Solvent free mechanochemical oxygenation of fullerene under oxygen atmosphere

Oxygenation of fullerene took place under mechanical stressing by a simple vibration mill in an oxygen atmosphere at 1 atm. Milled products were mixtures of poly-oxidized fullerene, C₆₀O_n, containing C-O-C and CO bonds. We observed a concurrent reaction as well, that is, polymerization of C₆₀ and C₆₀O. The average number of oxygen, n, of the overall products obtained by milling for 5 h was 8.6 per molecule of C₆₀. We confirmed generation of singlet oxygen during the present mechanochemical reaction by an ESR spin trapping method. Trapping of ¹O₂ was completely inhibited the oxygenation of fullerene. Formation of ¹O₂ is attributed to the energy transfer from mechanically excited state of fullerene and plays a decisive role on the present oxygenation of fullerene under mechanical stressing in O₂. In contrast, no ¹O₂ was observed by mechanically stressing the conventional photo-sensitizer, rosebengal. The difference in the behavior of C₆₀ and rosebengal is interpreted in terms of molecular deformation, being much easier for a 3D molecule, C₆₀, than a planar molecule, in line with the concept of inverse Jahn-Teller effects.     

Catalyst- and solvent-free mechanochemical synthesis of isoxazoles from N-hydroxybenzimidoyl chlorides and enamino carbonyl compounds

A regioselective, solvent-free and catalyst-free synthesis of isoxazoles has been successfully developed under ball milling conditions. Milling the mixtures of N-hydroxybenzimidoyl chlorides and enamino carbonyl compounds in a ball mill at a frequency of 14.6?Hz for 20–60?min afforded isoxazoles in up to 86% yields. A possible reaction mechanism leading to the formation of the observed isoxazoles is proposed.     

振磨降解制备的低分子量聚氯乙烯形态结构的研究

本文首次通过ＦＴＩＲ和扫描电镜等手段研究了振磨作用对聚氯乙烯（ＰＶＣ）颗粒尺寸、微晶结构、表现密度和增塑剂吸收量的影响。结果表明，该聚合物位于６３５ｃｍ＾－１处结晶吸收谱带的强度随振磨时间的增加而降低，逐步趋于消失。随振磨时间的增加，ＰＶＣ的颗粒尺寸减小，比表面积增加，增塑剂的吸收量增加。通过振磨可以制得用一般化学方法难于制得的超细、低微量含量、易于加工的较低分子量ＰＶＣ。     

Mechanochemistry in cancer cell metastasis

In this review, we introduced the mechanical factors in cancer cell metastasis, intracellular mechanical sensors and methods to measure the mechanical forces of tumor cells for evaluating the mechanochemistry in cancer metastasis.     

Electrophilic aryl-halogenation using N-halosuccinimides under ball-milling

We report here a methodology of chemo- and regio-selective aryl bromination and iodination using respective N-halosuccinimides at room temperature in the absence of any solvents, catalyst/additives under ball-milling condition. However, for chlorination ceric ammonium nitrate was used as additive. The coupled product succinimide, produced from the reactions, was recycled via regeneration of NBS. This methodology works with the electron-donor substituted or unsubstituted arenes.     

PbS nanostructures synthesized via surfactant assisted mechanochemical route

PbS nanocrystals using surfactant assisted mechanochemical route has been successfully prepared. The methods of XRD, SEM, surface area and particle size measurements were used for nanocrystals characterization. The XRD patterns confirmed the presence of galena PbS (JCPDS 5–592) whatever treatment conditions were applied. The strong observable peaks indicate the highly crystalline nature in formation of PbS nanostructures where preferential crystal growth in the (200) direction after chelating agent (EDTANa₂•2H₂O) addition has been observed. The mean volume weighted crystallite size 4.9 nm and 35 nm has been calculated from XRD data using Williamson-Hall method for PbS synthesized without and/or with chelating agent, respectively corresponding with surface weighted crystallites sizes of 2.9 and 18.8 nm. The sample prepared without surfactant yields the smaller crystallites and the higher microstrain compared with surfactant assisted synthesis. The obtained results illustrate a possibility to manipulate crystal morphology by combining effect of milling and surfactant application.      

Nanocrystalline CaF2 particles obtained by high-energy ball milling

Structural changes in mechanically treated CaF₂ powders have been studied by X-ray diffraction, transmission electron microscopy, thermal analysis, ¹⁹F and ¹H MAS Nuclear Magnetic Resonance and Electron Paramagnetic Resonance methods.Applying the same methods, the results could be compared with those of mechanochemically synthesized CaF₂ samples, prepared for the first time in this study by high-energy ball milling. The applied methods indicate that the mechanically treated samples become, under the applied conditions, nanocrystalline. Unexpectedly, the mechanochemically synthesized samples show the same effects, i.e., nanocrystalline samples were formed. In contrast to many oxide compounds, a weak amorphization takes place only after a strong mechanical impact, and essentially in grain boundaries of spherical particles. Observed effects after the application of mechanical impact like broadening of XRD reflections, broadening of ¹⁹F resonances, or the decreasing ability for H trapping at ambient temperature, are mainly due to decreasing particle sizes as well as very small structural changes in the bulk of the particles. Surprisingly, the spin relaxation of both nuclear spins (¹⁹F) and electron spins (H) appears to be the most sensitive tool for the investigation of mechanically and chemically induced changes indicating the increasing surface to bulk ratio with increasing mechanical impact.     

Allylation of C-, N-, and O-Nucleophiles via a Mechanochemically-Driven Tsuji–Trost Reaction Suitable for Late-Stage Modification of Bioactive Molecules

We present the first solvent-free, mechanochemical protocol for a palladium-catalyzed Tsuji–Trost allylation. This approach features exceptionally low catalyst loadings (0.5 mol %), short reaction times (<90 min), and a simple setup, eliminating the need for air or moisture precautions, making the process highly efficient and environmentally benign. We introduce solid, nontoxic, and easy-to-handle allyl trimethylammonium salts as valuable alternative to volatile or hazardous reagents. Our approach enables the allylation of various O-, N-, and C-nucleophiles in yields up to 99 % even for structurally complex bioactive compounds, owing to its mild conditions and exceptional functional group tolerance.     

Mechanochemical reactions between Ag2O and V2O5 to form crystalline silver vanadates

Solid-state reactions between Ag₂O and V₂O₅ were studied under ball-milling conditions. Single-phase crystalline Ag₄V₂O₇ was formed from the mixture of Ag₂O and V₂O₅ of corresponding (2:1) composition. The main component in the product when the Ag₂O mole fraction is less than V₂O₅ is amorphous AgVO₃, which is crystallized into needle-like α-AgVO₃ in the presence of water. Excess V₂O₅ was hydrated into V₂O₅·nH₂O intercalated with Ag⁺ ions. The mixtures with more than two parts of Ag₂O relative to V₂O₅ are composite materials of Ag₄V₂O₇ and Ag₃VO₄, together with Ag₂O. The crystalline phases in these systems resist attack by water.     

Studies on Mechanochemistry: Solid Coordination Compounds from Primary Aromatic Amines and Cobalt(II) Chloride Hexahydrate

Cobalt(II) chloride hexahydrate and primary aromatic amines were reacted by co‐grinding in 1:2 metal salt to ligand ratio under solvent‐free environment at room temperature. Out of 16 solid state reactions, seven cobalt‐amine complexes could be established as solid coordination compounds by elemental analysis, TGA, IR, PXRD, magnetic susceptibility etc., in addition to visual observation of the color change of reaction mixture. Based on investigation of reaction and analysis of products, conclusions with outlook could be made as follows: On top of the —NH₂ group on primary aromatic amines an additional substituent group should better be at para or meta positions and not at ortho position in order to realize the solid coordination compounds. On the other hand, an electron withdrawing substituent or an extra aromatic ring is negative towards formation of the solid coordination compounds. The solid coordination Co(II)‐compounds are labile in solution.