有序介孔三氧化二铟/还原氧化石墨烯纳米复合材料的制备及可见光催化性能

以有序介孔三氧化二铟(m-In2O3)和还原氧化石墨烯(RGO)为原料,采用紫外光照射法合成了介孔三氧化二铟/还原氧化石墨烯(m-In2O3-RGO)复合光催化剂.利用N2吸附-脱附、X射线衍射(XRD)、透射电子显微镜(TEM)、漫反射吸收光谱(DRS)和光电流测试等手段对样品进行表征.在可见光照射下,以对氯苯酚(4-CP)为目标污染物,考察了m-In2O3-RGO光催化剂的催化性能.结果表明,m-In2O3-RGO光催化剂具有完整的晶型和规则的孔道结构,有利于光生电子和空穴的分离.同时,作为固态电子受体与传输体的RGO促进了光生电子-空穴对的传输和分离,有效提高了可见光催化性能.掺杂2%(质量分数)RGO的复合光催化剂性能最佳,4 h可将4-CP降解96%以上,催化剂经多次循环使用后,其光催化活性基本保持不变.     

co-Condensation Synthesis of Salicylaldimine Calcium Complex Containing Mesoporous Silica Nanoparticles as Carriers for Drug Release

A series of functional mesoporous silica nanoparticles（MSNs） was synthesized by a one-step simple synthesis approach involving co-condensation of tetraethoxysilane（TEOS） and salicylaldimine ligand（Sal-Si） in the presence of cetyltrimethylammonium chloride（CTAC） under basic conditions.The target MSNs with different sizes （50,100 and 200 nm,respectively） were obtained.Furthermore,the Ca^2＋ cations were also introduced into MSNs.The prepared nanoparticles were characterized by means of infrared（IR） spectra,thermogravimetric analysis（TGA）,inductively coupled plasma（ICP）,CHN elemental analysis,nitrogen adsorption-desorption,scanning electron microscope（SEM） and transmission electron microscope（TEM）.Ibuprofen（IBU） which contains carboxyl groups was selected as a model drug.The results of drug loading and release reveal that the loading capacities and release behaviors of the model drug are highly dependent on the Ca^2＋ cations in MSNs.The release of IBU from the MSNs functionalized by Ca^2＋ cations is found to be effectively controlled when compared to the release from the MSNs without the functionalization of Ca^2＋ cations,which is due to the ionic interaction between carboxyl groups in IBU and Ca^2＋ cations in MSNs.     

Polymerization of Methyl Methacrylate with Samarocene Complex Supported on Mesoporous Silica

Synthesis of polymers with controlled molecular weight and narrow polydispersity is of both fundamental interest and practical importance. In recent years, high molecular weight poly (methyl methacrylate) (PMMA) having an unusually narrow polydispersity has been synthesized by using the unique initiating property of (C5Me5)2LnⅢR (R=H, Me, Ln=Sm, Yb) complexes1,2. Herein we report the results of the first example of the polymerization of methyl methacrylate (MMA) with samarocene complex …     

Chemical Immobilization of Heteropolyacid Catalyst on Inorganic Mesoporous Material for use as an Oxidation Catalyst

Recent progress on the chemical immobilization of heteropolyacid (HPA) catalyst on inorganic mesoporous material is reported in this review. Mesostructured cellular foam silica, mesoporous carbon, and nitrogen-containing mesoporous carbon were used as supporting materials. The mesoporous materials were modified to have a positive charge, and thus, to provide sites for the immobilization of HPA catalyst. By taking advantage of the overall negative charge of heteropolyanion, the HPA catalyst was chemically immobilized on the surface-modified mesoporous material as a charge-compensating component. Characterization results showed that the HPA catalyst was finely and molecularly dispersed on the surface of mesoporous material via strong chemical immobilization, and that the pore structure of mesoporous material was still maintained even after the immobilization of HPA catalyst. The supported HPA catalysts were applied to the model vapor-phase ethanol conversion, 2-propanol conversion, and methacrolein oxidation reactions. The supported HPA catalyst showed a better oxidation catalytic activity than the unsupported HPA catalyst in the model reactions. The enhanced oxidation catalytic performance of the supported HPA catalyst was attributed to the finely dispersed HPA catalyst, which was chemically immobilized on the positive site of mesoporous material by sacrificing its proton (Brönsted acid site). The HPA catalyst chemically immobilized on mesoporous material served as an excellent oxidation catalyst.     

Base Metal-terpyridine Complex Immobilized on Stationary Phase Aimed as Reusable Hydrosilylation Catalyst

The catalytic activity of a base metal-terpyridine complex immobilized on silica gel ( M(tpy)X₂@SiO₂/H₂O : M=Mn, Fe, Co, Ni, Cu; X=Cl, Br) for hydrosilylation was investigated. Co(tpy)Br₂@SiO₂/H₂O in the presence of NaBHEt₃ exhibited the highest catalytic activity for hydrosilylation of 1-octene with diphenylsilane (Ph₂SiH₂) to form the anti-Markovnikov-type hydrosilylation compound as the main product. The reusability of Co(tpy)Br₂@SiO₂/H₂O activated by NaBHEt₃ was examined. It was found that the catalytic activity decreased with repeated use because of the peeling off of the Co complex anchor portion from the silica gel surface upon the attack of NaBHEt₃. The introduction of Co(OAc)₂ instead of CoBr₂ to silica gel formed Co(tpy)(OAc)₂- and Co(tpy)(OH)₂-immobilized silica gel, which exhibited catalytic activity for the hydrosilylation in the absence of an activator such as NaBHEt₃. The glassware in which Co(tpy)(OH)₂ was immobilized on the inner wall was prepared. It was found that the hydrosilylation catalytically occurred on the surface of a pretreated glassware and that the catalytic activity did not decrease even after 10 repeated uses.     

介孔TiO2担载Cu（OH）2及其催化炔烃氧化偶联反应

在有序介孔TiO₂中原位担载了高分散的Cu（OH）₂,并将其应用于炔烃的氧化偶联（Glaser）多相催化反应,该催化剂表现出很高的催化活性.Cu（OH）₂为催化剂的主要活性组分,TiO₂的有序介孔和较大的比表面积有利于Cu（OH）₂的分散以及反应物和产物的扩散,具有重要的应用前景.     

Efficient CO2 Hydrogenation to Formate with Immobilized Ir-Catalysts Based on Mesoporous Silica Beads

The Nozaki Ir-based CO₂ hydrogenation catalyst was successfully immobilized on post-functionalized silica beads (d=200 μm) through click chemistry. This material hydrogenates CO₂ into formic acid with turnover numbers reaching 2.8×10⁴ in a batch reactor within 24 hours, paving the way towards the design of efficient heterogeneous catalysts for this transformation.     

N掺杂纳米TiO2可见光催化氧化丙烯的动力学行为

通过在不同温度的氨气气氛中处理纳米管钛酸(NTA)制得具有可见光响应的氮掺杂纳米二氧化钛. X射线衍射(XRD)谱表征结果显示, 当温度高于400 ℃时, 样品由正交晶系向锐钛矿相转变, 700 ℃处理得到的样品除了锐钛矿相TiO2外还有TiN 新相存在; 紫外-可见扩散漫反射(DRS)结果表明, 氮掺杂纳米TiO2在整个可见光区都有明显的吸收. 不同波长可见光及不同气体流速的光催化氧化丙烯动力学研究表明, 活性最好的N掺杂纳米TiO2催化剂(600 ℃ NH3处理)对可见光的利用范围可扩展至500 nm, 低浓度丙烯光催化氧化反应为一级反应.     

Efficient One-Pot Synthesis of Polyhydroquinoline Derivatives Using Silica Sulfuric Acid as a Heterogeneous and Reusable Catalyst Under Conventional Heating and Energy-Saving Microwave Irradiation

An efficient Hantzsch four-component condensation reaction for the synthesis of polyhydroquinoline derivatives was reported under two conditions: solvent-free conventional heating and energy-saving microwave irradiation. The process is simple and environmentally benign, and the use of a heterogeneous and reusable catalyst, high yields, and short reaction times are the key features of this protocol.     

Active and Recyclable Gold Metal Nanoparticles Catalyst Supported on Nitrogen-Doped Mesoporous Carbon for Chemoselective Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol

Several supported gold metal catalysts with different Au nanoparticles sizes were prepared and evaluated for the chemoselective hydrogenation of cinnamaldehyde (CA) to cinnamyl alcohol (CAL). To investigate the structure-activity relationship, stability of catalyst, heterogeneity and recyclability, the structural characteristics of materials and Au catalysts (fresh and spent catalysts) were studied by employing variety of physico-chemical techniques. The interrelationship among Au nanoparticles size (nm) with turnover frequency (h⁻¹) of Au catalysts has also been explored. Among the various Au catalysts tested, nitrogen-doped mesoporous carbon (NMC) supported Au catalyst having homogeneously dispersed (78.8%) Au nanoparticles (1.6 nm) synthesized by sol-immobilization method (Au-NMC-SI) demonstrated improved catalytic activity affording 78% CAL selectivity and 94.2% CA conversion without using any promoter. Moreover, Au-NMC-SI catalyst exhibited good recyclability and stability. The catalyst synthesis approach described in this investigation opens up a novel strategy for the design of highly efficient metal nano-catalysts supported on NMC materials.     

CuO Quantum‐Dot‐Sensitized Mesoporous ZnO for Visible‐Light Photocatalysis

How to extend ultraviolet photocatalysts to the visible‐light region is a key challenge for solar‐driven photocatalysis. Herein, we show that ultraviolet ZnO photocatalysts can present high visible‐light photocatalytic activity when combined with CuO quantum dots (QDs; <3 nm). Theoretical analysis demonstrates that the quantum size effect plays a key role in the photoactivity of the CuO/ZnO composite. For CuO QDs smaller than 3 nm, the separated charges could transfer from CuO QDs to the conduction bands of ZnO due to quantum splitting of the CuO energy level and phonon compensation for the difference in the conduction band minimum of CuO and ZnO; however, this process would not occur with the disappearance of the quantum size effect. Further structural analysis demonstrates that interfacial charge separation and transfer between ZnO and CuO dominate the photocatalytic processes instead of a single CuO or ZnO surface. Compared with ZnO? noble metal structures (e.g., ZnO? Ag or ZnO? Au), these ZnO? CuO QD composites present wider absorption bands, higher visible photocatalytic efficiencies, and lower costs.     

Immobilization of Pd Catalysts on Mesoporous Silica for Amine- and Copper-Free Sonogashira Coupling Reactions

Immobilization of catalysts on solid supports is a promising approach to combine the advantages of heterogeneous and homogeneous catalysts. Pd(PPh₃)₂Cl₂, known as an extremely active homogeneous catalyst for the Sonogashira coupling reaction, has been immobilized on high-surface-area MCF (mesocellular foams)–type mesoporous silica powder modified with 3-aminopropyltriethoxysilane and subsequently with diphenylphosphine. The functionalized MCF-type silica and supported catalysts have been characterized by x-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), elemental analysis, nitrogen sorption porosimetry, and scanning electron microscopy (SEM). Such supported Pd catalysts have proven to be useful recyclable reagents for copper- and amine-free Sonogashira coupling reactions of haloaromatic compounds with terminal alkynes.     

Palladium Supported on Porous Organic Polymer as Heterogeneous and Recyclable Catalyst for Cross Coupling Reaction

Palladium immobilized on an amide and ether functionalized porous organic polymer (Pd@AEPOP) is reported to be an effective heterogeneous catalyst for the Heck cross-coupling reaction of aryl iodides with styrene for the synthesis of diphenylethene derivatives. Excellent yields can be obtained using a 0.8 mol% Pd catalyst loading under the optimized reaction condition. The heterogeneous Pd@AEPOP catalyst can also be applied on the Suzuki reaction and the reduction of nitroarene.     

Heterogeneous Catalysis for Water Oxidation by an Iridium Complex Immobilized on Bipyridine‐Periodic Mesoporous Organosilica

Heterogenization of metal‐complex catalysts for water oxidation without loss of their catalytic activity is important for the development of devices simulating photosynthesis. In this study, efficient heterogeneous iridium complexes for water oxidation were prepared using bipyridine‐bridged periodic mesoporous organosilica (BPy‐PMO) as a solid chelating ligand. The BPy‐PMO‐based iridium catalysts (Ir‐BPy‐PMO) were prepared by postsynthetic metalation of BPy‐PMO and characterized through physicochemical analyses. The Ir‐BPy‐PMOs showed high catalytic activity for water oxidation. The turnover frequency (TOF) values for Ir‐BPy‐PMOs were one order of magnitude higher than those of conventional heterogeneous iridium catalysts. The reusability and stability of Ir‐BPy‐PMO were also examined, and detailed characterization was conducted using powder X‐ray diffraction, nitrogen adsorption, ¹³C DD MAS NMR spectroscopy, TEM, and XAFS methods.     

Alkane Oxidation by an Immobilized Nickel Complex Catalyst: Structural and Reactivity Differences Induced by Surface‐Ligand Density on Mesoporous Silica

Immobilized nickel catalysts SBA*‐ L ‐x/Ni ( L =bis(2‐pyridylmethyl)(1H‐1,2,3‐triazol‐4‐ylmethyl)amine) with various ligand densities ( L content (x)=0.5, 1, 2, 4 mol % Si) have been prepared from azidopropyl‐functionalized mesoporous silicas SBA‐N₃‐x. Related homogeneous ligand LtBu and its Ni^II complexes, [Ni( LtBu )(OAc)₂(H₂O)] ( LtBu /Ni) and [Ni( LtBu )₂]BF₄ (2 LtBu /Ni), have been synthesized. The L /Ni ratio (0.9–1.7:1) in SBA*‐ L ‐x/Ni suggests the formation of an inert [Ni L ₂] site on the surface at higher ligand loadings. SBA*‐ L ‐x/Ni has been applied to the catalytic oxidation of cyclohexane with m‐chloroperbenzoic acid (mCPBA). The catalyst with the lowest loading shows high activity in its initial use as the homogeneous LtBu /Ni catalyst, with some metal leaching. As the ligand loading increases, the activity and Ni leaching are suppressed. The importance of site‐density control for the development of immobilized catalysts has been demonstrated.     

A Rhodium Catalyst Superior to Iridium Congeners for Enantioselective Radical Amination Activated by Visible Light

A bis‐cyclometalated rhodium(III) complex catalyzes a visible‐light‐activated enantioselective α‐amination of 2‐acyl imidazoles with up to 99 % yield and 98 % ee. The rhodium catalyst is ascribed a dual function as a chiral Lewis acid and, simultaneously, as a light‐activated smart initiator of a radical‐chain process through intermediate aminyl radicals. Notably, related iridium‐based photoredox catalysts reported before were unsuccessful in this enantioselective radical C?N bond formation. The surprising preference for rhodium over iridium is attributed to much faster ligand‐exchange kinetics of the rhodium complexes involved in the catalytic cycle, which is crucial to keep pace with the highly reactive and thus short‐lived nitrogen‐centered radical intermediate.     

Silica Chloride/NaNO2 as a Novel Heterogeneous System for the Nitration of Phenols Under Mild Conditions

Nitrophenols can be obtained via direct nitration of phenols with silica chloride, NaNO₂, and wet SiO₂ at room temperature in moderate to high yields.

     

Intercalation Effect in NiAl-layered Double Hydroxide Nanosheets for CO2 Reduction Under Visible Light

Photocatalytic reduction of CO2(CO2PR)to valuable solar fuels is considered as a promising route to the amelioration of fossil fuel conundrum and the mitigation of greenhouse gases.Although progress has been made to enhance CO2PR performance,the available method that can promote the selectivity of CO2PR products remains to be a challenge.In this work,we synthesized NO3-or CO32-intercalated NiAl-layered double hydroxide(NiAl-LDH)photocatalysts and investigated the performance of CO2PR in the presence of an electron donor and a photosensitizer.Compared with Ni2Al-CO32-,Ni2Al-NO3-exhibited superior catalytic performance in the CO2PR,and the resulted selectivity of CH4 in Ni2Al-NO3-(6.1%)was 12.2 times that of Ni2Al-CO32-(0.5%)under visible light irradiation.X-Ray absorption fine structure(XAFS)result reveals a relative abundance of defects in Ni2Al-NO3-,which played as active sites and promoted charge transfer in CO2PR for the efficient CH4 evolution.     

N-杂环卡宾Ru配合物的合成及其在Suzuki偶联反应中的催化应用

合成了两个新的氮杂环卡宾金属钌配合物1和2,通过核磁共振氢谱、核磁共振碳谱、红外光谱和元素分析对其结构进行了表征,同时,X射线单晶衍射确证了配合物2的结构为cis(I)顺式构型.化合物1和2均能在温和的反应条件下有效催化卤代芳烃和苯硼酸的Suzuki偶联反应,并表现出较高的催化活性.