Stage Of Synthesis Research Articles

Design, synthesis and biological evaluation of simplified analogues of MraY inhibitory natural product with rigid scaffold

Muraymycins and caprazamycins are strong inhibitors of MraY, which is responsible for peptidoglycan biosynthesis. Although they are promising antibacterial agents with a novel mode of action, their chemical structures are rather complex. This study investigated the simplification of these natural products by structure-based drug design, synthesis, and biological evaluation. We developed a simplified rigid scaffold with an arylalkyne moiety, which shows sub-micromolar MraY inhibitory activity. The scaffold is suitable for further investigating the structure–activity relationship by virtue of our synthetic strategy, where the substituent of interest is installed in the last stage of synthesis. This scaffold shows the potential for further use in optimizing MraY inhibitory and antibacterial activities.

RETRACTED: Minimizing cosecant-squared pattern side lobe level of linear array antenna by genetic algorithm and optimizing feed network

This paper designs and synthesizes a 12-element linear array of microstrip patch antenna with cosecant-squared pattern for radar applications at the frequency 9.6 GHz. The antenna array consists of three microstrip sublayers including two lower sublayers designed for feed network, and radiating patches located on the upper sublayer which are excited through a slot in the ground plate. One of the most important advantages of this antenna array is the cross-polarization discrimination of less than −50 dB which is the result of removing undesirable and unwanted radiations caused by feed network. The Genetic Algorithm (GA) optimization method has been used to synthesize cosecant-squared pattern with considering the mutual coupling effect of array elements. In this method, the amplitude and phase of each element in the far field has been calculated by taking into account the mutual coupling effect, and applied in the optimization process. Finally, the feed network has been designed according to the amplitudes and phases obtained from the GA. The simulation results confirm the validity of all design and synthesis stages.

Determining energetic characteristics and selecting environmentally friendly components for solid rocket propellants at the early stages of design

This paper has investigated the possibility to theoretically calculate a value of the specific impulse for highly energetic compositions using only two parameters – the heat of the reaction and the number of moles of gaseous decomposition reaction products. Specific impulse is one of the most important energetic characteristics of rocket propellant. It demonstrates the level of achieving the value of engine thrust and propellant utilization efficiency. Determining the specific impulse experimentally is a complex task that requires meeting special conditions. For the stage of synthesis of new promising components, the comparative analysis of energetic characteristics, forecasting the value of specific impulse, especially relevant are calculation methods. Most of these methods were first developed to determine the energetic characteristics of explosives. Since explosives and rocket propellants in many cases have similar energy content and similar chemical composition, some estimation methods can be used to assess the specific impulse of solid rocket propellant. The specific impulse has been calculated for 45 compositions based on environmentally friendly oxidizers (ammonium dinitramide, hydrazinium nitroformate, hexanitrohexaazaisowurtzitane) and polymer binders polybutadiene with terminal hydroxyl groups, glycidylazide polymer, poly-3-nitratomethyl-3-methyloxetane). It was established that the estimation data obtained correlate well with literary data. Deviation of the derived values of the specific impulse from those reported in the literature is from 0.4 % to 1.8 %. The calculation results could be used for preliminary forecasting of energetic characteristics for highly energetic compositions, selecting the most promising components, as well as their ratios.

Synthesis of Epoxy Methacrylate Resin and Coatings Preparation by Cationic and Radical Photocrosslinking.

This work involves the synthesis of hybrid oligomers based on the epoxy methacrylate resin. The EA resin was obtained by the modification of industrial-grade bisphenol A-based epoxy resin and methacrylic acid has been synthesized in order to develop multifunctional resins comprising both epoxide group and reactive, terminal unsaturation. Owing to the presence of both epoxy and double carbon–carbon pendant groups, the reaction product exhibits photocrosslinking via two distinct mechanisms: (i) cationic ring-opening polymerization and (ii) free radical polymerization. Monitoring of EA synthesis reactions over time using PAVs, MAAC and NV parameters, and the FT-IR method reveals that esterification reactions proceed faster at the start, exhibiting over 40% of conversion within the initial 60 min, which can be associated with a relatively high concentration of reactive sites and low viscosity of the reaction mixture at the initial reaction stage. With the further increase in the reaction time, the reaction rate tends to decrease. The control of the EA synthesis process can guide how to adjust reactions to obtain EAs with desired characteristics. Based on obtained values, one can state that the optimum synthesis time of about 4–5 h should be adopted to prepare EAs having both epoxy groups and unsaturated double bonds. The structure of the obtained EA was confirmed by FT-IR and NMR methods, as well as the determination of partial acid value and epoxy equivalent. Samples at various stages of synthesis were cured with UV radiation in order to study the kinetics of the process according to cationic and radical polymerization determined via photo-differential scanning calorimetry (photo-DSC) and real-time infrared spectroscopy (RT-IR) and then the properties of the cured coatings were tested. It turned out that the cationic polymerization was slower with a lower conversion of the photoreactive groups, as compared to the radical polymerization. All the obtained EA coatings were characterized by good properties of cured coatings and can be successfully used in the coating-forming sector.

Thermoelectric properties of medium-entropy PbSbTeSe alloy prepared by reactive spark plasma sintering

Reactive spark plasma sintering combining the synthesis and densification stages has been at the first time applied to prepare medium-entropy grained PbSbTeSe alloy. This alloy is prospect medium-temperature p-type thermoelectric. Self-propagating high-temperature synthesis in initial mixture of elemental Pb, Sb, Te and Se powders, resulting in synthesis of single-phased PbSbTeSe, was stage of synthesis. Lattice thermal conductivity of the alloy is very low (∼0.7 at ∼ 755 K). Owing to this low lattice thermal conductivity, thermoelectric performance of PbSbTeSe alloy is promising . Highest thermoelectric figure-of-merit equal to ∼ 0.43 is observed at ∼ 720 K. Anomalies of thermoelectric properties were found at ∼ 490 K. These anomalies can be related to specific features of energy bands, consisting of two valence bands, which are close in energy.

Physiological, biochemical, and molecular responses of Linum album to digested cell wall of Piriformospora indica.

Plants synthesize a variety of metabolites in response to biotic elicitors. To comprehend how the digested cell wall of Piriformospora indica affects the response of ROS burst, antioxidant enzymes, amino acids profiling, and phenylpropanoid compounds such as lignans, phenolic acids, and flavonoids inLinum albumhairy roots; we accomplished a time-course analysis of metabolite production and enzyme activities in response to CDCW and evaluated the metabolic profiles. The results confirms that CDCW accelerates the H2O2 burst and increases SOD and GPX activity in hairy roots. The HPLC analysis of metabolic profiles shows that the H2O2 burst shifts the amino acids, especially Phe and Tyr, fluxes toward a pool of lignans, phenolic acids, and flavonoids through alterations in the behavior of the necessary enzymes of the phenylpropanoid pathway. CDCW changes PAL, CCR, CAD, and PLR gene expression and transiently induces PTOX and 6MPROX as the main-specific products of PAL and PLR genes expression. The production of phenolic acids (e.g., cinnamic, coumaric, caffeic, and salicylic acid) and flavonoids (e.g., catechin, diosmin, kaempferol, luteolin, naringenin, daidzein, and myricetin) show different behaviors in response to CDCW. In conclusion, our observations show that CDCW elicitation can generate H2O2 molecules in L. album hairy roots and consequently changes physiological, biochemical, and molecular responses such as antioxidant system and the specific active compounds such as lignans. Quantification of metabolic contents in response to CDCW suggests enzyme and non-enzyme defense mechanisms play a crucial role in L. album hairy root adaptation to CDCW. A summary revealed that the correlation between H2O2 generation and L. album hairy root defense system under CDCW. Increase of H2O2 generation led plant to response against oxidative conditions. SOD, and GPX modulated H2O2 content, Phe, and Tyr shifted to the phenylpropanoid compounds as a precursor ofPAL and TAL enzyme, the predominant phenylpropanoid compounds controlled oxidative conditions, and the other amino acids responsible for amino acid synthesis and development stages.

Modified Pechini method by PVP addition for Nd:Gd2O3 nanophosphors fabrication

Gadolinium oxide nanopowders doped with neodymium were prepared via modified Pechini method based on double stabilization of nanoparticles. Polyvinylpyrrolidone was used as an additional stabilizer at low-temperature stage of synthesis. This polymer also acts as a fuel during thermal treatment of precursors. Photoluminescence and FTIR spectroscopy, DTA/TG, XRD and SEM analysis were used for the analysis of thermal evolution of initial materials, chemical intermediates and final products at different stages of thermal treatment. Photoluminescence characterization included measurements of excitation and emission spectra of synthesized powders at different stages of thermal treatment.

SSH reveals different functional categories of putative resin synthesizing genes in the industrial insect, Kerria lacca (Kerr)

• SSH library was constructed by using crawler and female cDNA as driver and tester, respectively. • Genes of terpene biosynthesis, fatty acid biosynthesis and transcriptional regulation were present in the SSH library. • Decaprenyl diphosphate synthase and acyl-CoA delta desaturase were cloned from lac insects. • Their expression levels in lac insects were also found to be correlated with resin synthesis. Biosynthesis mechanism of the only animal resin, lac resin remains elusive to the scientific community. An attempt to identify the genes of resin biosynthesis in lac insects was made through SSH (Suppression Subtraction Hybridization) library by subtracting genes of resin non secreting stage (neonate nymphs) from the resin secreting stage (adult female) of the lac insect. SSH library yielded 107 non redundant clones with 61 clones having sequences homologous with known functions (defence, development, metabolism, regulation, transport, cell division, respiration, structural role), 7 clones having hypothetical proteins or uncharacterized proteins and 39 clones did not find any matches. Among the differentially expressed genes, few putative genes of terpene biosynthesis, fatty acid biosynthesis and transcriptional regulation were identified. Out of them, an IDS (Isopentenyl Diphosphate Synthase) type decaprenyl diphosphate synthase and a desaturase gene, acyl-CoA delta desaturase were cloned from lac insects and sequenced. Their expression levels were found to be more in lac resin synthesis stages such as settled nymphs and fertilized female insects in comparison with resin non secreting stage, crawlers (neonate nymphs). It gives a clear indication of their role in lac resin biosynthesis due to the correlation of their expression level with resin biosynthesis in lac insects.

Nanoarchitecturing bimetallic manganese cobaltite spinels for sonocatalytic degradation of oxytetracycline

Degradation of contaminants of emerging concern in aqueous media using bimetallic oxides is a promising novel strategy that requires engineering new catalytic routes in bimetallic oxides to perform advanced oxidation; however, several challenges to synthesizing and developing such materials with enhanced, sustainable catalytic features are still being investigated. This study presents the effective use of a manganese cobaltite bimetallic spinel compound for sonocatalysis. We prepared three morphologies of manganese cobaltite for using in the sonocatalytic degradation of oxytetracycline (OTC). The morphology of manganese cobaltite was tuned by changing the amounts of the Mn and Co precursors in the early stage of synthesis. Several manganese cobaltite spinels with different structures—porous layered-like cubes (MCO-PLC), layered-like ellipsoids (MCO-LE), and rough spheroids (MCO-RS) were obtained and characterized using various techniques. A promising catalytic degradation capability of MCO-PLC for OTC (10.0 mg L−1) was obtained at a natural pH within 120 min. We also investigated the reusability of MCO-PLC sonocatalyst and metal (Mn and Co) leaching in water media. The sonocatalytic mechanisms and fragments produced from OTC during degradation were determined via electron paramagnetic resonance and gas chromatography-mass spectroscopy analyses.

GrTCP11, a Cotton TCP Transcription Factor, Inhibits Root Hair Elongation by Down-Regulating Jasmonic Acid Pathway in Arabidopsis thaliana.

TCP transcription factors play important roles in diverse aspects of plant development as transcriptional activators or repressors. However, the functional mechanisms of TCPs are not well understood, especially in cotton fibers. Here, we identified a total of 37 non-redundant TCP proteins from the diploid cotton (Gossypium raimondii), which showed great diversity in the expression profile. GrTCP11, an ortholog of AtTCP11, was preferentially expressed in cotton anthers and during fiber initiation and secondary cell wall synthesis stages. Overexpression of GrTCP11 in Arabidopsis thaliana reduced root hair length and delayed flowering. It was found that GrTCP11 negatively regulated genes involved in jasmonic acid (JA) biosynthesis and response, such as AtLOX4, AtAOS, AtAOC1, AtAOC3, AtJAZ1, AtJAZ2, AtMYC2, and AtERF1, which resulted in a decrease in JA concentration in the overexpressed transgenic lines. As with the JA-deficient mutant dde2-2, the transgenic line 4-1 was insensitive to 50 μM methyl jasmonate, compared with the wild-type plants. The results suggest that GrTCP11 may be an important transcription factor for cotton fiber development, by negatively regulating JA biosynthesis and response.

Photoactive bismuth silicate catalysts: Role of preparation method

The published papers highlight the photocatalytic properties of bismuth silicates, especially Bi2SiO5. Meanwhile, there is limited information on the formation of bismuth silicates that hinders the controlled synthesis of pure phases of bismuth silicates or composites on the basis thereof. The study is focused on the influence of preparation conditions on the interaction of initial reagents at each stage of synthesis taking into account the roles of solvent (water or ethylene glycol (EG)), precipitation agent, Si-containing component as well as the calcination procedure. The key role in these transformations is played by the stable Bi(III)–EG complex that participates in the Bi3+ reduction to metallic state under solvothermal conditions. The phase formation process is accomplished during the thermal treatment of the samples synthesized from EG solution. A four-phased composite material demonstrates the highest photocatalytic performance in photodegradation of Rhodamine B and phenol solutions via selective deethylation and mineralization processes, respectively.

In situsmall-angle X-ray scattering investigation of X-ray-induced gold nanoparticle synthesis without stabilizer

The X-ray irradiation of gold salt aqueous solutions in the synthesis of gold nanoparticles (AuNPs) in the absence of any reducing agent or stabilizer is presented. The size, dispersion, number of particles, yield and morphology evolution during the radiolytic formation of AuNPs were followed simultaneously usingin situsmall-angle X-ray scattering. This study provides an insight into the overall kinetics and formation mechanisms at the initial stage of AuNP synthesis without reductants and stabilizers. The pH-dependent speciation of aqueous HAuCl4and its influence on the synthesis, structure and properties of AuNPs were observed. The result sheds light on the key parameters required to obtain stable monomodal particles and the influence of the surface charge and reactivity of the chemical solution on the final particle size and shape.

Designing Functionalized Polyelectrolyte Microcapsules for Cancer Treatment.

The engineering of delivery systems for drugs and contrasting labels ensuring the simultaneous imaging and treatment of malignant tumors is an important hurdle in developing new tools for cancer therapy and diagnosis. Polyelectrolyte microcapsules (MCs), formed by nanosized interpolymer complexes, represent a promising platform for the designing of multipurpose agents, functionalized with various components, including high- and low-molecular-weight substances, metal nanoparticles, and organic fluorescent dyes. Here, we have developed size-homogenous MCs with different structures (core/shell and shell types) and microbeads containing doxorubicin (DOX) as a model anticancer drug, and fluorescent semiconductor nanocrystals (quantum dots, QDs) as fluorescent nanolabels. In this study, we suggest approaches to the encapsulation of DOX at different stages of the MC synthesis and describe the optimal conditions for the optical encoding of MCs with water-soluble QDs. The results of primary characterization of the designed microcarriers, including particle analysis, the efficacy of DOX and QDs encapsulation, and the drug release kinetics are reported. The polyelectrolyte MCs developed here ensure a modified (prolonged) release of DOX, under conditions close to normal and tumor tissues; they possess a bright fluorescence that paves the way to their exploitation for the delivery of antitumor drugs and fluorescence imaging.

Effects of Alcell Lignin Methylolation and Lignin Adding Stage on Lignin-Based Phenolic Adhesives.

To investigate the effects of lignin methylolation and lignin adding stage on the resulted lignin-based phenolic adhesives, Alcell lignin activated with NaOH (AL) or methylolation (ML) was integrated into the phenolic adhesives system by replacing phenol at various adhesive synthesis stages or directly co-polymerizing with phenolic adhesives. Lignin integration into phenolic adhesives greatly increased the viscosity of the resultant adhesives, regardless of lignin methylolation or adding stage. ML introduction at the second stage of adhesive synthesis led to much bigger viscosity than ML or AL introduction into phenolic adhesives at any other stages. Lignin methylolation and lignin adding stage did not affect the thermal stability of lignin based phenolic adhesives, even though lignin-based adhesives were less thermally stable than NPF. Typical three-stage degradation characteristics were also observed on all the lignin-based phenolic adhesives. Three-ply plywoods can be successfully laminated with lignin based adhesives, and it was interesting that after 3 h of cooking in boiling water, the plywoods specimens bonded with lignin-based phenolic adhesives displayed higher bonding strength than the corresponding dry strength obtained after direct conditioning at 20 °C and 65% RH. Compared with NPF, lignin introduction significantly reduced the bonding strength of lignin based phenolic adhesives when applied for plywood lamination. However, no significant variation of bonding strength was detected among the lignin based phenolic adhesives, regardless of lignin methylolation or adding stages.

Exploring using NVivo software to facilitate inductive coding for thematic narrative synthesis

Background The author conducted a review on how power and hierarchy affect staff safety in maternity services, using a narrative synthesis of staff voices from relevant literature. The review was coded using NVivo software. This article aims to evaluate NVivo as a tool for thematic narrative synthesis. Methods Selected papers were coded inductively using NVivo software, a subjective idealist approach to knowledge where iteration is achieved at the coding and synthesis stages of the process. Results NVivo proved to be a versatile tool; the imported files could be word or pdf, the import tab made it possible to upload images and audio files and information could be transferred from OneNote, Outlook and bibliographic software such as Endnote and RefWorks. NVivo software provided numerous options to explore data within different tabs. Users could create relationships between files and there were opportunities to display the findings in word clouds, hierarchies and clusters. Conclusions NVivo was a user-friendly tool for a novice user, facilitating coding for thematic narrative synthesis. A discussion of the review findings were explored in a previous article.

Adaptive changes in the ornithine cycle and amino acid synthesis in sheep liver with different meat productivity

The aim of the research was to study the ornithine cycle as the process of fixing ammonia and the formation of urea in the body of highly productive animals. In our experiments, we used a protein-deficient diet and urea as a nitrogen substitute for nitrogen-containing materials in the diet to reveal the mechanism of action of urea on animals, in particular on the biochemical processes of the ornithine cycle. There are some differences between Bukovinian sheep of the Askanian meat-wool breed and outbreds in terms of the ability to build muscle tissue. Our study reveals that the slaughter yield and the average daily gain consumption of Bukovinian-type meat of the Askanian meat-wool breed were higher in summer and in autumn, compare with purebred sheep. Sheep of the Bukovynian type of Askanian meat-wool breed have the intensity of enzymatic formation of urea in liver homogenates that is much higher in all experiments than in outbred sheep. A sharp drop in the activity of all stages of urea formation and glutamic acid synthesis in liver homogenates and significantly weakened urea formation was found in all experiments of the fourth series in comparison with the experiments in the third series. Increased muscle growth, high nitrogen deposition, and a much lower percentage of urinary excretion of ammonia and urea nitrogen, as well as higher activity of enzymes of the ornithine cycle and glutamic acid synthesis in the Bukovinian sheep type of Askanian meat-wool breed compared to outbreeds allow concluding that ammonia and urea in highly productive animals act less as finishing products of nitrogen metabolism than in low-productive animals.

Health Care Professionals' Experiences and Perspectives on Using Telehealth for Home-Based Palliative Care: Protocol for a Scoping Review.

BackgroundTelehealth seems feasible for use in home-based palliative care. However, acceptance among health care professionals (HCPs) is essential for the successful delivery of telehealth in practice. No scoping review has mapped the experiences and perspectives of HCPs on the use of telehealth for home-based palliative care.ObjectiveThe aim of this review is to systematically map published studies on HCPs’ experiences and perspectives on the use of telehealth in home-based palliative care.MethodsThe proposed scoping review will employ the methodology of Arksey and O’Malley. This protocol is guided by the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocol (PRISMA-P). A systematic search will be performed in MEDLINE, PsycINFO, EMBASE, CINAHL, Allied and Complementary Medicine (AMED), and Web of Science for studies published between January 2000 and July 5, 2021. We will also hand search the reference lists of included papers to identify additional studies of relevance. The search will be updated in 2022. Pairs of authors will independently assess the eligibility of studies and extract data. The first 2 stages of thematic synthesis will be used to thematically organize the data. Because the scoping review methodology consists of reviewing and collecting data from publicly available materials, this study does not require ethics approval.ResultsThe database searches; testing of eligibility criteria; and screening of titles, abstracts, and full-text papers will be performed by fall 2021. The results from this scoping review will be presented as a descriptive summary of the results from all included papers, and will be inductively organized into descriptive themes. A frequency table illustrating which papers were included in which descriptive themes will be made. Results are anticipated by the fall of 2022.ConclusionsA mapping of studies could identify research gaps regarding HCPs’ experiences and perspectives on the use of telehealth in home-based palliative care and may determine the value and feasibility of conducting a full systematic review.International Registered Report Identifier (IRRID)PRR1-10.2196/33305

Environmental assessment of metal-organic framework DUT-4 synthesis and its application for siloxane removal

In this study, the effect of different solvents in metal-organic framework (MOF) synthesis was evaluated in a technical study and an environmental study. The technical study considered the octamethylcyclotetrasiloxane (D4) adsorption on MOF DUT-4 for biogas purification, while the environmental study was implemented using the Life Cycle Assessment (LCA) methodology. In addition, the obtained DUT-4 adsorbents were characterized by X-ray diffraction, N2 adsorption-desorption isotherms, solid-state 27Al magic-angle spinning nuclear magnetic resonance, scanning electron microscopy, and Fourier transform infrared spectroscopy techniques. The results indicated that technically similar materials are obtained through solvothermal synthesis with similar D4 siloxane adsorption capacities (9.8 mg/g). Conversely, hydrothermal synthesis led to a low D4 siloxane adsorption capacity (1.8 mg/g). The environmental study demonstrated that the solvothermal synthesis had the highest contribution to the environmental damage due to the use of toxic solvents in the synthesis, cleaning, and solvent exchange stages (environmental score factor up to 244 mPt). In addition, a techno-environmental impact factor was introduced to identify the most suitable synthesis route of DUT-4. The overall results pointed out that solvothermal synthesis is the best scenario for DUT-4 production due to its low environmental impact/adsorption capacity ratio (11.44). This study is a step toward a more holistic approach integrating technical and environmental criteria in MOF synthesis for adsorption applications.

(Invited) In Situ Pyrolysis: Direct Observations of Transformations during Synthesis of M-N-C Electrocatalysts

Transition metal-nitrogen-carbon (M-N-C) materials have been considered to be one of most promising platinum group metal-free (PGM-free) catalysts for polymer electrolyte fuel cells 1,2. They are usually obtained through pyrolysis of low molecular weight or polymetric precursors: heat treatment in inert atmosphere. Morphological, structural, interfacial and chemical changes during pyrolysis enable the emergence of the new material with atomically dispersed transition metal ions. These ions are incorporated in the graphene-like carbonaceous matrix, doped with nitrogen and forming various Fe-Nx catalytically active sites. Often, a secondary pyrolysis process is being carries out, after the completion of the initial one, resulting in better defined, and in many cases, more active and stable catalysts (a.k.a. “re-pyrolysis”). Understanding the process leading to formation of the active sites helps advancing their development addressing activity and durability conundrum and paves to way for their introduction in main-stream fuel cell technology.We have reported our findings on dramatic transformations during pyrolysis of M-N-C derived by the Sacrificial Support Method: a hard templating with amorphous silica, removed after the pyrolysis by reactive etching (HF).3 This talk will cover the observations made in situ for both stages of the pyrolytic synthesis via a set of synchrotron and laboratory techniques including (i) pyrolysis of charge-transfer organic salt (nicarbazin) when mixed with silica template and (ii) re-pyrolysis of the M-N-C material as a path to obtain atomically dispersed PGM-free catalyst. During the first pyrolysis we have observed for the first time the explicit melting of the precursor (at exact thermal signature), wetting of the hard template and followed major transformation in morphology. We established that the re-pyrolysis of M-N-C materials results in the rearrangement of multitudinous N-containing moieties, and increased content and a more uniform distribution of Fe-Nx sites.A new set of data will be introduced corresponding to structural changes in “self-templated” pyrolysis of metal-organic framework (MOF) compounds to yield M-N-C with defines morphology. The role of different transition metals and “morphology memory” in retaining MOF structure after pyrolysis will be discussed. Asset and P. Atanassov, Joule, 4 (2020) 33-44Specchia, P. Atanassov and J. Zagal, Current Opinion in Electrochemistry, (2021) 100687Huang, et al., Materials Today, (2021) DOI: 10.1016/j.mattod.2021.02.006

MgF2-Based Organized Porous Inorganic Nanofluorides as Heterogeneous Catalysts for Fluorination of 2-Chloropyridine

The successful preparation of organized porous inorganic fluorides (OPIFs) with a high specific surface area is demonstrated for MgF 2. For the first time, macroporous MgF 2 OPIFs with a surface area of above 200 m 2 g −1 and mesoporous MgF 2 powder were prepared through the assembly of preformed MgF 2 nanoparticles and homemade polymer templates with a tunable size. These OPIF materials have been fully examined at different synthesis stages by means of powder X-ray diffraction, N 2 sorption, scanning electron microscopy, and transmission electron microscopy analyses and 19 F and 1 H solid-state nuclear magnetic resonance. The relation between the nature, the size, and the amount of polymer template on the porous structure was deeply investigated. The MgF 2 OPIFs present a higher thermal stability under air and F 2 calcination than MgF 2 NPs as the structuration of the OPIF composite considerably slows down the crystallite growth during thermal treatment under air. OPIF materials were evaluated for the first time as heterogeneous catalysts for the fluorination of 2-chloropyridine under HF gas as a fluorinating agent at 350°C. This study evidences catalytic sites with two Lewis acidity strengths (medium and low).