Self-assembly process

The self-assembly process can be continued to form multilayer films of up to 25 layers [33,48,49]. The reliability of this process is illustrated in Fig. XI-3, where the thickness grows linearly with the number of reacted layers. These thick layers have many interesting applications. 

The overwhelming majority of AEM studies on organic surfaces has concerned organic thin films on inorganic snbstrates and, in particvilar, those deposited via Langmnir-Blodgett or self-assembly processes [35]. These films... 

Lowack K and Helm C A 1998 Molecular mechanisms controlling the self-assembly process of polyelectrolyte multilayers Macromolecules 31 823-33... 

Chemseddine A, Jungblut H and Boulmaz S 1996 Investigation of the nanocluster self-assembly process by scanning tunneling microscopy J. Phys. Chem. 100 12 546... 

The Alexander approach can also be applied to discover useful information in melts, such as the block copolymer microphases of Fig. 1D. In this situation the density of chains tethered to the interface is not arbitrary but is dictated by the equilibrium condition of the self-assembly process. In a melt, the chains must fill space at constant density within a single microphase and, in the case of block copolymers, minimize contacts between unlike monomers. A sharp interface results in this limit. The interaction energy per chain can then be related to the energy of this interface and written rather simply as Fin, = ykT(N/Lg), where ykT is the interfacial energy per unit area, q is the number density of chain segments and the term in parentheses is the reciprocal of the number of chains per unit area [49, 50]. The total energy per chain is then ... 

After the self-assembly process, the tropoelastin molecules are enzymatically crosslinked via the lysine residues in the hydrophihc domains. In this last step of the elastogenesis, the amines of the lysine residues are enzymatically converted... 

The general structural characteristics of ribosomes and their self-assembly process are discussed in Chapter 37. These particulate entities serve as the machinery on which the mRNA nucleotide sequence is translated into the sequence of amino acids of the specified protein. 

The main aim in host-guest chemistry is to construct molecular receptors by a self-assembly process so that such receptors could, to some extent, gain molecular recognition capability. The goal of such molecular recognition capability is to either mimic or block a biological effect caused by molecular interactions [157]. 

The non-enveloped human viruses all have icosahedral capsids. The structural proteins undergo a self-assembly process to form capsids into which the viral nucleic acid is packaged. Most non-enveloped viruses accumulate within the cytoplasm or nucleus and are only released when the cell lyses. 

Figure 8. TEM images of (a) 6.1 + 0.6 nm Fe36Pt64, (b) 5.8 + 0.7 nm Fe44Pt56, and 5.1+ 0.7 nm Fe49Pt5i nanoparticles formed by a self-assembly process of hexane solution on an amorphous carbon substrate. (Reprinted from Ref [23], 2006, American Chemical Society.)...

The value of EM for a cooperative self-assembled structure provides a measure of the monomer concentration at which trivial polymeric structures start to compete, and therefore EM represents the upper limit of the concentration range within which the cooperative structure is stable (Scheme 2). The lower limit of this range is called the critical self-assembly concentration (csac) and is determined by the stoichiometry of the assembly and the strength of the non-covalent binding interactions weaker interactions and larger numbers of components raise the csac and narrow the stability window of the assembly (8). Theoretical treatments of the thermodynamics of the self-assembly process have been reported by Hunter (8), Sanders (9), and Mandolini (10). The value of EM is lowered by enthalpic contributions associated with... 

The field of halogen bonding is still in its infancy. Nevertheless, this book proves its potential in the numerous and diverse fields in which recognition and self-assembly processes are crucial. Hopefully, this book will prompt new studies in the field that deepen the basic understanding of halogen interactions and implement its potential in the design of useful materials. 

Intermolecular recognition and self-assembly processes both in the solid, liquid, and gas phases are the result of the balanced action of steric and electronic factors related to shape complementarity, size compatibility, and specific anisotropic interactions. Rather than pursuing specific and definitive rules for recognition and self-assembly processes, we will afford some heuristic principles that can be used as guidelines in XB-based supramolecular chemistry. 

The ability of XB to control recognition, self-organization, and self-assembly processes in the different phases of matter is clearly emerging in the literature. This chapter focusses on self-assembly in the solid phase, while the chapters of B. Duncan and A. Legon (in this volume) deal with the liquid crystalline phase and gas phase, respectively. Relatively few papers are reported in the literature on self-assembly processes in solution [66-68,207,208]. Several analytical techniques have been used to detect XB formation, to define its nature, to establish its energetic and geometric characteristics, and to reveal... 

An alternative way for the generation of a bidentate ligand makes use of a self-assembly process of monodentate to bidentate ligands employing non-covalent interactions [87]. 

One of the most successful approaches to the synthesis of metalla-supramolecular systems has been by templated self-assembly processes. Most of the templating agents used by synthetic chemists are either cationic or neutral species. Anions, on the other hand, have only fairly recently been successfully utilized as templates. The new metalla-macrocycles [Pd2Ni2(atu)4(PPh3)4X]3+ (atu = deprotonated amidinothiourea, X = C1, Br, I) have been prepared using anion templated syntheses. Only in the presence of each of these three halides are the metalla-macrocycles... 

Figure 72 Generation of the cyclic species [(en)-Pd(dmpymo-lV. /VJ) ]4, by a self-assembly process.

Two-dimensional planar interpenetrating networks have been formed using the spacer ligand 2,2 -bis-l,6-naphthyridine with a zinc salt.274 Helicate structures have been synthesized which rely heavily on non-covalent interactions in the metal-assisted self-assembly process in solution.275... 

Self-Assembly Processes Related to Dendritic Amphiphiles... 

Probably the best example of the manifestation of self-assembly processes in dendritic systems via H-bonds is seen in the recent work of Zimmerman et al. [156]. Dendritic wedges possessing tetraacid moieties (67) self-assembling into a hexameric, disc-like framework (68) was confirmed by SEC and -NMR studies. The tetraacid unit (69) is known to form cyclic as well as linear aggregates in solution via carboxylic acid dimerization (Fig. 30). However, with incorporation of larger dendritic wedges on 69, the hexamer form is preferred. 

According to R. M. Hazen, these results are in agreement with the postulate that some self-assembly processes of chiral molecules are highly enantioselective (DiGregorio, 2006). 

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