Mechanochemical Reactions
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2021 ◽  
Author(s):  
Patrick A. Julien ◽  
Mihails Arhangelskis ◽  
Luzia S. Germann ◽  
Martin Etter ◽  
Robert E. Dinnebier ◽  
...  

We provide a proof-of-principle demonstration of the first dual-spectroscopic method for direct and real-time observation of mechanochemical reactions by ball milling, supported by high-level molecular and periodic density-functional theory (DFT) calculations, including periodic time-dependent (TD-DFT) calculations to model solid-state fluorescence spectra. By combining standard Raman and fluorescence benchtop spectrometers in a single readily accessible tandem monitoring technique, we simultaneously observe changes to the supramolecular structure during mechanochemical polymorph transformation and cocrystallization of the model pharmaceutical system indometacin. The observed time-resolved in situ spectroscopic data is supported by ex situ X-ray diffraction and solid-state nuclear magnetic resonance spectroscopy measurements. First principles calculations facilitate the interpretation of both real-time spectroscopic and ex situ data by demonstrating how changes in crystalline environment affect vibrational and electronic excited states.


2021 ◽  
Vol 1 (7) ◽  
pp. 340-349
Author(s):  
Resham Rana ◽  
Robert Bavisotto ◽  
Kaiming Hou ◽  
Nicholas Hopper ◽  
Wilfred T Tysoe

Author(s):  
Eva Gil-González ◽  
Luis A. Pérez-Maqueda ◽  
Pedro E. Sánchez-Jiménez ◽  
Antonio Perejón

Friction ◽  
2021 ◽  
Author(s):  
Jian Guo ◽  
Jian Gao ◽  
Chen Xiao ◽  
Lei Chen ◽  
Linmao Qian

AbstractMechanochemical reactions of the GaN-Al2O3 interface offer a novel principle for scientific and technological merits in the micro-/nano-scale ultra-precision surface machining. In this work, the mechanochemical reactions on Ga- and N-faced GaN surfaces rubbed by the Al2O3 nanoasperity as a function of the environmental humidity were investigated. Experimental results indicate that the N-face exhibits much stronger mechanochemical removal over the relative humidity range of 20%–80% than the Ga-face. Increasing water molecules in environmental conditions significantly promotes the interfacial mechanochemical reactions and hence accelerates the atomic attrition on N-face. The hypothesized mechanism of the selective water-involved mechanochemical removal is associated with the dangling bond configuration, which affects the mechanically-stimulated chemical reactions via altering the activation energy barrier to form the bonding bridge across the sliding interface. These findings can enrich the understanding of the underlying mechanism of mechanochemical reactions at GaN-Al2O3 interface and a broad cognition for regulating the mechanochemical reactions widely existing in scientific and engineering applications.


2021 ◽  
Vol 8 (3) ◽  
Author(s):  
C. Johnston ◽  
C. Hardacre ◽  
M. E. Migaud

Liquid-assisted mechanochemistry as a versatile approach for the coupling of a nucleoside phosphoramidite with a 5′-OH partially protected nucleoside has been investigated. Noted advantages over reported methods were a simplified reaction protocol, a drastic reduction in the use of toxic solvents, the facilitation of mechanochemical reactions through the improved mixing of solid reagents, and low hydrolytic product formation.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Takahiro Kozawa ◽  
Kayo Fukuyama ◽  
Kizuku Kushimoto ◽  
Shingo Ishihara ◽  
Junya Kano ◽  
...  

AbstractMechanochemical reactions can be induced in a solution by the collision of balls to produce high-temperature and high-pressure zones, with the reactions occurring through a dissolution–precipitation mechanism due to a change in solubility. However, only a fraction of the impact energy contributes to the mechanochemical reactions, while the rest is mainly consumed by the wear of balls and the heat generation. To clarify whether the normal or tangential component of collisions makes a larger contribution on the reaction, herein we studied the effect of collision direction on a wet mechanochemical reaction through combined analysis of the experimental reaction rates and simulated ball motion. Collisions of balls in the normal direction were found to contribute strongly to the wet mechanochemical reaction. These results could be used to improve the synthesis efficiency, predict the reaction, and lower the wear in the wet mechanochemical reactions.


2020 ◽  
Vol 534 ◽  
pp. 147630 ◽  
Author(s):  
Jin Cao ◽  
Dongdong Zhang ◽  
Xinyu Zhang ◽  
Shanmin Wang ◽  
Jiantao Han ◽  
...  

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