Formation of self-assembled

Pale-Grosdemange C, Simon E S, Prime K L and Whitesides G M 1991 Formation of self-assembled monolayers by ohemisorption of derivatives of oligo(ethylene glyool) of struoture FIS(CFl2),, (OCFl2CFl2)meta-OFI on gold J. Am. Chem. Soc. 113 12-20... 

Grosdemange GP, Simon ES, Prime KL, Whitesides GM (1991) Formation of self-assembled monolayers by chemisorption of derivatives of oligo(ethylene glycol) of structure HS (CH2)n(OCH2CH2)mOH on gold. J Am Chem Soc 113 12-20... 

Wu et al. (2000) showed the formation of self-assembled nanoparticles of P(SA -block-EG) in an aqueous environment and studied their degradation as a function of pH and temperature. Fu et al. (2002) repeated the synthesis of P(SA-Wock-EG) and studied the morphology and erosion kinetics of microspheres which they propose as vehicles for mucosal drug delivery. 

Thus, the adsorption of phosphonate or phosphate bearing long alkyl chains (typically from 8 to 18 C atoms) on metal oxide or metal surfaces leads to the formation of self-assembled monolayers (Fig. 13) [121, 127, 131, 132, 135, 150, 154, 174]. 

Since Upids are known to associate with DNA with high affinity, the adsorption of ssDNA at lipid membranes as a medium for DNA incorporation on a GC surface was extensively studied [60]. Exploiting DNA-Upid interactions, various approaches were designed for the incorporation of ssDNA [61] and dsDNA [62] at a modified bilayer lipid membrane (BLM) GC surface, such as (1) the formation of self-assembled BLMs over ssDNA previously adsorbed on GC, (2) the direct adsorption of ss- and dsDNA [62] into a previously BLM-modified GC and, (3) formation of a BLM with incorporated ssDNA at the GC surface using the monolayer folding technique [61]. 

Kotera M, Lehn JM, Vigneron JP. Design and synthesis of complementary components for the formation of self-assembled supramolecular rigid rods. Tetrahedron 1995 51 1953-1972. 

Figure 14.8 (Left) Primary sequence of peptide MAXI with /8-hairpin promoted intramolecular folding, leading to the reversible formation of self-assembled /8-sheets. (Right) Cryo-TEM image of self-assembled peptide scaffolds. Scale bar = 200 nm. Reprinted from Schneider et al. (2002). Copyright 2002 American Chemical Society.

Figure 14.8 (Left) Primary sequence of peptide MAXI with /3-hairpin promoted intramolecular folding, leading to the reversible formation of self-assembled...

In the formation of self-assembled layer, one can distinguish three steps [131, 132]. The first step lasts for several seconds and obeys chemisorption and formation... 

Semiconductor particle formation between Langmuir-Blodgett (LB) films is an alternative and promising approach to band-gap engineering [662-666]. The ease of formation of self-assembled (SA) films [183-185,203-246] promoted the incorporation of semiconductors into these media [663, 710]. 

Figure 3.8 Structures of the resorcinarenes 3 and 4 used in the formation of self-assembled, hexameric molecular capsules.

In 1980 Sagiv [357] pioneered the use of octadecyltrichlorosilane, hereafter referred to as OTS, in the formation of self-assembled monolayers. Subsequently Netzer and Sagiv [17] extended the use of this type of material to the formation of multilayers and this work will be discussed in Section 6.5. 

Figure 6.1. The use of OTS in the formation of self-assembled monolayers. The successive processes which take place are (1) hydrolysis, (2) adsorption and (3) polymerisation with the elimination of water. Further details are given in the text.

Figure 6.2. Trichlorosilanes containing an aromatic group which have been used for the formation of self-assembled monolayers.

Another important application of this interaction is in the formation of self-assembled bilayers on silver or gold surfaces. Ebersole et al. [457] showed that avidin and streptavidin molecules will adsorb onto clean layers of Au or Ag from an aqueous solution. Such layers can then be employed to capture biotinylated compounds. These authors used this technique to attach fragments of nucleic acid derived from the herpes virus to a solid support. A more popular approach to this general problem has, however, been to start by adsorption of a suitable biotin... 

This last section deals with a few examples of the formation of self-assembly structures from lanthanide complexes, which are formed by using transition metal ions. This area of research is very novel and relatively few examples have been developed to date. While the lanthanide ions have been used to mediate the formation of supramolecular structures, such as helicates, many of which can have both/-/ mdf-d metal ions, etc. the focus here will be on the use of lanthanide complexes and ligand structures similar to those described above [170-173]. 

Surfactants at Interfaces. Somewhat surprisingly, the successes described above in the in-situ studies of protein adsorption have not inspired extensive applications to the study of the adsorption of surfactants. The common materials used in the fabrication of IREs, thalliumbromoiodide, zinc selenide, germanium and silicon do, in fact, offer quite a range in adsorption substrate properties, and the potential of employing a thin layer of a substance as a modifier of the IRE surface which is presented to a surfactant solution has also been examined in the studies of proteins. Based on the appearance of the studies described below, and recent concerns about the kinetics of formation of self-assembled layers, (108) it seems likely that in-situ ATR studies of small molecules at solid - liquid interfaces ("wet" solids), will continue to expand in scope. 

FI1R methods were used to study the kinetics of formation of self-assembled monolayers of n-alkanoic acids by adsorption from solutions. 

Although the above discussion is centered on the synthesis of polymeric osmium and ruthenium complexes, the methods employed are also very successful in the preparation of mononuclear complexes. In this context, the preparation of ruthenium or osmium complexes which are suitable for the formation of self-assembled monolayers (see Section 4.3 above) can be prepared by using the same approach. Starting from the precursor [M(bpy)2Cl2], one chloride atom can be replaced to yield complexes of the type [M(bpy)2Cl L]+, where L is the surface active ligand. In the presence of water, species of the type [M(bpy)2(L)2]2+ are obtained. 

Hong, Y., Legge, R.L., Zhang, S., and Chen, P. "Effect of amino acid sequence and pH on nanofiber formation of self-assembling peptides EAK16-II and EAK16-IV". Biomacromolecules 4(5), 1433-1442 (2003). 

While the design and formation of self-assembled coordination cages described in the previous sections have received much attention, the corresponding metal-directed self-assembly of open multitopic receptors has been almost neglected so far. One reason is related to the need for partially derivatized precursors, which are synthetically more demanding than the corresponding fully derivatized ones. 

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