Self cage structure

Recent advances in nanotechnology have shown that self-assembled cage structures of nanometer dimensions can be used as constrained environments for the encapsulation of guest molecules with potential applications in drug delivery,... 

In recent years, there has been an enormous development in the construction of extended self-assembled structures with the participation of metal atoms, either in the comer or in the edges of molecular triangles, squares, rectangles, and cages. Cf5 - PdL2 can be used to define comers in square and triangular stmctures, using the two available... 

Fujita reported a wide range of systems formed by the self-assembly of several nitrogen-donor ligands and palladium and platinum centers.In the assembly of some of these systems, the ternplating properties of anions play an important role. When the square planar complex [Pd(en)2(N03)2] is reacted with l,3,5-rm(4-pyridyl-methyl)benzene in the presence of anionic species having a hydrophobic moiety (such as 4-methoxyphenylacetate), the nearly quantitative formation of the cage structure 9 is observed (see Fig. 3). In the absence of the anionic/ hydrophobic species, this reaction gives rise to a considerable amount of polymeric material. Similarly, the... 

In the field of self-assembly of molecular components to generate defined structures which can be used as molecular devices, structural and functional information must be contained at the molecular level. The approach described in 1993 in Lehn s group was to use two complementary components a mesa 5,15-diuracil-substituted porphyrin and an alkyl triaminopyrimidine.- The interaction between the hydrogen-bonded sites of both components led in large part to a bis-porphyrin supramolecular cage structure 6 as evidenced by proton NMR and fluorescence and electrospray mass spectroscopy as well as by vapour phase osmometry (Figure 7). 

The cage structure 6 is composed of two face-to-face porphyrins linked at both sides via six hydrogen bonds to two triaminopyridine entities. The distance between the cofacial porphyrins is estimated to be 10 A. The initial nieso 5,15-diuracil-substituted porphyrin has two rotameric forms, a syn and an anti, due to the relative orientations of the two uracil groups with respect to the porphyrin plane. In the self-assembling process, the syn rotamer yielded the major component, the cage structure, whereas the anti conformer yielded a zig-zag strand structure. As for the properties expected by such systems, metalation of one of the porphyrins allows for the creation of a self-assembled donor-acceptor system while complexation of the porphyrins with zinc(Il) allows for the cage cavity to be used as a... 

Figure 14 Synthesis of tritopic terpyridine ligands 52—54 using the Sonogashira coupling and their self-assembly into cage structures 55—57 under thermodynamic control with IVl = Zn". Energy minimized structures and dimensions and 2D DOSY NMR spectra of 55 (left), 56 (middle), and 57 (right). Adapted with permission from Ref. 14JA10499. Copyright 2014 American Chemical Society.

Some methylzinc thiolates with bulky groups on the sulfur form self-assembled aggregates with cage structures and four-coordinate zinc. Thus, the /crt-butyl derivative is a pentamer, [MeZnSBu js, 16, (in benzene solution) [33] and the isopropyl derivative is an octamer, [MeZnSPr jg, 17 [34]. According to cryoscopic measurements [4] the latter is hexameric in benzene solution, indicating facile interconversion between variously aggregated (supramolecular) forms. 

Self-assembled cage structures have been established for tert-butyl alumoxanes of various degrees of association formed by hydrolysis of AlBuS [81], Thus, compounds such as BuSAU02(0H), Bu 7Al503(0H)2, Bu 8Al604(0H)2 [93], and Bu 6Al604(OH)4 have been structurally characterized [98]. 

One particular asset of structured self-assemblies is their ability to create nano- to microsized domains, snch as cavities, that could be exploited for chemical synthesis and catalysis. Many kinds of organized self-assemblies have been proved to act as efficient nanoreactors, and several chapters of this book discnss some of them such as small discrete supramolecular vessels (Chapter Reactivity In Nanoscale Vessels, Supramolecular Reactivity), dendrimers (Chapter Supramolecular Dendrlmer Chemistry, Soft Matter), or protein cages and virus capsids (Chapter Viruses as Self-Assembled Templates, Self-Processes). In this chapter, we focus on larger and softer self-assembled structures such as micelles, vesicles, liquid crystals (LCs), or gels, which are made of surfactants, block copolymers, or amphiphilic peptides. In addition, only the systems that present a high kinetic lability (i.e., dynamic) of their aggregated building blocks are considered more static objects such as most of polymersomes and molecularly imprinted polymers are discussed elsewhere (Chapters Assembly of Block Copolymers and Molecularly Imprinted Polymers, Soft Matter, respectively). Finally, for each of these dynamic systems, we describe their functional properties with respect to their potential for the promotion and catalysis of molecular and biomolecu-lar transformations, polymerization, self-replication, metal colloid formation, and mineralization processes. 

Amouri H, Desmarets C, Bettoschi A, Rager MN, Boubekeur K, Rabu P, Drillon M (2007) Supramolecular cobalt cages and coordination polymers templated by anion guests self-assembly, structures, and magnetic properties. Chem Eur J 13 5401-5407... 

Crossley (89) described the self-assembly of a spherical cage-like structure made up of two zinc porphyrin dimers bound to a tetramine ligand. The 2 1 complex is stable at 10-6m concentrations, but addition of excess of ligand causes dissociation of the capsule with formation of a 1 1 complex. 

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