Strict self-assembly

In the previous chapters, examples of ID arrays of nanoclusters have been given, where self-assembly or ET were used to address the arrays for electrical transport measurements. So far it is evident that these methods did not lead to strictly ID defect-free arrangements. Furthermore, inherent disorder cannot be avoided. This means that the electrical transport properties through a perfect array could only be studies theoretically up to now. 

Caspar and Klug (1962) made an important distinction between two fundamental types of assembly processes. True self-assembly was conceptualized as a series of reactions relying on the propensity of subunits to condense and form assembled structures strictly as a result of the information encoded in the architecture of the components. On the other hand, template-directed assembly may be considered as a process depending on the presence of a separate template that imparts structural constraints on the pathway for constructing the final assembled structure. True self-assembly is observed, for example, in the formation of many oligomeric proteins. Indeed, Friedman and Beychok (1979) have re-... 

Although not strictly LB films, there are other types of self-assembled films containing Q-state MCs that resemble LB films. One example involves the self-assembly of the amphiphile DTG into an organized film by slow evaporation of solvent from a dispersion of the amphiphile (40). The structure of the cast film has the head-... 

We saw in Figure 1.2c that supramolecular chemistry is not just about solid state or solution host-guest chemistry but increasingly emphasises self-assembly and the construction of multi-nanometre scale devices and ultimately materials based on nanometre-scale components (a nanometre is 10 9 of a metre). Strict supramolecular self-assembly (Chapter 10) involves the spontaneous formation of a multi-component aggregate under thermodynamically controlled conditions based on information encoded within the individual building blocks (referred to as tectons ) themselves. The aggregate might comprise only one kind of molecule (as in the multiple copies of the same protein that comprise... 

In a strict self-assembly process, the final product is produced entirely spontaneously when the components are mixed together in the correct ratios under a given set of conditions of temperature, pH, concentration etc. The product formation must be completely reversible and represent the thermodynamic minimum for the system. In essence, all the information necessary for the assembly to occur is coded into the constituent parts. The concept of strict self-assembly is rooted in the Thermodynamic Hypothesis of Afinison who suggested that under physiological conditions the native structure of a protein is... 

Strict Self-Assembly The Tobacco Mosaic Virus and DNA... 

The most famous example of a strict self-assembly process is the formation of the DNA double helix (Figure 2.27), by the spontaneous association (by hydrogen bonding) of complementary... 

Figure 10.21 A strict self-assembling hexametallic cage13 and its assembly tree (reproduced with permission from [14]).

Coordination interactions are not the only way to use self-assembly to produce closed, capsular systems capable of binding guest species in solution. Work by Julius Rebek Jr (Scripps, USA)43 has shown that multiple hydrogen-bonding interactions, because of their relatively weak, but directional, nature, are ideal for the strict self-assembly of closed spherical molecules and capsules. For example, component 10.49 consists of two intrinsically curved diphenylglycoluril units linked by a durene-based (1,2,4,5-tetramethyl benzene-based) spacer. In both solution and in the solid state, 10.49 self-assembles spontaneously to produce the tennis ball-shaped dimer (10.49)2 shown in Figure 10.43. The formation of the dimer has been observed by ... 

Self-assembly can be divided into a number of classes 1. strict self-assembly, 2. irreversible self-assembly, 3. precursor modification followed by self-assembly, 4. self-assembly with post-modification, 5. assisted self-assembly, 6. directed self-assembly, 7. self-assembly with intermittent processing. 

Gibb, B. C., Strict self-assembly and self-assembly with covalent modification , in Encyclopedia of Supramolecular Chemistry, Atwood, J. L.. Steed, J. W., eds. Marcel Dekker New York, 2004. Vol. 2, pp. 1372-1378. 

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