Russian-doll structure

The discovery of perfect geodesic dome closed structures of carbon, such as C o has led to numerous studies of so-called Buckminster fullerene. Dislocations are important features of the structures of nested fullerenes also called onion skin, multilayered or Russian doll fullerenes. A recent theoretical study [118] shows that these defects serve to relieve large inherent strains in thick-walled nested fullerenes such that they can show faceted shapes. 

An important question relating to the structure of nanotubes is Are nanotubes made of embedded closed tubes, like "Russian dolls," or are they composed of a single graphene layer which is spirally wound, like a roll of paper Ijima et al. [2] espouse the "Russian doll" model based on TEM work which shows that the same number of sheets appear on each side of the central channel. Dravid et al. [4], however, support a "paper roll" structural model for nanotubes. 

The formation of fullerenes and CNTs has also been affected by their environmental atmosphere [22] and, in particular, a hydrogen atmosphere plays an important role in forming graphitic structures of multi-walled CNTs (MWCNTs) in the form of buckybundles [24]. Intercalation into MWCNTs has been difficult or impossible, because there is no space for intercalants to enter into a Russian-doll-type structure of the nanotubes. However, the buckybundles formed in the hydrogen arc discharge were found to be successfully intercalated with potassium and ferric chloride (FeCl3) without breaking the... 

Let us note in addition that the layered sulfides M0S2 and WS2 have been found to form nanotubes and other fullerene-type structures, on account of their highly folded and distorted nature that favors the formation of rag and tubular structures. Such materials have been synthesized by a variety of methods [78] and exhibit morphologies, which were described as inorganic fiillerenes (IF), single sheets, folded sheets, nanocrystals, and nested IFs (also known as onion crystals or Russian dolls ). 

Similarly, analogous Rh(III) hydrolytic cations can be isolated by crystallisation with the super-anion, however these complexes show quite different hydrogen bonding networks. A second type of Russian Doll super-anion is found in the complex [Rh4(OH)6(H2O)12](20.21+8H). 33H2O [46]. The dehydrated Russian Doll Na([18]crown-6)(19)2 7 21 is skewed by comparison with the capsule structure of 20. The two trans aquo ligands are not present in the dehydrated super-anion, and the axial Na coordination positions are occupied by oxygens... 

A ferris wheel assembly involving a 1 1 complex of 19 and metallated [18]crown-6 is found in the cationic supermolecule [La(H20)3([ 18]crown-6)] (19+2H) + [48]. The lanthanum ion is coordinated by one calixarene sulfonate group, the [18] crown-6 and three aquo ligands, and the metallated crown sits inside the calixarene cavity. A helical hydrogen bonded chain structure is formed between the cationic assembly, water and chloride ions. The ferris wheel structural motif is also found in Ce3+ complex which simultaneously contains a Russian Doll assembly [44]. 

P. W. Fowler (University of Exeter, U.K.). Please comment on finite analogues of your structures We have discussed previously the idea of making a Russian doll fullerene in which one fullerene is connected by tunnels to an outer shell. The matrix seems to comply with this. 

Figure 6.25 Channel structures of (a) the a-CD complex of ferrocene26 and (b) the Russian doll y CD complex of [Na([12] crown-4) 2]+-27...

In HRTEM the carbon nanotubes appeared as long fibers, [12,90-95] (Fig. 20) with diameters ranging from about 1 to many tens of nanometers. They are hollow and clearly graphitic, as evidenced from the layered structure with an interlayer spacing close to that of bulk graphite and from diffraction studies of the individual cylindrical layers or tubules [12]. These layered nanotube structures are called multi-walled carbon nanotubes (MWNTs) The tubes are closed at the end each tubule appears to close on itself and hence the entire structure resembles a Russian doll. 

At least five groups have attempted polymerization in vesicles [7-11]. Pertinent experimental conditions, results, and appropriate references are summarized in Table 1. The polymerized morphologies observed are hollow polymer shells, parachutes , matrioshka structures, and necklaces as shown in Fig. 3. ( Matrioshka refers to the concentric sphere morphology that resembles the nesting Russian dolls bearing the same name.) Structures of the surfactants and monomers used in the experiments are shown in Fig. 4. 

A giant heterometallic cluster with its 108 metal ions organized into a four-shell Russian doll-like structure has been reported recently (Kong... 

Well, fractals are everywhere— in the branching of the blood vessels that feed your heart, in the shaping of a snowflake, in Russian dolls within dolls. Once you see them, you see them everywhere tiny structures within larger ones within still larger ones in a self-similar cascade. ... 

The representation of molecular structure can be looked upon as a hierarchical process similar to the Russian doll, which contains a series of dolls hidden inside it. At the very elementary level, the structure of the model of an assembled entity, e.g., a molecule comprising atoms, can be represented by a graph G = (V, E), where y represents a non-empty set and is a binary relation defined on the set V. When V represents a set of atoms and E symbolizes the set of covalent (or any other) bonds, we have the simplest representation of molecular structure [13,18]. Invariants derived from such graphs or matrices derived from them are the simplest structural descriptors of molecules. 

It is possible to produce extended areas of homeotropically-aligned smectic phases, but when the mesophase is formed by cooling from the melt on an unprepared surface, a disordered pattern of distinct domains is usually formed. Textures of this kind are known as focal conics because of the geometry of the basic structural units. These are formed by stacking concentric, curved, cooling-tower shaped layers inside each other like Russian dolls (Fig. 1.21). The reason why such an apparently complex structure of this kind arises spontaneously is not immediately obvious, but... 

In addition to the possibility of a cluster containing a single interstitial atom as discussed above, there is the possibility of having a smaller cluster inside a larger cluster. Such a cluster has a structure resembling a Russian matryoshka nesting doll. 

In the final analysis in the structure of most hydrogeochemical models are identified the following groups of mutually associated parameters, which form three submodels, inserted into one another as in Russian nesting dolls ... 

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