Hierarchical supramolecular structure

Figure 6.3 Hierarchical supramolecular structure of cellulose [33, http //www.bio.miami.edu/ dana/226/226F09 3.html].

Biological macromolecules such as DNA and proteins are typical polyelectrolytes, which further hierarchically self-assemble into complicated supramolecular structures such as coiled coil (helix bundle) superstructures, which are responsible for their sophisticated functions [152,153]. Therefore, with implications for biological superstructures and functions, the design and synthesis of supramolecular helical assemblies with a controlled helicity have attracted great interest. 

AmphiphiUc block copolymers self-assemble into a variety of supramolecular structures that can be used as templates for the preparation of nanoparticles and mesoporous materials. Size and shape of nanoparticles and mesopores can be controlled via block lengths and polymer concentration. Templates can be used for the preparation of noble metals, semiconductors, and ceramic nanostructures. Concepts of consecutive and hierarchical templating allow one to prepare complex nanostructures for applications in catalysis, electro-optics, and particle separation. 

Progress in heterocyclic metaUosupramolecular constmction is reviewed by James Ludlow and George Newkome (University of Akron) in Chapter 6. They discuss in particular hierarchical self-assembly and interconversion between supramolecular structures. In Chapter 7, Mati Karelson (University of Tartu) and Dimitar Dobchev (Tallin University of Technology) describe the QSAR approach applied to heterocycles where large descriptor spaces... 

This chapter describes supramolecular assemblies in mesoscopic dimension and their recent developments. It also compliments earlier reviews [21,22]. The mesoscopic supramolecular assemblies are defined as hierarchically self-assembled amphiphilic supramolecular structures whose ternary and the higher assembly structures are controlled through solvophilic-solvophobic interactions. Here, pairs of molecules brought by secondary interactions are designed that acquire amphiphilicity upon complexation. They become units of self-assembly and hierarchically grow into mesoscopic-scale supermolecules that are dispersed stably in aqueous or in organic media. 

Aksay and coworkers [20] produced mesoscopic patterning of oriented nan-ostructured silica thin films polymerized by a surfactant-templated sol-gel technique [21] in combination with a micromolding technique, which is another microfabrication technique without photolithography proposed by Xia and Whitesides [19]. A network pattern of microcapillaries (submicrometer scale) was transferred to an elastomeric PDMS stamp as a microreplica molding. An aqueous mixture of tetraethoxysilane and a cationic surfactant (CTAC cetyltri-methylammonium chloride) was introduced into the microcapillaries. After hydrolysis of tetraethoxysilane at the cationic interface of the tubular surfactant assemblies, a mesoscopic supramolecular structure hierarchically constituted from hexagonally packed nanoscopic tubules of silica was formed in the microscopic capillary. 

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