Complexation metal-directed self-assembly

Metal-directed Self-assembly of Complex Supramolecular Architecture Chains, Racks, Ladders, Grids, Macrocycles, Cages, Nanotubes and Self-intertwining Strands (Helicates)... 

Metal-directed self-assembled cyclic complexes can exhibit remarkable... 

Further complex-chemical dendrimer syntheses ( metal-directed self-assembly utilising metal ions as convex templatef) are to be found in the literature [39]. 

METAL-DIRECTED SELF-ASSEMBLY OF MACROCYCLIC COMPLEXES... 

In this chapter, we cover the metal-directed self-assembly of 3D architectures using macrocycles as molecular scaffolds. Particular emphasis will be given to the synthetic strategies leading to coordination cages and to multitopic macrocyclic receptors, as well as to their complexation properties. 

The purpose of the present survey is to examine and visualize the potential that organotin(IV) complexes can have in metal-directed self-assembly of macrocycles and extended networks. Their application in the formation of cage- and cluster-type structures is only mentioned superficially, since this chemistry is described in other sections within this chapter. 

Metal-directed self-assembly has recently been the subject of explosive development which has made possible the synthesis of many fascinating and complex structures [1]. By combining building blocks derived from various families of molecules and metal ions, the structure of the resulting multicomponent systems can, in principle, be varied infinitely at will. Early examples involve simple linear bridging ligands with two linking sites, such as 4,4 -bipyridine and aromatic dicyanide or dicarboxylic acids, as summarized in Table 1 [2-7]. 

The non-cross-linked poly(acrylamide) 79 bearing the triarylphosphino groups was prepared from the acrylamide monomer and diphenyl(styryl) phosphine. The metal-directed self-assembly process between the non-cross-linked polymer ligand 79 and the palladium species afforded the networked supramolecular complex 80 [106, 109]. The complex catalyzed the Suzuki-Miyaura coupling [106,109] and the same concept, a tungsten-based self-assembly complex, has also been developed for the catalytic oxidation process. 

Helicates are formed in cooperative metal-directed self-assembly processes, usually from linear ligand strands possessing several metal coordination sites and appropriate numbers of metal ions (Scheme 2.1, top). As an alternative, helicates are obtained in a hierarchical process by initial formation of mononuclear complexes connected by non-covalent linkers (e.g., metal ions) in a subsequent step. Thus, in the... 

Metal-directed self-assembly is emerging as one of the most promising approaches to the generation of complex supramolecular architectures. The quantitative self-assembly of stable organopalladium and organoplatinum cage molecules composed of two tetracyanocavitand derivatives connected via four Pd (II) or Pt (II) square planar... 

In the twenty-first century, there will continue to be a noticeable trend from studies of classical crown ethers towards directed polysizamacromolecules for metal atom complexation and the introduction of multiple heteroatoms for tuned directed self-assembly, including most recently metal atom centers, as the heteroatom. 

Directed self-assembly shows promise in advanced lithography and a variety of other applications that have less complex requirements. For example, directed self-assembly could be used for enhancing etch selectivity, placing dopants in ordered arrays, or generating high-density, close-packed electrodes in capacitor arrays [6]. Additionally, the assembled nanostructures could be used for fabricating densely packed porous templates [12-14] or membranes [15, 16] at the nanoscale. Other potential applications of assembled block copolymer thin films include the fabrication of MOSFETs (metal-oxide-semiconductor field-effect transistors) [17], quantum dots [18], high surface area devices [19, 20], photovoltaic devices [21], and bit patterned media [22-24]. 

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