Template methods

The high-dilution and template methods are frequently used in the synthesis of cyclic compounds with the aim of increasing the yield. The former method is carried out at substrate concentrations lower than 1 mM [18-20]. This reaction condition decreases the contact of the substrate molecules in the solution. The linear intermediate produced prefers the intramolecular cyclization reaction rather than the intermolecular reaction. Therefore, this reaction condition is useful for the intramolecular reaction, method B (Fig. 2). 

The latter method, the template method, involves a reaction to produce a transition state similar to the desired product using a template. The template should have a shape similar to the space of the product. The template interacts with the substrate by forming noncovalent bonds such as coordination bonds (Fig. 3). The representative and most successful examples are found in crown ether chemistry. In the chemistry, alkali metals act as templates to create a crown-ether-like transition state with an ethylene glycol substrate by using metal-oxygen coordination bonds. 

Avdeef, A., Berger, C. M. pH-metric solubility. 3. Dissolution titration template method for solubility determination. Eur. J. Pharm. Sci. 2001, 14, 281-291. 

Sadakane, M., Asanuma, T., Kubo, J. et al. (2005) Facile procedure to prepare three-dimensionally ordered macroporous (3DOM) perovskite-type mixed metal oxides by colloidal crystal templating method, Chem. Mater. 17, 3546. 

Figure 74 The polyhexenyldecaborane (128) used in the production of nanostructured boron carbide materials by nanoscale templating methods utilizing porous alumina templates.

Coco, W.M. (2003) RACHITT gene family shuffling by random chimeragenesis on transient templates. Methods in Molecular Biology (Clifton, NJ), 231, 111-127. 

Coco, W. M., RACHITT Gene family shuffling by Random Chimeragenesis on Transient Templates. Methods. Mol.Biol., 2003. 231 pp. 111-127. 

Mesoporous Silica Prepared by the Lizard Template Method 65... 

Fig. 2.24 Concept of lizard template method for the preparation of mesoporous silica. Adapted from [106], Q. Zhang et al.,J. Am. Chem. Soc. 2004, J26, 988.

Fig. 2.27 HR-TEM images of mesoporous silica prepared by the lizard template method (A) before hydrolysis (as-synthesized) (B) after hydrolysis. Reprinted with permission from [106],...

The template methods have also been used for the synthesis of a number of substituted Ln di(naphthalocyanine) complexes, LnNc2 [82-88]. Apart from thermal fusion by conventional heating processes, complexation has been initiated by microwave radiation, although only a few publications are devoted to the template synthesis of lanthanide bis(phthalocyanine) complexes by this method [89, 90]. The use of microwave radiation (MW) reduces the reaction time from several hours to several minutes. Unsubstituted complexes LnPc2 (Ln = Tb, Dy, Lu) were prepared [90] by irradiation (650-700 W) of a mixture of phthalonitrile with an appropriate lanthanide salt for 6-10 min (yields >70%). 

Ngamsinlapasathian, S. Pavasupree, S. Suzuki, Y. Yoshikawa, S. 2006. Dye-sensitized solar cell made of mesoporous titania by surfactant-assisted templating method. Solar Energy Mater. Solar Cells 90 3187-3192. 

Over the past few years, a large number of experimental approaches have been successfully used as routes to synthesize nanorods or nanowires based on titania, such as combining sol-gel processing with electrophoretic deposition,152 spin-on process,153 sol-gel template method,154-157 metalorganic chemical vapor deposition,158-159 anodic oxidative hydrolysis,160 sonochemical synthesis,161 inverse microemulsion method,162 molten salt-assisted and pyrolysis routes163 and hydrothermal synthesis.163-171 We will discuss more in detail the latter preparation, because the advantage of this technique is that nanorods can be obtained in relatively large amounts. 

With framework development, the skeleton of the common behavior is one of two things either (1) an internal method specified on an interface that must be implemented by a specialized class, or (2) a template method in the superclass with the variant bits and pieces deferred to the subclasses. We will illustrate the latter design here. 

For an inheritance-based design, the template method (see Section 11.3.1.2, Framework-Style Reuse and the Template Method) forms the basis of plug-ins. This design style, common initially, has now fallen somewhat out of favor. 

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