Spontaneous self-assembly

Aggeli A, Bell M, Boden N et al (1997) Responsive gels formed by the spontaneous self-assembly of peptides into polymeric beta-sheet tapes. Nature 386 259-262... 

The observation that a repeating, relatively short sequence of amino acids directs the spontaneous self-assembly of a large protein is shared by other structural proteins from mammalian systems [6] as well as of plant origin [16], Hence, such sequences may inspire the construction of nanostructures made of polypeptides and small proteins, as discussed later. 

Diblock copolymers consist of contiguous sequences of two different covalently bound monomer units, arranged in an -A-A-A-B-B-B-B- structure. In an appropriate solvent, the diblock copolymers spontaneously self-assemble into micelles with cores which are essentially pure in one component and a diameter... 

The reaction of the cyclic P3-ligand l,3,5-triphospha-2,4,6-trisilacyclohexane with AgOTf results in the synthesis of complex (101) with a cyclic P6 ligand.794 Optically pure (S,5)-(+)-(PPh2CH2CH2)2(PPhCH2CH2PPh) spontaneously self-assembles into left-handed double-stranded D2-double helix (102) and C2-side-by-side helix conformers of the disilver(I) cation.795... 

Spontaneous self assembly of a dinuclear triple helical complex is observed with linked bis-[4,5]-pineno-2,2 -bipyridines. Studies by electrospray mass spectrometry, CD and NMR determined that the major species in solution was a complex of Zn L = 2 3 stoichiometry with a triple helical structure and an enantiomerically pure homochiral configuration at the metal centers. The preference for the formation of one of the possible stereoisomers over the other is of interest.265 Another binuclear triple helical complex is formed from zinc addition to bis[5-(l-methyl-2-(6-methyl-2 -pyridyl)benzimidazolyl)]methane. Spectrophotometric titrations with a zinc solution... 

Synthesize new substances that can spontaneously self-assemble into complex organized systems with important properties. 

Pseudorotaxanes are precursors of both rotaxanes and catenanes they consist of a guest molecule threaded through a macrocyclic host. Stoppering both ends of the threaded molecule gives a rotaxane, cycliza-tion of the thread gives a catenane. Pseudorotaxane formation may occur by spontaneous self-assembly, or may be template-controlled. Anion size can be of paramount importance for such templates - Cl- is effective, Br, I- less good, and PFe ineffective when the recognition motif demands a small template (454). 

Aggeli, A., Bell, M., Boden, N., Keen, J. N., Knowles, P. F., McLeish, T. C., Pitkeathly, M., and Radford, S. E. (1997). Responsive gels formed by the spontaneous self-assembly of peptides into polymeric beta-sheet tapes. Nature 386, 259-262. 

The functionality at the central core of the dendritic macromolecule can also be exploited as a unique reactive site for a variety of purposes. Perhaps the most dramatic example is the introduction of self-assembling units at the focal point to give dendritic fragments, 36, which undergo spontaneous self-assembly to give larger dendrimers [68] (Fig- 9). In this case the central core of the dendrimer is a self-as-... 

These two examples show how emulsion-based magnetic colloids can become the essential elements for two apparently very different issues. In fact, this section introduces the basics of using superparamagnetic emulsion-based colloids, and their spontaneous self-assembling ability under a field, as new biosensors. The... 

Four distinct types of Fe-S center have now been found in proteins, ranging from mono- to tetranuclear in addition, a novel Mo-Fe-S cluster is present in the enzyme nitrogenase. Synthetic analogs of most of these have been prepared and used to provide insight into the intrinsic properties of the metal-sulfur centers in the absence of protein-imposed constraints. The strategies used to prepare both Fe-S and Mo-Fe-S clusters are described they range from spontaneous self-assembly to the designed synthesis of clusters with specific structural features. 

Other Fe-S Clusters. Spontaneous self-assembly reactions using phosphines as terminal ligands have been reported to yield a variety of new Co-S (22) and Ni-S clusters (23). Extension to Fe-S clusters was initially effected by the following reaction in heterogeneous solution (2A). 

Polynuclear Fe-M-S Complexes from "spontaneous self assembly" reactions. Synthetic analog clusters for the Fe2S2 and Fe4S4 centers in the Fe/S proteins (ferredoxins) have been obtained by procedures that are based on the concept of "spontaneous self assembly". The latter (30) assumes that the cores of the Fe/S centers are thermodynamically stable units that should be accessible fiom appropriate reagents even in the absence of a protein environment. 

In the spontaneous self assembly approach to synthesis, the inherent kinetic lability of the Fe/Mo/S system allows for the fcnmation of various thermodynamically stable, heteronuclear products that, as of now, do not include one with the desir le Fe/Mo/S atom ratio of 6-7 1 6-8. 

The spontaneous self-assembly or template-directed assembly of component monomeric units into polymeric biological macromolecules. 2. The enzyme-catalyzed joining of monomeric units (such as amino acids, sugars, nucleotides) into covalently linked oligomeric or polymeric forms. 

Organic compounds functionalized with groups that chemically bind to substrate surfaces will spontaneously self-assemble into close-packed, organized monolayers upon immersing the substrates into solutions of such compounds. Self-assembly on... 

Introduction to the variety of types of surfactants, effect of surfactants on aqueous solution properties. Law of mass action applied to the self-assembly of surfactant molecules in water. Spontaneous self-assembly of surfactants in aqueous media. Formation of micelles, vesicles and lamellar structures. Critical packing parameter. Detergency. Laboratory project on determining the charge of a micelle. 

The all-important finding that carboxylate-appended sapphyrins can self-assem-ble was confirmed in the case of the sapphyrin monocarboxylate 6. ° For both compounds the self-assembly phenomena were shown to take place not only in the solid state, but also in solution and in the gas phase (see Section 3.3). This meant that the carboxylate-binding properties of the sapphyrins could be used as the key molecular recognition basis for engendering the spontaneous self-assembly of appropriately designed supramolecular ensembles. 

---