Schiff碱改性法制备SBA-15型介孔分子筛负载的纳米氧化镍

基于Schiff碱功能单体的改性作用,采用共缩聚方法,制备了SBA-15型介孔分子筛负载的氧化镍纳米粒子。 采用小角X射线散射（small angle XRD）、广角X射线衍射（wide angle XRD）、紫外-可见光谱（UV-Vis）、高分辨透射电子显微镜（HRTEM）和N2吸附-脱附测定对制得的样品进行了表征。 结果表明,制得的样品具有SBA-15型介孔分子筛典型的二维六方有序结构,NiO纳米粒子主要分布于SBA-15型介孔分子筛的孔道内。 当功能单体的含量不超过10%时,SBA-15型介孔分子筛的孔径在6~8 nm范围内;而当功能单体的含量达到15%时,SBA-15型介孔分子筛的孔道被严重堵塞,孔径降为3.8 nm。 NiO纳米粒子的尺寸随着功能单体含量的增加而增大。     

A Copper(II) Schiff base complex immobilized onto SBA-15 silica for selective oxidation of benzyl alcohol

A copper(II) Schiff base complex has been immobilized onto SBA-15 silica through a stepwise procedure and tested as an oxidation catalyst. BET surface area, total pore volume and average pore width of the SBA-15 all decrease after stepwise modification of SBA-15, while the structure of the support remains intact. The molar ratio of Cu²⁺/Schiff base is ca. 1/2 in the synthesized material. Catalytic tests showed that the supported copper complex catalyzes the oxidation of benzyl alcohol with 30 % conversion and 89 % selectivity to benzaldehyde when water is used as the solvent.     

Activation energy of the reaction between hexacyanoferrate (Ш) and thiosulfate ions catalyzed by platinum nanoparticles confined in nanometer space

Pt nanoparticles (NPs) have been successfully encapsulated in SBA-15 mesoporous silica support. The silica was firstly functionalized by polyaminoamine (PAMAM) dendrimers with various generations and provided different nanometer space for Pt NPs. The growth of Pt NPs is restricted by the double confinement effect of PAMAM dendrimers and SBA-15 mesopores. The Pt NPs can be precisely controlled to localize inter- or intradendrimeric within SBA-15 tunnels. The different pore structures of Gn-PAMAM-SBA-15 (Gn-PS15) support have great influence on the catalytic performance of the encapsulated Pt NPs. The blocking structure of higher generation Gn-PS15 support debased the catalytic performance and increased the activation energy of reaction between Fe(CN)(6)(3-) and S(2)O(3)(2-) in a certain degree.     

Synthesis,characterization, and applications of novel Co(II)-pyridoxal phosphate-Schiff base/SBA-15 as a nanocatalyst for the green synthesis of benzothiazole heterocycles

Mesoporous heterogeneous santa barbara amorphous (SBA)-15-supported cobalt complex, as a novel nanocatalyst containing N–O chelating Schiff-base ligand was successfully synthesized by the reaction of SBA-15 and Cobalt(II)-Schiff-base complex. The Co(II)-Schiff base complex also was prepared for the first time, by the reaction of pyridoxal 5′-phosphate or PLP (biological active form of vitamin B6), 3-(aminopropyl)-triethoxysilane in methanol that complexation with CoCl₂. The subsequent grafting of entitled complex to SBA-15 afforded Co(II)-PLP-Schiff base/SBA-15 mesoporous catalyst. Characterization of the product was carried out with powder X-ray diffraction, Brunauer–Emmett–Teller nitrogen adsorption–desorption, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, atomic absorption spectroscopy, and inductively coupled plasma, Fourier-transform infrared spectroscopy. The results revealed the retention of the textural properties and hexagonally uniform structures of SBA-15 during the grafting procedure. This nanocatalyst was applied successfully for one-pot synthesis of various benzothiazole heterocycles under green conditions. This catalyst is an active, reusable, and stable nanomaterial with no leaching of metal ions to the reaction medium. It was used for the synthesis of desired benzothiazole heterocycles by the cyclo-condensation of aryl-aldehydes with 2-aminothiophenol with good to excellent yields and under green conditions.     

新型复合介孔材料HPMo/SBA-15的合成与表征

合成了一种新型复合介孔材料HPMo/SBA-15, 通过XRD, TEM, UV-Vis和IR等方法表征证明HPMo均匀且稳定地包藏到介孔材料SBA-15的由SiO2网络组成的孔壁中. 催化实验结果表明, 该材料在大分子催化裂化反应中具有很高的活性, 在大分子催化氧化反应中连续循环使用未发现活性组分流失, 显示了其在大分子催化和均相催化反应多相化中具有很好的应用前景.     

Preparation and application of nanocatalysts via surface functionalization of mesoporous materials

Surface immobilization of active species onto mesoporous materials is gaining importance, especially in the design of functionalized mesoporous materials as a nanocatalyst through heterogenization of homogeneous catalytic systems. This article summarizes recent work on the synthesis, characterization and catalytic performance of the functionalized mesoporous catalysts performed by the present authors. A cationic rhenium(I) complex was encapsulated into mesoporous Al-MCM-41 molecular sieve using a ion-exchange method, yielding a new photocatalyst to be active for photocatalytic reduction of CO₂. Surface functionalization of mesoporous silica SBA-15 with sulfonic acid groups was investigated to give a solid acid catalyst. The chemically modified Fe-containing mesoporous materials, which are active for hydroxylation of phenol, were prepared by a surface-grafting method that iron salts are immobilized onto mesoporous Si-MCM-41 with the help of 3-aminopropyltrimethoxysilane as a linker. A cobalt(III) complex was heterogenized onto mesoporous silica SBA-15 containing carboxylic groups in order to utilize as a solid catalyst for the liquid-phase oxidation of aromatic hydrocarbons.     

A novel ZnII-sensitive fluorescent chemosensor assembled within aminopropyl-functionalized mesoporous SBA-15

A novel Zn2+-sensitive fluorescent chemosensor SC/SBA-15 has been obtained by the self-assembly of 4-chloroaniline-N-salicylidene (SC), a Schiff base ligand, within the channel of silylation-modified SBA-15 without destroying its hexagonally ordered mesoporous structure. The remarkable 200-fold fluorescence enhancement with a large Stokes shift of 180 nm in luminescence emission upon the addition of Zn2+ is attributed to the formation of a coordinate complex of a large rigid conjugate system and Zn2+ ions.     

Improved photoluminescence properties of ternary terbium complexes in mesoporous molecule sieves

Ternary terbium complexes were fully encapsulated and uniformly distributed into the channels of unmodified and modified mesoporous molecule sieves of SBA-15 and characterized by transmission electron micrographs (TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-vis) absorption spectra, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and elemental analysis. The luminescent properties for the encapsulated complexes were systematically studied in contrast to the pure complexes, including excitation and emission spectra, fluorescence dynamics, photostability under UV exposure, and the temperature dependence of intensity and lifetime. The results indicate that the excitation bands assigned to the pi-pi* electron transition of the ligands for Tb complexes encapsulated in SBA-15 were split into different components due to decreased symmetry and disappeared at long wavelengths. Owing to suppressed vibration transitions, the outer quantum efficiency of the 5D4-7FJ (J = 0-5) emissions was enhanced largely in comparison to the pure complexes. In addition, the photostability and thermostability of the emissions were also improved considerably.     

pH-Controllable drug release using hydrogel encapsulated mesoporous silica

Amine-functionalized mesoporous SBA-15 silica loaded with bovine serum albumin (BSA) has been successfully encapsulated with a thin layer coating of poly(acrylic acid) PAA, with the entrapped BSA being released from the PAA-encapsulated SBA-15 at the higher pH value of 7.4 rather than at the lower pH value of 1.2. This novel drug delivery system has a potential application in the release of protein drug to the site of higher pH value, such as small intestine or colon.     

Synthesis, characterization, and luminescence properties of the ternary europium complex covalently bonded to mesoporous SBA-15

A novel mesoporous SBA-15 type of hybrid material (phen-SBA-15) covalently bonded with 1,10-phenanthroline (phen) ligand was synthesized by co-condensation of tetraethoxysilane (TEOS) and the chelate ligand 5-[N,N-bis-3-(triethoxysilyl)propyl]ureyl-1,10-phenanthroline (phen-Si) in the presence of Pluronic P123 surfactant as a template. The preservation of the chelate ligand structure during the hydrothermal synthesis and the surfactant extraction process was confirmed by Fourier transform infrared (FTIR) and (29)Si MAS NMR spectroscopies. SBA-15 consisting of the highly luminescent ternary complex Eu(TTA)(3)phen (TTA = 2-thenoyltrifluoroacetone) covalently bonded to a silica-based network, which was designated as Eu(TTA)(3)phen-SBA-15, was obtained by introducing the Eu(TTA)(3).2H(2)O complex into the hybrid materials via a ligand exchange reaction. XRD, TEM, and N(2) adsorption measurements were employed to characterize the mesostructure of Eu(TTA)(3)phen-SBA-15. For comparison, SBA-15 doped with Eu(TTA)(3).2H(2)O and Eu(TTA)(3)phen complexes and SBA-15 covalently bonded with a binary europium complex with phen ligand were also synthesized, and were named SBA-15/Eu(TTA)(3), SBA-15/Eu(TTA)(3)phen, and Eu-phen-SBA-15, respectively. The detailed luminescence studies on all the materials showed that, compared with the doping sample SBA-15/Eu(TTA)(3)phen and binary europium complex functionalized sample Eu-phen-SBA-15, the Eu(TTA)(3)phen-SBA-15 mesoporous hybrid material exhibited higher luminescence intensity and emission quantum efficiency. Thermogravimetric analysis on Eu(TTA)(3)phen-SBA-15 demonstrated that the thermal stability of the lanthanide complex was evidently improved as it was covalently bonded to the mesoporous SBA-15 matrix.     

In-situ oxidation of block copolymer for producing copper oxalate or copper oxide nanowires in mesoporous channels

Copper oxalate nanowires inside the channels of mesoporous SBA-15 are created by in-situ oxidation of block copolymer in as-prepared SBA-15 samples. The pyrolysis of CuC₂O₄/SBA-15 composites under different conditions results in the formation of CuO or Cu₂O nanowires encapsulated in the nanoscale channels. The appearance, structure and composition of these materials are characterized by the X-ray power diffraction, transmission electron microscopy, N₂ adsorption-desorption isotherms, infrared spectra and inductive coupled plasma emission spectra. CuC₂O₄, CuO and Cu₂O nanomaterials filled in the channels of SBA-15 have been proven to possess the electrochemical hydrogen storage capacities of 102, 165 and 231 mAh/g in the second cycle, respectively, and are expected to have a high potential for use in practical applications.     

Effects of surface residual species in SBA-16 on encapsulated chiral (1S,2S)-DPEN-RuCl<Subscript>2</Subscript>(TPP)<Subscript>2</Subscript> in asymmetric hydrogenation of acetophenone

The SBA-16 obtained by different routes of elimination of organic templates were used as the hosts for encapsulation of chiral Ru complex (1S,2S)-DPEN-RuCl₂(TPP)₂ (1) (DPEN = 1,2-diphenylethylene-diamine, TPP = triphenyl phosphine). The methods for removing templates had distinct effects on the amount of residual template in SBA-16, which made the SBA-16 with different surface and structure properties. 1 encapsulated in SBA-16 extracted with the mixture of pyridine and ethanol showed higher activity and enantioselectivity for acetophenone asymmetric hydrogenation.     

An efficient and reusable silica/dendrimer supported platinum catalyst for electron transfer reactions

A series of Pt nanoparticles (NPs) smaller than 3 nm were successfully encapsulated in dendrimer/SBA-15 organic and inorganic hybrid composite. The obtained catalysts were characterized by XPS, XRD and TEM. The results of XPS and XRD indicate the existence of Pt NPs in the hybrid matrix. TEM images display the Pt NPs with narrow size distribution are monodispersed in SBA-15 channels. Catalytic property of the supported Pt catalysts was investigated in inorganic (ferricyanide to ferrocyanide by thiosulfate) and organic (p-nitrophenol to p-aminophenol by sodium borohydride) electron transfer (redox) reactions. In both cases, the reduction reactions followed smoothly and the catalysts showed excellent catalytic activity. Moreover, the catalysts can be easily separated and reused several times preserving good catalytic performance.     

New attempt at directly generating superbasicity on mesoporous silica SBA-15

Direct generation of superbasicity on mesoporous silica SBA-15 was realized by tailoring the host-guest interaction, and calcium species were selected as the guest in modifying SBA-15. The results show that calcium species could be homogeneously distributed on the surface of SBA-15. Because of the host-guest interaction, the decomposition of the supported calcium nitrate was apparently easier than the bulk one. Surprisingly, the calcium nitrates modified SBA-15 (CaNS) samples exhibited superbasicity with good preservation of the mesostructure after activation, differing from the potassium nitrate loaded SBA-15 samples that displayed weak basicity with collapsed mesostructure. The present superbasic CaNS materials also possess good water resistance and high surface areas, up to 429 m(2) g(-1), which is promising for their potential applications in adsorption and catalysis. Further investigation concerning the roles played by the guest in basicity formation on SBA-15 was conducted. The samples modified by Group 2 metal nitrates showed strong basicity with base strength (H-) of 22.5-27.0 and good preservation of mesostructure. In contrast, loading Group 1 metal nitrates on SBA-15 produced samples with weak basicity ( H-=9.3-15.0) and collapsed mesostructure after activation. Such differences can be related to the interaction between the resulting metal oxide and the silica support, as well as the mobility of the cations in the metal oxide.     

Co(Ⅲ)官能化SBA-15的制备、表征及其催化环己烯环氧化

通过环戊二烯基修饰的SBA-15(SBA-15-Cp)与马来酸酐的Diels-Alder反应及水解合成了邻二羧酸官能化的SBA-15,并将原位生成的Co(Ⅲ)络合物负载于其上制得Co(Ⅲ)官能化SBA-15样品SBA-15-Co(Ⅲ).傅里叶变换红外光谱、元素分析和X射线光电子能谱法结果证实羧酸官能团和Co(Ⅲ)成功地...     

Encapsulation of enzyme in large mesoporous material with small mesoporous windows

Trypsin has been encapsulated in the mesopores of a hierarchical mesoporous silica material synthesized via Cu(I) catalyzed azide-alkyne click reaction between azide functionalized large spherical SBA-15 particles and alkyne functionalized mesoporous silica nanoparticles (MSNs). Encapsulated trypsin functions as an efficient biocatalyst and can be recycled several times.     

pH值响应性毒死蜱/铜席夫碱配合物改性SBA-15的制备及缓释性能

以3-氨丙基三乙氧基硅烷（APTES）、水杨醛和铜离子为改性剂,通过后嫁接法制得铜席夫碱配合物改性SBA-15（Cu-SBA-15）,并以毒死蜱为模型药物,制备了毒死蜱/铜席夫碱配合物改性SBA-15缓释体系。利用TEM、SEM、XRD、N₂吸附-脱附、TG、FTIR和XPS对SBA-15、氨基改性SBA-15（NH₂-SBA-15）、水杨醛希夫碱改性SBA-15（SA-SBA-15）的形貌、结构和Cu-SBA-15的配位情况进行了表征,考察了SBA-15在改性前后对毒死蜱的吸附量和缓释性能,并着重探究了毒死蜱/铜席夫碱配合物改性SBA-15载药体系在不同pH值下的释药行为。结果表明,APTES和水杨醛能够通过后嫁接法修饰于SBA-15,修饰后仍保持十分有序的孔道结构。SBA-15通过改性后,其对毒死蜱的吸附量由100 mg·g^-1增加至195 mg·g^-1,且其对药物的缓释性能也得到改善。毒死蜱/铜席夫碱配合物改性SBA-15缓释体系显示出明显的pH值响应性,pH=3时的释药速率大于pH=11时,而在中性条件下的缓释效果相对最好。载药体系的释药行为可用Riger-Peppas动力学模型来描述,其药物释放由Fick扩散控制。     

pH值响应性毒死蜱/铜席夫碱配合物改性SBA-15的制备及缓释性能

以3-氨丙基三乙氧基硅烷(APTES)、水杨醛和铜离子为改性剂,通过后嫁接法制得铜席夫碱配合物改性SBA-15(Cu-SBA-15),并以毒死蜱为模型药物,制备了毒死蜱/铜席夫碱配合物改性SBA-15缓释体系。利用TEM、SEM、XRD、N2吸附-脱附、TG、FTIR和XPS对SBA-15、氨基改性SBA-15(NH_2-SBA-15)、水杨醛希夫碱改性SBA-15(SA-SBA-15)的形貌、结构和Cu-SBA-15的配位情况进行了表征,考察了SBA-15在改性前后对毒死蜱的吸附量和缓释性能,并着重探究了毒死蜱/铜席夫碱配合物改性SBA-15载药体系在不同pH值下的释药行为。结果表明,APTES和水杨醛能够通过后嫁接法修饰于SBA-15,修饰后仍保持十分有序的孔道结构。SBA-15通过改性后,其对毒死蜱的吸附量由100 mg·g~(-1)增加至195 mg·g~(-1),且其对药物的缓释性能也得到改善。毒死蜱/铜席夫碱配合物改性SBA-15缓释体系显示出明显的pH值响应性,pH=3时的释药速率大于pH=11时,而在中性条件下的缓释效果相对最好。载药体系的释药行为可用Riger-Peppas动力学模型来描述,其药物释放由Fick扩散控制。     

Direct synthesis and catalytic applications of ordered large pore aminopropyl-functionalized SBA-15 mesoporous materials

SBA-15 mesoporous silica has been functionalized with aminopropyl groups through a simple co-condensation approach of tetraethyl orthosilicate (TEOS) and (3-aminopropyl)triethoxysilane (APTES) using amphiphilic block copolymers under acidic conditions. The organic-modified SBA-15 materials have hexagonal crystallographic order, pore diameter up to 60 A, and the content of aminopropyl groups up to 2.3 mmol g(-1). The influences of TEOS prehydrolysis period and APTES concentration on the crystallographic order, pore size, surface area, and pore volume were examined. TEOS prehydrolysis prior to the addition of APTES was found essential to obtain well-ordered mesoporous materials with amino functionality. The amount of APTES incorporated in the silica framework increased with the APTES concentration in the synthesis gel, while the ordering of the mesoporous structure gradually decreased. Analysis with TG, IR, and solid state NMR spectra demonstrated that the aminopropyl groups incorporated in SBA-15 were not decomposed during the preparation procedure and the surfactant P123 was fully removed through ethanol extraction. The modified SBA-15 was an excellent base catalyst in Knoevenagel and Michael addition reactions.     

Self-assembly of a metallosupramolecular coordination polyelectrolyte in the pores of SBA-15 and MCM-41 silica

It is shown that intrinsically stiff chain aggregates of a metallosupramolecular coordination polyelectrolyte (MEPE) can form in the cylindrical nanopores of MCM-41 and SBA-15 silica by self-assembly of its constituents (metal ions and organic ligand). The UV/vis spectra of the resulting MEPE-silica composites exhibit the characteristic metal-to-ligand charge transfer band of the MEPE complex in solution. For the MEPE-silica composite in SBA-15 an iron content of 1.2 wt % was found, corresponding to ca. 10 MEPE chains disposed side by side in the 8 nm wide pores of the SBA-15 matrix. In the case of MCM-41 (pore width < 3 nm), where only one MEPE chain per pore can be accommodated, an iron content of 0.3 wt % was obtained, corresponding to half-filling of the pores. It was also found that MEPE chains spontaneously enter the pores of SBA-15, when a solution of MEPE is exposed to the silica matrix.