Supramolecular cylinders

Fig. 2. Schematic representation of the supramolecular cylinders of the dendrimer derived from macromonomer 9 (R=OC12H25,n=3) in the Qh mesophase atop view of a cylinder containing six repeat units in a stratum with the alkyl tails melted to match the average column radius determined by X-ray scattering experiments b side view of a cylinder containing 30 repeat units of the polymer assembled with melted alkyl tails. Reproduced with permission from references 5 a...

Fig. 3. An idealized representation of the supramolecular cylinder self-assembled from a single chain of the dendrimer derived from monomer 9 (R=OC12H25, n=3) in the hexagonal columnar phase, assuming one single backbone per cylinder, drawn to proportion with existing experimental data a tilted side view b top view. Reproduced with permission from references 5 a...

Terminal crown ethers with taper-shaped substituents often possess columnar phases. Sometimes, the columnar order is only observed after the complexation of specific salts. The uptake of salts often results in the crown ethers assembling side by side forming supramolecular cylinders with the crown moieties on the inside and the alkyl chains on the outside leading to possible ion-conducting arrangements within an insulating jacket. Indeed, it was shown that matrix-fixed tubular arrangements are ion conductors. 

Pascu GI, Hotze ACG, Sanchez-Cano C, Kariuki BM, Hannon MJ (2007) Dinuclear ruthenium (II) triple-stranded helicates luminescent supramolecular cylinders that bind and coil DNA and exhibit activity against cancer cell lines. Angew Chem Int Ed Engl 46 4374 -378... 

Malina J, Hannon MJ, Brabec V (2008) Interaction of dinuclear ruthenium(II) supramolecular cylinders with DNA sequence-specific binding, unwinding, and photocleavage. Chem Eur J 14 10408-10414... 

Percec V, Cho W-D, Ungar G, Yeardley DJP (2000) From molecular flat tapers, discs, and cones to supramolecular cylinders and spheres using Frechet-type monodendrons modified on their periphery. Angew Chem hit Ed 39(9) 1597-1602. doi 10.1002/(SlCl)1521-3773 (20000502)39 9<1597 A1D-AN1E1597>3.0.CO 2-1... 

Shiyanovskaya I, Singer KD, Percec V, Bera TK, Miura Y, Glodde M (2003) Charge transport in hexagonal columnar liquid crystals self-organized from supramolecular cylinders based on acene-fimctionalized dendrons. Phys Rev B Condens Matter Mater Phys 67 (3) 035204.doi 10.1103/PhysRevB.67.035204... 

The supramolecular transformation from sphere to cylinder is supported by X-ray data indicating that the spherical polymers adopt a cubic phase, whereas the cylindrical polymers adopt a hexagonal phase [23b]. Further studies involving a library of dendritic macromonomers led to the conclusion that the effect of DP on polymer shape is a general phenomenon [24], More recently, scanning... 

Controlling the size, shape and ordering of synthetic organic materials at the macromolecular and supramolecular levels is an important objective in chemistry. Such control may be used to improve specific advanced material properties. Initial efforts to control dendrimer shapes involved the use of appropriately shaped core templates upon which to amplify dendritic shells to produce either dendrimer spheroids or cylinders (rods). The first examples of covalent dendrimer rods were reported by Tomalia et al. [43] and Schluter et al. [44], These examples involved the reiterative growth of dendritic shells around a preformed linear polymeric backbone or the polymerization of a dendronized monomer to produce cylinders possessing substantial aspect ratios (i.e. 15-100) as observed by TEM and AFM. These architectural copolymers consisting of linear random... 

Clark TD, Ghadiri MR. Supramolecular design by covalent capture. Design of a peptide cylinder via hydrogen-bond-promoted intermolecular olefin metathesis. J Am Chem Soc 1995 117 12364-12365. 

Fig. 41. Schematic representation of the columnar triple-helical superstructure derived from the X-ray data for (LP2, LU2) each spot represents a PU or UP base pair spots of the same type belong to the same supramolecular strand the dimensions are compatible with an arrangement of the PTP and UTU components along the strands indicated (see also text) the aliphatic chains stick out of the cylinder, more or less perpendicularly to its axis a single helical strand and the full triple helix are respectively represented at the bottom and at the top of the column [9.152].

Hairy rigid rod polymers, in which flexible side chains are attached to a rigid core, present attractive properties [9.155]. A supramolecular version of such materials may be the triple helical supramolecular species described above (Figure 41), which presents the features of a hairy cylinder. Similarly, the components 176 and 177 bearing long R chains yield self-assembled, supramolecular hairy rigid rods. 

For diblock copolymers, periodically arranged spheres (micelles), hexago-nally packed cylinders, and a lamellar phase have been observed [1]. A more complex bicontinuous cubic phase with QIasymmetry (gyroid structure) has also been identified. These supramolecular structures, with length scales on the order of 1 to 102 nm, may be controlled by changing the amount of solvent, the length of blocks, or the proportions of A and B monomeric units [128-131]. 

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