Issue 10, 2019

Insights into mechanochemical reactions at the molecular level: simulated indentations of aspirin and meloxicam crystals

Abstract

Although solvent-free mechanochemical synthesis continues to gain ever greater importance, the molecular scale processes that occur during such reactions remain largely uncharacterised. Here, we apply computational modelling to indentations between particles of crystals of aspirin and meloxicam under a variety of conditions to mimic the early stages of their mechanochemical cocrystallisation reaction. The study also extends to the effects of the presence of small amounts of solvent. It is found that, despite the solid crystalline nature of the reactants and the presence of little or no solvent, mixing occurs readily at the molecular level even during relatively low-energy collisions. When indented crystals are subsequently drawn apart, a connective neck formed by a mixture of the reactant molecules is observed, suggesting plastic-like behaviour of the reacting materials. Overall the work reveals some striking new insights including (i) relatively facile mixing of crystals under solvent-free conditions, (ii) no appreciable local temperature increases, (iii) localised amorphisation at the contact region and neck of the reacting crystals, and (iv) small amounts of solvent have relatively little effect during this early stage of the reaction, suggesting that their accelerating effect on the reaction may be exerted at later stages.

Graphical abstract: Insights into mechanochemical reactions at the molecular level: simulated indentations of aspirin and meloxicam crystals

Supplementary files

Article information

Article type
Edge Article
Submitted
07 Nov 2018
Accepted
21 Jan 2019
First published
23 Jan 2019
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2019,10, 2924-2929

Insights into mechanochemical reactions at the molecular level: simulated indentations of aspirin and meloxicam crystals

M. Ferguson, M. S. Moyano, G. A. Tribello, D. E. Crawford, E. M. Bringa, S. L. James, J. Kohanoff and M. G. Del Pópolo, Chem. Sci., 2019, 10, 2924 DOI: 10.1039/C8SC04971H

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