Synthesis of Materials Science Libraries

Inorganic SP chemistry is an important branch of chemistry that has been the subject of extensive research and has also been extensively reviewed (12-15). The development of new materials with specific properties is a major endeavor for chemical research. New catalysts, or superconductors, or photoluminescent materials, or fer- 

2 Synthesis of Materials Libraries by Thin-Film Deposition 

In order to obtain combinatorial materials science libraries, sequential deposition must be coupled with a method to diversify the composition of small areas of the deposition surface. A moving-mask system, originally designed to obtain compositional gradients (20) and then used later for the synthesis of organic libraries (21), has been successfully and repeatedly used for this purpose. The first reported materials library LI (22) used this technique employing eight binary masks M0-M7, as shown in Fig. 11.2. 

Four metal oxides/carbonates (Bi, Sr, Ca, and Cu) were used to prepare an 128-member magnetoresistant library LI. Each hbrary component was assembled on a 1-mm-wide, 2-mm-long site inserted in a crystal substrate (Fig. 11.2). The sequential thin-film deposition was arranged according to the following scheme  

3 An Example Synthesis of Primary and Focused Libraries of Luminescent Materials 

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Solution-Phase Synthesis of Materials Science Libraries... 

While considerable efforts have been spent in the past few years in the field of solid supports for combinatorial chemistry [73], most of them were devoted to modified polystyrenic beads with different sizes, loadings or swelling properties [74], or carrying different functionalities or linkers for library synthesis [75], or to solid supports different from resin beads (pins [76], cellulose [77], soluble supports [78], and so on). Few reports dealt with labelled solid supports prepared by chemical reactions (see the previous paragraphs) and significant efforts in the field of material sciences to obtain intrinsically labeled, nonchemically encoded, easily readable, combinatorial solid supports have not been reported. 

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. 

Combinatorial chemistry is the production of libraries of compounds that represent permutations of a set of chemical or physical variables. In recent years, combinatorial chemistry has attracted considerable attention in materials science.11131 Originating from the discovery of new chugs by pharmaceutical companies, combinatorial methods have been employed in the areas of organic, biochemical, and inorganic chemistry, etc. In recent years, the combinatorial approach has been successfully applied to the hydro-thermal synthesis of zeolites and related materials.11141... 

Combinatorial chemistry is a synthesis strategy that enables the simultaneous production of large numbers of related compounds. These sets are referred to as libraries and they can be used in any discovery project associated with high-throughput analysis capabilities. The most common application is in drug discovery, but combinatorial methods also have been used, if less frequently, in the materials science area as well. 

Merrifield s revolutionary concept of solid-phase synthesis was not limited to peptides, and similar techniques have been developed for the synthesis of nucleic acids and carbohydrates on solid supports. For each application, specialized instrumentation that is computer-controlled is commercially available. Access to such equipment has enabled researchers in areas of biology, medicine, material science, and biomedical engineering to prepare thousands of peptides and polypeptides for study. In the pharmaceutical industry, for example, solid-phase synthesis has been used to prepare relatively large numbers of related molecules, so-called compound libraries, that... 

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