Solution-phase synthesis crystallizations

The concept of absolute asymmetric synthesis using a chiral crystal was applied to unimolecular photochemistry, and now many fine examples are reported. Scheffer et al. reported elegant unimolecular absolute asymmetric transformations (Scheme 4). [19] This group demonstrated that the well-studied solution-phase di-ir-mcthane photorearrangement can also occur in the solid state. Of over 20 symmetrical and unsymmetrical dialkyl 9,10-ethanoanthracene-l 1,12-decarboxylate 22, only two compounds were found to undergo absolute asymmetric di-ir-methane... 

Solution-phase synthetic methods, as they were described for synthetic organic libraries, can also be applied to materials science and are devoid of the diffusion problems encountered in thin-film deposition. The reagent solutions are mixed and incubated following an appropriate procedure, and the final products are usually isolated by precipitation or crystallization. Automated liquid dispensing units with extreme precision and high rehabiUty can be used in synthetic protocols. No major differences are presented in respect to solution-phase organic library synthesis (see Section 8.2.4). Several examples are briefly illustrated below to provide a quick overview of the currently reported synthetic methods in solution for materials libraries. 

Soluble supports for solution-phase combinatorial synthesis were extensively covered in Section 8.5. A recent survey of available soluble supports, with respect to their use in the soluble supported synthesis of various classes of chemicals (90), highlights the wide range of physicochemical properties (especially regarding solubility, tendency to crystallize, and solubilization power) that are embedded in different polymers and copolymers. The assessment of a sort of S AR for the composition of copol5miers versus their physicochemical properties would require the preparation of a large number of examples. Combinatorial approaches to soluble support libraries could be highly beneficial in this perspective. 

As shown above, the optimized combination of precursors (C0Q2, Co(CH3COO)2 or Co2(CO)8) and reducing agents (superhydride or polyalcohol) allows the selective preparation of monodisperse cobalt nanoparticles with a desired crystalline phase. Such behavior shows that the solution-phase chemical synthesis of magnetic nanocrystals is not thermodynamically controlled, and thus can allow the preparation of crystal phases that are metastable, such as the e-Co structure [9]. The control of size and the crystalline phase of nanoparticles is important, as these parameters greatly affect the magnetic properties (see Section 3.3.2.5). 

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