Tubular assemblies

More complicated supramolecular assemblies of p-sulfonatocalix[4] arene including giant spheres and tubular assemblies have been established through up-up, rather than up-down, associations [43]. 

Figure 5 Structure of the tubular assembly 6 (see also Plate 19).

In tubular assemblies the membrane is deposited either on the inside or outside of porous tube, most commonly inside for reverse osmosis and outside for ultrafiltration. Figure 19.3(a) shows a single-tube construction, but units with 7 or 19 tubes in a single shell are made as standard items. Table 19.5 lists some available sizes. Dynamic membranes may be deposited on porous stainless steel tubes from a feed solution that consists of polyacrylic acid and hydrous zirconium oxide. Such a membrane can be deposited in 1 hr and replaced as quickly. Fluxes are very high 100 gal/(sqft)(day) is shown in Table 19.6(a). Some apphca-tions are described by Turbak (Vol. II, 1981, pp. 434-A53). 

Loeb, S., "A Composite Tubular Assembly for Reverse Osmosis Desalina-... 

The nanotube of 2 is able to solubiUze single-walled carbon nanotubes (SWNTs) in water. On solubihzation of SWNTs, the organic nanotubes do not change their dimensions, as confirmed by TEM (Fig. 2c), but show significant fluorescence quenching. Based on these observations, the authors suggest that tubularly assembled 2 encapsulates SWNTs into its hydrophobic hollow space. In contrast, compound 2 is unable to solubiUze SWNTs in THF, where 2 is molecularly dispersed. Therefore, not only the ring-shape of... 

Fig. 8 Molecular structure of 8a (a). Electronic absorption spectral change of 8a upon self-assembly in THE (Imgml ) (b). SEM micrograph (c), proposed structure (d), and TEM micrograph (e) of tubularly assembled 8a. Proposed structure of the nanocoils of self-assembled 8a (f). TEM micrograph of a mixture of nanotuhes and nanocoUs formed by the self-assemhly of 8a in a mixture of THE and water (8/2 v/v) (1 mgml )...

Kondo et al. reported a novel fabrication method of polymer nanotubes by combination of an alternate layer-by-layer (LbL) assembly of PLLA and PDLA and the siliea template method. Silica nanoparticles with a diameter of 300 nm were alternately immersed in aeetonitrile solutions of PLLA and PDLA at 50 °C. The immersion process was performed for 10 cycles to deposit 10 double layers of PLLA and PDLA. The resulting partieles were then treated with 2.3% aqueous hydrofluoric acid to remove the siliea core. The hollow eapsules have a spherical shape with a diameter of 320 nm and a shell thiekness of approximately 60 nm. Tubular assemblies with an average diameter of 300 nm and lengths of 2-5 pm are obtained by evaporating water at ambient temperature from a water dispersion of the hollow eapsules on a polyethylene terephthalate (PET) substrate. 

Gallant, A. J. MacLachlan, M. J. Ion-induced tubular assembly of conjugated Schiff-base macrocycles. Angew. Chem. Int. Ed. 2003, 42, 5307-5310. 

Ryu, J.-H. Oh, N.-K. Lee, M. Tubular assembly of amphiphilic rigid macrocycle with flexible dendrons. Chem. Commun. 2005,1770-1772. 

Natural tubular assemblies show remarkable biological functions. For example, tubular shaped channels aid the transport of materials in and out of cells. Given that simple self-assembling macrocycles and disks form assemblies reminiscent of these biological structures, it is not surprising that they have been a very active area of research. 

Intact CCMV or its coat proteins have also been employed as viral building blocks for the self-assembly of molecular materials by Nolte, Comelissen and coworkers. For example, the coat proteins of CCMV were utilized to form DNA-templated tubular assemblies of viral coat proteins. As illustrated in Figure 11, the templates consisted of a single-strand DNA (ssDNA) of repeating thymine units of various lengths (T, where q is the number of thymine bases present). To form the negatively... 

As exemplified by the above case, the HBC nanotubes become totally insoluble after surface polymerization. Hence, reversible polymerization on the nanotube surface is interesting for lithographic patterning. For the realization of this possibility, HBC 4 appended with thiol groups was designed (Figure 1), which can be stitched at the tubularly assembled state by oxidative surface polymerization. The acetyl-protected version of thiol-appended HBC 4 self-assembles in THF to form nanotubes with a diameter of... 

Horoscope. The horoscope enables detailed visual inspection of internal cylinder surfaces and allows for close-up inspection of affected areas through a series of lenses within a tubular assembly. 

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