Nanoscopic assembly

Oenyuk, B., Whiteford, J.A. and Stang, P.J. (1996) Design and study of synthetic chiral nanoscopic assemblies. Preparation and characterization of optically active hybrid, iodonium-transition-metal and all-transition-metal macrocyclic molecular squares. J. Am. Chem. Soc., 118 (35), 8221-8230. 

A great variety of self-assembled supramolecular structures can be found in supramolecular gels . Association of low molecular weight compounds in a topologically defined way yields long fibres with often well defined diameters [420], An amazing variety of very complex superstructures has been described, i.e. rods and tubes formed from concentric or would up lamellae, helices, or braid-like structures. In all cases we can assume a hierarchy of superstructures which ultimately link the molecular structure to the nanoscopic assembly. However, this has only been investigated in detail in a few cases so far. 

The self-assembly of block polymers, in the bulk, thin film and solution states, produces uniformly sized nanostructured patterns that are very useful for nanofabrication. Optimal utilization of these nanoscopic patterns requires complete spatial and orientational control of the microdomains. However, the microdomains in the bulk state normally have grain sizes in the submicron range and have random orientations. In block copolymer thin films, the natural domain orientations are generally not desirable for nanofabrication. In particular, for composition-asymmetric cylindrical thin films, experimental... 

The design and synthesis of supramolecular architectures with parallel control over shape and dimensions is a challenging task in current organic chemistry [13, 14], The information stored at a molecular level plays a key role in the process of self-assembly. Recent examples of nanoscopic supramolecular complexes from outside the dendrimer held include hydrogen-bonded rosettes [15,16], polymers [17], sandwiches [18, 19] and other complexes [20-22], helicates [23], grids [24], mushrooms [25], capsules [26] and spheres [27]. 

Lipofullerenes such as 35-37 self-assemble within lipid bilayers into rod-like structures of nanoscopic dimensions [61, 62]. These anisotropic superstructures may be important for future membrane technology. Significantly, lipofullerenes 35 and 37 have very low melting points, 22 and 67 °C (DSC, heating scan), respectively, with 35 being the first liquid fuUerene derivative at room temperature. 

Finally, Majda has investigated a novel inorganic membrane-modified electrode [32]. The membrane used was a microporous alumina prepared by anodizing metallic aluminum in an acidic electrolyte [33]. Majda et al. lined the pores of these membranes with polymers and self-assembled monolayers and studied electron and ion transfer down the modified pore walls to a substrate electrode surface [32]. Martin and his coworkers have used the pores in such membranes as templates to prepare nanoscopic metal, polymer, and semiconductor particles [34],... 

Amphiphilic molecules (surfactants) can assemble into nanoscopic supramolecular structures with a hydrophobic core and a hydrophilic shell micellar arrangement. As surfactant concentration is increased in aqueous solutions, the separated molecules aggregate into micelles upon reaching a concentration interval known as the critical micellar concentration (CMC). 

Scheme 10.7 Self-assembly of nanoscopic cubeoctahedral 10.28 and 10.29 (conditions CH2C12, room temperature, 10 mins, yields > 98 %).27...

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