Supramolecular materials

Functional supramolecular materials, formation by self-assembly of phthalocyanins and porphyrazines 96CC2385. 

The potential of the cluster units described here to participate in intermolecular chalcogen-chalcogen interactions combined with the easy modification of their outer coordination sphere with ligands of different nature, i.e., redox active, hydrogen donors, bi-functional, etc., make these systems useful blocks for the construction of supramolecular materials with multi-physical properties. 

In this chapter we describe the basic principles involved in the controlled production and modification of two-dimensional protein crystals. These are synthesized in nature as the outermost cell surface layer (S-layer) of prokaryotic organisms and have been successfully applied as basic building blocks in a biomolecular construction kit. Most importantly, the constituent subunits of the S-layer lattices have the capability to recrystallize into iso-porous closed monolayers in suspension, at liquid-surface interfaces, on lipid films, on liposomes, and on solid supports (e.g., silicon wafers, metals, and polymers). The self-assembled monomolecular lattices have been utilized for the immobilization of functional biomolecules in an ordered fashion and for their controlled confinement in defined areas of nanometer dimension. Thus, S-layers fulfill key requirements for the development of new supramolecular materials and enable the design of a broad spectrum of nanoscale devices, as required in molecular nanotechnology, nanobiotechnology, and biomimetics [1-3]. 

Coco, S., Espinet, E., Espinet, P. and Palape, I. (2007) Functional isocyanide metal complexes as building blocks for supramolecular materials hydrogen-bonded liquid crystals. Dalton Transactions, (30), 3267-3272. 

Nanosized supramolecular materials have received increasing attention during the last two decades. Their properties have been surveyed for their ability to form aggregates in the solution phase, which form channel-like arrays in the solid state, and which ultimately form single channels in planar bilayer membranes. These systems therefore illustrate, in general, the convergence of supramolecular selforganization and supramolecular function. 

Reinhoudt, D. N., Supramolecular Materials and Technologies, John Wiley Sons, Chichester. 1999. 

In this contribution we have also underlined an emerging aspect of solid-state chemistry, namely that solvent-free solid-state synthetic procedures can be exploited to construct bottom-up new materials from molecular or ionic building blocks. This is at the core of molecular crystal engineering [81]. It is fascinating to think that the crystal engineer may free him/herself from operating with solvent to achieve the bottom-up construction of supramolecular materials completely from sohd to sohd . 

Lehn JM. Supramolecular chemistry—molecular information and the design of supramolecular materials. Makromol Chem Macromol Symp 1993 69 1-17. 

Hydrogen bonding interactions are important for the development of selfassembling supramolecular materials, which are defined as materials in which monomeric units are reversibly bound via secondary interactions to form polymer-like stmctures that exhibit polymeric properties in solution as well as in bulk (Bmnsveld et al. 2001). Rotello used hydrogen bond functional polymers to direct the formation of large vesicles (lUian et al. 2000), reversibly attach polymers on... 

Faul CFJ, Antonietti M. Ionic self-assembly facile synthesis of supramolecular materials. Adv Mater 2003 15 673-683. 

Stupp SI, LeBonheur V, Walker K, Li LS, Huggins KE, Keser M, Amstutz A. Supramolecular materials self-organized nanostructures. Science 1997 276 384-389. 

As far as the chemist is concerned, nanosized materials are huge macromolecules (with molecular weights of the order of 106 to 1010) constructed from millions of atoms. Atom-by-atom synthesis of nanostructures, via covalent bond formation, is a formidable task which has not as yet been achieved by synthetic chemists. Covalent polymerization is the best that chemists have done thus far [3]. Chemists have made spectacular progress, however, in forming self-organized and supramolecular materials in the size domain of nanostructures by the non-covalent bond assembly of molecules [7]. 

The directed manipulation of intermolecular interactions (hydrogen bonding, van der Waals forces, metal coordination) gives access to a supramolecular engineering of molecular assemblies and of polymers (see, for instance, [7.10-7.13, 7.44, 9.142, 9.157, 9.161-9.163]) through the design of instructed monomeric and polymeric species. It leads to the development of a supramolecular materials chemistry (see Section 9.8). 

Organic supramolecular materials may be devised on the basis of molecular components of various structures bearing recognition units [9.149, 9.235]. As shown above, liquid crystals and liquid crystalline polymers of supramolecular nature presenting various supramolecular textures are generated by the self-assembly of complementary subunits. 

Chapters 5 through 8 describe new polymeric materials that display useful optical properties. In Chapter 5, Lees discusses the use of photoluminescent metal complexes as probes to explore the properties of polymers while in Chapters 6, 7, and 8 Wang, Wiederrecht and Sponslor, respectively, and coauthors describe the properties of unique new polymer- and liquid crystalline-based materials. In the final chapters a variety of novel polymeric and supramolecular materials that display interesting and useful photochemical and optical properties are described. 

Klok, H. A. and Lecommandoux, S., Supramolecular materials via block copolymer self-assembly , Adv. Mater. 2001,13, 1217-1229. 

In this chapter, supramolecular chemistry related to developments in materials fabrication and functionalization at the mesoscale are discussed, with an emphasis on those systems based on organic-inorganic hybrid structures. The contents of this chapter are classified into (1) supramolecular chemistry within mesoscopic media, (2) supramolecular assembly at the mesoscale, and (3) supramolecular materials at the mesoscale. Despite this classification these topics have considerable similarities. 

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