Molecules self-assembly

The above results show that the structure of the system with the molecules self-assembled into the internal films is determined by their correlation functions. In contrast to simple fluids, the four-point correlation functions are as important as the two-point correlation functions for the description of the structure in this case. The oil or water domain size is related to the period of oscillations A of the two-point functions. The connectivity of the oil and water domains, related to the sign of K, is determined by the way four moleeules at distanees eomparable to their sizes are eorrelated. For > 0 surfactant molecules are correlated in such a way that preferred orientations... 

Xiao, X. D., Hu, J., Chayuch, D. H., and Salmeron, M., Chain Length Dependence of the Frictional Properties of Alkylsilane Molecules Self-Assembled on Mica Studied by Atomic Force Microscopy," Z,angmmr,Vol. 12,1996, pp. 235-240. 

Whitesides GM, Boncheva M (2002) Beyond molecules self-assembly of mesoscopic and macroscopic components. Proc Natl Acad Sci 99 4769-4774... 

Another direction in liquid crystal research is the fabrication of new molecules that mimic natural materials. The molecule shown here forms two different liquid crystals because of the cylindrical properties of the color-shaded portions of the molecule. These two trios are tethered together by long hydrocarbon chains. In addition to forming liquid crystals, this molecule self-assembles into organized larger units, as do proteins and DNA. The techniques used to synthesize this particular molecule can be adapted to incorporate... 

The experiments discussed in this chapter have shown that a variety of chiral molecules self-assemble into cylindrical tubules and helical ribbons. These are indeed surprising structures because of their high curvature. One would normally expect the lowest energy state of a bilayer membrane to be flat or to have the minimum curvature needed to close off the edges of the membrane. By contrast, these structures have a high curvature, with a characteristic radius that depends on the material but is always fairly small compared with vesicles or other membrane structures. Thus, the key issue in understanding the formation of tubules and helical ribbons is how to explain the morphology with a characteristic radius. 

A second example of homochiral columns formed by discotics are the complexes of tetrazoles (59 and 60) with l,3,5-tris(4,5-dihydroimidazol-2-yl)benzene (61).74 Four molecules self-assemble to give a supramolecular disc and these discs subsequently form columns in nonpolar solvents. Chiral discs were obtained from the self-assembly of the chiral tetrazole (60) with 61. The chirality of the side chains was found to induce a bias in the helic-ity of the supramolecular assembly. Sergeants-and-soldiers measurements75 were performed for which chiral (60) and achiral (59) molecules were mixed. The experiments showed no amplification of chirality, thus revealing that in these systems chirality transfer from the side chains into the column is... 

Figure 6.9 Schematic representation of hierarchical self-assembly process for chiral phthalocya-nine 64. Phthalocyanine molecules self-assembly into helical columns with right-handed screw sense (left). These right-handed helices subsequently aggregate to give left-handed super-helices.

The nanofibers formed by PAs are microns long and have a uniform diameter of approximately 6-8 nm, depending on the length of the PA molecule. Self-assembly of the nanofibers can be controlled by pH adjustment and/or addition of divalent... 

Whitesides, G. M. and Boncheva, M. (2002). Beyond molecules self-assembly of... 

Keywords Columnar mesophase Cubic mesophase Dendrimer Liquid crystal Metallomesogen Micro-segregation Organic semiconductor Perfluorinated molecule Polyphilic molecule Self-assembly... 

The columnar order in 52a,b was explained by molecular folding the molecules are assumed to be in their U- (or wedge-) shaped conformation and six molecules self-assemble to a supramolecular disc. These discs are stacked in columns and arranged within a columnar hexagonal lattice (Fig. 8). Folding of similar mesogens was also seen by Heiney [65]. 

Surprisingly, 133 with eight alkyl chains was not liquid crystalline (Table 9). With increasing number of alkyl chains a transition from a lamellar to a columnar organization of the molecules takes place. Due to the planar geometry around the Pd(II) centers linked by the macrocycle it is reasonable to assume that the molecules self-assemble in columnar phases. However, a certain number of chains are necessary to surround the molecules completely and to obtain columnar phases. 

Proteins and Foldamers Single Molecule Self-Assembly... 

The inclusion compounds of 1 and 2 were obtained by crystallization from an appropriate solvent system containing a guest (vide infra). (R) -1 hen y I <21 y cy I - (A1) - pheny lg I y cine (1) molecules self-assemble to form a layer structure and (.V)-isopropyl phenyl sulfoxide molecules are stereospecifically included in the void between the layers (Figure 4)7 A sheet structure was also observed in THF-included crystals of (/ )-(l-naphthyl)glycyl-(/ )-phenylglycine (2), which were formed by crystallization of 2 from a mixed solvent of tetrahydrofuran (THF) and... 

In early work to lay the foundation for the use of self-assembly in construction of electronic devices from molecules, self-assembled monolayers (SAMs) of various... 

---