Template Procedure Research Articles

Electrochemical capacitive behaviors of ordered mesoporous carbons with controllable pore sizes

Ordered mesoporous carbons (OMCs) with controllable pore sizes in the range of 4–10nm are prepared by a template procedure using 2D hexagonal MSU-H and 3D cubic KIT-6 as hard templates and boric acid as the pore expanding agent. The electrochemical performances of the as-synthesized OMCs as electrode materials for electrochemical double layer capacitors (EDLCs) are characterized by cyclic voltammetry (CV), galvanostatic charge/discharge (GC) and electrochemical impedance spectroscopy (EIS) experiments in 30wt% KOH electrolyte. The influence of the pore size distributions of OMCs on the electrochemical capacitive performances is discussed. The prepared OMCs exhibit good capacitive behaviors with the specific capacitance values ranging from 143 to 205.3Fg−1 at a voltage scan rate of 5mVs−1 and 81 to 86% retained at a high scan rate of 100mVs−1. OMC-M-2 shows the highest specific surface capacitance value of 27.5μFcm−2 at 5mVs−1 with a peak pore size of 7.8nm and a Brunauer–Emmet–Teller (BET) surface area of 729.3m2g−1. The analysis of two kinds of pore symmetries of OMCs with the same pore size of about 6.5nm shows that the 3D cubic OMC exhibited superior capacitive performance than the 2D hexagonal OMC.

Erbium complexes with tetra-15-crown-5-phthalocyanine: Synthesis and spectroscopic study

Erbium mono-, bis-, and tris(phthalocyaninates) with tetra-15-crown-5-phthalocyanine (H2R4Pc) were synthesized and studied by spectroscopic methods. The complexes were obtained by reacting H2R4Pc with erbium salts in high-boiling solvents. To compare the efficiency of two approaches to the synthesis of double-decker lanthanide phthalocyaninates, bis(phthalocyaninate) [Er(R4Pc)2] was also obtained by a template procedure from dicyanobenzo-15-crown-5. A combination of physicochemical methods (UV and IR spectroscopy, MALDI-TOF mass spectrometry, 1H NMR) was used for identifying the compounds and proving their individuality and structure. The photoluminescence method demonstrated that solutions of erbium bis- and tris(phthalocyaninates) in CHCl3 are nonfluorescent in the visible range of light whereas solutions of mono(phthalocyaninate) in CHCl3 and DMSO exhibit fluorescence with maxima at 707 and 695 nm, respectively. The oxidation of erbium mono(phthalocyaninate) leads to fluorescence quenching.

Stereoelectronic Factors in Iron Catalysis: Synthesis and Characterization of Aryl-Substituted Iron(II) Carbonyl P–N–N–P Complexes and Their Use in the Asymmetric Transfer Hydrogenation of Ketones

A series of five (S,S)-trans-[Fe(CO)(Br)(PR2-CH2CH═NCH(Ph)CH(Ph)N═CHCH2-PR2)][X] compounds (1a–c, X = BPh4; 1d,e, X = BF4) were synthesized and tested for the asymmetric transfer hydrogenation (ATH) of acetophenone. Three of the complexes had methyl-substituted aryl groups (a, R = para-CH3C6H4; b, R = ortho-CH3C6H4; c, R = 3,5-(CH3)2C6H3), and two had trifluoromethyl-substituted aryl groups (d, R = para-CF3C6H4; e, R = 3,5-(CF3)2C6H3). Using both known and new phosphonium dimers, [cyclo-(PR2CH2CH(OH)−)2][Br]2 (2a–c), in a one-pot template reaction, the corresponding (S,S)-trans-[Fe(CH3CN)2(PR2-CH2CH═NCH(Ph)CH(Ph)N═CHCH2-PR2)][BPh4]2 complexes (3a–c) were generated and then converted to precatalysts 1a–c via CO addition reactions. While investigating compounds 1a–c, an alternative route for synthesizing phosphonium dimers was developed that allowed the facile introduction of tetrafluoroborate counterions. Compounds 1d and 1e could not be synthesized using previously developed methods; phosphinoacetaldehyde diethyl acetal precursors (5d, 5e) were isolated because trifluoromethyl-substituted phosphonium dimers did not form. Precursors 5d and 5e were incompatible with a base-catalyzed template approach, so a new acid-catalyzed template procedure was developed to generate the tetrafluoroborate salts (S,S)-trans-[Fe(CH3CN)2(PR2-CH2CH═NCH(Ph)CH(Ph)N═CHCH2–PR2)][BF4]2 (3d, 3e). Both 3d and 3e were converted to precatalysts 1d and 1e via CO addition reactions. Complexes 1b, 1d, and 1e were inactive for the ATH of acetophenone, while complexes 1a and 1c were active. Compound 1a showed very high activity, with a turnover frequency of 30 000 h–1 at 28 °C, and is currently the most active iron ATH catalyst. Compound 1c produced more enantiopure (R)-1-phenylethanol, with an ee of 90%, and is the most selective iron catalyst reported to date for the ATH of acetophenone. The activity of complexes 1a–e for ATH was compared to those of known complexes 1f (R = Ph), 1g (R = Et), 1h (R = i-Pr), and 1i (R = Cy), and the most active catalysts were defined by a narrow range of electronic (ν(CO)) as well as steric (Tolman cone angles) parameters.

Structure-based approach to rationally design a chimeric protein for an effective vaccine against Group B Streptococcus infections

Structural vaccinology is an emerging strategy for the rational design of vaccine candidates. We successfully applied structural vaccinology to design a fully synthetic protein with multivalent protection activity. In Group B Streptococcus, cell-surface pili have aroused great interest because of their direct roles in virulence and importance as protective antigens. The backbone subunit of type 2a pilus (BP-2a) is present in six immunogenically different but structurally similar variants. We determined the 3D structure of one of the variants, and experimentally demonstrated that protective antibodies specifically recognize one of the four domains that comprise the protein. We therefore constructed a synthetic protein constituted by the protective domain of each one of the six variants and showed that the chimeric protein protects mice against the challenge with all of the type 2a pilus-carrying strains. This work demonstrates the power of structural vaccinology and will facilitate the development of an optimized, broadly protective pilus-based vaccine against Group B Streptococcus by combining the uniquely generated chimeric protein with protective pilin subunits from two other previously identified pilus types. In addition, this work describes a template procedure that can be followed to develop vaccines against other bacterial pathogens.

Leg Length Discrepancy in Cementless Total Hip Arthroplasty

The use of cementless total hip arthroplasty (THA) is on the increase. In order to achieve rotational and axial stability larger implants may be required than originally templated for. This could potentially result in a lar-ger leg length inequality. Our objective was to determine whether there is greater inequality in leg length post-operatively in cementless THA as compared to cemented implants. 136 consecutive patients undergoing elective THA between June 2007 and May 2008 were included. Post-operative digital radiographs were ex-amined to determine leg length. Twenty seven patients (20%) underwent a cemented procedure and 109 (80%) a cementless procedure. In the cemented group the mean leg length discrepancy was 7.3 mm (range 19 mm short to 21 mm long). In the cementless group the mean measured leg length discrepancy was 6.3 mm (range 18 mm short to 23 mm long). There was no significant difference between the two groups (P = 0.443). This study shows that with accurate pre-operative templating, both cemented and cementless proce-dures produce comparable and acceptable leg length discrepancies.

Synthesis of mesoporous composite materials of nitrogen-doped carbon and silica using a reactive surfactant approach

Mesoporous composite materials of nitrogen-doped carbon and silica were synthesised in a one-step-process applying a soft templating procedure. The template used in the sol–gel synthesis of the silica is a cationic surfactant with distinct reactivity to form nitrogen-doped graphitic carbon upon heating. This reactivity is derived from the combination of the dicyanamide anion with a nitrogen-containing pyridinium cation, as it is known from ionic liquids used as nitrogen-doped carbon precursors. Thus applying this surfactant in a conventional sol–gel synthesis yields a silica gel doped with a precursor for N-doped carbon. By subsequent annealing mesoporous composite materials of silica and nitrogen-doped carbon are obtained.

Amperometric biosensor for catechol using electrochemical template process

A novel amperometric biosensor for the determination of catechol was developed accordingly to the electrochemical template procedure. The optimum fabricating conditions of the biosensor were studied. The resulting biosensor with the limit of less than 0.05μM can be used for detection of catechol in the linear range of 2.5–140μM. The maximum response current (Imax) and the Michaelis–Menten constant (k′m) are 3.08μA and 77.52μM, respectively. The activation energy (Ea) of the polyphenol oxidase (PPO) catalytic reaction is 25.56kJmol−1 in the B–R buffer. The stability of the PANI-CA biosensor fabricated with the electrochemical template process (retains 86% of the original activity after four months) is much higher than that fabricated with one-step and two-step processes (retains 75% of the original activity after four months). The effects of potential and pH on the response current of the biosensor are also described.

Structural effects on magnetic property of reciprocal opalline structures of iron–nickel alloys prepared with template-assisted electrodeposition

Reciprocal opalline structures, opals and corresponding inverse opals, of iron–nickel alloys (FeNi 3) were successfully fabricated with template-assisted electrodeposition processes. The magnetic properties of the structures were studied against the structural features, including shape and characteristic length, of these reciprocal opals. The magnetic FeNi 3 opals and corresponding inverse opals were obtained from starting polystyrene opals via a double and single templating procedure, respectively. The structural feature sizes of the opal and corresponding inverse opal were adjusted with the diameter of the starting PS spheres, from 250 to 440 nm. The coercive fields of the inverse opals were found much larger than those of the corresponding opals, attributable to the strong local shape anisotropy and intersections of the thin backbone of the inverse opal. The coercive fields increased with decreasing structural feature size, because of the increase in the densities of domain wall pinning sites and domain vortex sites caused by the feature size reduction. The present work demonstrated the drastic effects of shape and characteristic length on the coercive fields of reciprocal structures.

Effect of the preparation method on high-temperature de-N2O performance of Na–CaO catalysts. A mechanistic study

A simple cellulose-templating (CT) method was used to prepare Na–CaO catalysts for high-temperature N2O decomposition to N2 and O2 in excess of NO, O2, and H2O. According to this method, cellulose materials were soaked in aqueous solution of calcium and/or sodium nitrates followed by burning out the template material. Depending on the nature of cellulose template and calcination procedure, the obtained catalysts consisted of regularly shaped particles of 100–400nm. Conventionally prepared Na–CaO reference materials had randomly shaped particles on a micron scale. Compared to the latter catalysts, the CT ones showed higher de-N2O activity and resistance against inhibition by NO and O2, which make them interesting from industrial point of view. Transient analysis of NO interaction with the studied catalysts in the presence and the absence of O2 enabled us to conclude that the superior de-N2O performance of the CT materials is due to improved desorption of surface NOx species acting as inhibitors for N2O decomposition.

Mesoporous, 2D Hexagonal Carbon Nitride and Titanium Nitride/Carbon Composites

A multistep templating procedure is used to prepare graphitic carbon nitride (g-C3N4) and titanium nitride/carbon composites with ordered, 2D hexagonal porosity. First, the carbon nitride is prepared by nanocasting using a silica (SBA-15) template. This carbon nitride is then replicated as a metal nitride carbon composite, using a simultaneous templating/conversion scheme (“reactive templating”). Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Fabrication of a Macroporous Microwell Array for Surface‐Enhanced Raman Scattering

AbstractHere, a colloidal templating procedure for generating high‐density arrays of gold macroporous microwells, which act as discrete sites for surface‐enhanced Raman scattering (SERS), is reported. Development of such a novel array with discrete macroporous sites requires multiple fabrication steps. First, selective wet‐chemical etching of the distal face of a coherent optical fiber bundle produces a microwell array. The microwells are then selectively filled with a macroporous structure by electroless template synthesis using self‐assembled nanospheres. The fabricated arrays are structured at both the micrometer and nanometer scale on etched imaging bundles. Confocal Raman microscopy is used to detect a benzenethiol monolayer adsorbed on the macroporous gold and to map the spatial distribution of the SERS signal. The Raman enhancement factor of the modified wells is investigated and an average enhancement factor of 4 × 104 is measured. This demonstrates that such nanostructured wells can enhance the local electromagnetic field and lead to a platform of ordered SERS‐active micrometer‐sized spots defined by the initial shape of the etched optical fibers. Since the fabrication steps keep the initial architecture of the optical fiber bundle, such ordered SERS‐active platforms fabricated onto an imaging waveguide open new applications in remote SERS imaging, plasmonic devices, and integrated electro‐optical sensor arrays.

Ordered Arrays of Ferroelectric Nanoparticles by Pulsed Laser Deposition on PS-b-P4VP(PDP) Supramolecule-Based Templates

Thin films of comb-shaped supramolecules have been used to create arrays of spatially separated ordered nanorods with a polystyrene core and a poly(4-vinyl pyridine) corona. Room temperature pulsed laser deposition of a uniform layer of lead titanate on top of these nanorod arrays and subsequent heating to 565 °C, far above the degradation temperature of the block copolymer nanorods, resulted in ordered arrays of ferroelectric lead titanate nanoparticles, due to the evaporation of the polymer rods and the SrTiO3 substrate-nucleated crystallization of the lead titanate. The spacing in between the ordered cylinders of the template and the nonselective nature of the coating procedure sets the method apart from conventional block copolymer templating techniques involving parallel cylindrical structures. Given the nonselective nature of the coating method, this template procedure is applicable for a large variety of inorganics.

Synthesis and characterization of nanostructured sulfated zirconias

Thermally stable sulfated zirconia catalysts were synthesized via a new templating procedure and compared with standard zirconia materials prepared by precipitation without templates. Two preparation routes with various amphiphilic systems were employed as structure directing agents: (1) synthesis with hexadecyltrimethylammonium bromide, and (2) combined use of surfactant Brij-56® and triblock-copolymer Pluronic P123®. The formation of materials was characterized by TEM, SEM, X-ray diffraction as well as nitrogen adsorption and mercury intrusion techniques. Different self-assembling properties of the structure directing compounds led to sulfated zirconia materials exhibiting improved morphological and structural properties in terms of thermal stability, specific surface areas, pore diameters and porosity factors. Notably, hierarchical pore structures were obtained for the synthesis route via a combined use of Brij-56® and P123®. Moreover, the morphological features of these materials were evidenced by a significantly improved isomerization activity of n-butane.

Silica nanoparticle-templated methacrylic acid monoliths for in-line solid-phase extraction–capillary electrophoresis of basic analytes

Polymeric ion-exchange monoliths typically exhibit low capacities due to the limited surface area on the globules of the monoliths. The ion-exchange binding of protonated weakly basic analytes on deprotonated carboxylate sites on methacrylate polymer monoliths has been increased by templating the monoliths with silica nanoparticles. The templating method is achieved by adding the nanoparticles as a suspension to the polymerisation mixture. After polymerisation, the nanoparticles are removed by washing the monolith with strong base. Monolithic columns prepared using this procedure have exhibited a 33-fold increase in ion-exchange capacity when compared to untemplated monoliths prepared and treated under similar conditions. The templating procedure does not alter the macroporous properties of the polymer monolith, confirmed through scanning electron microscopy and BET surface area analysis, but provides increased capacity predominantly through the re-orientation of more carboxylic acid groups. The resulting increase in ion-exchange capacity has proven to be useful for the preconcentration and separation of neurotransmitters by in-line solid-phase extraction–capillary electrophoresis. The increased capacity of the templated monolith allowed the injection time to be increased 10 times over that of an untemplated monolith, allowing 10 times more sample to be injected with the efficiencies and recoveries remaining unaffected. The enhancement in sensitivity for the test mixture of neurotransmitter (dopamine, norepinephrine and metanephrine) ranged 1500–1900 compared to a normal hydrodynamic injection in capillary electrophoresis. Efficiencies obtained for the neurotransmitters were 100 000–260 000 plates, typical of those obtained in capillary zone electrophoresis. The applicability of the increased capacity silica nano-templated polymer monolith was demonstrated by analysing trace levels of caffeine in biological, food and environmental samples.

Structures and fluorescence of two new hetero-dinuclear lanthanide(III) complexes derived from a Schiff-base ligand

Two isostructural dinuclear lanthanide(III)/Schiff-base complexes [{Ce1.5Eu0.5(clapi)}2]·2CH3CN (1) and [{La1.5Eu0.5(clapi)}2]·2CH3CN (2) {H3clapi = 2-(5-chloride-2-hydroxyphenyl)-1,3-bis[4-(5-chloride-2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine} have been prepared by template procedure and characterized by elemental analyses, ICP, IR, and single-crystal X-ray diffraction analyses. Lanthanide ions Ce(III) and Eu(III) in 1, and La(III) and Eu(III) in 2 are disordered with occupancies 0.75 for Ce and 0.25 for Eu in 1; 0.75 for La and 0.25 for Eu in 2. In the compounds, each lanthanide is coordinated to four N and four O atoms from two clapi3− ligands, forming a distorted square antiprism. Two phenol oxygen atoms from the middle arms of the two heptadentate μ2-bridging ligands connect the two Ce(Eu) atoms in 1, and La(Eu) in 2. The solution of the two complexes in CH2Cl2 exhibits red fluorescence from Eu3+ ions at 77 K, very weak at room temperature.

Multicomponent macroporous materials with a controlled architecture

We describe the elaboration of organized macroporous electrode surfaces with a complex composition using the hard sphere template procedure. In a first approach, different metals are subsequently generated in the template leading finally to a multicomponent porous material showing interesting electrochemical features combining the redox properties of the different metals. In a complementary second approach, alternating porous and compact metal layers are formed, with the compact layer being introduced on purpose as a defect layer allowing the controlled destruction of the sandwich-type architecture using a chemical or electrochemical trigger.

Structure and Fluorescence of Three New Homodinuclear Lanthanide (III)/Schiff-base Compounds [{Ln(clapi)}2] · 2CH3CN {Ln=La, Ce, Eu; H3clapi = 2-(5-Chloride-2-hydroxyphenyl)-1,3-bis [4-(5-chloride-2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine}

Three new homodinuclear lanthanide(III)/Schiff-base compounds [{Ln(clapi)}2] · 2CH3CN {Ln = La 1, Ce 2, and Eu 3; H3clapi = 2-(5-chloride-2-hydroxyphenyl)––1,3-bis [4-(5-chloride-2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine} have been prepared successfully by template procedure and characterized by elemental analysis, IR spectra, and the dinuclear cerium compound (2) selected as a representative was structurally characterized. The crystal system is triclinic with space group P-1, a = 10.588 A, b = 11,521(2) A, c = 13.979(3) A, α = 109.66(3)°, β = 97.77(3)°, γ = 106.33(3)°, V = 1486.2(5) A3 and Z = 1. In compound 2, each Ce atom is coordinated to four N and four O atoms from two clapi3− ligands, forming a distorted square antiprism. Two phenol oxygen atoms from the middle arms of the two heptadentate ligands as μ2-bridging connect the two Ce atoms. Compounds 1, 2 and 3 in CH2Cl2 exhibit strong blue fluorescence at room temperature, compound 3 has no typical red emission of Eu3+ at room temperature while exhibits strong red fluorescence at 77 K in CH2Cl2. Three new dinuclear lanthanide (III)/Schiff-base compounds were synthesized by template method and the structure and fluorescence of the complexes were studied.

A new series of dinucleating macrocyclic ligands and their complexes of zinc(II)

A new category of dinucleating macrocyclic Schiff base ligands with ring sizes from 34- to 52-membered have been synthesised employing metal template procedures involving the reaction of o-phenylenediamine with a series of α,ω-bis(3′-hydroxy-4′-formylphenyloxy)alkanes in the presence of calcium(II), barium(II) or manganese(II). The latter cations act as ‘transient’ templates for formation of the corresponding metal-free Schiff base macrocyclic ligands, H 4L n (where n signifies the number of carbons in each linking bis-alkoxy chain); the macrocycles corresponding to n = 4, 6 and 8 were isolated and characterised while, for n = 1, in which single methylene groups acts as the bridges between salicyl moieties, the cyclic product was used directly for preparation of its dinuclear complex, [Zn 2L 1], without prior isolation. Evidence for the templating role of barium in the preparation of H 4L 6 and H 4L 8 was obtained by isolation of the corresponding species of type H 4L n ·2Ba(ClO 4) 2 ( n = 6 or 8) as ‘intermediates’ before generation of the respective metal-free macrocycles. Reaction of zinc(II) acetate with the free macrocycles in methanol yielded complexes of type [Zn 2L n ] in all cases. A related non-cyclic ligand, H 2L 0 and its corresponding mononuclear complex, [ZnL 0]·H 2O, were also synthesised and its spectral properties compared with those of the macrocyclic derivatives. The elemental analyses, 1H NMR, IR, UV–Vis and MS spectra of the respective zinc complexes in each case were in accord with the formation of the expected 2:2 condensation product. The results of DFT calculations to probe aspects of the electronic and structural natures of both H 2L 1 and H 4L 4 are briefly presented.

Nanotechnology and Food Quality Control

The preparation and attractive performance of nanomaterials for innovative detection schemes of food related compounds are described. Nickel nanowires growths by the template procedure were used for magnetoswitchable control of electrochemical processes of sugar-like compounds at the electrode surface. Gold nanoparticles were also prepared by reducing a gold solution with different phenolic compounds. The different antioxidant power of these compounds allow to modulate the kinetic growth of gold nanoparticles. Finally, an index of the antioxidant power based on the growth of gold nanoparticle is reported.

Hierarchical aluminosilicate macrochannels with structured mesoporous walls: Towards a single catalyst for multistep reactions

Two novel and simple synthesis pathways, one surfactant-assisted and one template-free, have recently been developed for the formation of aluminosilicate macrochannels with mesoporous walls. These thermally stable materials are made of straight tubular macrochannels separated by wormhole-like mesopores. This paper gives a comparative study of the materials obtained by both ways in order to determine the role played by the surfactant. High specific surface area materials with homogeneous tubular macrochannels are spontaneously formed without needing any templating procedure. The use of a non-ionic surfactant favors the incorporation of Al atoms in tetrahedral sites and also controls the homogeneity of the mesopores. The formation of the macrochannels is believed to result from the spontaneous and strong release of alcohol molecules due to high hydrolysis and condensation rates of the inorganic sources, which creates a hydrodynamic flow, thus channels of the solvent. The mesopores are generated by interparticular voids.