Cetyltriethylammonium Bromide Research Articles

Yolk@shell layered NiCo hydroxide: Controllable synthesis, sulfuration and electrochemical applications for hybrid supercapacitors

Developing electrode materials with rational structures is an important strategy for constructing high-performance hybrid supercapacitors (HSCs). Herein, designing a yolk@shell structure composed of layered nickel-cobalt hydroxide with a Ni/Co feed ratio of 4:1 (denoted as layered Ni4Co1 hydroxide) and nickel-cobalt sulfide with a sulfuration duration of 2 h (labeled as Ni4Co1S-2h) to enhance the capacity and stabilize the cyclic performances of HSCs was conducted. The yolk@shell structured microspheres of layered Ni4Co1 hydroxide were synthesized using a cetyltriethylammonium bromide (CTAB) template-assisted solvothermal treatment. Subsequently, nickel-cobalt sulfide microspheres with the unique yolk@shell structure were prepared from layered Ni4Co1 hydroxide precursor. Notably, yolk@shell Ni4Co1S-2h microspheres feature a large specific surface area and an interspace between the yolk and shell, facilitating charge transfer but also effectively alleviating volume expansion during ion transport and electron transfer. The resultant Ni4Co1S-2h material demonstrates a superior capacity of 902.2 C·g−1 at 3·A g−1, while the assembled Ni4Co1S-2h//porous carbon (PC) HSC shows a relatively higher energy density (83.1 Wh·kg−1) and power density (15000 W·kg−1). The design of yolk@shell structured layered Ni4Co1 hydroxide and Ni4Co1S-2h electrode materials holds significant implications for the advancement of high-performance HSCs.

Self-assembly of hard anions around cationic gold nanorods: potential structures for SERS.

The placement of polyoxometalates next to the surface of noble metallic nanoparticles has been found to enhance the surface-enhanced Raman scattering (SERS) effect. The enhancement is believed to stem from either charge (electrostatic attraction) or chemical effects. Anisotropic gold nanorods are recognized as useful nanostructures for SERS, mainly due to the high electric field enhancement at their ends. The presented work examines the use of a polyoxometalate encapsulated gold nanorod for SERS, to assess whether the two enhancement pathways would be synergetic. For this, a gold nanorod-polyoxometalate composite was synthesized by coating cetyltrimethylammonium bromide-stabilized gold nanorods with a silicotungstic Keggin anion through electrostatic attraction. The structure was characterized, confirming that the nanorods have been fully encapsulated by the polyoxometalate. The SERS performance of the composite was assessed in solution using crystal violet as a SERS indicator, finding an analytical enhancement factor of 1.8 × 104 in colloidal solution. The enhancement mechanism was examined first by comparison to gold nanorods stabilized by a cetyltriethylammonium bromide bilayer, cationic thiol bound polyoxometalate, and polyelectrolyte coating. Next, composites made using polyoxometalates of different atomic composition and charge were examined. It was concluded that the polyoxometalate charge had a noticeable effect on the enhancement while the atomic composition did not. Furthermore, high enhancement is observed mainly in cases where the nanorod monolayer allows the sequestration of the dye molecule into the nanoparticle's ligand layer. The proposed mechanism therefore involves the negative charge of the polyoxometalate attracting the positively charged dye, and facilitating the sequestration of the dye within the ligand bilayer, closer to the nanorod's surface.

Molecular co-localization of multiple drugs in a nanoscopic delivery vehicle for potential synergistic remediation of multi-drug resistant bacteria

Anti-microbial resistant infection is predicted to be alarming in upcoming years. In the present study, we proposed co-localization of two model drugs viz., rifampicin and benzothiazole used in anti-tuberculosis and anti-fungal agents respectively in a nanoscopic cationic micelle (cetyl triethyl ammonium bromide) with hydrodynamic diameter of 2.69 nm. Sterilization effect of the co-localized micellar formulation against a model multi-drug resistant bacterial strain viz., Methicillin resistant Staphylococcus aureus was also investigated. 99.88% decrease of bacterial growth in terms of colony forming unit was observed using the developed formulation. While Dynamic Light Scattering and Forsters Resonance Energy Transfer between benzothiazole and rifampicin show co-localization of the drugs in the nanoscopic micellar environment, analysis of time-resolved fluorescence decays by Infelta-Tachiya model and the probability distribution of the donor–acceptor distance fluctuations for 5 μM,10 μM and 15 μM acceptor concentrations confirm efficacy of the co-localization. Energy transfer efficiency and the donor acceptor distance are found to be 46% and 20.9 Å respectively. We have also used a detailed computational biology framework to rationalize the sterilization effect of our indigenous formulation. It has to be noted that the drugs used in our studies are not being used for their conventional indication. Rather the co-localization of the drugs in the micellar environment shows a completely different indication of their use in the remediation of multi-drug resistant bacteria revealing the re-purposing of the drugs for potential use in hospital-born multi-drug resistant bacterial infection.

Insight into the role of anions in the formation of mesoporous silicates

Cationic surfactants can form micellar structures in solution and the condensation of silicate around these micellar structures results in the inorganic/organic mesostructured composites. Anions other than silicates in the solution were believed to be located closely to the headgroup of the cationic surfactant micelle and thus affected the effective headgroup area, a component of the surfactant packing parameter g (g = V/a0l, where V is the chain volume, a0 is the effective headgroup area, and l is the chain length). In the presence of H2SO4, HCl, HBr, and HNO3, the surfactant cetyltriethylammonium bromide (CTEABr) directed the well-ordered mesophases of three-dimensional (3D) hexagonal P63/mmc, cubic Pm3‾n, 2D hexagonal p6mm, and cubic Ia3‾d, respectively. The diversity of the mesophases from CTEABr was attributed to the anion tuning of the effective headgroup area of CTEA+ in surfactant packing parameter g by closely located anions of SO42−, Cl−, Br−, and NO3− with various radii and hydratability. In this work, we discovered that part of Cl−, Br−, and NO3− can penetrate into the micellar system of CTEA+, which may increase the chain volume V of CTEA+ to some degree. The distance of anions to the center of the micelle, determined by the liquid 1H NMR analyses, was in the order of SO42− > Cl− > Br− > NO3−, which is consistent with the Hofmeister series. The deeper penetration of anions into the micelle may lead to the larger chain volume V and surfactant packing parameter g. Such insight into the location of anions in micellar system provided us a new picture on the formation mechanism of mesoporous silica and other mesostructured materials in solution.

First Report of Brown Spot Needle Blight on Pinus thunbergii Parl. Caused by Aureobasidium pullulans in China.

Pinus thunbergii Parl., known as black pine, is widely distributed all over China. This pine variety can prevent soil desertification and promote soil conservation and is excellent for constructing fast-growing forests and shelter belts. The timber of this species can be used for infrastructure construction and furniture production. In August 2020, needle blight symptoms were found on several trees of black pine in Sichuan Province, China. Further surveys showed that these symptoms are common while the disease incidence is less than 30% which indicated the severity of the disease is mild. The tips of old needles first turn grayish green and developed into brown bands ranging from 1 to 2 mm. To determine the pathogen, 20 needle samples with typical symptoms were disinfected with 75% alcohol, and sections of the tissue were cut from joints of diseased and healthy tissues (visually healthy) with a sterilized scalpel, surface sterilized for 45 seconds in 75% alcohol, soaked for 90 seconds in 1.5% NaCIO, rinsed in sterilized water and dried. Small cut tissues were placed on potato dextrose agar (PDA) at 25℃ for 10 days. Pure cultures were obtained by monosporic isolation. The colonies initially appeared white to cream, yeast-like, and later turned to pink and remained at least 10 days. Conidia were hyaline, smooth-walled, single-celled, and ellipsoidal with variable shape and size, 7.5 to 16 × 3.5 to 7 µm (Zalar et al. 2008). DNA was extracted from the mycelium of the isolate by the cetyltriethylammonium bromide (CTAB) method and amplified through polymerase chain reaction (PCR) with the internal transcribed spacer (ITS) region of rDNA and partial β-tubulin genes of a representative isolate (SC05) were amplified using the ITS1/ITS4 and Bt2a/Bt2b primer pairs, respectively(Wu et al. 2017). The sequences submitted to GenBank (Accession Nos. MW228368 for ITS and MW256762 for β-tubulin) showed high similarity with BLAST sequences of Aureobasidium pullulans (ITS, KR704881 [100%]; β-tubulin, MT671934 [99.49%]). For the pathogenicity test, a conidial suspension was prepared with a concentration of 2.0 × 107 conidia/ml. The suspension was sprayed onto 3 annual seedlings' needles, and the control was sprayed with sterile water. Inoculated and non-inoculated plants were kept in humid chambers in a glasshouse. After 10 days, typical symptoms appeared on inoculated needles, whereas control needles remained symptomless. The fungus, A. pullulans, was reisolated from those lesions, confirming Koch's postulates. No symptoms were observed on control plants. Aureobasidium pullulans, a ubiquitous saprophytic fungus on many fruits and very rarely reported to cause disease on pine needles. Only reported invasion of Ozone-injured needles in P. strobus (Costonis and Sinclair 1972) and needles damaged by acid rain in P. sylvestris (Ranta 1990). To our knowledge, this is the first report of brown spot needle blight on P. thunbergii caused by A. pullulans in China. The disease represents a threat to pine manufactures and more research on the pathogenesis and management is needed. .

Formulation induces direct DNA UV-A photooxidation. Part II. Pro-oxidant effect of formulated Vitamin E via generation of singlet oxygen

The study focuses on the photosensitization of DNA in nanoemulsion-type systems containing Vitamin E under UVA radiation. Cetyltriethylammonium bromide (CTEAB) surfactant was first combined with Vitamin E to form a CTEAB-Vitamin E nanoemulsion to complex the plasmid pBR322, in TRIS/HCl buffer. The self-organization properties of the CTEAB-Vitamin E system were studied by complementary physico-chemical characterizations (tensiometry, pyrene fluorimetry and scattering experiments). It formed a nanoemulsion composed of CTEAB micelles (that can incorporate Vitamin E) as well as larger Vitamin E droplets. This nanoemulsion was then contacted with DNA and the resulting formulated CTEAB-Vitamin E-DNA lipoplex was irradiated under UVA radiation (λ ≥ 335 nm). The presence of Vitamin E generated a significant enhancement of the DNA photodamage as shown by agarose gel electrophoresis and quantified by photodensitometry. It underlines the pro-oxidant role of the Vitamin E in this self-assembled system. A mechanistic study based on the use of specific scavengers reveals that the singlet oxygen is responsible for the UVA DNA photooxidation in the CTEAB-Vitamin E-DNA lipoplex.

Formulation induces direct DNA UVA photooxidation. Part I. Role of the formulating cationic surfactant

Cetyltriethylammonium bromide (CTEAB) was considered as a cationic surfactant to form lipoplexes with DNA. In TRIS/HCl buffer, CTEAB self-assembles above its critical micelle concentration (CMC = 0.15 mM) into small spherical micelles as determined by complementary scattering techniques. This surfactant readily interacts with the supercoiled plasmid DNA pBR322 via electrostatics and hydrophobic interactions. Upon increasing surfactant concentration, successive phase transitions are observed from partial neutralization to full compaction of DNA as evidenced by agarose gel electrophoresis, tensiometry, pyrene fluorescence, UV–Vis absorbance and circular dichroism measurements. Under UVA radiation (λ ≥ 335 nm), we show that the presence of the surfactant increases photooxidized damage on DNA especially in the compacted state. A mechanistic study using selective scavengers shows the involvement of singlet oxygen in these oxidative processes due to the direct UVA absorption of DNA itself.

Surfactant effect on controllable phase transformation and UV-shielding performance of titanium dioxide

The crystalline structure, size and morphology of TiO2 have crucial influence on its physicochemical performance. The crystal growth process includes crystal transformation and morphology evolution, which is closely related to the solution environment. In this work, rutile TiO2 was synthesized via surfactant-assisted method by using titanium sulfate as titanium source. Factor associated with crystalline structure of TiO2 were investigated including surfactant type and concentration. Results showed that when the concentration of cetyltriethylammonium bromide (CTMAB) was greater than or equal to 3 mmol/L, or the concentration of dodecyltriethylammonium bromide (1231) was greater than or equal to 4 mmol/L, surfactants promoted transformation from anatase to rutile titania. The UV-shielding performance of the surfactant-aided titania increased, and the band gap width decreased by 0.2–0.3 eV. More importantly, we found that the cationic surfactant played a decisive role in anatase-rutile transformation of titania. The microspherical cationic surfactant micelles were chelated by electrostatic adsorption and [TiO6] octahedron, and the [TiO6] octahedron tended to grow to the opposite side, which was formed to form rutile titania.

Enhanced sunlight photocatalytic degradation of methylene blue by rod-like ZnO-SiO2 nanocomposite

This work aims to develop a novel and economical rod-like zinc oxide–silicon dioxide (ZS) nanocomposite by a simple co-precipitation method with different surfactants, such as cationic surfactant cetyl triethylammonium bromide (CTAB), non-ionic polymer polyvinyl pyrrolidone (PVP), and an anionic surfactant sodium dodecyl sulfate (SDS). The phase identification, surface topography and optical properties were analyzed by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), UV-Visible and Photoluminescence Spectroscopy. The photocatalytic degradation efficiency of the prepared nanocomposite was measured using model organic pollutant of methylene blue (MB) in water under sun light irradiation. Due to surface plasmon resonance (SPR) effect of SiO2 nanoparticles, ZS nanocomposite shows an absorption peak (434 nm) in the visible region. Hence the maximal MB degradation efficiency of 97.8% was achieved under 90 min of sunlight irradiation. Among the three surface-active agents, cationic surfactant shows the highest degradation ability with ZS nanocomposite. This work will open a new platform for further development of ZS-based nanocomposites to solve the global photocatalytic and waste water treatment problem.

Radial-like mesoporous silica sphere: A promising new candidate of supporting material for storage of low-, middle-, and high-temperature heat

In the study, polyethylene glycol (PEG), lithium nitrate (LiNO3), and sodium sulfate (Na2SO4) were employed as the low-, middle-, and high-temperature heat storage media, respectively. A series of novel shape-stabilized phase change materials were tailored by a post-preparation method with previously synthesized radial-like mesoporous silica and their structural and thermal properties were characterized. The silica was synthesized through a facile self-assembly process using cetyltriethylammonium bromide as the main template and tetraethyl orthosilicate as silica precursor. The obtained phase change composites showed good shape stability and high thermal energy storage capacity. The morphology and structure of the radial-like mesoporous silica were investigated after combining with different heat storage media. These composites exhibited excellent thermal stability, chemical compatibility, and thermal reliability. The efficient silica support has opened up some new application of energy materials based on novel phase change material/silica composites, such as energy conversion and heat storage for different temperature requirements.

Influence of surfactants on the microstructure and electrochemical performance of the tin oxide anode in lithium ion batteries

Different SnO2 micro–nano structures are prepared by precipitation using a surfactant-assisted process. The surfactants, such as cetyltriethylammonium bromide (CTAB) or sodium dodecyl benzene sulfonate (SDBS), can change the crystal growth direction and microstructure of SnO2 primary and secondary particles. Larger SnO2 nanosheets were synthesized without surfactant, and micro-fragments composed of small nanospheres or nanocubes were synthesized using CTAB and SDBS. The CTAB-assisted process resulted in smaller primary particles and larger specific surface area and larger pore volume, as a lithium-ion-battery anode that exhibits superior electrochemical performance compared to the other two anodes. Further investigation showed that the concentration of CTAB had a substantial influence on the growth of the crystal face, morphology and size of the SnO2 secondary particles, which influenced the electrochemical performance of the anode. A simple mechanism for the influence of surfactants on SnO2 morphology and size in the precipitation and annealing process is proposed.

Investigation on the structural properties of CeO2 nanofibers via CTAB surfactant

The solvothermal reaction of cerium oxide (CeO2) in ethanol by using cetyltriethylammonium bromide (CTAB) as surfactant resulted in the formation of hexagonal cubic shaped CeO2 nanofibers. Low concentration of CTAB in ethanol was conductive for the formation of CeO2 nanofibers. The Fourier transform infrared (FTIR) spectroscopic analysis showed a standard peak of CeO2 at 541cm−1. The as-synthesized products were characterized by high resolution transmission electron microscopy (HRTEM) and room temperature Photoluminescence (PL) studies. The chemical composition of the samples and the valence states of elements were determined by X-ray photoelectron spectroscopy (XPS) in detail.

Oil detachment from silica surface modified by carboxy groups in aqueous cetyltriethylammonium bromide solution

Using molecular dynamics simulations, we investigated the process of oil detachment from silica surface modified by carboxy groups in aqueous surfactant (cetyltriethylammonium bromide (CTAB)) solution. It is demonstrated that CTAB molecules promote the formation of water channel between oil molecules and silica surface, which is vital to the detachment of oil drop from silica surface. In this paper, the effects of temperature, surfactant concentration, and calcium ion concentration on the oil detachment from silica surface have been extensively examined. We find that appropriate temperature, surfactant concentration, and calcium ion concentration are crucial for improving oil detachment efficiency. Our study can provide a simple method to design and choose appropriate oil-displacing agents, which is important for its applications in oil recovery, ore floatation, detergency, printing fields, and so on.

Hierarchical porous silicon carbide with controlled micropores and mesopores for electric double layer capacitors

Three-dimensional hierarchical micro and mesoporous silicon carbide spheres (MMPSiC) are prepared by the template method and carbonization reaction via the aerosol spray drying method. The mesopores are generated by the self-assembly of the structure-directing agents, whereas the micropores are derived from the partial evaporation of Si atoms during carbonization. To investigate the effect of mesopore size on electrochemical performance, three types of MMPSiC with different mesopore size were fabricated by using three different structure directing agents (cetyltriethylammonium bromide (CTAB), Polyethylene glycol hexadecyl ether (Brij56), and Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123)). The MMPSiC electrode prepared with Brij56 exhibits the highest charge storage capacity with a specific capacitance of 253.7 F g−1 at a scan rate of 5 mV s−1 and 87.9% rate performance from 5 to 500 mV s−1 in 1 M Na2SO4 aqueous electrolyte. The outstanding electrochemical performance might be because of the ideal mesopore size, which effectively reduces the resistant pathways for ion diffusion in the pores and provides a large accessible surface area for ion transport/charge storage. These encouraging results demonstrate that the MMPSiC prepared with Brij56 is a promising candidate for high performance electrode materials for supercapacitors.

ChemInform Abstract: One‐Pot Synthesis of Bi24O31Br10/Bi4V2 O11 Heterostructures and Their Photocatalytic Properties.

AbstractThe title heterostructures are solvothermally synthesized from ethylene glycol solutions containing Bi(NO3)3, NH4VO3, and cetyltriethylammonium bromide (pH 8 adjusted with aq.

Preparation and catalytic properties of mesoporous titanosilicate of cubic Pm3n structure

Mesoporous titanosilicate of cubic Pm3n structure was prepared for the first time using cetyltriethylammonium (CTEA+) bromide as pore-directing agent in alkaline condition (pH around 9) with the aid of NaCl salt. The alkaline synthesis condition facilitated the incorporation of Ti(IV) into the silica framework as well as the assembly of mesoporous silica with zeolite seeds. Two kinds of silica sources were used. The material prepared with sodium silicate was named Ti-SBA-1-alk, and the other named Ti-ZSBA-1 was prepared with the seeds of titanosilicalite-1 (TS-1). The studies by UV–Vis and Ti K-edge XANES spectra indicated that the Ti(IV) in Ti-SBA-1-alk was favorably in tetrahedral (Td) coordination and should be incorporated into the framework of mesoporous silica, whereas a larger amount of Ti(IV) in Ti-ZSBA-1 was in octahedral coordination. In oxidation of 2,3,6-trimethylphenol (TMP) to 2,3,5-trimethylbenzoquinone (TMBQ) using hydrogen peroxide as the oxidant, the mesoporous titanosilicate materials were found to be efficient catalysts, while only trace TMP conversion was observed over TS-1 due to its small zeolitic pores. In comparison of mesoporous titanosilicate materials in similar pore diameters, Ti-SBA-1-alk and Ti-ZSBA-1 both of cubic Pm3n structure gave higher TMBQ selectivities than Ti-MCM-41 of 2D channeling pores, attributing to the better diffusion of the phenoxyl radicals in the three-dimensional pores. Moreover, Ti-SBA-1-alk which contained more Td-coordinated Ti(IV) showed higher catalytic activities than Ti-ZSBA-1.

Development of a Reference Standard of Escherichia coli DNA for Residual DNA Determination in China

This collaborative study developed the first national Escherichia coli (E. coli) DNA reference standard for standardizing quantitative residual DNA assay methods, fluorescence dye (PicoGreen) and quantitative PCR (q-PCR), which were widely employed to measure residual DNA contents of prokaryotic-derived recombinant products. High purity of E. coli strain BL21 was extracted by the cetyl triethyl ammonium bromide (CTAB)/phenol chloroform method, analyzed by UV-visible spectrophotometry and electrophoresis, diluted with tris-EDTA (TE) buffer and manually dispensed. Then, with a cooperative calibration among six laboratories, including five manufacturers and one national control laboratory, the concentration of E. coli DNA standard solution was determined as 96.2 μg/mL (95% C.I: 95.5–96.9 μg/mL, CV 3.4%). The candidate showed excellent stability both from accelerated degradation study and real time stability study. The applicability study showed that the E. coli DNA reference could reach the sensitivity of 0.781 ng/mL and 1 fg/μL, respectively, in fluorescent dye and q-PCR assay, and also had good linearity and precision. The consistency of the reference could meet the requirements of the national reference standard. As a conclusion, the candidate material was suitable to serve as a China national standard for E. coli residual DNA determination. The successful establishment of the E. coli DNA standard will facilitate the standardization of quantitative methods for testing residual host cell DNA.

GNP confinement at the interface of cationic reverse micelles: influence in improving the lipase activity

The present work reports thiol-assisted confinement of gold nanoparticles (GNPs) at the interface of reverse micelles with the aim to enhance the interfacial area and thereby the efficiency of surface-active Chromobacterium viscosum lipase. The strong gold capping ability of optimally hydrophobic thiols (1-dodecanethiol and 1,6-hexanedithiol) was aptly utilized to pull GNPs (∼3–5 nm) from the water pool to the oil/water interface of cetyltrimethylammonium bromide (CTAB) reverse micelles. These small sized GNPs were fitted at the microscopic interface of CTAB reverse micelles possibly because of the comparable thickness of the interface (∼1–2 nm) to that of the GNP diameter. Lipase solubilized within this augmented interface enjoys a flexible conformation, which resulted in the improvement of its activity (∼2.5 fold) with respect to only CTAB microemulsion. The activity of lipase within CTAB reverse micelles was thoroughly studied in the presence of mono and dithiols with varying chain length, where a greater improvement in activity was observed with dithiols. Bidentate ligand property of dithiols led to firm localization of higher number of GNPs at the interface which enhanced the total space in vicinity of enzyme at the interfacial domain. Fitting fusion of small sized GNPs within CTAB reverse micellar interface was confirmed by microscopic and spectroscopic studies. Smooth localization of lipase at the enhanced interface was also confirmed from the improvement in its secondary structure (α-helical content) in circular dichroism spectroscopic analysis. Interestingly, large sized GNPs (∼8 and 20 nm) were found to be well fitted at the interface of bigger head group-containing surfactants, cetyltriethylammonium bromide (CTEAB) and cetyltripropylammonium bromide (CTPAB). The hydrolytic efficiency of lipase in 1,6-hexanedithiol included GNP (∼20–25 nm)-doped CTPAB reverse micelles improved by ∼3.4 fold compared to that observed in only CTAB.

Synthesis and solid-state NMR characterization of cubic mesoporous silica SBA-1 functionalized with sulfonic acid groups

Well-ordered cubic mesoporous silicas SBA-1 functionalized with sulfonic acid groups have been synthesized through in situ oxidation of mercaptopropyl groups with H2O2 via co-condensation of tetraethoxysilane (TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) templated by cetyltriethylammonium bromide (CTEABr) under strong acidic conditions. Various synthesis parameters such as the amounts of H2O2 and MPTMS on the structural ordering of the resultant materials were systematically investigated. The materials thus obtained were characterized by a variety of techniques including powder X-ray diffraction (XRD), multinuclear solid-state Nuclear Magnetic Resonance (NMR) spectroscopy, 29Si{1H} 2D HETCOR (heteronuclear correlation) NMR spectroscopy, thermogravimetric analysis (TGA), and nitrogen sorption measurements. By using 13C CPMAS NMR technique, the status of the incorporated thiol groups and their transformation to sulfonic acid groups can be monitored and, as an extension, to define the optimum conditions to be used for the oxidation reaction to be quantitative. In particular, 29Si{1H} 2D HETCOR NMR revealed that the protons in sulfonic acid groups are in close proximity to the silanol Q3 species, but not close enough to form a hydrogen bond.

One-Step Synthesis of Metal-Doped Mesoporous MCM-41 Materials and Their Application in Esterification Catalysis

Metals (Fe, Ti, Zr) were doped into mesoporous MCM-41 by a one-step method using cetyltriethylammonium bromide (CTAB) micelles with micellar solubilized metallocenes as templates. X- ray diffraction (XRD) and N2 adsorption-desorption isotherms show that after metallocene doping, M- MCM-41(T ) materials still preserved the ordered hexagonal structure and high BET surface area. Inductively coupled plasma atomic emission spectrometry (ICP-AES) indicated that the mass fractions of the metals in the corresponding samples are: 1.71% Fe in Fe-MCM-41(400), 0.95% Ti in Ti-MCM-41(550) and 0.81% Zr in Zr-MCM-41(550). All the M-MCM-41(T) materials showed a particular high catalysis effect for the esterification of acetic acid and n-butanol. The TOF of Fe-MCM-41(400) and Zr-MCM-41(550) were 55643 g·h - 1 ·g - 1 and 125320 g·h - 1 ·g - 1 , respectively, which is much higher than that of the corresponding pure metallocenes.