inorganic-organic compound: Synthesis and structural characterization of tin(II) phenylbis(phosphonate), Sn2(PO3C6H4PO3)

A novel tin(II) phenylbis(phosphonate) compound has been synthesized hydrothermally and its structure has been determined by single crystal X-ray diffraction. The structure is monoclinic, space group P2₁/c (no. 14), a=4.8094(4), b=16.2871(13), ; β=106.292(6)°, , Z=2. The three-dimensional structure consists of 3-coordinated tin and 4-coordinated phosphorus double layers separated (pillared) by phenyl rings. These phenyl rings are placed 4.8 Å apart along the a-axis in the structure resulting in lower surface area (∼14 m²/g). The porosity has been increased by replacing phenyl groups by methyl groups (∼31 m²/g).     

PMMA: A key macromolecular component for dielectric low-κ hybrid inorganic-organic polymer films

Inorganic-organic composite and hybrid films find widespread applications for the development of functional materials. Polymer matrices with embedded inorganic fillers, nanoparticles or clusters are particularly appealing for optical, electronic, dielectric and magnetic applications. In particular, the development of hybrid layers with tailored dielectric properties represents a key issue in many technological fields.In this framework, poly(methyl methacrylate) (PMMA), due to its outstanding chemico-physical properties, represents a particularly suitable polymer component for the embedding of both microscopic and nanoscopic functional inorganic fillers. The wide use of such a matrix has to be traced back to the favourable combination of chemical and physical properties and easy processing. In this review, the main features and properties of PMMA, with a particular focus on dielectric ones, are firstly briefly described. Selected examples to illustrate the state-of-the art of its corresponding use as dielectric matrix are given and several examples are provided and surveyed.Finally, three case studies concerning PMMA-based hybrid films, produced for very different application fields, are described and discussed. The first example deals with the entrapment of micrometric zinc sulphide powders in PMMA, which acts as a host matrix for the electroluminescent particles in thick film-based Alternate Current Powder Electroluminescent Lamps (ACPELs). The second example describes the preparation of low-κ inorganic-organic hybrid dielectric films based on a PMMA-polyvinylchloride(PVC) blend and a hydrophobic silica powder functionalised on the surface with trimethylsiloxane groups (m-SiO₂). The composition of the investigated materials is [(PMMA)_x(PVC)_y]/(m-SiO₂)_z with z ranging from 0 to 38.3 wt% and x = y = (100 − z)/2. The third case concerns the use of PMMA as a matrix to embed zirconium oxoclusters through the formation of covalent bonds. The obtained material, characterised by a dielectric constant value remarkably lower (1.93 at 1 kHz and 25 °C) than in pristine PMMA (3.0 at 1 kHz and 25 °C), appears as very appealing for the development of microelectronic devices based on low dielectric constant polymer films such as, for instance, field-effect transistor (FET).These three cases are paradigms of three different approaches to composite and hybrid materials based on the embedding of particles in PMMA polymer matrix.     

Organic/inorganic hybrid epoxy nanocomposites based on octa(aminophenyl)silsesquioxane

Octa(aminophenyl)silsesquioxane (OAPS) was used as the curing agent of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin. A study on comparison of DGEBA/OAPS with DGEBA/4,4′-diaminodiphenyl sulfone (DDS) epoxy resins was achieved. Differential scanning calorimetry was used to investigate the curing reaction and its kinetics, and the glass transition of DGEBA/OAPS. Thermogravimetric analysis was used to investigate thermal decomposition of the two kinds of epoxy resins. The reactions between amino groups and epoxy groups were investigated using Fourier transform infrared spectroscopy. Scanning electron microscopy was used to observe morphology of the two epoxy resins. The results indicated that OAPS had very good compatibility with DGEBA in molecular level, and could form a transparent DGEBA/OAPS resin. The curing reaction of the DGEBA/OAPS prepolymer could occur under low temperatures compared with DGEBA/DDS. The DGEBA/OAPS resin didn’t exhibit glass transition, but the DGEBA/DDS did, which meant that the large cage structure of OAPS limited the motion of chains between the cross-linking points. Measurements of the contact angle indicated that the DGEBA/OAPS showed larger angles with water than the DGEBA/DDS resin. Thermogravimetric analysis indicated that the incorporation of OAPS into epoxy system resulted in low mass loss rate and high char yield, but its initial decomposition temperature seemed to be lowered.     

Two inorganic-organic hybrid materials based on polyoxometalate anions and methylene blue: Preparations, crystal structures and properties

Two novel inorganic-organic hybrid materials based on an organic dye cation methylene blue (MB) and Lindqvist-type POM polyanions, [C₂₂H₁₈N₃S]₂Mo₆O₁₉ 2DMF (1) and [C₂₂H₁₈N₃S]₂W₆O₁₉ 2DMF (2) were synthesized under ambient conditions and characterized by CV, IR spectroscopy, solid diffuse reflectance spectrum, UV-vis spectra in DMF solution, luminescent spectrum and single crystal X-ray diffraction. Crystallographic data reveal that compounds 1 and 2 are isostructural and both crystallize in the triclinic space group P1¯. Their crystal structures present that the layers of organic molecules and inorganic anions array alternatively, and there exist strong π···π stacking interactions between dimeric MB cations and near distance interactions among organic dye cations, Lindqvist-type POM polyanions and DMF molecules. The solid diffuse reflectance spectra and UV-vis spectra in DMF solution appear new absorption bands ascribed to the charge-transfer transition between the cationic MB donor and the POM acceptors. Studies of the photoluminescent properties show that the formation of 1 and 2 lead to the fluorescence quenching of starting materials.     

Synthesis of molecular imprinted organic-inorganic hybrid polymer binding caffeine

Random copolymers of poly{(methacrylamide)-co-(vinyl trimethoxysilane)} and poly{(methacrylic acid)-co-(vinyl trimethoxysilane)} were synthesized via a free radical polymerization reaction. Acid catalyzed sol-gel process of tetraethylorthosilicate (TEOS) with aforementioned polymers in the presence of methyl xanthine class of alkaloid like caffeine resulted in the formation of highly transparent monoliths. Solvent extraction of the template leaves behind the recognition sites intact with high selectivity towards the print molecule. The ionic and non-specific adsorptions, which are considered to be the main disadvantages of the molecularly imprinted polymers (MIP), are prevented to a considerable extent by the end capping of surface silanol groups. The template binding efficiencies of MIP were determined by HPLC analysis.     

The synthesis and characterization of a new 3-D inorganic-organic hybrid framework porous material Zn3(bbdc)3(4,4′-bpy)·2(DMF)·4(H2O)

A new 3-D inorganic-organic hybrid framework microporous material Zn₃(bbdc)₃(4,4′-bpy)·2(DMF)·4(H₂O) (1), which is constructed by coordination of zinc ions with 4,4′-bibenzene-dicarboxylic acid (H₂bbdc) and 4,4′-bipyridine (4,4′-bpy), was obtained at mild synthesis condition. Crystallographic data for the compound (1), C₅₈H₅₄N₄O₁₈Zn₃, orthorhombic, space group Pbcn, a=14. 532(3) Å, b=25.037(5) Å, c=18.184(4) Å, Z=4, V=6616(2) Å³.     

Luminescence spectroscopy as a tool for testing of cure kinetics of epoxy resins

In this paper, steady-state luminescence spectroscopy is used for the analysis of curing of epoxy resin. The advantage of this method is its rapidity, simplicity and sensitivity. Moreover, this method is contactless, and thus non-invasive. The aim is to analyze epoxy resin, mathematically describe its curing kinetics and determine its storage temperature. Using the photoluminescence method, a rapid procedure for obtaining the necessary technological data is achieved. This method is suitable for continuous measurement in production because there is no contact with the material, and the measurement itself can be performed very quickly. The elaborated mathematical model can serve as a basis for creating algorithms for automated data processing in case of fully robotic workplaces.     

Effect of tertiary amine accelerators with different substituents on curing kinetics and reactivity of epoxy/dicyandiamide system

Non-isothermal Differential Scanning Calorimetry and gel time measurements were employed to study the effects of four different tertiary amine accelerators with different molecular structure and substituents on the curing behavior and reactivity of epoxy/dicyandiamide (DICY) system. Results showed that the acceleration behavior depends on three factors: the bulkiness, the number of nitrogen atoms in molecular structure and the electron density of accelerator. Among these, the former two factors demonstrated stronger effect. The results of model fitting kinetic demonstrated that Šesták–Berggren model can well simulate the reaction rates especially for the samples accelerated by 2,4,6-tris(dimethylaminomethyl)-phenol and (Dimethylaminomethyl)phenol. The activation energy projected by Flynn-Wall-Ozawa and Kissinger–Akahira–Sunose methods exposed different amounts for each accelerator while both models revealed similar trends. Moreover, 1-methylimidazol-accelerated samples showed shortest storage life and gel time mainly due to the presence of two nitrogen atoms in a compact structure of accelerator.     

Study on the reaction kinetics between PBT and epoxy by a novel rheological method

In the present study, the reaction kinetics of polybutylene terephthalate (PBT) and epoxy system was studied by a novel rheological method. The reaction process was determined by rheological test and the results showed that there were three stages in the reaction between PBT and epoxy, which were reaction-controlling stage (stage I), reaction-stagnation stage (stage II) and diffusion-controlling stage (stage III). In addition, the stage I was selected to study the reaction kinetics by the rheological method. The results showed that the reaction between PBT and epoxy could be classified as a pseudo-first-order reaction due to the excessive amount of epoxy group. Furthermore, the reaction apparent activation energy of the stage I determined by the rheological method was 143 kJ/mol. To confirm these results, the reaction kinetics was also evaluated by the endgroup determination method, and the results showed that the reaction could also be classified as a pseudo-first-order reaction. Moreover, the apparent activation energy of the reaction was 116 kJ/mol, which was similar to that of the value obtained by the rheological method.     

Monitoring of visible light photopolymerization of an epoxy/dimethacrylate hybrid system by Raman and near-infrared spectroscopies

Hybrid systems formulated with epoxy and methacrylate monomers at mass fraction either 50:50 or 75:25 were studied. The individual monomer conversions during photopolymerization with visible light were monitored by Raman and near-infrared spectroscopies. The rate of polymerization and final degree of conversion of the methacrylate groups were raised when the epoxy monomer was present. This is attributed to enhancement of the mobility of the reactive species caused by the presence of the epoxy monomer. Conversely, the earlier vitrification of the system due to the faster polymerizing methacrylate network resulted in reduced conversion of epoxy rings.     

Inorganic-organic hybrid polyoxometalate: Preparation, characterization and electrochemistry properties

The solid hybrid material (H_3/4pbpy)₄[PMo₁₂O₄₀]·1.25H₂O (1) (pbpy=5-phenyl-2-(4-pyridinyl)pyridine) has been prepared and characterized. A structural feature of compound 1 is that the polyoxometalate anions exhibit a one-dimensional inorganic double chain-like structure via weak interactions of O…O. The organic moiety exhibits regular packing with offset aromatic-aromatic interactions between the pbpys, leading to a compact supramolecular framework structure to accommodate the inorganic chains. Compound 1 was employed to fabricate the three-dimensional bulk-modified carbon paste electrode (1-CPE) to research on its electrochemistry properties. The results indicate that 1 retained Keggin molybdate anion electrocatalytic activities toward the reduction of chlorate, hydrogen peroxide and nitrite.     

Ultrathin zinc selenide nanosheet-based intercalation hybrid coupled with CdSe quantum dots showing enhanced photocatalytic CO_2 reduction

Fabrication of well-designed heterojunctions is an extraordinarily attractive pathway for boosting the photocatalytic activity toward CO_2 photoreduction.Herein,a novel kind of na nosheet-based intercalation hybrid coupled with CdSe quantum dots(QDs) was successfully fabricated by a facile solvothermal method and served as photocatalyst for full-spectrum-light-driven CO_2 reduction.Ultra-small CdSe QDs were rationally in-situ introduced and coupled with lamellar ZnSe-intercalation hybrid nanosheet,resulting in the formation of CdSe Q.Ds/ZnSe hybrid heterojunction.Significantly,the concentration of Cd~(2+) could change directly the crystallinity and micromorphology of ZnSe intercalation hybrid,which in turn would impact on the photocatalysis activity.The optimized CdSe QDs/ZnSe hybrid-5 composite demonstrated a considerable CO yield rate of the 25.6 μmol g~(-1) h~(-1) without any additional cocatalysts or sacrificial agents assisting,making it one of the best reported performance toward CO_2 photoreduction under full-spectrum light.The elevated CO_2 photoreduction activity could be attributed to the special surface heterojunction,leading to improving the ability of light absorption and promoting the separation/transfer of photogenerated carriers.This present study developed a new strategy for designing inorganic-organic heterojunctions with enhanced photocatalyst for CO_2 photoreduction and provided an available way to simultaneously mitigate the greenhouse effect and alleviate energy shortage pressure.