Organic templates structure-directing agents

Since then, organic amines, quaternary-ammonium bases, metal complexes, and other compounds have been extensively used in zeolite synthesis, acting as space fillers with low specificity, structure-directing agent, or true templates ... 

Besides their obvious role as templates or structure directing agents (12) or as stabilizing pore fillers (2,1A) the organic cations will also compete with alkali ions for the stabilization of the negatively charged framework (12,11,12). 

Often organic ions (e.g. tetraalkylammonium cations such as tetramethylammo-nium, TMA+, ions) or neutral molecules are used as templates (i.e. structure-directing agents). In the past certain templates were introduced empirically although they are now widely used, their action is still not fully understood. 

In the last 10 yr, the field of chemistry of organized matter has opened the path to create organized or textured inorganic or hybrid networks, templated by organic structure directing agents (Fig. 1, Routes B and The success of this strategy is also... 

The most general definition of a template is as a structure-directing agent. In surfactant solutions the final templated polymers can be either discrete nanoparticles or mesostructured bulk materials as a consequence of polymerization, respectively, in the non-continuous or continuous domains of the template. Thermodynamically stable media, such as microemulsions, equilibrium vesicles, or lyotropic mesophases are especially useful as templates because of their structural definition and reproducible morphologies. The mesostructure of a thermodynamically stable template is defined by composition and temperature, but this same feature makes the structure unstable to changes in temperature, pH, or concentration. The aim of template synthesis is to transfer the self-organized template structure into a mechanically and chemically stable, durable, and processable material. 

---