Precursor Reagents Research Articles

Copper Catalyzed Fluoroalkyl‐Selenization of Olefins

An efficient copper catalyzed fluoroalkyl‐selenization reaction of olefins has been developed, providing 1,2‐difluoroarylselenides in moderate to excellent yields. The readily available ethyl bromodifluoroacetate and diphenyl diselenide (Ph2Se2) have been employed as efficient radical precursor and selenization reagents to react with olefins. The reaction features a broad substrate scope, including substituted alkenes with various functional groups.

A unified flow strategy for the preparation and use of trifluoromethyl-heteroatom anions.

The trifluoromethyl group (CF3) is a key functionality in pharmaceutical and agrochemical development, greatly enhancing the efficacy and properties of resulting compounds. However, attaching the CF3 group to heteroatoms such as sulfur, oxygen, and nitrogen poses challenges because of the lack of general synthetic methods and reliance on bespoke reagents. Here, we present a modular flow platform that streamlines the synthesis of heteroatom-CF3 motifs. Our method uses readily available organic precursors in combination with cesium fluoride as the primary fluorine source, facilitating the rapid generation of N-trifluoromethyl(R) [NCF3(R)], SCF3 (trifluoromethylthio), and OCF3 (trifluoromethoxy) anions on demand without reliance on perfluoroalkyl precursor reagents. This strategy offers a more environmentally friendly synthesis of trifluoromethyl(heteroatom)-containing molecules, with the potential for scalability in manufacturing processes facilitated by flow technology.

Radical Difunctionalization of Unsaturated Hydrocarbons Employing the Same Functional Reagent

AbstractThe radical difunctionalization of unsaturated hydrocarbons serves as an efficient means to rapidly construct molecular skeletons and synthesize‐highly valuable compounds. In this transformational process, diverse positions within unsaturated hydrocarbons are sequentially functionalized by a single radical precursor reagent, thereby achieving highly efficient and selective transformations that promote atom economy. Furthermore, this approach minimizes the generation of numerous byproducts stemming from cross‐coupling reactions between reactants, owing to the reduction of the number of participating components. Therefore, this review provides an in‐depth analysis of the radical difunctionalization of unsaturated hydrocarbons utilizing a single functional reagent in recent decades. The discussion is based on eight different radical classes (carbon‐, nitrogen‐, phosphine‐, oxygen‐, sulfur‐, selenium‐, tellurium‐, and chlorine‐centered radicals), emphasizing the mechanism of specific radical difunctionalization. It also analyzes in detail the regulation of key factors such as regional selectivity, and provides unique insights into reaction transformations.

Biodiesel photoelectrocatalytic synthesis employing α-Fe2O3 film decorated with Pt nanoparticles as photoanode

In this work, photoelectrochemical route for biodiesel production using an electrochemical cell configured with platinum and α-Fe2O3 modified with Pt nanoparticles as electrodes was investigated. XRD patterns registered for film prepared by modified hydrothermal method revealed a trigonal structure of the hematite (α-Fe2O3) phase. The α-Fe2O3 film surface was decorated by metallic Pt nanoparticles (PtNP) in order to reduce the charge recombination and improve the photocatalytic efficiency. The band gap energy (EBG) of the α-Fe2O3 and PtNP/α-Fe2O3 films was estimated by UV-Vis spectroscopy at approximately 2.1 eV. Electrochemical measurements showed that the oxide is an n-type semiconductor adequate to be used as a photoanode in biodiesel synthesis. Under polarization conditions, the electrochemical cell changed the pH from 7 to 14 when the system was polarized at 5.0 V. In the synthesis of biodiesel by esterification reaction, oleic acid, 300 µL of 0.1 mol L−1 aqueous KCl solution and methanol were used as precursor reagents. The reaction was carried out free of strong base, such as KOH or NaOH, as a supporting electrolyte. In this route, the reduction of the water molecule occurred on the cathode, with the formation of hydroxyl (OH-) species, methoxy, and consequently fatty acid methyl esters (FAMEs). Thermogravimetric analysis (TGA) and Gas chromatography coupled to mass spectrometry (CG-MS) were performed to evaluate the catalysis products. GC-MS analyzes show that the reaction has a yield of about 7 % with the formation of FAMEs, such as methyl 9-octadecenoate, methyl hexadecanoate and methyl hexadecanoate.

Rapid (Deuterio)difluoromethylation of Heteroatoms using R‐22 Gas: A Demonstration of Flow Chemistry in Suppressing Intrinsic Reaction Pathways

The exploration and use of deuteriodifluoromethyl heteroatom groups (X‐CF2D) has been limited by persistent challenges, including the unavailability of CF2D precursor reagents, as well as safety, scalability, and environmental concerns associated with conventional batch‐mode syntheses. In this study, we report the use of atom‐efficient and cost‐effective R‐22 gas (ClCF2H) in continuous flow for the rapid installation of CF2H and CF2D groups on heteroatom centers. However, the intrinsic nucleophilic substitution between heteroatom anions and ClCF2H decreases the deuterium incorporation levels. Notably, a judiciously designed continuous flow system proves to suppress the previously unavoidable SN2 reaction and allows for the selective carbene coupling to generate X‐CF2D products with high deuterium incorporation levels up to 96%. Our continuous flow systems provide a broad scope of X‐CF2H and X‐CF2D products (X = S, O, N) within a short residence time of 5 minutes and scalability is also demonstrated.

Stereodivergent Synthesis of Pyridyl Cyclopropanes via Enzymatic Activation of Pyridotriazoles.

Hemoproteins have recently emerged as powerful biocatalysts for new-to-nature carbene transfer reactions. Despite this progress, these strategies have remained largely limited to diazo-based carbene precursor reagents. Here, we report the development of a biocatalytic strategy for the stereoselective construction of pyridine-functionalized cyclopropanes via the hemoprotein-mediated activation of pyridotriazoles (PyTz) as stable and readily accessible carbene sources. This method enables the asymmetric cyclopropanation of a variety of olefins, including electron-rich and electrodeficient ones, with high activity, high stereoselectivity, and enantiodivergent selectivity, providing access to mono- and diarylcyclopropanes that incorporate a pyridine moiety and thus two structural motifs of high value in medicinal chemistry. Mechanistic studies reveal a multifaceted role of 7-halogen substitution in the pyridotriazole reagent toward favoring multiple catalytic steps in the transformation. This work provides the first example of asymmetric olefin cyclopropanation with pyridotriazoles, paving the way to the exploitation of these attractive and versatile reagents for enzyme-catalyzed carbene-mediated reactions.

Novel Bi-Functional MoS2/α-Fe2O3 Nanocomposites for High Photocatalytic Performance

In this study, 3-dimensional molybdenum disulfide (MoS2) structures, integrated with hematite (α-Fe2O3) nanoparticles, were fabricated under a convenient two-step hydrothermal route. The fabricated photocatalytic nanocomposites consist of well-arranged MoS2 flakes, resembling spherical flower-like morphology, and the nanoparticulate α-Fe2O3 structures decorate the 3D network. By raising the α-Fe2O3 weight ratio, the composites’ specific surface area and morphology were not affected, regardless of the partial cover of the cavities for higher hematite content. Moreover, the crystallinity examination with XRD, Raman, and FTIR techniques revealed that the precursor reagents were fully transformed to well-crystalized MoS2 and Fe2O3 composites of high purity, as no organic or inorganic residues could be detected. The photocatalytic oxidation and reduction performance of these composites was evaluated against the tetracycline pharmaceutical and the industrial pollutant hexavalent chromium, respectively. The improvement in the removal efficiencies demonstrates that the superior photoactivity originates from the high crystallinity and homogeneity of the composite, in combination with the enhanced charge carriers’ separation in the semiconductors’ interface.

Green synthesis of ZnO nanoparticles by Myrtus communis plant extract with investigation of effect of precursor, calcination temperature and study of photocatalytic performance

An elegant approach was made for the synthesis of ZnO nanoparticles by Myrtus Communis plant extract using two different precursors at variable temperatures (400,600, and 800 °C). The properties of nanoparticles were investigated with PXRD, SEM-EDX, PL, FTIR, and UV–Vis spectrometer. PXRD results inferred that all samples have pure wurtzite phase confirming with JCPDS card No. 36–1451. The UV–Vis spectroscopy exhibited that all estimated bandgaps are a little less than those for bulk ZnO. It was confirmed by EDX spectra that Zn and O atoms are the main compositions of the material. FESEM images displayed hexagonal-like shapes of nanoparticles for all samples prepared with acetate. Hexagonal morphology was observed in the samples having green emission at room temperature PL measurements. It was seen that methylene blue degraded about 90 % after about 20 min of irradiation of UV light for samples calcined at 400 °C. It was also observed that the samples calcined at 400 °C degraded methylene blue by approximately 99 %. This work is the first paper on the morphological utilization and photocatalytic performance of green synthesized ZnO with Myrtus communis plant extract with various calcination temperatures via two different precursor reagents.

Silver-based SERS substrates fabricated using a 3D printed microfluidic device.

The detection of harmful chemicals in the environment and for food safety is a crucial requirement. While traditional techniques such as GC-MS and HPLC provide high sensitivity, they are expensive, time-consuming, and require skilled labor. Surface-enhanced Raman spectroscopy (SERS) is a powerful analytical tool for detecting ultralow concentrations of chemical compounds and biomolecules. We present a reproducible method for producing Ag nanoparticles that can be used to create highly sensitive SERS substrates. A microfluidic device was employed to confine the precursor reagents within the droplets, resulting in Ag nanoparticles of uniform shape and size. The study investigates the effects of various synthesis conditions on the size distribution, dispersity, and localized surface plasmon resonance wavelength of the Ag nanoparticles. To create the SERS substrate, the as-synthesized Ag nanoparticles were assembled into a monolayer on a liquid/air interface and deposited onto a porous silicon array prepared through a metal-assisted chemical etching approach. By using the developed microfluidic device, enhancement factors of the Raman signal for rhodamine B (at 10-9 M) and melamine (at 10-7 M) of 8.59 × 106 and 8.21 × 103, respectively, were obtained. The detection limits for rhodamine B and melamine were estimated to be 1.94 × 10-10 M and 2.8 × 10-8 M with relative standard deviation values of 3.4% and 4.6%, respectively. The developed SERS substrate exhibits exceptional analytical performance and has the potential to be a valuable analytical tool for monitoring environmental contaminants.

Combustion synthesis and characterization of dysprosium nano-composite melilite

Light emitting nano-scale materials have attracted a great interest in recent days. In view of this, a nanocrystal solid luminescent composite material was prepared using combustion processing technique and its identity was analyzed and further investigated. The precursor reagents were measured using the single pan analytical balance. A sample was synthesized and its functional group was identified using the FTIR spectroscopy and XRD studies as having similar properties to those in Batch No. JCPDS No. 77-1149 and in Base Code AMCSD 0008032. Its photoluminescence spectrum identified peaks located at 476 nm, 578 nm and 615 nm that were attributed to electronic transition from 4F9/2 to 6H15/2, from 4F9/2 to 6H13/2 and from 4F9/2 to 6H11/2 respectively as the finger blue-prints of dysprosium [Dy3+] ion. Its crystalline sizes and strains were calculated using the Debay Scherrer’s equation and analyzed using the UDM model. The findings showed that the prepared sample had a superior homogeneity and further that the Dy3+ influenced its formation. The mellite sample was identified to be Ca2MgSi2O7:Dy3+. Further analysis on the sample suggested that was a potential white light emitting luminescent material just like Ca2MgSi2O7:Tb3+ phosphor and Sr2MgSi2O7:Dy3+ phosphor.

COMBUSTION SYNTHESIS AND CHARACTERIZATION OF DYSPROSIUM NANO-COMPOSITE MELILITE FOR DIODE APPLICATIONS

Light emitting nano-scale materials have attracted a great interest in recent days. In view of this, a nanocrystal solid luminescent composite material was prepared using combustion processing technique and its identity was analyzed and further investigated. The precursor reagents were measured using the single pan analytical balance. A sample was synthesized and its functional group was identified using the FTIR spectroscopy and XRD studies as having similar properties to those in Batch No. JCPDS No. 77-1149 and in Base Code AMCSD 0008032. Its photoluminescence spectrum identified peaks located at 476 nm, 578 nm and 615 nm that were attributed to electronic transition from 4F9/2 to 6H15/2, from 4F9/2 to 6H13/2 and from 4F9/2 to 6H11/2 respectively as the finger blue-prints of dysprosium [Dy3+] ion. Its crystalline sizes and strains were calculated using the Debay Scherrer’s equation and analyzed using the UDM model. The findings showed that the prepared sample had a superior homogeneity and further that the Dy3+ influenced its formation. The melllite sample was identified to be Ca2MgSi2O7:Dy3+. Further analysis on the sample suggested that was a potential white light emitting luminescent material just like Ca2MgSi2O7:Tb3+ phosphor and Sr2MgSi2O7:Dy3+ phosphor.

Tuning magnetic and luminescent properties of iron oxide@C nanoparticles from hydrothermal synthesis: Influence of precursor reagents

Magneto-luminescent nanocomposites were obtained by coating coprecipitated iron oxide nanoparticles with a functionalized carbon layer by hydrothermal treatment, using different organic precursors (D-glucose and p-phenylenediamine). The nanomaterials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), RAMAN, infrared (FTIR), UV-vis and photoluminescence (PL) spectroscopic analysis, vibrating sample magnetometry (VSM) and zetametry. Remarkable contrasting changes in the structural and magnetic properties of nanocomposites were identified after the carbon coating, which was directly related to the precursor used. Crystalline phase transformations were observed with a decrease in the saturation magnetization (-80%) using p-phenylenediamine and an increase (+22%) using glucose, relative to uncoated magnetic core. The distinct photoluminescent properties with multicolored emissions on long-wavelength are ascribed to the carbon shell and to the chemical moieties, such as amino, carbonyl, carboxylate, and hydroxyl groups on the surface. This makes it possible for different surface states to be responsible for emission, and these chemical groups are also responsible for a higher colloidal stability of nanocomposites in alkaline medium. The tunability of the properties of nanocomposites from the conditions of synthesis opens a wide range of applications for these nanomaterials, such as ion detection, magnetohyperthermia, and theranostics.

Microfluidic-assisted fiber production: Potentials, limitations, and prospects.

Besides the conventional fiber production methods, microfluidics has emerged as a promising approach for the engineered spinning of fibrous materials and offers excellent potential for fiber manufacturing in a controlled and straightforward manner. This method facilitates low-speed prototype synthesis of fibers for diverse applications while providing superior control over reaction conditions, efficient use of precursor solutions, reagent mixing, and process parameters. This article reviews recent advances in microfluidic technology for the fabrication of fibrous materials with different morphologies and a variety of properties aimed at various applications. First, the basic principles, as well as the latest developments and achievements of microfluidic-based techniques for fiber production, are introduced. Specifically, microfluidic platforms made of glass, polymers, and/or metals, including but not limited to microfluidic chips, capillary-based devices, and three-dimensional printed devices are summarized. Then, fiber production from various materials, such as alginate, gelatin, silk, collagen, and chitosan, using different microfluidic platforms with a broad range of cross-linking agents and mechanisms is described. Therefore, microfluidic spun fibers with diverse diameters ranging from submicrometer scales to hundreds of micrometers and structures, such as cylindrical, hollow, grooved, flat, core-shell, heterogeneous, helical, and peapod-like morphologies, with tunable sizes and mechanical properties are discussed in detail. Subsequently, the practical applications of microfluidic spun fibers are highlighted in sensors for biomedical or optical purposes, scaffolds for culture or encapsulation of cells in tissue engineering, and drug delivery. Finally, different limitations and challenges of the current microfluidic technologies, as well as the future perspectives and concluding remarks, are presented.

Crosslinking starch with Diels–Alder reaction: water‐soluble materials and water‐mediated processes

AbstractThe click Diels–Alder cycloaddition is a one‐step high‐yield reaction that does not require catalysts, does not generate side products and can be performed at mild conditions in an aqueous medium, representing a good method for biomaterials coupling and synthesis. It exploits functional groups that can be grafted onto natural polymers or other molecules and can be used for the preparation of biomaterials such as biocompatible hydrogels, a nascent field of application of the Diels–Alder reaction. If performed in an aqueous medium, at biological pH and body temperature, it can be used in internal body systems for drug and cell release. Here we report the grafting of the furan ring from furfuryl alcohol to chemically oxidized starch and its crosslinking via the Diels–Alder reaction, in aqueous medium, at 37 °C, mimicking the body conditions in vitro. Since the functional groups used in this chemical strategy are sparingly studied for such applications, and their behavior is not described in the literature, the biocompatibility of the crosslinked starch as well as that of the precursor reagents were evaluated by cytotoxicity tests using GM07492 human cells. The results reveal that the furan‐crosslinked starch is a promising candidate for cell encapsulation and delivery within the body. © 2022 Society of Industrial Chemistry.

Fabrication of Mn-Doped SrTiO3/Carbon Fiber with Oxygen Vacancy for Enhanced Photocatalytic Hydrogen Evolution.

With carbon fiber, it is difficult to load semiconductor photocatalysts and easy to shed off thanks to its smooth surface and few active groups, which has always been a problem in the synthesis of photocatalysts. In the study, SrTiO3 nanoparticles were loaded onto the Tencel fibers using the solvothermal method, and then the Tencel fibers were carbonized at a high temperature under the condition of inert gas to form carbon fibers, thus SrTiO3@CF photocatalytic composite materials with solid core shell structure were prepared. Meanwhile, Mn ions were added into the SrTiO3 precursor reagent in the solvothermal experiment to prepare Mn-doped Mn-SrTiO3@CF photocatalytic composite material. XPS and EPR tests showed that the prepared Mn-SrTiO3@CF photocatalytic composite was rich in oxygen vacancies. The existence of these oxygen vacancies formed oxygen defect states (VOs) below the conduction band, which constituted the capture center of photogenerated electrons and significantly improved the photocatalytic activity. The photocatalytic hydrogen experimental results showed that the photocatalytic hydrogen production capacity of Mn-SrTiO3@CF composite material with 5% Mn-doped was six times that of the SrTiO3@CF material, and the doping of Mn ions not only promoted the red shift of the light absorption boundary and the extension to visible light, but also improved the separation and migration efficiency of photocarriers. In the paper, the preparation method solves the difficulty of loading photocatalysts on CF and provides a new design method for the recycling of catalysts, and we improve the hydrogen production performance of photocatalysts by Mn-doped modification and the introduction of oxygen vacancies, which provides a theoretical method for the practical application of hydrogen energy.

A bench-stable reagent for C-4 selective deuteriodifluoromethylation of azines

Deuteriodifluoromethyl (CF2D) is a challenging and important functional group due to difficult deuterium incorporation and lack of effective precursor reagents. Herein, we report a bench-stable reagent, deuteriodifluoromethyl phosphine (DDFP) from cheap deuterium source for selectivity deuteriodifluoromethylation of azines with a high deuterium incorporation yield. The late-stage modification of complex molecules further confirmed the potential of this reagent for practical applications. We expect that our reagent to find applications in synthesis of isotope-labelled molecules of interests for drug-discovery and related ilucidation of mechanism of action.

Prepare and Utilize Mesoporous Silica SBA-15 for Efficient Photocatalytic Adsorption of Methylene Blue and Copper(II)

This work has provided a novel technique for preparation, characterization, and utilization of mesoporous silica SBA-15 in waste treatment to remove methylene blue as an organic pollutant and copper(II) as inorganic pollutant sampling with a photocatalytic adsorption system. To process of mesoporous silica SBA-15 was prepared by the sol-gel method for Pluronic as a surfactant template and following the hydrothermal process to high interaction between Pluronik and tetraethyl ortho silicate (TEOS) as precursor reagent. The proceed materials were characterized by the surface analyzer, X-ray diffraction, and Fourier transform infrared. Mesoporous silica SBA-15 was obtained with hexagonal structure having 72 percent amorphous content, high surface area, large pore-volume, approximately 948 m2/g, and 1.3 cm3/g. The second major finding was that mesoporous silica SBA-15 have a high photocatalytic adsorption capacity to remove methylene blue and copper(II). These present results suggest several courses of action in order to utilize SBA-15 samples in waste treatment.

Manganese-Doped Carbon Dots Via Inner Filter Effect for the Sensitive Detection of Tetracycline in Poultry Meat Samples

In this study, a rapid and sensitive analytical method has been developed to detect tetracycline hydrochloride (TC) using manganese-doped carbon dots (Mn-CDs) prepared by one-step hydrothermal procedure using 1-(2-pyridinylazo)-2-naohthalenol (PAN) and MnCl2 as precursor reagents. The obtained Mn-CDs showed an ultraviolet emission at 360 nm with an excitation wavelength of 300 nm. TC has a strong characteristic absorption peak at 356 nm, which has a large spectral overlap with the emission band of the Mn-CDs. The fluorescence intensity (FI) of Mn-CDs at 360 nm is linearly quenched within the TC concentration range of 0.1-200 µM. The developed assay for the detection of TC was based on an inner filter effect (IFE) mechanism and is rapid, sensitive, and was successfully applied for the determination of TC in different poultry meat samples with satisfactory results.

Efficient and sustainable Co3O4 nanocages based nickel catalyst: A suitable platform for the synthesis of quinoxaline derivatives

The Co 3 O 4 nanocages has been synthesized based on the Kirkendall effect involving the thermal decomposition of prussian blue analogue Co 3 [Co(CN) 6 ] 2 nanocubes. Thereafter, the hollow cavity of Co 3 O 4 cages was loaded with Ni nanoparticles to synthesize the final nanocatalyst (Ni@Co 3 O 4 ). Highly versatile Co 3 O 4 nanocages based nickel catalytic system has been effectively exploited for the condensation of 1,2-diamines with α-diketones for the synthesis of quinoxaline derivatives. • 3D hollow architecture of Co 3 O 4 cages permits the integration of multiple catalytic active sites. • The synthesized nanocatalyst showed high catalytic efficacy with high conversions and TON of targeted products. • The developed nanomaterial exhibits excellent durability and reusability for 6 subsequent runs. • It is anticipated thatNi@Co 3 O 4 nanocatalyst would open new avenues in the field of catalysis. Engineered nanocages have emerged at the forefront of nanomaterial investigation as they possess tremendous potential to boost key chemical processes owing to their hollow architectures that can help in achieving high reactivity. With an intention to make profitable use of their morphological features guided chemical activity, we developed dispersable Co 3 O 4 nanocages decorated with nickel nanoparticles for accessing a broad spectrum of pharmaceutically and biologically active N-heterocyclic quinoxaline nuclei using α-dicarbonyls and 1,2-diamines as precursor reagents. For designing Co 3 O 4 nanocages, we employed a simple and scalable method involving Kirkendall effect in which thermal decomposition of Co 3 [Co(CN) 6 ] 2 was carried out thereafter, nanocages were loaded with Ni nanoparticles to obtain the final Ni@Co 3 O 4 catalyst. Results revealed that Ni@Co 3 O 4 catalyst possesses immense potential to accelerate condensation of diamines and di-carbonyls in absence of any additives under mild reaction conditions. The superior catalytic efficiency has been attributed to the hollow architecture of the nanocatalyst comprising of abundant catalytic sites. This protocol exhibits several remarkable attributes such as mild reaction conditions outstanding functional group tolerance, high yield, immense durability and reusability for six subsequent runs.

Observing and Understanding the Corrosion of Silver Nanowire Electrode by Precursor Reagents and MAPbI3 Film in Different Environmental Conditions

AbstractSince metal electrode is an important component in the perovskite solar cells, which can be used as back contact, transparent electrode, and the transparent interlayer of tandem devices, the corrosion of metal electrode by perovskite film, should be understood. Here, the corrosion of conventional reagents of organic–inorganic perovskite material, i.e., CH3NH3X (MAX) and PbX2, X = I, Br, and Cl, against silver nanowire (AgNW) based transparent electrode are investigated under four different environments, i.e., nitrogen protection, light irradiation, oxygen exposure, and moisture exposure, separately. The corrosion process is inspected by monitoring the time‐dependent resistance variation of the electrode coated by the film of precursor reagent. In addition, the perovskite film of CH3NH3PbI3 (MAPbI3) is also coated on the silver nanowire electrode without or with the hole transporting layer of poly(3,4‐ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS) or nanostructured CuSCN for understanding the corrosion process under different environmental conditions. The experimental results presented in this paper would be helpful to the understanding of metal electrode stability in perovskite solar cells.