Supramolecular architectures/synthesis

Avnir D., Braun S., Ottolenghi M. Encapsulation of organic molecules and enzymes in sol-gel glasses. In Supramolecular architecture synthesis control in thin films and solids, T. Bein, ed., ACS symposium series No. 499, American Chemical Society Washington, DC, 1992. pp. 384— 404... 

The design and synthesis of supramolecular architectures with parallel control over shape and dimensions is a challenging task in current organic chemistry [13, 14], The information stored at a molecular level plays a key role in the process of self-assembly. Recent examples of nanoscopic supramolecular complexes from outside the dendrimer held include hydrogen-bonded rosettes [15,16], polymers [17], sandwiches [18, 19] and other complexes [20-22], helicates [23], grids [24], mushrooms [25], capsules [26] and spheres [27]. 

Zeolites 2D for classical, 2D and 3D for superzeolites varies Chemical synthesis Months to years Particles could be grown in situ or incorporated into channels complex supramolecular architecture was possible 463,464... 

Clays-pillared clays or organoclays 2D, 3D varies Purification and ion exchange by surfactants of naturally occurring products or synthesis Weeks to months Interlayer distance could be varied and precisely determined X-ray diffraction measurements particles could be grown in situ or incorporated between layers complex supramolecular architecture was possible 478,480,482... 

Supramolecular, non-covalent, synthesis consists in the generation of supramolecular architectures through the designed assembly of molecular components directed by the physico-chemical features of intermolecular forces like molecular, covalent, synthesis, it requires strategy, planning and control. 

So far, peptide synthesis has mainly involved the preparation of biologically or pharmaceutically relevant substances, total chemical synthesis of natural proteins or protein engineering. The objective of this chapter is to show how the different methods that have been developed for peptide synthesis can be used to prepare biologically-inspired supramolecular architectures and polymeric materials, which might be of potential interest for a variety of advanced applications. 

Peptide ligation strategies used so far have mainly been used for protein total synthesis and protein engineering purposes. The ability to prepare perfectly mono-disperse and relatively high molar mass peptides with precise control over the a-amino acid sequence could also afford unprecedented opportunities for the development of novel biologically-inspired supramolecular architectures and materials. As a final, recent, example, the preparation of a protein[2]catenane using NCL is shown in Figure 6.6.5 [34]. 

Besides metallocycles, metallodendrimers, and metallo-supramolecular polymers [58], few examples of hollow supramolecular architectures have been obtained from polytopic ligands containing terpyridine units. Lehn et al. used heteroaromatic ligands with terpyridine type coordination sites to obtain cylindrical self-assembled architectures (Fig. 11) [60]. For synthesis of the cage 37, tris-2,4,6-(2-pyrimidyl)-l,3,5-triazine (35) was mixed with lead triflate in... 

This topic was partially covered in CHEC-II(1996) <1996CHEC-II(9)809> under the subentry Catenanes and Rotaxanes . In this section, emphasis is given to the design and construction (and to some extent, the properties) of supramolecular architectures derived from or incorporating crown ethers rather than to the synthesis of the crown ether component present in them. The crown ether rings described herein are either covalently linked (dendrimers), mechanically interlocked (rotaxanes, catenanes), or just bound by noncovalent interactions (pseudorotaxanes) to the rest of the supermolecule to which they belong. 

For all these reasons, the guanine building blocks and the sol-gel chemistry were used as molecular precursor to conceive hybrid chiral materials at nanometric and micrometric scales. Our efforts involved the synthesis and the self-assembly of a guaninesiloxane monomer Gsi (Fig. 3) in the G-quartet and G-quadruplex supramolecular architectures (Fig. 6), which are fixed in a hybrid organic-inorganic material by using a sol-gel transcription process, followed by a second inorganic transcription in silica, by calcination. 

A self-assembly reaction that involves the connection of individual building blocks via noncovalent interactions permits the rational integration of desired functional groups into the resulting molecules. Transition metal coordination bonds have been exploited in the synthesis of numerous metal-based supramolecular architectures in recent years. Complexation of metal ions to multidentate ligands generates equilibrium mixtures of various structures based on numerous possible combinations of metals and ligands.In the situation of thermodynamic control (see Thermodynamics Laws), the... 

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