Mechanical Preparation of Crystalline Materials. An Oxymoron?

Abstract

The thesis developed in this chapter is that reactions taking place between molecular materials (intersolid) or within a molecular material (intrasolid) can be used to produce new crystalline materials in solvent‐free conditions and often with quantitative yields. The most common approach to intersolid and, to lesser extent, intrasolid processes is based on the mechanical cogrinding of the solid reactants, which implies comminution of the reactants. The implicit consequence of this is the lack of crystals of the product suitable for single‐crystal X‐ray diffraction. The mechanical process yields a polycrystalline or amorphous product, with structure and composition that often differ from that obtained from solution crystallization.

Designing a Palette of Cocrystals Based on Essential Oil Constituents for Agricultural Applications

“…As predicted by HBP, all the combinations between EOs and PHE and HMT coformers afforded six cocrystals, 1a–6 (Figure ), giving the possibility to verify the extent to which the modifications in the cocrystal structures can influence the properties of the materials. Bulk materials were all quantitatively synthesized by green solvent-free mechanochemical procedures ,, such as grinding or direct mixing, thus avoiding the use of solvent as for conventional synthetic environment. Other rather complicated molecules, such as vanillin (VAN), theobromine (THE), and riboflavin (RIB), decorated with different hydrogen bond functionalities have been taken into account as potential coformers suitable for cocrystallization with the above-mentioned EOs.…”

“…As predicted by HBP, all the combinations between EOs and PHE and HMT coformers afforded six cocrystals, 1a−6 (Figure 1), giving the possibility to verify the extent to which the modifications in the cocrystal structures can influence the properties of the materials. Bulk materials were all quantitatively synthesized by green solventfree mechanochemical procedures 21,32,34 Crystal structures of 1a−6 were solved via single-crystal Xray diffraction (SCXRD), whereas the purity of the bulk powder was checked by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC). Interaction energy between the EOs and the coformers in all the cocrystals was computed to investigate the relationship between crystal packing and physical properties.…”

“…We show that these cocrystals span a broad range of properties, thus extending the applicability of these materials in various circumstances that might need different responses to external conditions, such as high or low ambient temperature and short-term or long-term release. Moreover, the synthetic procedure here proposed for the preparation of cocrystals is based on the use of solvent-free mechanochemical protocols − having the advantage of reducing costs and preventing environmental contamination from solvents to be disposed of.…”

Dispensing Essential Oil Components through Cocrystallization: Sustainable and Smart Materials for Food Preservation and Agricultural Applications

“…The combinations of all GRAS-EO/GRAS-coformer pairs (Figure and Table ) resulted in eight cocrystals having a possible advantage for the application in the agrochemical and food-related industry. All of the samples were synthesized by solvent-free mechanochemical procedures − such as manual grinding and ball milling. Providing a sustainable and cheaper strategy for synthesis compared with traditional solution methods, mechanochemistry was dubbed by the International Union of Pure and Applied Chemistry (IUPAC) among the 10 chemical innovations that will change our world .…”

Mechanochemical bottom-up synthesis of phosphorus-linked, heptazine-based carbon nitrides using sodium phosphide

“…Yet, examples of carbon nitride materials linked together via phosphorus atoms are limited, likely due to challenges in controlling the insertion of phosphorus atoms as linkers under high energy conditions. Mechanochemistry [9][10][11][12] has proven to be effective for the synthesis of a variety of polymers [13][14][15][16][17], nanomaterials [18][19][20][21][22], in crystal engineering [23][24][25], as well as in the synthesis of inorganic materials [26][27][28][29][30] and organic small molecules [31][32][33][34][35][36][37]. The ability to avoid bulk solvent and mild reaction conditions allowed by such techniques are beneficial not only from a green chemistry perspective [11], but they also afford conditions conducive to new reactivities and the development of novel materials [9].…”