Acidic Hybrid Research Articles

Investigation of N,N′‐Disulfopiperazinium Chlorometallates of Fe(III), Ni(II) and Co(II) as Hybrid Catalysts for the Synthesis of 1,2‐Dihydroquinazoline Derivatives

AbstractThree organic salts of N,N′‐disulfopiperazinium cation with complex metal chloride anions of Fe(III), Ni(II) and Co(II) cations were developed as Brønsted‐Lewis acidic hybrid materials in solid state. Their structural compositions were established by FT‐IR, UV‐Visible, SEM, EDX, Powder XRD and Raman techniques. Thermogravimetric analyses showed removal of physisorbed water around 100 °C for Fe(III) salt in contrast to 150–170 °C for Ni(II) & Co(II) organic salts for strongly bound water molecules in highly crystalline state. Their Brønsted acidities were determined from comparative UV‐visible spectra of 4‐nitroaniline in water in presence of the halometallates while Lewis acidity strength was observed via FT‐IR spectra of these salts in presence of pyridine as probe molecule. The catalytic activity of these acidic organic salts was investigated for three‐component synthesis of 1,2‐dihydroquinazolines as recyclable heterogeneous catalysts.

Solvent responsive self-separation behaviour of Brønsted acidic ionic liquid-polyoxometalate hybrid catalysts on H2O2 mediated oxidation of alcohols

Two solvent responsive self-separative ionic liquid-based POM hybrids [DEDSA]3[PW12O40] and [DEDSA]3[PMo12O40] were prepared by combination of diethyldisulphoammonium chloride [DEDSA]Cl with Keggin phosphotungstic acid and phosphomolybdic acid. Properties like water tolerance, high activity, high thermal stability and reusability in these POM hybrid compounds facilitate a new type of POM based catalysis used for oxidation of organic alcohols using hydrogen peroxide as oxidizing agent. Due to varied solubility of the hybrid with different solvents, the hybrid can effectively catalyze the oxidation reaction in homogenous condition and then can finally switch back to heterogenous system and convert as self-precipitating catalyst on addition of suitable solvent at the end of the reaction, which made the recovery and reuse of the hybrid very convenient. The catalysts are characterized via different analytical and spectroscopic tools like FT-IR, 1H NMR, 13C NMR, 31P NMR, TGA, UV–Visible, Powder XRD techniques, Raman etc. It was found that the prepared material was highly acidic, thermally stable in nature and was recycled up to 7 times without much loss of catalytic activity.

Catalytic production of biodiesel from esterification of lauric acid over a solid acid hybrid

In this study, an acidic heterogeneous hybrid (H4SiW/MIL-100(Fe)) was synthesized by incorporation of 12-silicotungstic acid (H4SiW) into a porous metal-organic framework MIL-100(Fe) via a simple hydrothermal method. The hybrid was characterized by XRD, FT-IR, SEM, and TGA, and those characterization analyses showed the H4SiW/MIL-100(Fe) hybrid was successfully synthesized and exhibited good structural stability. The catalytic activity of H4SiW/MIL-100(Fe) was determined by esterification of lauric acid (LA) to produce biodiesel. Optimum LA conversion of 80.3% was achieved over the H4SiW/MIL-100(Fe) hybrid under the reaction conditions of lauric acid/methanol mole ratio of 1/12, 0.3 g catalyst dosage at 160°C for 3 h. After being repeatedly used for eleven cycles, the lauric acid conversion of the catalyst could still maintain with >60%, which indicates potential cost-saving and affordable biodiesel synthesis possibilities.

Supersaturable organic-inorganic hybrid matrix based on well-ordered mesoporous silica to improve the bioavailability of water insoluble drugs

Mesoporous silica with uniform 2-D hexagonal pores has been newly employed as facile reservoir to impove the dissolution rate of water insoluble drugs. However, rapid drug release from mesoporous silica is usually accompanied by the generation of supersaturated solution, which leads to the drug precipitation and compromised absorption. To address this issue, a supersaturated ternary hybrid system was constructed in this study by utilizing inorganic mesoporous silica and organic precipitation inhibitor. Vinylprrolidone-vinylacetate copolymer (PVP VA64) with similar solubility parameter to model drug fenofibrate (FNB) was expected to well inhibit the precipitation. Mesoporous silica Santa Barbara amorphous-15 (SBA-15) was synthesized in acidic media and hybrid matrix was produced by hot melt extrusion technique. The results of in vitro supersaturation dissolution test obviously revealed that the presence of PVP VA64 could effectively sustain a higher apparent concentration. PVP VA64 was suggested to simultaneously reduce the rate of nucleation and crystal growth and subsequently maintain a metastable supersaturated state. The absorption of FNB delivered by the organic-inorganic hybrid matrix was remarkably enhanced in beagle dogs, and its AUC value was 1.92-fold higher than that of FNB loaded mesoporous silica without PVP VA 64. In conclusion, the supersaturated organic-inorganic hybrid matrix can serve as a modular strategy to enhance the oral availability of water insoluble drugs.

Green emitter and thermally stable layered tetraethyl ammonium lead bromoiodide perovskite

We report herein the synthesis of new layered organic-inorganic acidic hydrogen-free lead halide perovskite (Et4N)2PbBr2I2via wet chemical approach. The as-prepared layered perovskite showed very good thermal stability up to 300 °C as confirmed by thermogravimetric analysis (TGA/DTA). The phase and structural confirmation was performed by powered-X-rays diffraction (p-XRD). UV–vis spectroscopy, steady state photoluminescence and time resolved photoluminescence have shown that as-prepared perovskite is green emitter with band gap of 3.4 eV. The acidic hydrogen-less hybrid cation as potential spacer for layered perovskite structure have influenced the optical properties of the compound, showing its potential towards optoelectronic devices.

Novel High-Energy-Density Rechargeable Hybrid Sodium-Air Cell with Acidic Electrolyte.

Low-cost, high-energy-density, and highly efficient devices for energy storage have long been desired in our society. Herein, a novel high-energy-density hybrid sodium-air cell was fabricated successfully on the basis of acidic catholytes. Such a hybrid sodium-air cell possess a high theoretical voltage of 3.94 V, capacity of 1121 mAh g-1, and energy density of 4418 Wh kg-1. First, the buffering effect of an acidic solution was demonstrated, which provides relatively long and stable cell discharge behaviors. Second, the catholytes of hybrid sodium-air cells were optimized systematically from the solutions of 0.1 M H3PO4 + 0.1 M Na2SO4 to 0.1 M HAc + 0.1 M NaAc and it was found that the cells with 0.1 M H3PO4 + 0.1 M Na2SO4 displayed a maximum power density of 34.9 mW cm-2. The cell with 0.1 M H3PO4 + 0.1 M Na2SO4 displayed higher discharge capacity of 896 mAh g-1. Moreover, the fabricated acidic hybrid sodium-air cells exhibited stable cycling performance in ambient air and they delivered a low voltage gap around 0.3 V when the current density is 0.13 mA cm-2, leading to a high energy efficiency up to 90%. Therefore, the present study provides new opportunities to develop highly cost-effective energy storage technologies.

Preparation and Application of Acidic Ionic Liquid Hybrid Solid Catalytic Materials

Preparation and Application of Acidic Ionic Liquid Hybrid Solid Catalytic Materials

Ionic liquid on the acidic organic-inorganic hybrid mesoporous material with good acid-water resistance for biodiesel production

Different amounts of acidic ionic liquid sulfonic acid functionalized imidazolium hydrogen sulfate ([Ps-im]HSO4) were immobilized on the acidic organic-inorganic hybrid mesoporous material SO42−/ZrO2-SiO2(Et) by the chemical grafting. The structure of the catalyst was characterized by FT-IR, XRD, N2 absorption–desorption measurement, XPS and TG. The results showed that the ethane-bridge organosilica moieties were incorporated into the framework of SO42−/ZrO2, enhancing the acidity of SO42−/ZrO2-SiO2(Et) with respect to SO42−/ZrO2. Meanwhile, the ionic liquid was successfully immobilized onto the acidic mesoporous materials SO42−/ZrO2-SiO2(Et) and with the increase of ionic liquid loading, the BET surface areas and the pore volumes decreased and the average pore diameters increased. SO42−/ZrO2-SiO2(Et)-IL-i were very efficient in the transesterification of soybean oil with methanol and gave an approximate 99% biodiesel yield when the reaction was carried out at 150 °C with a 5 wt% catalyst amount at 18:1 methanol/oil molar ratio for 3.0 h. And they not only own the abilities of water and acid resistance, but also maintain satisfactory catalytic activity after five runs.

The synthesis of weak acidic type hybrid monolith via thiol-ene click chemistry and its application in hydrophilic interaction chromatography.

In this work, a porous structure and good permeability monolithic column was polymerized in UV transparent fused-silica capillaries via photo-initiated thiol-ene click polymerization of 2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane (TMTVS), pentaerythritol tetra(3-mercaptopropionate)(PETMP), itaconic acid, respectively, in the presence of porogenic solvents (tetrahydrofuranand methanol) and an initiator (2,2-dimethoxy-2-phenylacetophenone) (DMPA) within 30 min. The physical properties of this monolith were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and nitrogen adsorption/desorption measurements. For an overall evaluation of the monolith in chromatographic application, separations of polycyclic aromatic hydrocarbons (PAHs), phenols, amides and bases were carried out. The column efficiency of this monolith could be as high as 112 560 N/m. It also possesses a potential application in fabrication of monoliths with high efficiency for c-LC. In addition, the resulting monolithic column demonstrated the potential use in analysis of environment waters.

Poly(PEGA)-b-poly(L-lysine)-b-poly(L-histidine) Hybrid Vesicles for Tumoral pH-Triggered Intracellular Delivery of Doxorubicin Hydrochloride.

A series of poly(ethylene glycol) methyl ether acrylate-block-poly(L-lysine)-block-poly(L-histidine) [p(PEGA)30-b-p(Lys)25-b-p(His)n] (n = 25, 50, 75, 100) triblock copolypeptides were designed and synthesized for tumoral pH-responsive intracellular release of anticancer drug doxorubicin hydrochloride (Dox). The tumoral acidic pH-responsive hybrid vesicles fabricated were stable at physiological pH 7.4 and could gradually destabilize in acidic pH as a result of pH-induced swelling of the p(His) block. The blank vesicles were nontoxic over a wide concentration range (0.01-100 μg/mL) in normal cell lines. The tumor acidic pH responsiveness of these vesicles was exploited for intracellular delivery of Dox. Vesicles efficiently encapsulated Dox, and pH-induced destabilization resulted in the controlled and sustained release of Dox in CT26 murine cancer cells, and dose-dependent cytotoxicity. The tumor-specific controlled release Dox from vesicles demonstrates this system represents a promising theranostic agent for tumor-targeted delivery.

Polymeric Ionic Hybrid as Solid Acid Catalyst for the Selective Conversion of Fructose and Glucose to 5‐Hydroxymethylfurfural

AbstractThe dehydration of fructose to 5‐hydroxymethylfurfural (HMF) in the presence of a SO3H‐functionalized heteropolyanion‐based polymeric hybrid catalyst is investigated. Poly(1‐vinyl‐3‐propane sulfonate imidazolium)‐H3PW12O40 [poly(VMPS)‐PW], a supported ionic liquid catalyst (SILC) was prepared and used as a heterogeneous Brønsted‐acidic catalyst. We demonstrate that an 83% yield of HMF can be obtained at 130 ºC after 60 min using DMSO as the solvent, under atmospheric pressure. The catalytic scope of poly(VMPS)‐PW is studied by using it as a catalyst for the dehydration of glucose. We demonstrate that the catalyst is also suitable for conversion of glucose to HMF, with a yield of 26 % under mild conditions. Moreover, the acidic hybrid catalyst is easily separated from the reaction mixture by centrifugation. The ability to recycle the catalyst is demonstrated and poly(VMPS)‐PW is reused five times without significant loss of activity.

Synthesis of Polyvinyl Pyrrolidone-Heteropolyacid Acidic Hybrid Catalyst and Its Catalytic Activity for Esterification Reactions

Synthesis of Polyvinyl Pyrrolidone-Heteropolyacid Acidic Hybrid Catalyst and Its Catalytic Activity for Esterification Reactions

A novel Brønsted acidic heteropolyanion-based polymeric hybrid catalyst for esterification

Abstract A new SO3H-functionalized HPA-based acidic polymeric hybrid was prepared by coupling task-specifically designed SO3H-functionalized polymeric ionic liquid with Keggin-structured heteropolyanion, and characterized by 1H NMR, FT-IR, TG, XRD, BET, Hammett indicator, melting point, and elemental analysis. Its catalytic performance for esterification of alcohols with carboxylic acids was studied under solvent-free conditions. The results demonstrate that the polymeric hybrid is a highly active and selective solid catalyst for various esterifications, and can be easily recovered and steadily reused.

On-farm evaluation of improved Brachiaria grasses in low rainfall and aluminium toxicity prone areas of Rwanda

The aim of this study was to determine the production of improved Brachiaria grass in comparison with indigenous Brachiaria under low rainfall and aluminium toxicity areas of Rwanda. Three varieties and five hybrids of Brachiaria grass from CIAT and two local grasses (control) were used for on-farm participatory trials without fertilizer application. Twelve farms were selected in each study area and on each farm ten grasses were established in 2 × 3 m plots. Herbage was harvested six times during the year at two monthly intervals. Each cut, dry matter (DM) was measured. The crude protein (CP), calcium (Ca) and phosphorus (P) were also measured once in the wet season and once in the dry season. In the low rainfall area, Brachiaria brizantha cv. Toledo and Brachiaria decumbens (local) had the highest DM yields (5.71 and 5.61 t ha-1 respectively), while DM of the rest of the grasses ranged from 1.2 to 5.13 t ha-1. In the acidic soil area, Brachiaria hybrid Bro2/1485 had higher DM (5.95 t ha-1) than the rest of the grasses (1 to 4.47 t ha-1). The highest quality grass was Brachiaria hybrid Bro2/1485 which obtained a CP value of 12.15% in the low rainfall area, whereas in the acidic soil area hybrid cv. Mulato II obtained the highest CP value of 11.6%. In the low rainfall area the Brachiaria hybrid cv. Mulato obtained a high mean Ca value of 2.15% while in the acidic soil area, cv. Marandu obtained a high Ca value of 2.41% during the wet and dry seasons. The cv. Toledo had high P (0.28%) compared to the other grasses (0.07 to 0.11%) in the low rainfall area. In the acidic soil area, the Brachiaria hybrid Bro2/1485 had high P of 0.53% as compared to other grasses in which P varied between 0.16 and 0.47%. Local control grasses had lower nutrients than the improved Brachiaria grass in the low rainfall and acidic soil area. Although, Brachiaria hybrid cv. Mulato II was not the most productive grass, it was selected by farmers as the preferred cultivar at both sites because of its adaptability to low rainfall and acidic soil stress, and its production of green forage year round without any input of fertilizer. Key words: Dry matter production, forage quality, forage selection.

Preparation and Water Tolerance Study of SiO2-supported Perfluorobutylsulfonylimide

A new style of acidic perfluorobutylsulfonylimide-functionalized organosilica (PSFSI-MSMA15/ SiO2) was synthesized by incorporating a sulfonimide prepolymer (2) into the SiO2 network. The prepolymer was synthesized by free-radical copolymerization of sodium 4-styrenesulfonyl(perfluorobutylsulfonyl)imide (1) with 3-(trimethoxysilyl)propyl methacrylate (MSMA), and then hydrolyzed and co-condensed with tet- raethyl orthosilicate by two-step sol-gel method to afford the acidic hybrid material having acid contents of 0.62 mmol/g. The chemical composition were analyzed by FT-IR, XPS and TG/DTG, and hydrothermal sta- bility was investigated. The results indicated that PSFSI-MSMA15/SiO2 was high-temperature (210 ℃) and water tolerant. The study of catalytic property and recoverability are in progress.

Temperature Dependence of Electric Double-Layer Capacitor Operation Utilizing Acidic Cellulose-Chitin Hybrid Gel Electrolytes

An acidic cellulose-chitin hybrid gel electrolyte consisting of cellulose, chitin, 1-butyl-3-methylimidazolium, 1-allyl-3-methylimidazolium bromide, and an aqueous H2SO4 solution is investigated for electric double layer capacitors (EDLCs). This gel electrolyte shows a high ionic conductivity comparable to that observed in an aqueous 2 mol dm-3 H2SO4 solution. An EDLC cell with the acidic hybrid gel electrolyte has higher capacitance than that with an aqueous H2SO4 solution in the operation temperature. Moreover, the capacitance retention of the EDLC cell with the acidic hybrid gel electrolyte is better than a cell with a H2SO4 solution over 10,000 cycles. This suggests that the present acidic gel electrolyte has excellent stability in the presence of a strong acid even at a high temperature.

High/low temperature operation of electric double layer capacitor utilizing acidic cellulose–chitin hybrid gel electrolyte

An acidic cellulose–chitin hybrid gel electrolyte consisting of cellulose, chitin, 1-butyl-3-methylimidazolium, 1-allyl-3-methylimidazolium bromide, and an aqueous H 2SO 4 solution is investigated for electric double layer capacitors (EDLCs) with activated carbon fiber cloth electrodes. The acidic cellulose–chitin hybrid gel electrolyte shows a high ionic conductivity comparable to that for an aqueous 2 mol dm −3 H 2SO 4 solution at 0–80 °C. This system's temperature dependence in EDLC performance is investigated by galvanostatic charge–discharge measurement. An EDLC cell with the acidic hybrid gel electrolyte has higher capacitance than that with the aqueous H 2SO 4 solution in the range of operation temperatures (−10 to 60 °C). Moreover, the capacitance retention of the EDLC cell with the acidic hybrid gel electrolyte is better than that of a cell with the H 2SO 4 solution at 60 °C over 10,000 cycles. This suggests that the proposed acidic gel electrolyte has excellent stability in the presence of a strong acid, even at a high temperature of 60 °C.

Acid hybrid catalysts from poly(styrenesulfonic acid) grafted onto ultra-large-pore SBA-15 silica using atom transfer radical polymerization

Poly(styrenesulfonic acid)-functionalized materials based on poly(styrenesulfonic acid sodium salt) incorporated via aqueous atom transfer radical polymerization (ATRP) initiated from the surface of large-pore mesoporous SBA-15 silica support have been synthesized. The inorganic–organic nature of these hybrid materials makes them particularly desirable for acid-catalyzed reactions that require extended and hydrophobic surface areas with a narrow pore diameter distribution in the mesoporous range. Acidic hybrid materials were prepared by grafting the ATRP-initiator (3-(chlorodimethylsilyl)propyl bromoisobutyrate) on the silica surface, subsequent polymerization of the styrenesulfonic acid sodium salt monomer, and final sodium ion exchange by acid activation. Conventional and ultra-large-pore SBA-15 silica supports with nominal (BJH) pore diameter ranging from 8 to 32 nm were used for the incorporation of different polymer loadings at different polymerization times. The silylation of ATRP-initiator-functionalized SBA-15 supports has allowed a better control of the ATRP within the mesoporous structure. The use of ultra-large-pore SBA-15 supports provides a remarkable increase of the porosity which allowed us to properly allocate the polymer. The hybrid poly(styrenesulfonic acid)-modified materials showed good catalytic activities in the esterification of oleic acid with n-butanol, particularly in terms of intrinsic activity per acid site.

Performance of Electric Double-Layer Capacitor with Acidic Cellulose–Chitin Hybrid Gel Electrolyte

An acidic cellulose–chitin hybrid gel electrolyte is prepared from cellulose, chitin, binary ionic liquids, and an aqueous solution for an electric double-layer capacitor (EDLC). The obtained acidic hybrid gel shows a high ionic conductivity of at a room temperature of , which is comparable to of an aqueous electrolyte. The acidic cellulose–chitin hybrid gel electrolyte is applied to an EDLC cell with activated carbon fiber cloths as polarizable electrodes, and its electrochemical performance is investigated by galvanostatic cycling, cyclic voltammetry, and a self-discharge test. The EDLC cell with the acidic cellulose–chitin hybrid gel electrolyte exhibits a higher capacitance and a better cycle life than cells with the reference aqueous electrolyte. The self-discharge measurement suggests that leakage current and potential decay are suppressed by the application of the acidic cellulose–chitin hybrid gel electrolyte. These results indicate that the acidic cellulose–chitin hybrid gel electrolyte has a practical applicability to an advanced EDLC with excellent stability and working performance.

Charge-Discharge Behavior of Electric Double Layer Capacitor with Acidic Cellulose-Chitin Hybrid Gel Electrolyte

A novel acidic cellulose-chitin hybrid gel electrolyte including binary ionic liquids (ILs) with an aqueous H2SO4 solution was prepared for an electric double layer capacitor (EDLC). Its electrochemical characteristics were investigated by galvanostatic charge-discharge measurements. The cell with the hybrid gel containing binary ILs and H2SO4 has higher capacitance than that containing only the aqueous H2SO4 solution. This hybrid gel electrolyte exhibits excellent high-rate discharge capability in a wide range of current densities as well as an aqueous H2SO4 solution. The discharge capacitance of the test cell can retain over 80% of its initial value in 100,000 cycles even at a high current density of 5,000 mA g-1.