Solid-state template effect

Synthesis of solid state materials using surfactant molecules as template has been extensively used in this decade. Among the advantages of the use of amphiphilic molecules, the self-assembling property of the surfactants can provide an effective method for synthesising ceramic and composite materials with interesting characteristics, such as nanoscale control of morphology, and nano or mesopore structure with narrow and controllable size distribution [1-5]. 

Crystallization amounts by nature to the self-assembly of very large, boundaryless supramolecular species. Its control is a goal of major importance in order to be able to generate solid-state materials of specific structural and physical properties (see also Sections 7.1, 7.2, 9.4.4 [7.39-7.42, 9.105, 9.245]). Supramolecular effects play a crucial role. Directional growth of materials may be induced by a template and involve molecular recognition [9.246], occurring by epitaxy [9.247] or on oriented thin films [9.248]. 

When chemical reactions are carried out in inclusion complexes, reactions can proceed selectively due to template control effects caused by the host compound. In some cases, reaction occurs only in the inclusion complex, but not in solution, since molecules can be arranged in the appropriate positions for reaction in an inclusion crystal. When an optically active host compound is used, enantiose-lective reactions can be accomplished. For some time we have been studying such selective reactions in inclusion complex crystals in the solid state. However, these reactions have already been published in the book Organic Solid State Reactions [1], In this present chapter, some representative topics and some recent new results of selective thermochemical and photochemical reactions in inclusion crystals are briefly summarized. 

To enable linear templates to be used as general devices for building molecules, we have identified an ability of rigid bifunctional molecules to serve as linear templates in the organized environment of the solid state [6-12], The templates operate by assembling two complementary molecules by way of hydrogen bonds for a UV-induced [2 + 2] cycloaddition reaction [18]. By using the solid state as a medium for reaction, we have been able to circumvent the structure effects of... 

The sol—gel process can be used to obtain lamellar silica (LS) samples by using neutral amines as template molecules. Its is found that such LS samples are able to act as sequestrating agents toward transition metal cations and that the coordination of such metal cations of the three dimensional network structure of the sffica exerts remarkable effects on its nanostructure and thermal stabffity [4]. Furthermore, such metal sequestrating abffity and the consequent nanostructure modifications are observed even if the metal—sffica reaction is performed in the solid state and room temperature [5]. By performing a solution calorimetric study, it is possible to verify that the total amount of metal cations that the lamellar matrix is able to sequester as well as its affinity by the metal cations, for example, Ni > Cu > Co [6] is a consequence of the influence of main two factors the metal—nitrogen coordination enthalpies and the structural disorder provoked into the lamellar network by the metal—nitrogen coordination. 

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