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Mechanochemical synthesis has the potential to provide more sustainable preparative routes to catalysts than the current multistep solvent-based routes. In this review, the mechanochemical synthesis of catalysts is discussed, with emphasis placed on catalysts for environmental, energy and chemical synthesis applications. This includes the formation of mixed-metal oxides as well as the process of dispersing metals onto solid supports. In most cases the process involves no solvent. Encouragingly, there are several examples where the process is advantageous compared with the more normal solvent-based methods. This can be because of process cost or simplicity, or, notably, where it provides more active/selective catalysts than those made by conventional wet chemical methods. The need for greater, and more systematic, exploration of this currently unconventional approach to catalyst synthesis is highlighted.

The yields of the presented approach are equal to or greater than conventional DMF-based methods.

Although phosphines have been less widely investigated in coordination self-assembly than have N- and O-donor ligands, interesting and unusual chemistry has been observed from their study in this context. This includes the selective formation of large rings, unsaturated as well as complete coordination cages, solvent- and anion-dependent aggregation, in addition to ring-opening polymerisation to give crystalline or non-crystalline coordination polymers. Important aspects which underpin this chemistry include (i) soft donor character, (ii) pyramidal geometry at the donor atom, (iii) highly bulky and irregular shapes, (iv) the applicability of 31P NMR spectroscopy, and (v) their relevance to organometallic chemistry and homogeneous catalysis. In this critical review, findings which precede the concept of self-assembly as adopted by synthetic chemists as well as the latest ‘supramolecular’ chemistry of phosphines are discussed together in an attempt to give the current state of the topic in its historical context. Finally, some aspects and opportunities which may be of interest in the future are suggested (107 references).

Biphenyl dioxygenase-catalysed cis-dihydroxylation of 2-chloroquinoline, 2-chloro-3-methylquinoline and 2-chloro-6-phenylpyridine substrates yielded the corresponding enantiopure cis-dihydrodiols; enantiopure 2,2'-bipyridines, synthesised in four steps from 2-chloroquinoline, proved to be efficient chiral ligands in catalytic asymmetric allylic oxidation and cyclopropanation reactions of alkenes.

The first enantiopure 4,4′-bipyridyls, 6, 8, and 9 have been prepared in four or five steps via bacterial dioxygenase-catalysed cis-dihydroxylation of 4-chloroquinoline1 and C–C coupling; ligands 6 and 9 are found to be effective building blocks for the preparation of chiral metal–organic frameworks as demonstrated with the rational synthesis of two pillared-grid structures [Zn2(fumarate)2(L)], which exhibit interesting structural and dynamic aspects.

Persilylation of nucleoside hydroxyls was effected in quantitative yields under solvent-free conditions using a ball mill. In addition, one-pot persilylation and acylation of cytidine was performed as an exemplar reaction demonstrating the utility of solvent-free approaches to nucleoside chemistry.

Avoiding the use of solvents in synthesis can reduce environmental contamination and even be more convenient than using solvent-based synthesis. In this tutorial review we focus on recent research into the use of mechanochemistry (grinding) to synthesise metal complexes in the absence of solvent. We include synthesis of mononuclear complexes, coordination clusters, spacious coordination cages, and 1-, 2- and 3-dimensional coordination polymers (metal organic frameworks) which can even exhibit microporosity. Remarkably, in many cases, mechanochemical synthesis is actually faster and more convenient than the original solvent-based methods. Examples of solvent-free methods other than grinding are also briefly discussed, and the positive outlook for this growing topic is emphasised.