Direct Synthesis Route Research Articles

Novel combustion synthesis of carbon foam‑aluminum fluoride nanocomposite materials

The facile, rapid and bulk production of composite materials consisting of carbon nanostructures doped with metal-based compounds has been a significant challenge for various research areas where such types of materials can be applied, including catalysis, energy storage and water purification. In this work, a carbon foam‑aluminum fluoride composite (C-AlF3) was developed by adopting a combustion synthesis approach, which is an attractive alternative to wet chemical methods usually employed for such purposes. The flame ignition and combustion of a solid-state mixture comprising a fluoropolymer and nano-sized Al powder leads to the formation of a porous carbon foam network doped with dispersed cubic-like AlF3 nanoparticles (100 to 500 nm in size), as observed by high-resolution microscopy methods. Selective area electron diffraction and X-ray diffraction studies revealed a rhombohedral α-AlF3 crystal structure for these embedded particles, while micro-Raman spectroscopy indicated typical carbonaceous features for the foamy matrix. The C-AlF3 composite also showed a combination of micro-, meso- and macro-porous characteristics (i.e. pore sizes in the nanometer scale) based on the analysis of N2 sorption data collected at 77 K. The findings of this study provide useful insights for further research on carbon-based nanocomposite materials prepared via direct combustion synthesis routes.

Biphasic nickel phosphide nanosheets: Self-supported electrocatalyst for sensitive and selective electrochemical H2O2 detection and its practical applications in blood and living cells

Abstract Electrochemical nonenzymatic detection has received enormous attentions from analytic chemistry communities. However, the complicated design and fabrication procedures of electrocatalysts hinder its practical application. Pursing of simple and direct synthesis route is vital and desirable to minimize the discrepancy between electrodes, and is essential for implementing of reliable detection. Herein, we propose a one-step synthesis strategy for direct phosphidation of nickel foam (NF) to fabricate effective biphasic nickel phosphide nanosheets (BNPNS) electrocatalyst. This self-supported BNPNS electrocatalyst realizes sensitive and selective electrochemical nonenzymatic detection of hydrogen peroxide (H2O2) with wide concentration regions. Benefiting from its high sensitivity, low detection limit, wide sensing range, and good reproducibility, repeatability, stability, the BNPNS has been successfully employed to detect H2O2 in practical samples of human blood and living cells. The simple and straightforward preparation process of BNPNS opens up a new avenue for practical applications of non-noble metal based electrocatalysts in analytical chemistry field for reliable detections.

Molecular Structure and Confining Environment of Sn Sites in Single-Site Chabazite Zeolites

Chabazite (CHA) molecular sieves, which are industrial catalysts for the selective reduction of nitrogen oxides and the conversion of methanol into olefins, are also ideal materials in catalysis research because their crystalline frameworks contain one unique tetrahedral site. The presence of a single lattice site allows for more accurate descriptions of experimental data using theoretical models and consequently for precise structure–function relationships of active sites incorporated into framework positions. A direct hydrothermal synthesis route to prepare pure-silica chabazite molecular sieves substituted with framework Sn atoms (Sn-CHA) was developed, which is required to predominantly incorporate Sn within the crystalline lattice. Quantitative titration with Lewis bases (NH3, CD3CN, and pyridine) demonstrates that framework Sn atoms behave as Lewis acid sites which catalyze intermolecular propionaldehyde reduction and ethanol oxidation as well as glucose–fructose isomerization. Aqueous-phase glucose...

Plant-wide modeling and analysis of the shale gas to dimethyl ether (DME) process via direct and indirect synthesis routes

A plant-wide model of the shale gas to dimethyl ether (DME) process with integrated CO2 capture via direct and indirect synthesis routes has been developed in Aspen Plus V8.4®. In this study, models of the pre-reforming reactor, autothermal reforming (ATR) reactor and DME synthesis reactors using kinetic data have been developed. For CO2 capture, Rectisol and methyl diethanolamine (MDEA)/piperazine (PZ) technologies have been evaluated and results have been compared with the experimental data. A novel DME separation process has been developed and evaluated for efficient separation of DME, syngas, and CO2. Binary interaction parameters for the vapor-liquid equilibrium (VLE) model of the methanol-DME-CO-CO2-H2O-H2 system are regressed using the experimental data. Effects of the key parameters like CO2 recycle ratio and H2/CO ratio on the utility consumption in the syngas synthesis unit, acid gas removal (AGR) unit, DME synthesis unit and DME separation unit are studied. It is observed that the direct shale gas to DME production process operated with an optimal H2/CO ratio of 1 has a higher DME yield and overall equivalent electrical efficiency than the indirect shale gas to DME production process.

Design, synthesis and molecular docking study of novel pyrrole-based α-amylase and α-glucosidase inhibitors

In an effort to design and synthesize a new class of α-glucosidase and α-amylase inhibitors, we have synthesized novel pyrrole based molecules using molecular hybridization approach. These novel analogs were synthesized by the novel methodology developed in our lab which comprises of the multi-component direct synthesis route using hypervalent iodine reagent. The compounds were characterized by infrared, 1H nuclear magnetic resonance (NMR), 13C NMR and Mass Spectroscopy. These compounds were screened for their α-amylase and α- glucosidase activity. They showed a varying degree of inhibition with IC50 values ranging between 0.4 to 4.14 µmol/mL and 0.8 to 4.14 µmol/mL for α-amylase and α-glucosidase respectively. Compounds 3, 7, 12, and 18 showed excellent activity as compared to standard acarbose. This has identified a new class of α-amylase and α-glucosidase inhibitor which can be further developed as antihyperglycemic agents. The molecular docking analysis was carried out to better understand of interaction between α-amylase and α-glucosidase target and inhibitors in this series. We also generated a homology model for human α-glucosidase enzyme and identified the key residues at the binding site. The outcome of the study could be used for the rational design of potent and selective α-amylase and α-glucosidase inhibitors, respectively.

Improved solar light stimulated charge separation of g-C3N4 through self-altering acidic treatment

Herein, we report the use of acid treatment to treat g-C3N4 nanostructured by a direct and facile synthesis route. The adopted treatment enhanced photoactivity of g-C3N4 and reflected in the removal of recalcitrant organic pollutant, Bisphenol A under direct sunlight. A complete removal of Bisphenol A was attained in a short duration (225min) as compared to pure g-C3N4. The analysis clearly substantiated the robustness of acid exfoliation that promoted a blue shift, extended the conjugated length of its respective conduction and valance band. It also drastically prolonged the recombination rate of charge carriers, by producing excess of unpaired electrons in the conduction band for active radicals’ generation. Thus, this new findings could offer a new sight of self-alteration in improving the photoactivity of complex organic pollutants for sustainable environmental remediation.

Natural Template Mediated Sustainable Synthesis of Nanocrystalline Zeolite with Significantly Improved Catalytic Activity

AbstractA novel, natural template mediated, one‐step, direct synthesis route was developed for the preparation of nanocrystalline zeolites. Bio‐template (pollen grains and yeast) was used along with a microporous zeolite structure director to obtain nanocrystalline ZSM‐5. Nanocrystalline ZSM‐5 exhibited large surface area, pore volume and intercrystalline mesopores when compared to the conventional ZSM‐5. Bio‐template (containing different functional groups) cooperatively participated in the zeolite crystallization process with the assistance of microporous zeolite structure director to form nanocrystalline ZSM‐5 framework, while the cell walls of the bio‐templates exerted an influence on restraining the growth of zeolite nanoparticles. Bio‐template mediated synthesis strategy of the present investigation was extended for the preparation of other related materials such as silicalite, zirconosilicate, and titanosilicate. Nanocrystalline ZSM‐5 and metallosilicates exhibited excellent catalytic activities involving large organic molecules, which are important for the synthesis of a wide range of industrially important fine chemicals.

Direct synthesis of sulfonic group tethered mesoporous poly(ionic liquid) for catalyzing deoximation reactions

Exploring new strategy towards efficient solid acids is significant for acid reactions. In this work, sulfonic group tethered mesoporous ionic copolymer Poly(DVB-VMPS), a kind of mesoporous poly(ionic liquid), was directly synthesized through the free radical copolymerization of sulfonic ionic liquid (IL) monomer (1-vinyl-3-propane sulfonate imidazolium) and divinylbenzene (DVB). Poly(DVB-VMPS) was used as an efficient polycation for pairing heteropolyacid (HPA) to fabricate HPA-based solid acid through solidification process. The obtained 12-tungstophosphoric acid (H3PW) derived hybrid Poly(DVB-VMPS)PW acted as a robust solid acid in the acid-catalyzed hydrolysis deoximation reaction. High yield, stable reusability and well substrate compatibility were achieved, rendering a remarkable heterogeneous recyclable catalyst for this reaction. Compared with previous post-sulfonate analogue, Poly(DVB-VMPS)PW exhibited not only improved activity but also enhanced stability, reflecting the specialty and advantage of this direct synthesis route.

Surface-functionalization of mesoporous SBA-15 silica materials for controlled release of methylprednisolone sodium hemisuccinate: Influence of functionality type and strategies of incorporation

Mesoporous SBA-15 silica materials functionalized with several organic moieties, that include different polarities and hydrophobicities, were investigated as matrices for controlled drug delivery. The functionalities were incorporated into SBA-15 using two methods: direct synthesis or co-condensation route and post-synthesis grafting. Methylprednisolone sodium hemisuccinate, a synthetic pharmaceutical compound used as anti-inflammatory and immunosuppressant, was loaded onto the pristine and functionalized mesoporous SBA-15 silica materials. The influence of the type of organic moieties as well as their incorporation method onto the inorganic silica framework has been evaluated. The results show that SBA-15 functionalized with aminopropyl trimethoxysilane groups has the largest capacity of drug adsorption, clearly higher than the provided by materials functionalized with other groups, independently of the synthesis route. Additionally, materials synthesized by the co-condensation approach show a lower degree of drug retention than the same material synthesized by grafting technique. This fact is attributed to the distinct localization of the functionality, more accessible in the case of the grafting procedure, and hence suggesting that stronger interactions among the SBA-15 functionalized surfaces and the model drug are established. To ascertain whether other organosilanes containing amino groups can provide more effective loading and controlled drug delivery, at neutral and acidic conditions (pH of 7.4 and 4.6, respectively), it was also investigated the incorporation by grafting of several amino organic moieties onto the SBA-15 silica materials. It was concluded that as the number of amino groups incorporated into SBA-15 material increased, not only the drug loading capacity was higher, but the functionalized silica material vehicles slowed down the drug delivery. Finally, it was confirmed that cell viability was largely unaffected by amino-functionalized mesoporous SBA-15 silica materials after 72 h of incubation time.

Direct Synthesis of Hydrogen Peroxide from Hydrogen and Oxygen Using Tailored Pd Nanocatalysts: A Review of Recent Findings

Direct synthesis of hydrogen peroxide from hydrogen and oxygen is being actively studied as an alternative to the current manufacturing process. The direct synthesis route has not reached the point of commercialization because of low yields, but significant effort is being spent on enhancing the productivity. With advances in computational capacity, simulation studies based on DFT calculations now offer directions for catalyst improvement, but such modifications can only be realized through the application of nanoparticle synthesis techniques that allow for nanocrystal morphology and size control and unique immobilization. To date, there have only been a small number of studies on such nanoparticles with size and crystallographic homogeneity for the direct hydrogen peroxide synthesis. According to our knowledge no other group has systematically investigated application of nanoparticles in direct synthesis of hydrogen peroxide, and thus included in this review are primarily previous studies conducted by our group. In this review, we discuss the utilization of nanotechnology for the synthesis of Pd catalysts and its effect on the direct synthesis of hydrogen peroxide, and we suggest a direction for future studies.

SBA-15:TiO2 nanocomposites: II. Direct and post-synthesis using acetylacetone

Nanosized titanium dioxide (TiO2) is used in different applications that require a specific crystalline structure. In this work, SBA-15:TiO2 nanocomposites (80 mol% Si and 20 mol% Ti) were prepared using two different synthesis routes (direct and post-synthesis), with and without acetylacetone and a modified hydrothermal route (M). The small angle X-ray diffraction data showed that all nanocomposites are ordered mesoporous materials. N2 adsorption-desorption analysis showed that the materials exhibit a narrow pore size distribution with mean pore diameters up to 9.9 nm, high surface areas up to 810 m2 g−1 and large pore volumes up to 1.3 cm3 g−1. The analysis of the morphology by scanning electron microscopy (SEM) revealed different particle shapes due to the inclusion of Ti together with the Si source in the direct synthesis route. The characterization by X-ray diffraction revealed that the presence of acetylacetone and the M route in the direct synthesis method favored the formation of the rutile phase (>90%). Additionally, the posterior inclusion of Ti (post-synthesis) favored the formation of single phase anatase (100%). In addition, the SEM images showed that the silica particle size is about 1 μm, thus being biologically safe and making the composite a very promising photoprotector.

One-Step Dual Template Mediated Synthesis of Nanocrystalline Zeolites of Different Framework Structures

A novel, dual template mediated, one-step direct synthesis route is reported here for the preparation of nanocrystalline zeolites of different framework structures (such as ZSM-5, mordenite, and sodalite). In this synthesis strategy, a suitably designed dicationic/tetra-cationic soft template was used along with a conventional zeolite structure director to obtain nanocrystalline zeolites with nanosheet morphology. Nanocrystalline zeolites exhibited large surface area, pore volume, and intercrystalline mesopores. The long hydrophobic chain containing a multiammonium template cooperatively participates in the zeolite crystallization process along with a conventional microporous zeolite structure director to form the ultrathin microporous zeolite framework, while the hydrophobic interaction between the long chains restricted the excessive growth of zeolites and induced the formation of intercrystalline mesopores. Nanocrystalline zeolites exhibited exceptionally high activity in the acid-catalyzed reactions i...

Automated synthesis of [(18)F]DCFPyL via direct radiofluorination and validation in preclinical prostate cancer models.

BackgroundProstate-specific membrane antigen (PSMA) is frequently overexpressed and upregulated in prostate cancer. To date, various 18F- and 68Ga-labeled urea-based radiotracers for PET imaging of PSMA have been developed and entered clinical trials. Here, we describe an automated synthesis of [18F]DCFPyL via direct radiofluorination and validation in preclinical models of prostate cancer.Methods[18F]DCFPyL was synthesized via direct nucleophilic heteroaromatic substitution reaction in a single reactor TRACERlab FXFN automated synthesis unit. Radiopharmacological evaluation of [18F]DCFPyL involved internalization experiments, dynamic PET imaging in LNCaP (PSMA+) and PC3 (PSMA−) tumor-bearing BALB/c nude mice, biodistribution studies, and metabolic profiling. In addition, reversible two-tissue compartmental model analysis was used to quantify pharmacokinetics of [18F]DCFPyL in LNCaP and PC3 tumor models.ResultsAutomated radiosynthesis afforded radiotracer [18F]DCFPyL in decay-corrected radiochemical yields of 23 ± 5 % (n = 10) within 55 min, including HPLC purification. Dynamic PET analysis revealed rapid and high uptake of radioactivity (SUV5min 0.95) in LNCaP tumors which increased over time (SUV60min 1.1). Radioactivity uptake in LNCaP tumors was blocked in the presence of nonradioactive DCFPyL (SUV60min 0.22). The muscle as reference tissue showed rapid and continuous clearance over time (SUV60min 0.06). Fast blood clearance of radioactivity resulted in tumor-blood ratios of 1.0 after 10 min and 8.3 after 60 min. PC3 tumors also showed continuous clearance of radioactivity over time (SUV60min 0.11). Kinetic analysis of PET data revealed the two-tissue compartmental model as best fit with K1 = 0.12, k2 = 0.18, k3 = 0.08, and k4 = 0.004 min−1, confirming molecular trapping of [18F]DCFPyL in PSMA+ LNCaP cells.Conclusions[18F]DCFPyL can be prepared for clinical applications simply and in good radiochemical yields via a direct radiofluorination synthesis route in a single reactor automated synthesis unit. Radiopharmacological evaluation of [18F]DCFPyL confirmed high PSMA-mediated tumor uptake combined with superior clearance parameters. Compartmental model analysis points to a two-step molecular trapping mechanism based on PSMA binding and subsequent internalization leading to retention of radioactivity in PSMA+ LNCaP tumors.Electronic supplementary materialThe online version of this article (doi:10.1186/s13550-016-0195-6) contains supplementary material, which is available to authorized users.

Topotactic Transformation Route to Monodisperse β-NaYF4:Ln3+ Microcrystals with Luminescence Properties

A novel nonorganic wet route for direct synthesis of uniform hexagonal β-NaYF4:Ln(3+) (Ln = Eu, Tb, Ce/Tb, Yb/Er, and Yb/Tm) microcrystals with various morphologies has been developed wherein the intermediate routine cubic-hexagonal (α → β) phase transfer process was avoided. The morphology can be effectively tuned into hexagonal disc, prism, and novel hierarchical architectures by systematically fine manipulating the Na2CO3/F(-) feeding ratio. It has been found that the routine α → β phase transfer for NaYF4 was not detected during the growth, while NaY(CO3)F2 emerged in the initial reaction stage and fast transformed into β-NaYF4 via a novel topotactic transformation behavior. Detailed structural analysis showed that β-NaYF4 preferred the [001] epitaxial growth direction of NaY(CO3)F2 due to the structural matching of [001]NaY(CO3)F2//[0001]β-NaYF4. Besides, the potential application of the as-prepared products as phosphors is emphasized by demonstrating multicolor emissions including downconversion, upconversion, and energy transfer (Ce-Tb) process by lanthanides doping.

IR studies of Fe modified ZSM-5 zeolites of diverse mesopore topologies in the terms of their catalytic performance in NH3-SCR and NH3-SCO processes

The desilication and direct synthesis route techniques were used to prepare mesostructured ZSM-5 zeolites. Iron was introduced to purely microporous and to hierarchical analogs by two-fold ion-exchange procedure using a Fe(NO3)3 solution. The results of the catalytic studies of the NH3-SCR process showed that the Fe-exchanged ZSM-5 sample prepared by direct synthesis route with amphiphilic organosilanes as a mesopore-directing agents presented the highest catalytic activity in the low temperature range comparing to the other catalyst studied. Moreover, the Fe-catalysts revealed high catalytic performance in the NH3-SCO process. High catalytic activity of the studied samples was related to high concentration of mononuclear Fe3+ cations with pseudo-Td or Oh coordination, guaranteed by the enhanced mesopore area of zeolite support, as well as with high acidity of the zeolite itself. The facility of the transport of the reactants to and from the active surface sites seems to be also ensured by highly developed system of mesopores. IR studies of adsorption forms both of nitrogen monoxide and ammonia as well as the products of their conversion gave insight into the NH3-SCR and NH3-SCO reaction mechanisms.

Direct Aqueous-Phase Synthesis of Sub-10 nm "Luminous Pearls" with Enhanced in Vivo Renewable Near-Infrared Persistent Luminescence.

Near-infrared (NIR) persistent luminescence nanoparticles (PLNPs), possessing unique NIR PL properties, have recently emerged as important materials for a wide variety of applications in chemistry and biology, for which they must endure high-temperature solid-state annealing reactions and subsequent complicated physical post-treatments. Herein, we report on a first direct aqueous-phase chemical synthesis route to NIR PLNPs and present their enhanced in vivo renewable NIR PL. Our method leads to monodisperse PLNPs as small as ca. 8 nm. Such sub-10 nm nanocrystals are readily dispersed and functionalized, and can form stable colloidal solutions in aqueous solution and cell culture medium for biological applications. Under biotissue-penetrable red-light excitation, we found that such nanocrystals possess superior renewable PL photoluminescence in vitro and in vivo compared to their larger counterparts currently made by existing methods. We believe that this solid-state-reaction-free chemical approach overcomes the current key roadblock in regard to PLNP development, and thus will pave the way to broad use of these advanced miniature “luminous pearls” in photonics and biophotonics.

Ultrafast Graphene Growth on Insulators via Metal-Catalyzed Crystallization by a Laser Irradiation Process: From Laser Selection, Thickness Control to Direct Patterned Graphene Utilizing Controlled Layer Segregation Process.

Despite the vast progress in chemical vapor deposition (CVD) graphene grown on metals, the transfer process is still a major bottleneck, being not devoid of wrinkles and polymer residues. In this paper, a structure is introduced to directly synthesize few layer graphene on insulating substrates by a laser irradiation heating process. The segregation of graphene layers can be manipulated by tuning the metal layer thickness and laser power at different scanning rates. Graphene deposition and submicrometer patterning resolution can be achieved by patterning the intermediate metal layer using standard lithography methods in order to overcome the scalability issue regardless the resolution of the laser beam. The systematic analysis of the process based on the formation of carbon microchannels by the laser irradiation process can be extended to several materials, thicknesses, and methods. Furthermore, hole and electron mobilities of 500 and 950 cm(2) V(-1) s(-1) are measured. The laser-synthesized graphene is a step forward along the direct synthesis route for graphene on insulators that meets the criteria for photonics and electronics.

ChemInform Abstract: Gold Catalysis. A Reflection on Where We Are Now

AbstractReview: 32 refs.

Long-Chain Polyhydroxyesters from Natural Occurring Aleuritic Acid as Potential Material for Food Packaging

Fatty polyhydroxyesters (C≥16) are present in nature as barrier polymers like cutin in some protective tissues of higher plants. The mimicry of these biopolymers is regarded as a strategy to design nontoxic and fully biodegradable food packaging films and coatings. To obtain cutin inspired materials we have used a natural occurring polyhydroxylated monomer like aleuritic (9,10,16-trihydroxypalmitic) acid and a direct and scalable synthesis route consisting in the noncatalyzed melt-condensation polymerization in air. To reduce the number of hydroxyl groups and to increase hydrophobicity, palmitic acid has been used as a capping agent. Aleuritic-palmitic polyhydroxyesteres films have been obtained and characterized.

One-pot direct synthesis route to self-assembled highly ordered Zn-decorated mesoporous aluminium oxide toward efficient and sustainable metathesis heterogeneous catalyst design

Zn-modified well-ordered mesoporous alumina successfully synthesizedviaone-pot process and evaluated as support for rhenium-based catalyst for methyl oleate self-metathesis.