Main group mechanochemistry: from curiosity to established protocols

Abstract

In the last few decades, mechanochemistry has become rapidly established as a powerful tool enabling environmentally-benign and sustainable chemical syntheses. Not only have these techniques been demonstrated as viable alternatives to traditional solution-based syntheses, but they have also received attention for their ability to enable new reactivity and ''unlocking'' novel compounds inaccessible by conventional methods. Reflecting the rising popularity of mechanochemistry, many excellent reviews highlighting its benefits have recently been published. Whilst the scope of most of these focuses on organic chemistry, transition-metal catalysis, porous framework materials, coordination compounds and supramolecular synthesis, few have addressed the use of mechanochemical ball milling for the synthesis of compounds containing s-and p-block elements. This tutorial review turns the spotlight towards mechanochemical research in the field of inorganic main group chemistry, highlighting significant advantages that solid-state inorganic reactions often possess, and the potential for these to drive the development of greener methodologies within the modern main group arena. Key learning points(1) Mechanochemistry and its historical background.(2) Tools and parameters affecting mechanochemical syntheses. (3) Solid and liquid additives in mechanochemistry. (4) In situ vs. ex situ reaction monitoring. (5) Key examples of mechanochemically synthesised main group compounds and complexes.

Making by Grinding: Mechanochemistry Boosts the Development of Halide Perovskites and Other Multinary Metal Halides

“…Chen et al noted that in the case of FAPb(Br:Cl) 3 , pure-bromide FAPbBr 3 seemed to form preferentially at shorter grinding times, with the subsequent anion-exchange with chloride only at longer times. [31] Protesescu et al also synthesized mixed-halide FAPb(Br:I) 3 NCs by first synthesizing the pure-bromide counterpart and performing anion-exchange in a following step with oleylammonium iodide and obtained better results than by direct synthesis of the mixed composition. [15] The authors mentioned that their method was not applicable to pure iodide compositions.…”

“…Dr that favors completion of the desired chemical reaction. [3] Despite its operational simplicity, mechanochemistry has long been overlooked in contrast to other synthetic methods such as (green) solvent based synthesis, supercritical CO 2 assisted chemistry, or the use of ionic liquids. Nevertheless, in view of several recent reviews and perspectives it appears we are experiencing a renaissance of this underestimated field.…”

Development of an SBU‐Based Mechanochemical Approach for Drug‐Loaded MOFs

“…Next, we investigated the mechanosynthesis of HKUST-1 by neat grinding of the pre-assembled molecular precursor 1 with 1,3,5-benzenetricarbocylic acid (H 3 BTC) in the required 3:4 stoichiometric ratio; we note that the coordinated DMF molecules in 1 may act as internal solvent and potentially enhance the mechanochemical reactivity along the same line as liquid-assisted grinding. [57] Recently, the mechanochemical transformation of Cu(OAc) 2 ·H 2 O with H 3 BTC to quantitatively obtain HKUST-1 was demonstrated. [37,42] The reaction between 1 and H 3 BTC should generate ibuprofen molecules as shown in Scheme 1 (the resulted as grounded composite was further designated as IBU@HKUST-1).…”

Mechanoenzymatic Transformations in the Absence of Bulk Water: A More Natural Way of Using Enzymes

“…Much more akin to low η conditions of liquid‐assisted mechanochemistry, enzymes secreted by microorganisms thrive on moist surfaces, and intracellular enzymes function in highly concentrated, organized environments. This observation is consistent with the ongoing change in our understanding of chemical transformations, with the growing realization that many reactions readily proceed in solvent‐less mechanochemical environments . Indeed, mechanochemistry, which was recently proposed to be involved in the emergence of small organic molecules on the early Earth, has successfully provided routes to chemical selectivity, as well as reactions or molecules that have otherwise been considered difficult or even impractical to access.…”

“…It is our view that solvent-less environments found in liquidassistedg rinding and/ora ging in moist air,a re more effective than conventional dilute solutions in replicating the natural environmento fm any enzymes.M uch more akin to low h conditions of liquid-assisted mechanochemistry,e nzymes secreted by microorganisms thrive on moist surfaces, and intracellular enzymes functioni nh ighly concentrated, organized environments.T his observation is consistent with the ongoing change in our understanding of chemical transformations, [161] with the growingr ealization that many reactions readily proceed in solvent-less mechanochemicale nvironments. [18,115,[162][163][164][165][166][167][168] Indeed, mechanochemistry,w hichw as recently proposed to be involved in the emergence of small organic molecules on the early Earth, [169] has successfully provided routes to chemical selectivity, [19,170,171] as well as reactions [172,173] or molecules [174][175][176] that have otherwiseb een considered difficult or even impractical to access. Although mechanoenzymatic reactivity is in a very early stage of development, it has already sparked as ignificanta mount of interest, [177] and provided simple solutions to streamline industrial processing of, for example, lignocellulosic material.…”