Templating approach

Colloidal crystals can be grown by a templated approach too. Thus van Blaadcren and Wiltzius (1997) have shown that allowing colloidal spheres to deposit under gravity on to an array of suitably spaced artificial holes in a plate quickly generates a single crystalline layer of colloidal spheres, and a thick crystal will then grow on this basis. 

The organic templating approach was first introduced by Barrer and Deimy... 

Bourlinos AB, Karakassides MA, Petridis D (2001) Synthesis and characterisation of hollow clay microspheres through a resin template approach. Chem Commun 16 1518-1519... 

Orendorff, C.l. and Pemberton, J.E., Alkylsilane-based stationary phases via a displaceable surface template approach synthesis, characterization, and chromatographic performance. Ana/. Chem., 77, 6069, 2005. 

Murray et al. [273] described an implementation of the preoriented template approach, which also forms the basis for recent extensions of QXP [204] and GOLD [274]. 

There have been two main approaches to the development of dipolarophile facial selectivity (1) the use of chiral substrates, templates, and auxiharies and (2) the use of chiral rhodium catalysts [35]. In one of the earhest examples of chiral substrate selectivity, Pirmng and Lee reported a selective hydroxy-directed cycloaddition with chiral hydroxy-substituted vinyl ethers [95]. This effort was followed by a number of chiral template approaches to diastereocontrol, including the use of (R)- or (S)-phenylglycinol to form a cycHc phenyloxazinone for the facially selective cycloaddition of isomtinchnones [96, 97]. Padwa and Prein demonstrated acycHc diastereofacial control in the cycloaddi-... 

Very recently, MacGillivray et al. succeeded in the supramolecular construction of molecular ladders in the solid state using a linear template approach [48]. They designed the cocrystals 1,3-benzenediol (resorcinol) or a derivative with an all-trans-bis(4-pyridyl)butadiene or hexatriene, in which two resorcinol molecules preorganize two polyene molecules through two hydrogen bond interactions, for [2-1-2] photoaddition (Scheme 5). In this design, two polyenes would... 

Few reports are available in the literature, in which cationic surfactants have been used to prepare the silica nanoparticles [82] and particularly those encapsulating an optical component. In a surfactant template approach Lin et al. [83] prepared Gd(III)-loaded mesoporous silica... 

The rational method features the functional approach and structural template approach. 

We started this templated approach to catalyst encapsulation using tris(mefa-pyridyl)phosphine and zinc(ii)TPP (TPP = tetraphenylporphyrin) [7]. From NMR and UV/Vis titration experiments we found a selective assembly process via coordination of the nitrogen to the zinc(ii)TPP, rendering the phosphine donor atom completely encapsulated by the three porphyrin components (Figure 8.4). The phosphine center is still available for coordination to transition metals, providing... 

Figure 8.3 Templated approach to ligand encapsulation. Molecular modeling demonstrates that the phosphine ligand is completely encapsulated (see also Figure 8.4).

After the very early achievements due to the real pioneers of chemical topology who forty years ago first acceeded to that intriguing molecule that is a catenane (by statistical threading approach Wasserman, 1960 or by a directed approach Liittringhaus and Schill, 1964), this peculiar field of research concerned with molecules whose prime feature rests without doubt on beauty and non trivial spacial arrangement, has in the beginning of the 80 s literaly exploded with the apparition of various templated approaches. 

Wan Y Zhao DY, On the controllable soft-templating approach to mesoporous silicates, Chem. Rev., 2007, 107, 2821-2860. 

These results show unambiguously that templates are an attractive alternative to the tedious precursor synthesis commonly used for the preparation of shape-persistent macrocydes. They allow the preparation of symmetrically and even of nonsymmetrically functionalized PAMs in high yields. Moreover, the increased amount of the shape-persistent macrocyde in the crude product simplifies the purification procedure in most cases. However, both the supramolecular and the covalent template approach require the presence of appropriate functional groups that bind (are bound) to the template. 

Most of the systems described in Chapter 5 contain small- or medium-sized or multinuclear benzenoid and non-benzenoid arenes. In Chapter 6, Hoger gives an overview over the mastery of the synthesis of macro- and megacycles. He shows different approaches towards shape-persistent macrocycles and carefully examines and discusses selected examples that display the advantages and disadvantages of macrocycle synthesis under kinetic and thermodynamic control. The template approach (both supramolecular and covalent) towards functionalized rings is also discussed and introduces a strong motif of supramolecular chemistry, which is much further developed but in a more polymer-oriented topic, in the next chapter. 

Siegel and coworkers have recently applied a similar metal template approach with Ru(II), terpyridyl- (40) and pyridyl/phenanthroline-based (41) ligands using 20 equivalents of Cu(OAc)2/MeCN to enact a double ring closure (42-45) in the final step, with yields of [2]catenates (46, 47) ranging from 20 to 25% (Scheme 10.8) [37]. 

N.K. Raman and C.J. Brinker, Organic Template Approach to Molecular Sieving Silica Membranes , J. Membrane Sci., 105 273-79 (1995). 

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