Structure zigzag

The tubes (a, a) and (a, 0) are generated from hexagons with 0 = jt/6 and 0, respectively. These tubes become non-helical and are called, respectively, armchair and zigzag structures. Other condition (0 < 0 < Jt/6) generates the tube (a, b) of helical structures (see Fig. 2). 

These values lie between those of the corresponding armchair and zigzag structures. The explicit expressions have been given in ref. 16. 

Armchair structure Zigzag structure Helical structure All other tubes ... 

In a class of reahstic lattice models, hydrocarbon chains are placed on a diamond lattice in order to imitate the zigzag structure of the carbon backbones and the trans and gauche bonds. Such models have been used early on to study micelle structures [104], monolayers [105], and bilayers [106]. Levine and coworkers have introduced an even more sophisticated model, which allows one to consider unsaturated C=C bonds and stiffer molecules such as cholesterol a monomer occupies several lattice sites on a cubic lattice, the saturated bonds between monomers are taken from a given set of allowed bonds with length /5, and torsional potentials are introduced to distinguish between trans and "gauche conformations [107,108]. 

ISimilaar zigzag structures have been observed in two-dimensional systems, where they appear as a checkerboard pattern (kapralSS). 

Bcgiine I Frozeit Pattern a basic zigzag structure is first formed in space. 

We conclude this section with a few general observations about the zigzag regime (see [crutch87]) (i) For small diffusive-couplings, zigzag structures typically start... 

The number (nj) of the cross ct conjugations of the trios of a C-C bond and two antiperiplanar C-H bonds is important for the stabilities of alkanes. The cross conjugation number (nj) of an alkane is defined as that of the conformer where the longest C-C chain has trans a zigzag structure. For example, there are three cross conjugations (n = 3) in isobutene and none in n-butane (n = 0) (Scheme 27). Isobutane is more stable than n-butane [34, 35]. 

The zinc complex of 1,1,1,5,5,5-hexafluoroacetylacetonate forms coordination polymers in reaction with either 2,5-bis(4-ethynylpyridyl)furan or l,2-bis(4-ethynylpyridyl)benzene. The X-ray crystal structures demonstrate an isotactic helical structure for the former and a syndio-tactic structure for the latter in the solid state. Low-temperature 1H and 19F NMR studies gave information on the solution structures of oligomers. Chiral polymers were prepared from L2Zn where L = 3-((trifluoromethyl)hydroxymethylene)-(+)-camphorate. Reaction with 2,5-bis(4-ethy-nylpyridyl)furan gave a linear zigzag structure and reaction with tris(4-pyridyl)methanol a homo-chiral helical polymer.479... 

Figure 8.5 Structure and phase sequence of DOBAMBC is shown. Terminology used to describe parts of LC mesogen is given, in addition to graphical representation (zigzag structure) of molecule as it exists in tilted smectic phase.

Fig Planar zigzag structure of polymer molecules showing (I) isotactic, (II) syndiotactic, and (III) heterotactic configurations, (Hydrogen atoms are not shown for the purpose of clarity.)... 

Figure 6. The zigzag structure of chloride anions in bmimCl Crystal (1).

In the presence of small amounts of water, however, the zigzag structure was observed ... 

Since sugar charcoal—and nearly any other carbon—always contains some hydrogen, the zigzag structure should be expected after oxida-... 

DeDu05] M. Deza and M. Dutour, Zigzag structure of simple two-faced polyhedra, Combinatorics, Probability and Computing 14-1 2 (2005) 31-57. 

The [Hg3(OH)2]4+ cation has a zigzag structure 78 the [Hg(OH)]+ cation, in its chlorate and bromate salts, is an infinite chain analogue (17).79 A related cyclic /x-hydroxo trimer (18) is found in a platinum(II)-diaminocyclohexane complex.69... 

As pointed out earlier, the fluorine atoms are too large to allow planar zigzag structure, which confers rigidity on the polymer.20 The PTFE molecule has a regular folded structure, which produces a laminar crystal.16... 

The polymeric cyclopentadienylindium(I) has also been analyzed theoretically (153). The zigzag structure of the polymer is shown to be due to a minimization of repulsion. Bending of the linear structure changes the character of the highest energy band to make it essentially nonbonding. 

FIGURE 6.22 The spatial distribution of the populations of the HOMO level for nanographene sheets with their edges having (a) armchair and (b) zigzag structures. (From Stein, S.E. and Brown, R.L., J. Am. Chem. Soc., 109, 3721, 1987. With permission.)... 

If more than two carbon atoms join together to form a chain, they necessarily form a zigzag structure, on account of the tetrahedral angle between bonds. Thus in Fig. XXV-2 we show propane CH3CH2CHJ... 

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