Lanthanide (Eu3+, Tb3+) Centered Mesoporous Hybrids with 1,3‐Diphenyl‐1,3‐Propanepione Covalently Linking SBA‐15 (SBA‐16) and Poly(methylacrylic acid)

1,3‐Diphenyl‐1,3‐propanepione (DBM)‐functionalized SBA‐15 and SBA‐16 mesoporous hybrid materials (DBM‐SBA‐15 and DBM‐SBA‐16) are synthesized by co‐condensation of modified 1,3‐diphenyl‐1,3‐propanepione (DBM‐Si) and tetraethoxysilane (TEOS) in the presence of Pluronic P123 and Pluronic F127 as a template, respectively. The as‐synthesized mesoporous hybrid material DBM‐SBA‐15 and DBM‐SBA‐16 are used as the first precursor, and the second precursor poly(methylacrylic acid) (PMAA) is synthesized through the addition polymerization reaction of the monomer methacrylic acid. These precursors then coordinate to lanthanide ions simultaneously, and the final mesoporous polymeric hybrid materials Ln(DBM‐SBA‐15)₃PMAA and Ln(DBM‐SBA‐16)₃PMAA (Ln=Eu, Tb) are obtained by a sol‐gel process. For comparison, binary lanthanide SBA‐15 and SBA‐16 mesoporous hybrid materials (denoted as Ln(DBM‐SBA‐15)₃ and Ln(DBM‐SBA‐16)₃) are also synthesized. The luminescence properties of these resulting materials are characterized in detail, and the results reveal that ternary lanthanide mesoporous polymeric hybrid materials present stronger luminescence intensities, longer lifetimes, and higher luminescence quantum efficiencies than the binary lanthanide mesoporous hybrid materials. This indicates that the introduction of the organic polymer chain is a benefit for the luminescence properties of the overall hybrid system. In addition, the SBA‐15 mesoporous hybrids show an overall increase in luminescence lifetime and quantum efficiency compared with SBA‐16 mesoporous hybrids, indicating that SBA‐15 is a better host material for the lanthanide complex than mesoporous silica SBA‐16.     

Imidazolium‐functionalized SBA‐15 type silica: efficient organocatalysts for Henry and cycloaddition reactions

We report the synthesis of mesoporous SBA‐15 type silica bearing ionic imidazolium substructures. Surface functionalization was achieved via post‐synthesis grafting reactions using bis‐silylated imidazolium precursors onto a mesoporous SBA‐15 type silica support. The grafting reactions were monitored via solid‐state NMR spectroscopy, nitrogen sorption, transmission electron microscopy and thermogravimetry. Post‐synthesis grafting is the most convenient way to achieve highly stable functionalized solids displaying excellent accessibility of the immobilized functional groups combined with high chemical stability. The solids obtained via post‐synthesis grafting reactions appeared as highly efficient and reusable heterogeneous organocatalysts for Henry reactions and the cycloadditions of CO₂ to epichlorohydrin. Copyright © 2013 John Wiley & Sons, Ltd.     

Pd(OAc)2@SBA‐15/PrEn nanoreactor: a highly active,reusable and selective phosphine‐free catalyst for Suzuki–Miyaura cross‐coupling reaction in aqueous media

A series of ordered mesoporous organic–inorganic hybrid material was designed by using the amine‐functionalized SBA‐15 (PdX₂@SBA‐15/N_Y, Y = 1, 2) as solid support for palladium complexes. Among them, the Pd(OAc)₂/ethylenediamine complex encapsulated into SBA‐15 (Pd(OAc)₂@SBA‐15/PrEn or Pd(OAc)₂@SBA‐15/PrNHEtNH₂) exhibits higher activity and selectivity toward Suzuki cross‐coupling reaction under aerobic conditions and water solvent mixture. The SBA‐15/PrEn supported palladium pre‐catalyst could be separated easily from reaction products and used repetitively several times, showing its superiority over homogeneous catalysts for industrial and chemical applications. Copyright © 2013 John Wiley & Sons, Ltd.     

Bio‐assisted synthesized Ag(0) nanoparticles immobilized on SBA‐15/cyclodextrin nanosponge adduct: Efficient heterogeneous catalyst for the ultrasonic‐assisted synthesis of benzopyranopyrimidines

For the first time, SBA‐15/cyclodextrin nanosponge adduct was synthesized through reaction of Cl‐functionalized SBA‐15 and amine‐functionalized cyclodextrin nanosponge (CDNS). This adduct, which benefits from features of both SBA‐15 and CDNS, was then used for immobilization of Ag(0) nanoparticles which were prepared and capped using a bio‐based approach. Ag@CDNS–SBA‐15 was applied as a heterogeneous catalyst for promoting the three‐component reaction of benzaldehydes, 4‐hydroxycoumarin and urea or thiourea under ultrasonic irradiation to furnish benzopyranopyrimidines. The reaction variables were optimized using response surface methodology. The catalytic activity of Ag@CDNS–SBA‐15 was higher than those of Ag@CDNS, Ag@SBA‐15 and Ag@SBA‐15 + CDNS, confirming the contribution of both components to catalysis as well as a synergistic effect between CDNS and SBA‐15. The role of CDNS was to accommodate the substrates and bring them to the vicinity of the Ag(0) nanoparticles. Notably the catalyst was reusable and could be recovered and reused for up to four reaction runs with slight Ag(0) leaching and loss of catalytic activity.     

An efficient,mild and selective Ullmann‐type N‐arylation of indoles catalysed by Pd immobilized on amidoxime‐functionalized mesoporous SBA‐15 as heterogeneous and recyclable nanocatalyst

A wide range of N‐arylated indoles were selectively synthesized through intermolecular C(aryl)? N bond formation from the corresponding aryl iodides and indoles through Ullmann‐type coupling reactions in the presence of a catalytic amount of Pd immobilized on amidoxime‐functionalized mesoporous SBA‐15 (SBA‐15/AO/Pd(0)) under mild reaction conditions. These cross‐coupled products were obtained in excellent yields under mild conditions at extremely low palladium loading (ca 0.3 mol%), and the heterogeneous catalyst can be readily recovered by simple filtration and reused seven times with loss in its activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Solid‐phase purification and extraction for the determination of trace neonicotinoid pesticides in tea infusion

An analytical protocol that includes solid‐phase purification and extraction is successfully developed for the determination of trace neonicotinoid pesticides in tea infusion. The method consists of a purification on amino‐functionalized mesoporous silica SBA‐15 followed by a solid‐phase extraction based on graphene oxide before ultra high performance liquid chromatography with tandem mass spectrometry analysis. Parameters that significantly affected the extraction of the neonicotinoids onto graphene oxide, such as the amount of adsorbent, extraction time, pH, elution solvent, etc. were optimized. The amino‐functionalized mesoporous silica SBA‐15 has been proved to be an efficient adsorbent for removal of polyphenols especially catechins from tea infusion. Graphene oxide exhibits a very rapid adsorption rate (within 10 min) and high adsorption capacities for neonicotinoids at low initial concentration (0.01–0.5 mg/L). The analysis method gave a good determination coefficient (r² > 0.99) for each pesticide and high recoveries in the range of 72.2–95.0%. Powder X‐ray diffraction, Raman spectroscopy, transmission electron microscopy, and UV‐vis spectroscopy were utilized to identify the structure and morphology of graphene oxide. The adsorption driving force of neonicotinoids on graphene oxide mainly depends on π–π electron donor–acceptor interaction and electrostatic interaction.     

Epoxidation of cyclohexene with H2O2 over efficient water‐tolerant heterogeneous catalysts composed of mono‐substituted phosphotungstic acid on co‐functionalized SBA‐15

A series of Keggin‐type heteropolyacid‐based heterogeneous catalysts (Co‐/Fe‐/Cu‐POM‐octyl‐NH₃‐SBA‐15) were synthesized via immobilized transition metal mono‐ substituted phosphotungstic acids (Co‐/Fe‐/Cu‐POM) on octyl‐amino‐co‐functionalized mesoporous silica SBA‐15 (octyl‐NH₂‐SBA‐15). Characterization results indicated that Co‐/Fe‐/Cu‐POM units were highly dispersed in mesochannels of SBA‐15, and both types of Brønsted and Lewis acid sites existed in Co‐/Fe‐/Cu‐POM‐octyl‐NH₃‐SBA‐15 catalysts. Co‐POM‐octyl‐NH₃‐SBA‐15 catalyst showed excellent catalytic performance in H₂O₂‐mediated cyclohexene epoxidation with 83.8% of cyclohexene conversion, 92.8% of cyclohexene oxide selectivity, and 98/2 of epoxidation/allylic oxidation selectivity. The order of catalytic activity was Co‐POM‐octyl‐NH₃‐SBA‐15 > Fe‐POM‐octyl‐NH₃‐SBA‐15 > Cu‐POM‐octyl‐NH₃‐SBA‐15. In order to obtain insights into the role of ‐octyl moieties during catalysis, an octyl‐free catalyst (Co‐POM‐NH₃‐SBA‐15) was also synthesized. In comparison with Co‐POM‐NH₃‐SBA‐15, Co‐POM‐octyl‐NH₃‐SBA‐15 showed enhanced catalytic properties (viz. activity and selectivity) in cyclohexene epoxidation. Strong chemical bonding between ‐NH₃⁺ anchored on the surface of SBA‐15 and heteropolyanions resulted in excellent stability of Co‐POM‐octyl‐NH₃‐SBA‐15 catalyst, and it could be reused six times without considerable loss of activity.     

N‐heterocyclic carbene–palladium(II) complex supported on magnetic mesoporous silica for Heck cross‐coupling reaction

Magnetic mesoporous silica was prepared via embedding magnetite nanoparticles between channels of mesoporous silica (SBA‐15). The prepared composite (Fe₃O₄@SiO₂‐SBA) was then reacted with 3‐chloropropyltriethoxysilane, sodium imidazolide and 2‐bromopyridine to give 3‐(pyridin‐2‐yl)‐1H‐imidazol‐3‐iumpropyl‐functionalized Fe₃O₄@SiO₂‐SBA as a supported pincer ligand for Pd(II). The functionalized magnetic mesoporous silica was further reacted with [PdCl₂(SMe₂)₂] to produce a supported N‐heterocyclic carbene–Pd(II) complex. The obtained catalyst was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy‐dispersive X‐ray analysis, vibrating sample magnetometry, Brunauer–Emmett–Teller surface area measurement and X‐ray diffraction. The amount of the loaded complex was 80.3 mg g^?1, as calculated through thermogravimetric analysis. The formation of the ordered mesoporous structure of SBA‐15 was confirmed using low‐angle X‐ray diffraction and transmission electron microscopy. Also, X‐ray photoelectron spectroscopy confirmed the presence of the Pd(II) complex on the magnetic support. The prepared magnetic catalyst was then effectively used in the coupling reaction of olefins with aryl halides, i.e. the Heck reaction, in the presence of a base. The reaction parameters, such as solvent, base, temperature, amount of catalyst and reactant ratio, were optimized by choosing the coupling reaction of 1‐bromonaphthalene and styrene as a model Heck reaction. N‐Methylpyrrolidone as solvent, 0.25 mol% catalyst, K₂CO₃ as base, reaction temperature of 120°C and ultrasonication of the catalyst for 10 min before use provided the best conditions for the Heck cross‐coupling reaction. The best results were observed for aryl bromides and iodides while aryl chlorides were found to be less reactive. The catalyst exhibited noticeable stability and reusability.     

Detailed Structural Characterizations of SBA‐15 and MCM‐41 Mesoporous Silicas on a High‐Resolution Transmission Electron Microscope

Using high‐resolution transmission electronic micrograph (HR‐TEM) observation, one can clearly see the pore geometry of the MCM‐41 and SBA‐15 mesoporous silicas to determine that their pore shapes are hexagonal and round, respectively. With the perpendicular orientations of the nanochannels to the electron beam, parallel line images of the (100) and (110) repeating spacings were observed. In the SBA‐15 mesoporous silicas, there are byproducts of the granular silica and disordered mesostructures, attributed to the weak hydrogen interactions between Pluronic 123 blockcopolymer and the silica species. There are also many different and significant +π disclination defects in SBA‐15 and MCM‐41 surfactant‐silica composites. The SBA‐15 with a thicker silica wall is more stable under irradiation by high‐energy electron beams compared to MCM‐41, which has thinner wall thickness. Some carbon nanostructure impurities were found in some carbon films on the metal grids.     

Synthesis of a metal–organic framework confined in periodic mesoporous silica with enhanced hydrostability as a novel fiber coating for solid‐phase microextraction

A metal–organic framework/periodic mesoporous silica (MOF‐5@SBA‐15) hybrid material has been prepared by using SBA‐15 as a matrix. The prepared MOF‐5@SBA‐15 hybrid material was then deposited on a stainless‐steel wire to obtain the fiber for the solid‐phase microextraction of phenolic compounds. Modifications in the metal–organic framework structure have proven to improve the extraction performance of MOF/SBA‐15 hybrid materials, compared to pure MOF‐5 and SBA‐15. Optimum conditions include an extraction temperature of 75°C, a desorption temperature of 260°C, and a salt concentration of 20% w/v. The dynamic linear range and limit of detection range from 0.1–500 and from 0.01–3.12 ng/mL, respectively. The repeatability for one fiber (n = 3), expressed as relative standard deviation, is between 4.3 and 9.6%. The method offers the advantage of being simple to use, rapid, and low cost, the thermal stability of the fiber, and high relative recovery (compared to conventional methods) represent additional attractive features.     

Organotin(IV)‐Loaded Mesoporous Silica as a Biocompatible Strategy in Cancer Treatment

The strong therapeutic potential of an organotin(IV) compound loaded in nanostructured silica (SBA‐15pSn) is demonstrated: B16 melanoma tumor growth in syngeneic C57BL/6 mice is almost completely abolished. In contrast to apoptosis as the basic mechanism of the anticancer action of numerous chemotherapeutics, the important advantage of this SBA‐15pSn mesoporous material is the induction of cell differentiation, an effect unknown for metal‐based drugs and nanomaterials alone. This non‐aggressive mode of drug action is highly efficient against cancer cells but is in the concentration range used nontoxic for normal tissue. JNK (Jun‐amino‐terminal kinase)‐independent apoptosis accompanied by the development of the melanocyte‐like nonproliferative phenotype of survived cells indicates the extraordinary potential of SBA‐15pSn to suppress tumor growth without undesirable compensatory proliferation of malignant cells in response to neighboring cell death.     

Palladium‐anchored multidentate SBA‐15/di‐urea nanoreactor: A highly active catalyst for Suzuki coupling reaction

Modification of mesoporous silica was carried out by reaction of SBA‐15 with di‐urea‐based ligand. Next, with the help of this ligand, palladium ions were anchored within the multidentate SBA‐15/di‐urea pore channels with high dispersion. The SBA‐15/di‐urea/Pd catalyst was characterized using various techniques. Theoretical calculations indicated that each palladium ion was strongly interacted with one nitrogen and two oxygen atoms from the multidentate di‐urea ligand located in SBA‐15 channels and these interactions remained during the catalytic cycle. These results are in good agreement with those of hot filtration test: the palladium ions have very high stability against leaching from the SBA‐15/di‐urea support. The catalytic performance of SBA‐15/di‐urea/Pd nanostructure was examined for the Suzuki coupling reaction of phenylboronic acid and electronically diverse aryl halides under mild conditions with a minimal amount of Pd (0.26 mol%). Compared to previous reports, this protocol afforded some advantages such as short reaction times, high yields of products, catalyst stability without leaching, easy catalyst recovery and preservation of catalytic activity for at least six successive runs.     

Bismuth‐Containing SBA‐15 Mesoporous Silica Catalysts for Solvent‐Free Liquid‐Phase Oxidation of Cyclohexane by Molecular Oxygen

Bismuth (Bi)‐containing SBA‐15 mesoporous silica catalysts, Bi/SBA‐15, with different Bi loadings were synthesized by a direct hydrothermal method. The materials were characterized in detail by various techniques. Powder‐X‐ray‐diffraction (PXRD), N₂‐adsorption/desorption, and transmission‐electron‐microscopic (TEM) analyses revealed that the well‐ordered hexagonal structure of SBA‐15 is maintained after Bi incorporation. Diffuse‐reflectance UV/VIS, Raman, and X‐ray photoelectron spectroscopy (XPS) showed that the incorporated Bi‐atoms are highly dispersed, most of them entering the internal surface of SBA‐15. The new, very stable catalysts were found to be highly efficient for the oxidation of cyclohexane in a solvent‐free system, molecular oxygen (O₂) being used as oxidant.     

Adsorption of Acid Dyes by Functionalized SBA‐15 Mesoporous Silica of Different Pore Lengths

SBA‐15 materials of different pore lengths and functionalized with various organic groups were synthesized by one‐pot co‐condensation and applied as adsorbents for the acid orange 12 (AO12) and acid red 73 (AR73) dyes. The materials were characterized by techniques such as X‐ray powder diffraction, nitrogen sorption isotherms, scanning electron microscopy, and infrared (FTIR) spectroscopy. The adsorption behaviors of the SBA‐15 materials toward AO12 and AR73 dyes were investigated by varying several factors including morphologies of adsorbents, pH of solution, functional groups on SBA‐15, and temperature. The equilibrium adsorption data agreed with Langmuir isotherms. The kinetic parameters were also calculated and the first‐order kinetic model fitted well for amino‐functionalized SBA‐15 material. The short channeling pores of the amino‐functionalized SBA‐15 platelets facilitated the diffusion of dye molecules inside the pores and prevented the aggregation of dye molecules from the blocking of the pores. To conclude, however, the adsorption capacity is dependent on the amount of amino‐loading and surface area of the SBA‐15 materials.     

Polyurethane‐mesoporous silica gas separation membranes

The concept of mixed matrix membrane comprising dispersed inorganic fillers into a polymer media has revealed appealing to tune the gas separation performance. In this work, the membranes were prepared by incorporation of mesoporous silica into polyurethane (PU). Mesoporous silica particles with different pore size and structures, MCM‐41, cubic MCM‐48 and SBA‐16, were synthesized by templating method and functionalized with 3‐aminopropyltriethoxysilane (APTES). High porosity and aminated surface of the mesoporous silica enhance the adhesion of the particles to the PU matrix. The SEM and FTIR results showed strong interactions between the particles and the PU chains. Moreover, the thermal stability of the hybrid PUs improved compared to the pure polymer. Gas transport properties of the membranes were measured for pure CO₂, CH₄, O₂, and N₂ gases at 10 bar and 25°C. The results showed that the gas permeabilities enhanced with increasing in the loading of modified mesoporous silica particles. High porosity and amine‐functionalized particles render opportunities to enhance the gas diffusivity and solubility through the membranes. The enhanced gas transport properties of the mixed matrix membranes reveal the advantages of mesoporous silica to improve the gas permeability (CO₂ permeability up to ~70) without scarifying the gas selectivity (α(CO₂/N₂)~ 30 for 5 wt% SBA‐16 content).     

Composites of poly(L‐lactide‐trimethylene carbonate‐glycolide) and surface modified SBA‐15 as bone repair material

This work aims to develop novel composites from a poly(L ‐lactide‐co‐trimethylene carbonate‐co‐glycolide) (PLTG) terpolymer and mesoporous silica (SBA‐15) nanofillers surface modified by post‐synthetic functionalization. SBA‐15 first reacts with a silane coupling agent, γ‐aminopropyl‐trimethoxysilane to introduce ammonium group. PLLA chains were then grafted on the surface of SBA‐15 through ammonium initiated ring‐opening polymerization of L ‐lactide. Composites were prepared via solution mixing of PLTG terpolymer and surface modified SBA‐15. The structures and properties of pure SBA‐15, γ‐aminopropyl‐trimethoxysilane modified SBA‐15 (H₂N‐SBA‐15), PLLA modified SBA‐15 (PLLA‐NH‐SBA‐15), and PLTG/PLLA‐NH‐SBA‐15 composites were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, N₂ adsorption‐desorption, differential scanning calorimetry, contact angle measurement, and mechanical testing. The results demonstrated that PLLA chains were successfully grafted onto the surface of SBA‐15 with grafting amounts up to 16 wt.%. The PLTG/PLLA‐NH‐SBA‐15 composites exhibit good mechanical properties. The tensile strength, Young's modulus, and elongation at break of the composite containing 5 wt.% of PLLA‐NH‐SBA‐15 were 39.9 MPa, 1.3 GPa, and 273.6%, respectively, which were all higher than those of neat PLTG or of the composite containing 5 wt.% of pure SBA‐15. Cytocompatibility tests showed that the composites present very low cytotoxicity.     

Surface‐Passivated SBA‐15‐Supported Gold Nanoparticles: Highly Improved Catalytic Activity and Selectivity toward Hydrophobic Substrates

Silanol groups on a silica surface affect the activity of immobilized catalysts because they can influence the hydrophilicity/hydrophobicity, matter transfer, or even transition state in a catalytic reaction. Previously, these silanol groups have usually been passivated by using surface‐passivation reagents, such as alkoxysilanes, bis‐silylamine reagents, chlorosilanes, etc., and surface passivation has typically been found in mesoporous‐silicas‐supported molecular catalysts and heteroatomic catalysts. However, this property has rarely been reported in mesoporous‐silicas‐supported metal‐nanoparticle catalysts. Herein, we prepared an almost‐superhydrophobic SBA‐15‐supported gold‐nanoparticle catalyst by using surface passivation, in which the catalytic activity increased more than 14 times for the reduction of nitrobenzene compared with non‐passivated SBA‐15. In addition, this catalyst can selectively catalyze hydrophobic molecules under our experimental conditions, owing to its high (almost superhydrophobic) hydrophobic properties.     

Facile Synthesis of Prussian Blue Derivate‐Modified Mesoporous Material via Photoinitiated Thiol–Ene Click Reaction for Cesium Adsorption

A novel strategy to synthesize a functional mesoporous material for efficient removal of cesium is reported. Specifically, Prussian blue derivate‐modified SBA‐15 (SBA‐15@FC) was prepared by photoinitiated thiol–ene reaction between thiol‐modified SBA‐15 and pentacyano(4‐vinyl pyridine)ferrate complex. The effects of weight percentage of the Prussian blue derivate, pH, adsorbent dose, co‐existing ions, and initial concentration were evaluated on the adsorption of cesium ions. The adsorption kinetically follows a pseudo‐second‐order model and reaches equilibrium within 2 h with a high adsorption capacity of about 13.90 mg Cs g^?1, which indicates that SBA‐15@FC is a promising adsorbent to effectively remove cesium from aqueous solutions.     

Ordered mesoporous SBA‐15/PrSO3Pd and SBA‐15/PrSO3PdNP as active,reusable and selective phosphine‐free catalysts in CX activation Heck coupling process

The incorporation of sulfonate into mesoporous SBA‐15 molecular sieves as ligands for palladium ions was used. Then SBA‐15/PrSO₃Pd and SBA‐15/PrSO₃Pd_NP were prepared and applied for the Heck arylation reaction of conjugate alkenes with aryl halides, to afford corresponding cross‐coupling products under phosphine‐free aerobic conditions with good to excellent yields. These supported palladium pre‐catalysts could be separated easily from reaction products and reused several times, showing superiority over homogeneous catalysts for industrial and chemical applications. Copyright © 2015 John Wiley & Sons, Ltd.