Self-assembling template layer

Our approach to a "self-assembling" template layer is outlined in Scheme 2. In the first step, co-hexadecenylbromide (27) is hydrosilylated with trichlorosilane and self-assembled to a silicon oxide surface to form a bromide terminated monolayer. Conversion of the bromide to the phosphonate, by reaction with triethylphosphite, is carried out on the assembled monolayer and followed by acid hydrolysis to the phosphonic acid. All of the conversions performed on the surface are followed by ATR-FTIR and XPS, and go to completion to the extent that can be determined by XPS (22). To form the zirconium phosphonate bilayer, the phosphorylated substrate is immersed into an aqueous solution of ZrOCh to bind Zr + at the phosphonic acid sites. To form the complete bilayer, the zirconated surface is then rinsed with water and placed into a solution of octadecylphosphonic acid in order to self-assemble the capping layer according to Scheme 1. 

A huge number of other applications exist, where the chemical and physical requirements are totally different. These applications include reflectors, temperature measurement with thermochromic materials, nonlinear optics, polymer materials, SAMs (self-assembled mono-layers) and LB (Langmuir-Blodgett) Aims, the use of liquid crystals in template synthesis of porous materials, drug delivery, and many more. 

Membranes can act as both active and passive templates for the formation of well-defined nanostructures in a number of ways. In the biological realm, they have a limited role in the formation of nanowires, where virus capsids are much more effective, as described elsewhere in this volume (see Viruses as Self-Assembled Templates, Self-Processes). An interesting exception that takes place close to the membranes of living cells is the formation of iron oxyhydroxide (akaganeite, /1-FeOOH) in a natural ecosystem, in which polysaccharides are shown to be important as they are contained in the filaments of the inorganic material. It is believed that the sugar is extruded from the cell and then acts as a template to promote the formation of the mineral. On the other hand, entirely synthetic lipids can be used for the preparation of pipes of organically functionalized layered materials—clays —in... 

In the second part of this Chapter the thickness of the organic layer under discussion is slightly increased and a closer look at recent developments of more complex surface-bonded systems involving polymers is outlined. Despite the introduction of flexible polymer chains, the surface coating should still be defined and uncontrolled heterogeneities minimized. Here, especially, polymer brush-type layers where self-assembled monolayers (SAMs) are used as two-dimensional template systems for the preparation of well-defined surface coatings will be subject of a more detailed discussion. 

The self-assembly of an imprinted layer on the surface of a transducer was realized through the adsorption of the template on gold, Si02, or ln02 surfaces followed by treatment with an alkylthiol or organosilane (Hirsch et al. 2003). The first example of this type of sensor was reported in 1987 by Tabushi and coworkers (1987). Octadecylchlorosilane was chemisorbed in the presence of n-hexadecane onto tin dioxide or silicon dioxide for electrochemical detection of phylloquinone, menaqui-none, topopherol, cholesterol, and adamantane. Another MlP-based sensor was... 

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