Mechanochemical Reaction Research Articles

Solvent/ligand free synthesis of Mn-doped CsPbCl3 perovskites with enhanced fluorescence for color sensor of bromide ions

For the detection of anions from wastewater, the perovskite materials synthesized should have suitable stability and be as hydrophilic as possible, and it’s not appropriate to introduce organic ligands. Mechanochemical reaction can avoid the use of organic solvents and provide improved stability for the perovskite materials due to their large particle size and compact structure, but their fluorescence is often too weak. To solve this problem, the Mn2+ doping effect was introduced into the CsPbCl3 crystals, and their synthesis doping strategies driven by mechanical grinding were systematic studied. The optimal Mn2+-doped CsPbCl3 (CsPbCl3:Mn) product was obtained by optimizing the synthesis conditions of Mn2+ source, grinding time on each reaction stage, Mn: Pb feeding ratio, and the sintering temperature. CsPbCl3:Mn had the same crystal structure as its undoped counterpart, while an obvious photoluminescence emission peak at 604 nm was obtained, which was originated from the doped Mn2+ ions. CsPbCl3:Mn had good stability against the ethanol environment and there was no organic ligands to hinder the ion exchange between Cl- and Br- from wastewater. Through testing the color difference of the resultant powders, a linear relationship with high correlation coefficient above 0.99 was established between chroma and Br- concentrations, and the Br- concentration in wastewater was accurately determined, demonstrating a promising application prospect of CsPbCl3:Mn in the fast detection of Br- ions.

Pt nanoparticles on activated phosphorus-doped graphitic nanoplatelets for high performance hydrogen evolution reaction

The method of producing hydrogen through water splitting is eco-friendly and efficient. This process requires catalysts with excellent hydrogen evolution reaction (HER) activities and good stability. However, most of the water splitting catalysts currently contain precious metals that have problems such as high cost, low reserves, and low durability. Therefore, to utilize hydrogen energy, developing a new catalyst with a non-precious metal is required to solve these problems. This work fabricated phosphorus-doped graphitic nanoplatelets (PGnP) through a mechanochemical reaction between graphite and phosphorus pentoxide (P2O5). Then, the PGnP was activated at 900 °C for 1 h under CO2 to increase the specific surface area (SSA) and porosity increasing the mass transfer of the catalysts. As a result, a Pt/A_PGnP with a lower Pt content (12.75 wt%) exhibits a similar overpotential and lower Tafel slopes but higher stability compared with a commercial Pt/C (Pt: 20 wt%). The A_PGnP, with its numerous active sites, high surface area, and incorporation of phosphorus (P), improves the performance of the HER in an acidic media. Thus, the A_PGnP, as a new support, enhances the catalytic performance in the HER.

Mechanochemical synthesis of nanostructured and composite oxide ceramics: From mechanisms to tailored properties

AbstractMechanochemical synthesis is a technology formed in the 1950s. By applying mechanical energy, mechanochemical synthesis stimulates chemical reactions, causing structural and phase changes and enabling difficult or otherwise impossible reactions to occur. Mechanochemical reactions are relatively safe, clean and efficient. At present, the synthesis of oxide ceramic materials by mechanochemical methods has attracted widespread attention. In the production of oxide ceramic materials, the characteristics of ceramic powder have a certain influence on the molding, sintering, microstructure, and mechanical properties of subsequent ceramics. In this paper, the research progress of mechanical chemistry in the synthesis of nanostructures and composite oxide ceramic powders is reviewed. The effects of process parameters such as ball milling time, speed, atmosphere, grinding media, additives, and ball‐to‐powder ratio on reaction kinetics, phase formation, and powder properties are summarized. In addition, challenges and opportunities for ceramic powder synthesis are also discussed.

Enhanced Cd2+ removal from aqueous solution using olivine and magnesite combination: New insights into the mechanochemical synergistic effect

In this study, an efficient stabilizer material for cadmium (Cd2+) treatment was successfully prepared by simply co-milling olivine with magnesite. Several analytical methods including XRD, TEM, SEM and FTIR, combined with theoretical calculations (DFT), were used to investigate mechanochemical interfacial reaction between two minerals, and the reaction mechanism of Cd removal, with ion exchange between Cd2+ and Mg2+ as the main pathway. A fixation capacity of Cd2+ as high as 270.61 mg/g, much higher than that of the pristine minerals and even the individual/physical mixture of milled olivine and magnesite, has been obtained at optimized conditions, with a neutral pH value of the solution after treatment to allow its direct discharge. The as-proposed Mg-based stabilizer with various advantages such as cost benefits, green feature etc., will boosts the utilization efficiency of natural minerals over the elaborately prepared adsorbents.

Synthesis and Characterization of Na3SbS4 Solid Electrolytes via Mechanochemical and Sintered Solid-State Reactions: A Comparative Study

A sulfide-based solid electrolyte is an enticing non-organic solid-state electrolyte developed under ambient conditions. Na3SbS4, a profoundly enduring substance capable of withstanding exceedingly elevated temperatures and pressures, emerges as a focal point. Within this investigation, we employ dual distinct techniques to fabricate Na3SbS4, encompassing ball milling and the combination of ball milling with sintering procedures. A remarkable ionic conductivity of 3.1 × 10−4 S/cm at room temperature (RT), coupled with a meager activation energy of 0.21 eV, is achieved through a bifurcated process, which is attributed to the presence of tetragonal Na3SbS4 (t-NSS). Furthermore, we delve into the electrochemical performance and cyclic longevity of the Na2/3Fe1/2Mn1/2O2|t-NSS|Na system within ambient environs. It reveals 160 mAh/g initial charge and 106 mAh/g discharge capacities at 0.01 A/g current density. Furthermore, a cycle life test conducted at 0.01 A/g over 30 cycles demonstrates stable and reliable performance. The capacity retention further highlights its enduring energy storage capabilities. This study underscores the sustainable potential of Na3SbS4 as a solid-state electrolyte for advanced energy storage systems.

Solid-State Generation of Diarylisonaphthofuran and Its Mechanochemical Diels-Alder Reaction with Epoxynaphthalene.

A solid-state method was developed for generating diarylisonaphthofurans from 1,3-diaryl-1,3-dihydronaphthofuranols. The generated reactive molecules were stable in the solid state and could be stored without any precaution. Their X-ray diffraction analysis revealed a typical quinoidal structure. Furthermore, the mechanochemical Diels-Alder reaction of 1,3-diarylisonaphthofurans with epoxynaphthalenes afforded synthetically attractive diepoxypentacenes.

A novel mechanochemical synthesis of LiMnPO4 with manganese violet and ammonium manganese phosphate as precursors

Olivine lithium manganese phosphate was synthesized by a mechanochemical method. Inorganic cathode materials can be divided into three kinds of lithium metal oxide layered, spinel oxide and olivine metal phosphate. One important of the cathode materials used in Li-ion cells is LiMnPO4. In this paper two different precursors, manganese violet and ammonium manganese phosphate proposed as reactant in the synthesis of LiMnPO4 nanostructures. Reaction between NH4MnP2O7 and Li2CO3 takes placed in solid state at room temperature. In this mechanochemical process, a solid acid and base reaction occurred between ammonium and carbonate ions. In addition, MnIII is unstable oxidation state and convert to crystalline β-MnO2, Li2MnP2O7 and NH4H2PO4 in the disproportionation reaction. Results showed that mechanochemical reaction between NH4MnP2O7 with Li2CO3 as precursors lead to concurrent redox and acid-base reaction. As a result, we observed there is a tendency for manganese violet to disproportionation into MnO2 and manganese pyrophosphate salt in a solid-state reaction. Finally, a redox reaction between β-MnO2 and Li2MnP2O7 in pyrolysis reaction under inert atmosphere give LiMnPO4. In the other hand in the mechanochemical reaction between NH4MnPO4 and Li2CO3, only acid and base reaction occurred and the NH4+ ions were replaced with Li+ ions and amorphous LiMnPO4 was prepared. The amorphous LiMnPO4 convert to crystalline LiMnPO4 by annealing the powder under inert atmosphere. The chemical changes in formation of LiMnPO4 compound was characterized by X-Ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersion x-ray analyses (EDX). FTIR spectra showed that the NH4+ ions were replaced with Li+ ions. X-ray diffraction show that by variation of precursor from manganese violet to ammonium manganese phosphate in the mechanochemical reaction the crystalline pattern changes to amorphous and also the reaction pathway was changed. The SEM images of LiMnPO4 nanoparticles that obtained by two precursors exhibit squamous morphologies with well-defined grain boundaries and nonuniform particle size distributions. The particle size distributions of crystalline LiMnPO4 obtained by NH4MnP2O7 and NH4MnPO4 were found in the region 60–260 and 20–130 nm respectively.

Energy-efficient Approach to Multicomponent Reaction for the Synthesis of Therapeutically Relevant Heterocycles

Abstract: Multi-component reactions have been used as an important synthetic strategy for the synthesis of diverse varieties of therapeutically useful heterocyclic scaffolds. High atom economy, one-pot reaction, and involvement of synthetically simple steps are some of the interesting features that make MCRs greener compared to conventional methods. The development of environmentally benign and eco-friendly synthetic methods has been a very demanding area of research in the past few decades. In particular, the development of energyefficient methods has attracted the attention of the research community due to heavy dependence on nonrenewable energy resources, which is depleting fast. Therefore, the present review has highlighted the multicomponent reactions developed under the energy efficient protocol, which mainly include the reactions developed under the microwave, ultra-sonication, mechano-chemical, and photochemical reaction conditions for the synthesis of therapeutically relevant heterocycles.

Opportunities and Challenges in Applying Solid-State NMR Spectroscopy in Organic Mechanochemistry.

In recent years it is shown that mechanochemical strategies can be beneficial in directed conversions of organic compounds. Finding new reactions proved difficult, and due to the lack of mechanistic understanding of mechanochemical reaction events, respective efforts have mostly remained empirical. Spectroscopic techniques are crucial in shedding light on these questions. In this overview, the opportunities and challenges of solid-state nuclear magnetic resonance (NMR) spectroscopy in the field of organic mechanochemistry are discussed. After a brief discussion of the basics of high-resolution solid-state NMR under magic-angle spinning (MAS) conditions, seven opportunities for solid-state NMR in the field of organic mechanochemistry are presented, ranging from ex situ approaches to structurally elucidated reaction products obtained by milling to the potential and limitations of in situ solid-state NMR approaches. Particular strengths of solid-state NMR, for instance in differentiating polymorphs, in NMR-crystallographic structure-determination protocols, or in detecting weak noncovalent interactions in molecular-recognition events employing proton-detected solid-state NMR experiments at fast MAS frequencies, are discussed.

Mechanochemical synthesis and anticonvulsant activity of 3-aminopyrrolidine-2,5-dione derivatives

A series of 3-aminopyrrolidine-2,5-dione derivatives was synthesized and tested for anticonvulsant activity. Succinimide derivatives were obtained from a simple solvent-based reaction and a mechanochemical aza-Michael reaction of maleimide or its N-substituted derivatives with selected amines. The structure of the compounds was confirmed by spectroscopic methods (NMR, FT-IR, HPLC, ESI-MS, EA and XRD for four compounds). The cytotoxic activity of the succinimide derivatives was evaluated using HepG2 cells for hepatocytotoxicity and SH-SY5Y cells for neurocytotoxicity. None of the studied compounds showed hepatocytotoxicity and two showed neurocytotoxicity. Initial anticonvulsant screening was performed in mice using the psychomotor seizure test (6 Hz, 32 mA). The selected compounds were evaluated in the following acute models of epilepsy: the maximal electroshock test, psychomotor seizure test (6 Hz, 44 mA), subcutaneous pentylenetetrazole seizure test, and acute neurotoxicity (rotarod test). The most active compound 3-((4-chlorophenyl)amino)pyrrolidine-2,5-dione revealed antiseizure activity in all seizure models (including pharmacoresistant seizures) and showed better median effective doses (ED50) and protective index values than the reference compound, ethosuximide. Furthermore, 3-(benzylamino)pyrrolidine-2,5-dione and 3-(phenylamino)pyrrolidine-2,5-dione exhibited antiseizure activity in the 6 Hz and MES tests, and 3-(butylamino)−1-phenylpyrrolidine-2,5-dione and 3-(benzylamino)−1-phenylpyrrolidine-2,5-dione exhibited antiseizure activity in the 6 Hz test. All active compounds demonstrated low in vivo neurotoxicity in the rotarod test and yielded favourable protective indices.

Investigation on Nonisothermal Dehydrogenation Behavior of Mg–Ni–La–H Materials Prepared by Mechanochemical Reaction

Mg10NixLa–H alloys are synthesized by mechanochemical reaction starting with Mg–Ni–La multiphase polycrystalline alloys prepared by resistance melting furnace. The nonisothermal hydrogen desorption behaviors are investigated herein. All prepared samples are characterized by scanning electron microscopy, X‐ray diffraction, fully automatic fast surface and porosity analysis meter Brunauer–Emmett–Teller (BET), differential scanning calorimetry, and thermogravimetric analyzer to get information of phase compositions, microstructure, BET surface area, and dehydrogenation properties. The results demonstrate that Mg10NixLa–H exhibits enhanced nonisothermal hydrogen desorption behavior owing to the synergistic effects among hydrides. The main peak dehydrogenation temperatures for Mg10Ni5La–H, Mg10Ni10La–H, and Mg10Ni15La–H alloys are 375.3, 374.4, and 359.7 °C at 5 °C min−1, respectively. And the apparent activation energy for Mg10Ni5La–H, Mg10Ni10La–H, and Mg10Ni15La–H is 111.7, 275.5, and 184.7 kJ mol−1, respectively. However, the actual hydrogen release capacities of Mg10Ni5La–H, Mg10Ni10La–H, and Mg10Ni15La–H are about 5.09, 3.98, and 4.49 wt%, respectively. Mg10Ni15La–H exhibits the lowest onset dehydrogenation temperature due to its reduced particle size and uniformly distributed hydride phase. The modification of Mg‐based hydrogen storage materials by combining mechanochemical reaction and multiple microalloying is essential for further improvement of thermal properties.

Polymer Mechanochemistry in Microbubbles.

Polymer mechanochemistry is a promising technology to convert mechanical energy into chemical functionality by breaking covalent and supramolecular bonds site-selectively. Yet, the mechanochemical reaction rates of covalent bonds in typically used ultrasonication setups lead to reasonable conversions only after comparably long sonication times. This can be accelerated by either increasing the reactivity of the mechanoresponsive moiety or by modifying the encompassing polymer topology. Here, a microbubble system with a tailored polymer shell consisting of an N2 gas core and a mechanoresponsive disulfide-containing polymer network is presented. It is found that the mechanochemical activation of the disulfides is greatly accelerated using these microbubbles compared to commensurate solid core particles or capsules filled with liquid. Aided by computational simulations, it is found that low shell thickness, low shell stiffness and crosslink density, and a size-dependent eigenfrequency close to the used ultrasound frequency maximize the mechanochemical yield over the course of the sonication process.

Investigation of the Processes of Structure Formation during Explosion Welding of Copper and Molybdenum

This article examines the processes of structure formation occurring during joint plastic deformation by the explosion of copper and molybdenum. These components are dissimilar metals with very limited mutual solubility under normal conditions, and the circumstances allowing for their interaction, as well as the products of the mechanochemical reactions of such interactions, have not been sufficiently studied and require new approaches. A cluster approach was used to describe the processes of structure formation, which describes phase formation as the process transitioning of the polyhedron of the initial phase into the polyhedron of the final phase. This work shows that under the conditions under consideration, not only is the formation of solid solutions in the contact zone with smooth concentration transitions from one component to another possible, but also the formation of new structural states, which can be represented as localized icosahedral atomic configurations (amorphous metal clusters). Such a structure is capable of locally strengthening the composite, which is confirmed by microhardness studies.

Sacrificial Mechanical Bond is as Effective as a Sacrificial Covalent Bond in Increasing Cross-Linked Polymer Toughness.

Sacrificial chemical bonds have been used effectively to increase the toughness of elastomers because such bonds dissociate at forces significantly below the fracture limit of the primary load-bearing bonds, thereby dissipating local stress. This approach owes much of its success to the ability to adjust the threshold force at which the sacrificial bonds fail at the desired rate, for example, by selecting either covalent or noncovalent sacrificial bonds. Here, we report experimental and computational evidence that a mechanical bond, responsible for the structural integrity of a rotaxane or a catenane, increases the elastomer's fracture strain, stress, and energy as much as a covalent bond of comparable mechanochemical dissociation kinetics. We synthesized and studied 6 polyacrylates cross-linked by either difluorenylsuccinonitrile (DFSN), which is an established sacrificial mechanochromic moiety; a [2]rotaxane, whose stopper allows its wheel to dethread on the same subsecond time scale as DFSN dissociates when either is under tensile force of 1.5-2 nN; a structurally homologous [2]rotaxane with a much bulkier stopper that is stable at force >5.5 nN; similarly stoppered [3]rotaxanes containing DFSN in their axles; and a control polymer with aliphatic nonsacrificial cross-links. Our data suggest that mechanochemical dethreading of a rotaxane without failure of any covalent bonds may be an important, hitherto unrecognized, contributor to the toughness of some rotaxane-cross-linked polymers and that sacrificial mechanical bonds provide a mechanism to control material fracture behavior independently of the mechanochemical response of the covalent networks, due to their distinct relationships between structure and mechanochemical reactivity.

Mechanochemical in-situ construction of ionic liquid-functionalized covalent organic frameworks for anti-wear and friction reduction

Herein, ionic liquid-functionalized covalent organic frameworks (COFs) were prepared via mechanochemical reaction. The rich-aldehyde terminated COFs (LZU1) was firstly synthesized via the excess aldehyde monomer and amino monomer. Then, the ionic liquid (NH2-IL) with amino group can graft onto the aldehyde terminated-COFs through Schiff base reaction between amino and aldehyde group driven by ball milling, and then through anion-exchange with NTf2- resulting in the ionic liquid-functionalized COFs (LZU1-NH2IL-NTf2). The LZU1-NH2IL-NTf2 displays good lubricating performance as lubricant additive, the friction coefficient is maintained at 0.106 and the wear volume is reduced by 85.4% compared with 500SN. The remarkable lubrication performance is mainly due to the physical adsorption film promoted by ionic liquid and the robust protective film formed by tribochemical reaction.

Solid-state mechanochemical synthesis of chitosan from mud crab (Scylla serrata) chitin

This study presents a method for solvent-free mechanochemical synthesis of chitosan from chitin, sourced from the shells of mud crabs (Scylla serrata). The procedure involves a sequence of demineralization and deproteinization to extract chitin from the crab shells, followed by mechanochemical deacetylation. The chitin was deacetylated by grinding it as a solid blend with sodium hydroxide (NaOH) using a stainless steel mortar and pestle. After grinding, chitosan is isolated from the blend by repetitive washing and centrifugation. The chitosan product is then characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction analysis. These characterization techniques confirm the successful deacetylation of chitin to form chitosan. A high degree of deacetylation (DD) is achieved when the weight ratio of NaOH to chitin is 1:1 or higher, implying that the DD value can be enhanced by increasing this weight ratio. The mechanochemical reaction mechanism involves the hydroxyl groups on the NaOH particles reacting with the acetamide groups of the chitin strands, yielding solid chitosan and sodium acetate. This mechanochemical deacetylation approach is more practical than the conventional heterogeneous deacetylation in strong basic solutions, since it could suppress depolymerization of the resulting chitosan and requires significantly less base. This makes it a promising method for large-scale industrial applications.

Hydrolytic hydrogen production behavior in NaCl solution of Mg and Mg-GO composite synthesized by mechanochemical reaction

With the help of the mechanochemical reaction (MCR) strategy, the composition optimization, structure regulation and surface modification of metallic Mg are realized by introducing GO in the high energy mechanical ball milling process to enhance the hydrogen production performance in NaCl solution. The synthetic process of Mg and Mg-GO composite by MCR is systematically optimized and the microstructure evolution as well as the hydrolytic hydrogen production behavior are investigated. Phase composition optimization and microstructure regulation can be effectively implemented during the MCR process. The response rate of the repeated hydrogen-filling MCR sample is faster than that of the single hydrogen-filling MCR sample. The hydrogen production rates at 298 K of 4, 8, 12, 16 and 20 h MCR Mg with repeated H2-filling can reach to 922, 934, 890, 917 and 1131 mL/g/min, respectively. The internal microstructure refinement, surface modification, moderate activity, appropriate particle size, surface defects and reasonable mass transfer channels of MCR 8 h Mg-GO composite are the reasons for the fast rates and high yields of hydrolytic hydrogen production. 365.3, 864.4 and 933.8 mL/g H2 can be produced by 8 h MCR Mg-GO composite within 1, 3 and 10 min, respectively. The hydrogen production rate of 8 h MCR Mg-GO composite is as high as ∼600 mL/g/min. Mechanochemical reaction strategy with catalyst is a useful method to improve the hydrolysis hydrogen production performance of metallic Mg when well matched with the added catalyst.

Hybridization of quinacridone and synthetic hectorite and the photoluminescence quenching by metal ions

Quinacridone, a red pigment, was hybridized with a synthetic hectorite by a mechanochemical reaction. Though quinacridone was not photoluminescent, the products were photoluminescent and the photoluminescence quantum yield was 0.89 when the dye loading was 0.00009 g dye/g clay. The product was dispersed in water to give stable suspensions with varied viscosities depending on the concentration of the hybrids. The photoluminescence of the aqueous suspension was quenched by Cr3+, Co2+, Cu2+, Fe2+, Ni2+ and Pb2+ as described by linear Stern-Volmer plots at the concentration of 1–600 ppm. Among the tested metal ions, Cr3+ gave the most efficient quenching (the KSV value of 0.0125). The quenching of the photoluminescence of the quinacridone-synthetic hectorite hybrid was applicable to detect Cu2+ and Cr3+ at ppb level.

Anionic ring-opening polymerization of functional epoxide monomers in the solid state

Despite recent advancements in mechanochemical polymerization, understanding the unique mechanochemical reactivity during the ball milling polymerization process still requires extensive investigations. Herein, solid-state anionic ring-opening polymerization is used to synthesize polyethers from various functional epoxide monomers. The critical parameters of the monomers are investigated to elucidate the unique reactivity of ball milling polymerization. The controllable syntheses of the desired polyethers are characterized via NMR, GPC, and MALDI-ToF analyses. Interestingly, bulky monomers exhibit faster conversions in the solid-state in clear contrast to that observed for solution polymerization. Particularly, a close linear correlation is observed between the conversion of the ball milling polymerization and melting point of the functional epoxide monomers, indicating melting point as a critical predictor of mechanochemical polymerization reactivity. This study provides insights into the efficient design and understanding of mechanochemical polymerization.

Remote control of mechanochemical reactions under physiological conditions using biocompatible focused ultrasound.

External control of chemical reactions in biological settings with spatial and temporal precision is a grand challenge for noninvasive diagnostic and therapeutic applications. While light is a conventional stimulus for remote chemical activation, its penetration is severely attenuated in tissues, which limits biological applicability. On the other hand, ultrasound is a biocompatible remote energy source that is highly penetrant and offers a wide range of functional tunability. Coupling ultrasound to the activation of specific chemical reactions under physiological conditions, however, remains a challenge. Here, we describe a synergistic platform that couples the selective mechanochemical activation of mechanophore-functionalized polymers with biocompatible focused ultrasound (FUS) by leveraging pressure-sensitive gas vesicles (GVs) as acousto-mechanical transducers. The power of this approach is illustrated through the mechanically triggered release of covalently bound fluorogenic and therapeutic cargo molecules from polymers containing a masked 2-furylcarbinol mechanophore. Molecular release occurs selectively in the presence of GVs upon exposure to FUS under physiological conditions. These results showcase the viability of this system for enabling remote control of specific mechanochemical reactions with spatiotemporal precision in biologically relevant settings and demonstrate the translational potential of polymer mechanochemistry.