Molecular self-assembly technique

Three different techniques are frequently used to obtain SAMs Langmuir-Blod-gett techniques, involving an air-water interface to transfer the assembled film to a solid substrate solution adsorption of film molecules onto the substrate and a vapor-phase molecular self-assembling technique [2], which uses vapor deposition of the film onto the substrate. Our functionalized SAMs were prepared by the last of these techniques, which had been slightly improved in the laboratory... 

Ordered monolayers of organic compounds, which can be prepared using the Langmuir-Blodgett or molecular self-assembly technique, have received growing attention both as model systems for synthetic organic interfaces and as technological products such... 

Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates, joined by noncovalent bonds. The molecular self-assembly technique [163-166] has been widely used in forming complex biological systems and in organic synthesis for nanostructures. Molecular self-assembly has also been used as an alternative method to form noncentrosymmetric structures for NLO applications. 

The types of molecules synthesized by biotechnological techniques are restricted to those biomolecules whose stmctures can be encoded in the DNA of organisms capable of translating them into functional nanomaterials. Other types of molecules and nanomaterials can be synthesized by chemical synthetic approaches, such as covalent syntheses and molecular self-assembly of molecular units. 

Since multiple electrical and optical functionality must be combined in the fabrication of an OLED, many workers have turned to the techniques of molecular self-assembly in order to optimize the microstructure of the materials used. In turn, such approaches necessitate the incorporation of additional chemical functionality into the molecules. For example, the successive dipping of a substrate into solutions of polyanion and polycation leads to the deposition of poly-ionic bilayers [59, 60]. Since the precursor form of PPV is cationic, this is a very appealing way to tailor its properties. Anionic polymers that have been studied include sulfonatcd polystyrene [59] and sulfonatcd polyanilinc 159, 60]. Thermal conversion of the precursor PPV then results in an electroluminescent blended polymer film. 

Molecular Self-Assembly. Reductive techniques, such as those used in the microelectronics industry, can produce structural features smaller than about 200 nm. The use of proximal probes and other nanomanipulative techniques can be considered to be a hybrid of the reductive lithographic techniques and die synthetic strategies of assembling functional nanostructures atom by atom, or molecule by molecule. The organization of nanostructures and devices by the self-assembly of the component atoms and molecules, a ubiquitous phenomenon in biological systems, forms die noncovalent synthetic approach to nanotechnology. 

Molecular self-assembly is a technique to form highly ordered, closely packed mono-layers on various substrates via a spontaneous chemisorption process at the interface.11,12 Earlier research done in this field includes the self-assembly of fatty acids monolayers on metal oxides,14,15 SAMs of organosilicon derivatives on metal and semiconductor oxides,16,17 and organosulfur SAMs on metal and semiconductor surfaces.18,19 Among the organosulfur SAMs, the most thoroughly investigated and characterized one is alkanethiol SAM formed on Au(l 11) surfaces.12... 

The use of self-assembly techniques in molecular electronics has proven to be useful, as shown by the many publications cited. We expect the field to continue to develop and mature as researchers fine-tune their procedures and new methods are developed. Processes refined for the molecular electronics field will find applications in other nanotechnology areas the reverse will also be true. Thus, as it will be beneficial for those in the solid-state microelectronics field to look toward molecular electronics for solutions to their problems, it will also be beneficial for those in the field of self-assembled molecular electronics to look outside that narrow range of technology for potential solutions to their problems. The coming years will surely see many exciting developments. 

Both the molecular template and the self-assembly techniques presented above have limited control over the final shape of the solid, since this is generally obtained in the form of a powder, fibers, or thin films. It is possible, however, to control the shape and size of solids by combining the former techniques with techniques that restrict the volume in which the synthesis takes place. The final goal is to have control over the solids at the molecular as well as macroscopic level, in order to have in a single material properties emerging from several levels of scale. Such structures are referred to as hierarchical [2, 6]. 

The simultaneous combination of the all three aforementioned techniques allows for a precise control over the structure of materials at several scales [52]. One of the most useful characteristics of molecular self-assembly is that it can take place simultaneously at multiple scales, producing highly hierarchical structures. This allows for the programmed organization of molecules, biological structures, and nanoparticles in the final architecture of the material in a bottom-up fashion [5],... 

We study MESA for three reasons, (i) MESA bridges the gap between molecular self-assembly, which has been successful at the nanometer level, and conventional fabrication of machines and parts, which has been successful for scales greater than 100 pm [refs. 16-23], Few techniques exist to assemble or fabricate objects or arrays in the size region between several nanometers and hundreds of microns, and new techniques in this regime would be welcome, (ii) We wished to develop systems of self-assembly in which we could control the parameters affecting self-assembly more easily than we can with molecules, (iii) We wished to extend the ideas and methods of self-assembly in chemistry and biology to self-assembly on the mesoscale. 

Molecular self-assembly is a synthetic technique that has been widely used to produce nano- and microstructures in a quick and efficient manner. It has become all the more crucial to the formation of nanostructures due to the control attainable over the end product and the relative ease with which nanostructures of defined structure and function can be produced using bulk manufacturing methods. 

The incorporation a redox-active transition metal head group into a self-assembling molecule provides a ready means for the immobilization of transition-metal complexes onto an electrode surface [13,24]. Unlike other approaches to immobilization which generally yield rough, unordered arrays of molecules, self-assembly techniques can produce well-ordered, atomically smooth molecular arrays. 

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